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Raspberry ketone (RK) is a high-value bioactive component in the growing demand for natural compounds in food and flavour industries. However, limited production persists due to low-yield microorganisms and complex biosynthetic pathway. Here, an Nidula niveo-tomentosa fungi-based fermentation system was developed to investigate and optimize the cultivation parameters for natural RK production. While optimizing glucose and phenylalanine concentrations ensured sufficient substrate supply, it unexpectedly induced stress on the substrates. Despite having minimal impact on biomass growth, UV-A radiation effectively boosted RK biosynthesis, but also reaching a ceiling with extended exposure times. Younger precultures exhibited higher specific productivity, older cultures ultimately yielded more RK due to their higher inoculum concentration. Mycelial fungi, compared to fungal pellets, outperformed in RK production, likely facilitated by enhanced nutrient uptake and bioproduct transport. Ultimately, the combination of optimized parameters unlocked a peak RK yield of 154.4 mg/L, underscoring the remarkable potential for natural RK production. [Display omitted] • Raspberry ketone (RK) was biosynthezed by fungus of Nidula niveo tomentosa. • Cultication parameters were systematically investigated and optimized. • UV radiation had little effects on fungal biomass but stimulated RK production. • Mycelial fungi enhanced nutrient intake and RK external transportation. • A highest RK yield of 154.4 mg/L was achieved by submerged fungal fermentation. [ABSTRACT FROM AUTHOR]

Raspberry ketone (RK) is an active constituent obtained from Rubus idaeus (Rosaceae), which has been traditionally used against diabetes, hypertension, etc. The objective of this study was to assess the cardioprotective effect of RK against isoproterenol (ISO)-induced cardiac hypertrophy in Wistar rats. Rats were arbitrarily divided into six groups and were treated daily with raspberry ketone (100 and 200 mg/kg), fenofibrate (80 mg/kg) and propranolol (10 mg/kg) along with ISO (3 mg/kg, subcutaneously) for 28 days. Twenty-four hours after the last dose administration, serum and heart tissue samples from the animals were taken and their hemodynamic (blood pressure, heart rate], biochemical (CK-MB, LDH, troponin-T, PPAR-α, apolipoprotein C III, c-reactive protein, total cholesterol, triglycerides, high-density lipoprotein, low-density lipoprotein, very-low-density lipoprotein, malondialdehyde, reduced glutathione, superoxide dismutase, catalase, Na+-K+-ATPase, total antioxidant capacity, and nitric oxide), histopathological, and immunohistochemical (caspase-3, nuclear factor-κB, tumor necrosis factor-α) analysis was performed along with gravimetric analysis. Administration of ISO significantly altered the cardiac integrity and physiology and these changes were significantly averted by the administration of RK (100 and 200 mg/kg). These results were also found to be comparable with those of the standard drugs, fenofibrate and propranolol. The assessment of cardiac morphology by histopathological and immunohistochemical analysis further validated these results. This study thus demonstrated that RK at doses of 100 and 200 mg/kg showed a dose-dependent decrease in inflammation, oxidative stress, and dyslipidemia against ISO-induced cardiac hypertrophy in Wistar rats, which could be due to agonistic action of RK at PPAR-α receptor subtype. [ABSTRACT FROM AUTHOR]

Background: Queensland fruit fly (Qfly) males exhibit accelerated sexual maturation when their diet is supplemented with raspberry ketone (RK) for 48 h following emergence, which is beneficial for sterile insect technique operation. The present study tests whether RK supplementation makes Qfly more vulnerable to starvation or desiccation. Results: Flies were fed for 48 h with a yeast hydrolysate and sugar diet (1:3) that contained 0% RK (control), 1.25% RK (low dose) or 5% RK (high dose) to test subsequent vulnerability to starvation and desiccation. RK feeding decreased body weight and water content in males and increased lipid levels in both sexes before exposure to any stress treatment. Under nutritional stress, flies fed the low RK dose, but not the high RK dose, had higher survival than controls. Under desiccation stress, flies fed both the low and high RK doses had lower survival than the controls. Body weight, water content and lipid reserves at death were all affected by RK dose when under nutritional stress, but not when under desiccation stress. In the absence of stress, body weight at death was higher than controls in flies provided with the high RK dose and lipids were lower than controls in flies provided with the low RK dose. Conclusion: Feeding with RK makes Qflies more vulnerable to desiccation but not starvation. In most conditions, it is expected that the disadvantage of increased desiccation vulnerability would be outweighed by the benefits of accelerated sexual maturation in RK‐fed young adult Qflies. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Gentamicin (GEN), a widely used antibiotic, is known to induce nephrotoxicity. Raspberry ketone (RK), a natural compound found in red raspberries has demonstrated potential protective effects against various pathological conditions. This study aimed to evaluate the protective effect of raspberry ketone in gentamicin-induced nephrotoxicity in Wistar rats. Twentyfour Wistar rats were randomly divided into four groups: normal control group; rats received 0.5ml normal saline for 14 days i.p., diseased control group(GEN); rats received GEN (100 mg/kg,i.p.) for 7 consecutive days. GEN+ RK1: rats received GEN (100 mg/kg/) i.p. for 7 consecutive days + raspberry ketone (RK) (100 mg/kg/day) p.o. for 14 days. GEN+ RK2: rats received gentamicin (100 mg/kg/) i.p. for 7 consecutive days + RK (200 mg/kg/day) p.o. for 14 days At the end of the treatment period urine samples were collected from metabolic cages, animal were anaesthetized and blood and kidney tissue samples were collected for biochemical and histopathological evaluations. The gentamicin treated group showed significant increased in oxidative stress manifested by decrease in GSH, SOD, CAT and increased in TBARS level. Further, increased in serum creatinine, albumin and blood urea nitrogen levels compared to the control group, indicating renal dysfunction. However, the administration of raspberry ketone in gentamicin treated mice significantly lowers the levels of these markers compared to the disease control group, suggesting a protective effect of raspberry ketone against gentamicin-induced nephrotoxicity. The histopathological analysis also revealed severe tubular necrosis and interstitial inflammation in the gentamicin treated group, whereas the raspberry ketone treated groups showed reversal in these changes. In conclusion, raspberry ketone supplementation attenuated renal dysfunction by modulating oxidative stress parameters, creatinine, albumin and blood urea nitrogen levels and reduced histopathological changes associated with gentamicin toxicity. [ABSTRACT FROM AUTHOR]

Reductive amination is a powerful tool in sustainable organic synthesis that allows chemists to access a wide range of valuable amine products using renewable feedstocks and mild reaction conditions, with minimal waste generation. Practical applications can be found in various fields, including pharmaceuticals, contributing to greener and more sustainable chemical processes. In this work, we present a heterogeneous (Rh and Pt) catalyzed protocol for the fast and efficient synthesis of ractopamine hydrochloride (β-adrenergic drug) under microwave-assisted reductive amination protocol starting from raspberry ketone and octopamine. Microwave (MW) successfully accelerated the hydrogenation reaction and reduced the reaction time from 13 h to only 3 h under mild conditions (50 °C at 10 bar). The best catalysts were Pt/C and Rh/C, which led to high conversion and selectivity towards ractopamine:HCl. Different solvents and ketone substrates were also experimented. Acetophenone, cyclohexanone, and 2-butanone reacted at lower H2 pressure (5 bar), and highest selectivity was observed with cyclohexanone (99%). These preliminary experiments may be useful for further process improvements in the synthesis of β-adrenergic agonists and related structures and underline the positive synergy between MW and heterogeneous catalysis. [ABSTRACT FROM AUTHOR]

Objectives: To investigate the therapeutic role of calorie-restricted diet (CR) and raspberry ketone (RK) in non-alcoholic fatty liver disease (NAFLD) and the implication of sphingosine kinase-1 (SphK1)/sphingosine-1-phosphate (S1P) and toll-like receptor 4 (TLR4) signalling. Methods: NAFLD was induced by feeding rats high-fat-fructose-diet (HFFD) for 6 weeks. Rats were then randomly assigned to three groups (n = 6 each); NAFLD group continued on HFFD for another 8 weeks. CR group was switched to CR diet (25% calorie restriction) for 8 weeks and RK group was switched to normal diet and received RK (55 mg/kg/day; orally) for 8 weeks. Another six rats were used as normal control. Key findings: HFFD induced a state of NAFLD indicated by increased fat deposition in liver tissue along with dyslipidemia, elevated liver enzymes, oxidative stress and inflammation. Either CR diet or RK reversed these changes and decreased HFFD-induced elevation of hepatic SphK1, S1P, S1PR1 and TLR4. Of notice, RK along with a normal calorie diet was even better than CR alone in most studied parameters. Conclusions: SphK1/S1P and TLR4 are interconnected and related to the establishment of HFFD-induced NAFLD and can be modulated by RK. Supplementation of RK without calorie restriction to patients with NAFLD unable to follow CR diet to achieve their treatment goals would be a promising therapeutic modality. [ABSTRACT FROM AUTHOR]

In this article, we designed one-step economic eco-harmonious microwave-assisted procedure to prepare nitrogen-doped carbon dots. We selected egg white as a cheap glycoprotein-based carbon source without the assistance of any chemicals. The synthetic process requires only 3 min during which carbonization and nitrogen doping are realized at the same time. The fabricated carbon dots were characterized for particle size, structure and photoluminescence behaviour. The nanodots were amorphous carbon-rich naturally nitrogen-doped particles with plentiful attached hydrophilic functional groups. They had average particle size 2.98 ± 1.57 nm, emitted strong blue fluorescence and showed excitation-dependant emission behaviour. What is more, the practical use of this system for raspberry ketone determination in commercially available weight loss dietary supplement product is demonstrated successfully. In ethylene glycol medium, the addition of raspberry ketone enhances the emission intensity of the synthesized carbon dots. The effect of reaction time and solvent was investigated. After optimization, the intensity enhancement was linear to the amount of raspberry ketone added to the assay solution in the concentration range of 100–1000 ng/ml, with detection and quantitation limits of 15.10 and 45.45 ng/ml, respectively. The method was validated in accordance to International Conference on Harmonization (ICH) guidelines and further applied to raspberry ketone capsules showing excellent results. [ABSTRACT FROM AUTHOR]

Raspberry ketone (RK) has high commercial value in the food and healthcare industries. A biological route to this flavour compound is an attractive prospect, considering the need to meet consumer demands and sustainable goals; however, it is yet to become an industrial reality. In this work, fungal production of raspberry ketone (RK) and raspberry compounds (RC) via submerged fermentation of Nidula niveo-tomentosa was characterized in flask, stirred-tank reactor (STR), panel bioreactor (PBR), and fluidized bed reactor (FBR) configurations. The results indicate that the panel bioreactor resulted in larger, floccose pellets accompanied by maximum titres of 20.6 mg/L RK and 50.9 mg/L RC. The stirred-tank bioreactor with impeller mixing yielded compact elliptical pellets, induced the highest volumetric productivity of 2.0 mg L−1 day−1, and showed RK selectivity of 0.45. While differing mixing strategies had clear effects on pellet morphology, RK production presented a more direct positive relationship with cultivation conditions, and showed appropriate mixing and aeration favour RK to raspberry alcohol (RA). Overall, this paper highlights the importance of bioreactor design to fungal fermentation, and gives insight into green and industrial bioproduction of value-added natural compounds. [ABSTRACT FROM AUTHOR]

Raspberry Ketone (RK) and Resveratrol (RSV) are natural phenolic antioxidants and anti‐inflammatory agents. However, its combined pharmacokinetic and pharmacodynamics potentials are not reported. The study aims to assess the combined effect of RK with RSV to protect rats from carbon‐tetrachloride (CCl4) induced oxidative stress and NASH. The toxicant CCl4 was employed at a concentration of 1 mL/kg as a 1:1 (v/v) mixture with olive oil twice weekly for 6 weeks to induce liver toxicity. Animal treatment was followed for 2 weeks. Silymarin was used as a standard control drug to compare the hepatoprotective effect of RK and RSV. Hepatic histology, oxidative stress, MMP, reduced glutathione (GSH), plasma levels of SGOT, SGPT, and lipid profile (total cholesterol and triglycerides) were measured. Anti‐inflammation genes (IL‐10), and fibrotic genes (TGF‐β) were also examined in liver tissue. Oral administration of combined RK with RSV (50 + 50 mg/kg for 2 weeks) showed significantly more hepatoprotection by significantly decreasing elevated plasma markers and lipid profile than alone RK and RSV (100 mg/kg daily for 2 weeks). It also significantly alleviated the hepatic lipid peroxidation, restoring the activities of GSH levels in the liver. RT‐PCR and Immunoblotting studies confirmed that significantly upregulation of anti‐inflammation genes and protein expression (MMP‐9) ameliorated the disease. Pharmacokinetic studies confirmed more synergistic stability in simulated gastric‐intestinal fluids (FaSSGF, FaSSIF) and rat liver microsomes (CYP‐450, NADPH oxidation & glucuronidation. Moreover, coadministration of drugs augmented the relative bioavailability, Vd/F (L/Kg), and MRT0‐∞(h), which leads to more efficacy. This pharmacokinetic and pharmacodynamic reveals a new adjuvant therapy for the treatment of steatohepatitis. [ABSTRACT FROM AUTHOR]

Salmonella enterica is an important foodborne pathogen that causes gastroenteritis and systemic infection in humans and livestock. Salmonella biofilms consist of two major components—amyloid curli and cellulose—which contribute to the prolonged persistence of Salmonella inside the host. Effective agents for inhibiting the formation of biofilms are urgently needed. We investigated the antibiofilm effect of Raspberry Ketone (RK) and its mechanism of action against Salmonella Typhimurium 14028 using the Congo red agar method, Calcofluor staining, crystal violet method, pellicle assay, and the TMT-labeled quantitative proteomic approach. RK suppressed the formation of different types of Salmonella biofilms, including pellicle formation, even at low concentrations (200 µg/mL). Furthermore, at higher concentrations (2 mg/mL), RK exhibited bacteriostatic effects. RK repressed cellulose deposition in Salmonella biofilm through an unknown mechanism. Swimming and swarming motility analyses demonstrated reduced motility in RK-treated S. typhimurium. Proteomics analysis revealed that pathways involved in amyloid curli production, bacterial invasion, flagellar motility, arginine biosynthesis, and carbohydrate metabolism, were targeted by RK to facilitate biofilm inhibition. Consistent with the proteomics data, the expressions of csgB and csgD genes were strongly down-regulated in RK-treated S. typhimurium. These findings clearly demonstrated the Salmonella biofilm inhibition capability of RK, justifying its further study for its efficacy assessment in clinical and industrial settings. [ABSTRACT FROM AUTHOR]

Mitochondrial dysfunction and oxidative stress play essential roles in the pathogenesis of diabetic nephropathy (DN). The respiratory oxygen consumption and oxidative stress status of kidney mitochondria are closely associated with the development of DN. In this study, raspberry ketone (RK), the predominant bioactive component extracted from raspberry, was applied to treat the established DN mice model. This study investigated whether RK protects the kidneys of high-fat and high-sugar/streptozotocin (STZ)-induced diabetic rats by inhibiting oxidative stress and ameliorating mitochondrial dysfunction. Besides, the DN mice models were established by injecting high-fat and high-sugar/STZ (130 mg/kg, intraperitoneal injection). The animals were randomly divided into the control group (normal saline, ig), DN group (normal saline, ig), DN + RK group (200 mg/kg RK + normal saline, ig), DN + RK group (400 mg/kg RK + normal saline, ig), and DN + Metformin (Met) (200 mg/kg Met + normal saline, ig). Regular monitoring of fasting blood glucose (FBG) levels was observed in mice. After 10 weeks of drug treatment, the kidneys of mice in each group were analyzed using ultrasound, and the mice were euthanized humanely. Kidney weight (KW)/body weight (BW) and kidney injury, mitochondrial function, and oxidative stress indicators were determined. The histopathological changes in renal tissue were observed after hematoxylin and eosin (H&E) staining. The results recommended that RK has a renoprotective function on DN mice by improving mitochondrial dysfunction and inhibiting oxidative stress. [ABSTRACT FROM AUTHOR]

Obesity is a global health problem and a risk factor for cardiovascular diseases and cancers. Exercise is an effective intervention to combat obesity. Fibronectin type III domain containing protein 5 (FNDC5)/irisin, a myokine, can stimulate the browning of white adipose tissue by increasing uncoupling protein 1 (UCP1) expression, and therefore may represent a link between the beneficial effects of exercise and improvement in metabolic diseases. Thus, upregulating the endogenous expression of FNDC5/irisin by administering medication would be a good approach for treating obesity. Herein, we evaluated the efficacy of raspberry ketone (RK) in inducing FNDC5/irisin expression and the underlying mechanisms. The expression of brown fat-specific proteins (PR domain containing 16 (PRDM16), CD137, and UCP1), heme oxygenase-1 (HO-1), FNDC5, and peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α) in differentiated 3T3-L1 adipocyte was analyzed by western blotting or immunofluorescence. The level of irisin in the culture medium was also assayed using an enzyme-linked immunosorbent assay kit. Results showed that RK (50 μM) significantly induced the upregulation of FNDC5 protein in differentiated 3T3-L1 adipocytes; however, the irisin level in the culture media was unaffected. Moreover, RK significantly increased the levels of PGC1α, brown adipocyte markers (PRDM16, CD137, and UCP1), and HO-1. Furthermore, the upregulation of PGC1α and FNDC5 and the browning effect induced by RK were significantly reduced by SnPP or FNDC5 siRNA, respectively. In conclusion, RK can induce FNDC5 protein expression via the HO-1 signaling pathway, and this study provides new evidence for the potential use of RK in the treatment of obesity.

Raspberry ketone (RK) has high commercial value in the food and healthcare industries. A biological route to this flavour compound is an attractive prospect, considering the need to meet consumer demands and sustainable goals; however, it is yet to become an industrial reality. In this work, fungal production of raspberry ketone (RK) and raspberry compounds (RC) via submerged fermentation of Nidula niveo-tomentosa was characterized in flask, stirred-tank reactor (STR), panel bioreactor (PBR), and fluidized bed reactor (FBR) configurations. The results indicate that the panel bioreactor resulted in larger, floccose pellets accompanied by maximum titres of 20.6 mg/L RK and 50.9 mg/L RC. The stirred-tank bioreactor with impeller mixing yielded compact elliptical pellets, induced the highest volumetric productivity of 2.0 mg L−1 day−1, and showed RK selectivity of 0.45. While differing mixing strategies had clear effects on pellet morphology, RK production presented a more direct positive relationship with cultivation conditions, and showed appropriate mixing and aeration favour RK to raspberry alcohol (RA). Overall, this paper highlights the importance of bioreactor design to fungal fermentation, and gives insight into green and industrial bioproduction of value-added natural compounds.

We reported that raspberry ketone (RK) is produced from rhododendrol (RD) in excised mouse skin. We confirmed that RK is also produced from RD in human skin homogenates. We also observed more conversion of RD to RK when the oxidized form of nicotinamide adenine dinucleotide (NAD+), a coenzyme of alcohol dehydrogenase (ADH), was added to human skin homogenates. Chiral column analysis of the consumption of RD enantiomers in human skin homogenates also showed that more of the R enantiomers of RD remained than the S enantiomers of RD. This suggests that the S-enantiomer of RD is more easily oxidized in human skin. We confirmed that RD is partially metabolized to RK in human skin, thus suggesting that ADH in the skin may be the main cause of the appearance of this oxidation product. [ABSTRACT FROM AUTHOR]

Abstract Background A key focus of synthetic biology is to develop microbial or cell-free based biobased routes to value-added chemicals such as fragrances. Originally, we developed the EcoFlex system, a Golden Gate toolkit, to study genes/pathways flexibly using Escherichia coli heterologous expression. In this current work, we sought to use EcoFlex to optimise a synthetic raspberry ketone biosynthetic pathway. Raspberry ketone is a high-value (~ £20,000 kg−1) fine chemical farmed from raspberry (Rubeus rubrum) fruit. Results By applying a synthetic biology led design-build-test-learn cycle approach, we refactor the raspberry ketone pathway from a low level of productivity (0.2 mg/L), to achieve a 65-fold (12.9 mg/L) improvement in production. We perform this optimisation at the prototype level (using microtiter plate cultures) with E. coli DH10β, as a routine cloning host. The use of E. coli DH10β facilitates the Golden Gate cloning process for the screening of combinatorial libraries. In addition, we also newly establish a novel colour-based phenotypic screen to identify productive clones quickly from solid/liquid culture. Conclusions Our findings provide a stable raspberry ketone pathway that relies upon a natural feedstock (L-tyrosine) and uses only constitutive promoters to control gene expression. In conclusion we demonstrate the capability of EcoFlex for fine-tuning a model fine chemical pathway and provide a range of newly characterised promoter tools gene expression in E. coli.

Abstract Background Phenylpropanoid including raspberry ketone, is a kind of important natural plant product and widely used in pharmaceuticals, chemicals, cosmetics, and healthcare products. Bioproduction of phenylpropanoid in Escherichia coli and other microbial cell factories is an attractive approach considering the low phenylpropanoid contents in plants. However, it is usually difficult to produce high titer phenylpropanoid production when fermentation using glucose as carbon source. Developing novel bioprocess using alternative sources might provide a solution to this problem. In this study, typical phenylpropanoid raspberry ketone was used as the target product to develop a biosynthesis pathway for phenylpropanoid production from fatty acids, a promising alternative low-cost feedstock. Results A raspberry ketone biosynthesis module was developed and optimized by introducing 4-coumarate-CoA ligase (4CL), benzalacetone synthase (BAS), and raspberry ketone reductase (RZS) in Escherichia coli strains CR1–CR4. Then strain CR5 was developed by introducing raspberry ketone biosynthesis module into a fatty acids-utilization chassis FA09 to achieve production of raspberry ketone from fatty acids feedstock. However, the production of raspberry ketone was still limited by the low biomass and unable to substantiate whole-cell bioconversion process. Thus, a process by coordinately using fatty-acids and glycerol was developed. In addition, we systematically screened and optimized fatty acids-response promoters. The optimized promoter Pfrd3 was then successfully used for the efficient expression of key enzymes of raspberry ketone biosynthesis module during bioconversion from fatty acids. The final engineered strain CR8 could efficiently produce raspberry ketone repeatedly using bioconversion from fatty acids feedstock strategy, and was able to produce raspberry ketone to a concentration of 180.94 mg/L from soybean oil in a 1-L fermentation process. Conclusion Metabolically engineered Escherichia coli strains were successfully developed for raspberry ketone production from fatty acids using several strategies, including optimization of bioconversion process and fine-tuning key enzyme expression. This study provides an essential reference to establish the low-cost biological manufacture of phenylpropanoids compounds.

The current investigation was accomplished to evaluate the hepatoprotective effect of White tea and Raspberry Ketone against toxicity induced by acrylamide in rats. Sixty adult male rats were divided randomly into group (I) control; group (II) rats received RK with dose (6 mg/kg/day); Group III: rats received 5 ml of WT extract/kg/day; Group IV rats received AA (5 mg/kg/day); Group V: rats administrated with both AA (5 mg/kg/day) and RK (6 mg/kg/day) and Group VI: rats administrated AA (5 mg/kg/day) and 5 ml of WT extract/kg/day. The biochemical assays exhibited a significant increase in serum levels of Adiponectin, AST, ALT, ALP of the group treated with acrylamide if compared to the control group and an improvement in their levels of groups V and VI. The histopathological and immunohistochemical findings confirm the biochemical observations. In conclusion, the present investigation proved that the supplementation of WT and RK enhanced the liver histology, immunohistochemistry and biochemistry against the oxidative stress induced by acrylamide. [ABSTRACT FROM AUTHOR]

The demand for raspberry ketone (RK) as a plant-based natural flavoring agent is high, but natural RK is one of the most expensive flavor compounds due to its limited content in plants. Here, we produced RK de novo from simple carbon sources in Escherichia coli. We genetically engineered E. coli metabolism to overproduce the metabolic precursors tyrosine and p-coumaric acid and increase RK production. The engineered E. coli produced 19.3- and 1.9 g/L of tyrosine and p-coumaric acid from glucose, respectively. The p-coumaric acid CoA ligase from Agrobacterium tumefaciens and amino acid substituted benzalacetone synthase of Rhemu palmatum (Chinese rhubarb) were overexpressed in E. coli overproducing p-coumaric acid. The overexpression of fabF, encoding β-ketoacyl-acyl carrier protein synthetase II increased intracellular malonyl-CoA, the precursor of benzalacetone synthase for RK biosynthesis, and improved RK production. Fed-batch cultures given glucose as a carbon source produced 62 mg/L of RK under optimized conditions. Our production system is inexpensive and does not rely on plant extraction; thus, it should significantly contribute to the flavor and fragrance industries.

Novel food and food compounds interventions have attracted a lot of attention nowadays for the prevention and treatment of metabolic diseases. Raspberry ketone (RK) is aromatic compound found within red fruits and berries, has been used as an over‐the‐counter product for weight loss. However, actually, the effect of RK on weight loss is still controversial, and the mechanism is largely unknown. Besides, in vivo and in vitro studies have demonstrated the beneficial effect of RK on the development of other metabolic diseases. In this review, we comprehensively highlighted the synthesis, bioavailability, and metabolism of RK, and summarized the progress made in our understanding of the potential biological activities of RK, including antiobesity, antidiabetes, cardioprotection, and hepatoprotection, as well as their underlying mechanisms. This paper provides a critical overview about the current findings and proposes the future studies in the area of RK on human health. Practical applications: Raspberry ketone (RK) has been used for weight control for years, but this effect is controversial considering food intake. Additionally, RK is beneficial for T2DM, liver and heart injury. The underlying mechanisms of the protective effect of RK including accelerating fatty acid oxidation, balancing serum glucose level, anti‐inflammation, antioxidant process, and so on. In this context, we provide a comprehensive analysis of the benefits of RK against many metabolic diseases and discuss the underlying molecular mechanisms. We hope our work will be helpful for further researches on RK and improve its public recognition. [ABSTRACT FROM AUTHOR]

Recent advances in the synthesis and applications of raspberry ketone are reviewed in this paper. Different routes to this material including chemical and biotechnological synthetic methods and extraction from natural sources are compared, and the applications of the ketone in flavour and fragrance, pharmaceuticals and in food and tobacco processing are discussed. Synthesis from petrochemical raw materials has the advantages of ready availability of ingredients and well‐understood synthetic steps, but direct synthesis from petrochemicals will eventually be replaced because of low yields and hazardous results to environment. The ketone can be made from natural raw materials, and the methods are promising if their disadvantages such as limited availability and complex, multi‐step reactions and harsh reaction conditions can be overcome. Biotechnological preparation methods have the advantages of reaction specificity, mild reaction conditions, but are limited in applicability because of complications associated with their synthetic and purification procedures at present. With the development of biotechnology, biotechnological preparation methods of the ketone may be the most important route in the future. Direct extraction of the ketone from natural raw materials is possible, but the cost is very high. From the view of syntheses and applications, the research perspectives of raspberry ketone are outlined in the end of this paper, which are the development of green and effective synthetic methods for raspberry ketone from natural raw materials and the preparation and application of raspberry ketone by biotechnological preparation methods. [ABSTRACT FROM AUTHOR]

Abstract Background The phenylbutanoid 4-(4-hydroxyphenyl)butan-2-one, commonly known as raspberry ketone, is responsible for the typical scent and flavor of ripe raspberries. Chemical production of nature-identical raspberry ketone is well established as this compound is frequently used to flavor food, beverages and perfumes. However, high demand for natural raspberry ketone, but low natural abundance in raspberries, render raspberry ketone one of the most expensive natural flavoring components. Results In this study, Corynebacterium glutamicum was engineered for the microbial synthesis of the character impact compound raspberry ketone from supplemented p-coumaric acid. In this context, the NADPH-dependent curcumin/dihydrocurcumin reductase CurA from Escherichia coli was employed to catalyze the final step of raspberry ketone synthesis as it provides a hitherto unknown benzalacetone reductase activity. In combination with a 4-coumarate: CoA ligase from parsley (Petroselinum crispum) and a monofunctional benzalacetone synthase from Chinese rhubarb (Rheum palmatum), CurA constitutes the synthetic pathway for raspberry ketone synthesis in C. glutamicum. The resulting strain accumulated up to 99.8 mg/L (0.61 mM) raspberry ketone. In addition, supplementation of other phenylpropanoids allowed for the synthesis of two other naturally-occurring and flavoring phenylbutanoids, zingerone (70 mg/L, 0.36 mM) and benzylacetone (10.5 mg/L, 0.07 mM). Conclusion The aromatic product portfolio of C. glutamicum was extended towards the synthesis of the flavoring phenylbutanoids raspberry ketone, zingerone and benzylacetone. Key to success was the identification of CurA from E. coli having a benzalacetone reductase activity. We believe, that the constructed C. glutamicum strain represents a versatile platform for the production of natural flavoring phenylbutanoids at larger scale.

Objective: To investigate the molecular mechanisms of the anti-obese effect of raspberry ketone against high-fat diet fed rats. Methods: Fifty adult male rats were randomly assigned to receive a standard diet, a high fat diet, and the high-fat diet and 0.5%, 1% or 2% raspberry ketone. Body weight, biochemical parameters and gene expression of CCAAT enhancer-binding protein (C/EBP)δ, fatty acid synthase (FAS), acetyl CoA carboxylase (ACC), peroxisome proliferator-activated receptor alpha (PPAR-α), hormone-sensitive lipase (HSL) and hepatic carnitine palmitoyltransferase 1 A (CPT1A) were investigated. Results: Body weight, blood glucose, insulin, total lipids, triacylglycerols, total cholesterol and low-density lipoprotein cholesterol were increased in high-fat diet fed rats. These high fat diet-induced changes were attenuated by treatment with raspberry ketone. High-density lipoprotein cholesterol was decreased in highfat diet fed rats but increased in rats treated with raspberry ketone. Molecular investigations showed induction of gene expression of C/EBP-δ, FAS, ACC, CPT1A and inhibition of gene expression of PPAR-α and HSL in high-fat diet fed rats as compared with control. Raspberry ketone treament reversed these changes except CPT1A. Conclusions: Raspberry ketone can prevent obesity induced by a high-fat diet in rats by induction of the expression of enzymes, controlling lipolysis and fatty acids β oxidation as well as inhibition of gene expressions of adipogenic factors.

Salmonella enterica is an important foodborne pathogen that causes gastroenteritis and systemic infection in humans and livestock. Salmonella biofilms consist of two major components—amyloid curli and cellulose—which contribute to the prolonged persistence of Salmonella inside the host. Effective agents for inhibiting the formation of biofilms are urgently needed. We investigated the antibiofilm effect of Raspberry Ketone (RK) and its mechanism of action against Salmonella Typhimurium 14028 using the Congo red agar method, Calcofluor staining, crystal violet method, pellicle assay, and the TMT-labeled quantitative proteomic approach. RK suppressed the formation of different types of Salmonella biofilms, including pellicle formation, even at low concentrations (200 µg/mL). Furthermore, at higher concentrations (2 mg/mL), RK exhibited bacteriostatic effects. RK repressed cellulose deposition in Salmonella biofilm through an unknown mechanism. Swimming and swarming motility analyses demonstrated reduced motility in RK-treated S. typhimurium. Proteomics analysis revealed that pathways involved in amyloid curli production, bacterial invasion, flagellar motility, arginine biosynthesis, and carbohydrate metabolism, were targeted by RK to facilitate biofilm inhibition. Consistent with the proteomics data, the expressions of csgB and csgD genes were strongly down-regulated in RK-treated S. typhimurium. These findings clearly demonstrated the Salmonella biofilm inhibition capability of RK, justifying its further study for its efficacy assessment in clinical and industrial settings.

Raspberry ketone is one of the characteristic flavors of raspberry fruits, and it is an important and expensive ingredient in the flavor and fragrance industries. It is present at low levels in plant tissues, and its occurrence is limited to a few taxa. In this context, the stable production of nature-identical raspberry ketone using heterologous synthesis in plants hosts has recently garnered the attention of plant biochemists. In this study, we demonstrate the rational switching of the metabolic flow from anthocyanin pigments to volatile phenylbutanoid production via the phenylpropanoid pathway. This shift led to the efficient and stable production of raspberry ketone and its glycosides via heterologous expression of the biosynthetic enzymes benzalacetone synthase (BAS) and raspberry ketone/zingerone synthase 1 (RZS1) in the transgenic tobacco (Nicotiana tabacum ‘Petit Havana SR-1’). Additionally, we achieved improved product titers by activating the phenylpropanoid pathway with the transcriptional factor, production of anthocyanin pigment 1 (PAP1), from Arabidopsis thaliana. We further demonstrated another metabolic-flow switching by RNA interference (RNAi)-mediated silencing of chalcone synthase (CHS) to increase pathway-intermediate p-coumaroyl-CoA in transgenic tobacco for raspberry-ketone production. The redirection of metabolic flux resulted in transgenic lines producing 0.45 μg/g of raspberry ketone and 4.5 μg/g, on the fresh weight basis, of its glycosides in the flowers. These results suggest that the intracellular enforcement of endogenous substrate supply is an important factor while engineering the phenylpropanoid pathway. This strategy might be useful for the production of other phenylpropanoids/polyketides that are produced via the pathway-intermediate p-coumaroyl-CoA, in tobacco plants.

Hepatic fibrosis is a compensatory response to chronic liver injury and inflammation, and dietary intervention is recommended as one of the fundamental prevention strategies. Raspberry ketone (RK) is an aromatic compound first isolated from raspberry and widely used to prepare food flavors. The current study investigated the hepatoprotection and potential mechanism of RK against hepatic fibrosis. In vitro , hepatic stellate cell (HSC) activation was stimulated with TGF-β and cultured with RK, farnesoid X receptor (FXR), or peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) agonist or inhibitor, respectively. In vivo , C57BL/6 mice were injected intraperitoneally with thioacetamide (TAA) at 100/200 mg/kg from the first to the fifth week. Mice were intragastrically administrated with RK or Cur once a day from the second to the fifth week. In activated HSCs, RK inhibited extracellular matrix (ECM) accumulation, inflammation, and epithelial-mesenchymal transition (EMT) process. RK both activated FXR/PGC-1α and regulated their crosstalk, which were verified by their inhibitors and agonists. Deficiency of FXR or PGC-1α also attenuated the effect of RK on the reverse of activated HSCs. RK also decreased serum ALT/AST levels, liver histopathological change, ECM accumulation, inflammation, and EMT in mice caused by TAA. Double activation of FXR/PGC-1α might be the key targets for RK against hepatic fibrosis. Above all, these discoveries supported the potential of RK as a novel candidate for the dietary intervention of hepatic fibrosis.

Scope: Depression, a prevalent mental disorder, has significantly impacted the lives of 350 million people, yet it holds promise for amelioration through food-derived phenolics. Raspberries, renowned globally for their delectable flavor, harbor a phenolic compound known as raspberry ketone (RK). However, the impact of RK on depressive symptoms remains ambiguous. This study aims to investigate the impact of RK on lipopolysaccharide (LPS)-induced depressed mice and elucidates its potential mechanisms, focusing on the gut-brain axis., Methods and Results: Through behavioral tests, RK exerts a notable preventive effect on LPS-induced depression-like behaviors in mice. RK proves capable of attenuating gut inflammation, repairing gut barrier impairment, modulating the composition of the gut microbiome (Muribaculaceae, Streptococcus, Lachnospiraceae, and Akkermansia), and promoting the production of short-chain fatty acids. Furthermore, RK alleviates neuroinflammation by suppressing the TLR-4/NF-κB pathway and bolsters synaptic function by elevating levels of neurotrophic factors and synapse-associated proteins., Conclusion: The current study provides compelling evidence that RK effectively inhibits the TLR-4/NF-κB pathway via the gut-brain axis, leading to the improvement of LPS-induced depression-like behaviors in mice. This study addresses the research gap in understanding the antidepressant effects of RK and illuminates the potential of utilizing RK as a functional food for preventing depression., (© 2024 Wiley‐VCH GmbH.)

Background: A key focus of synthetic biology is to develop microbial or cell-free based biobased routes to value-added chemicals such as fragrances. Originally, we developed the EcoFlex system, a Golden Gate toolkit, to study genes/pathways flexibly using Escherichia coli heterologous expression. In this current work, we sought to use EcoFlex to optimise a synthetic raspberry ketone biosynthetic pathway. Raspberry ketone is a high-value (~ £20,000 kg−1) fine chemical farmed from raspberry (Rubeus rubrum) fruit. Results: By applying a synthetic biology led design-build-test-learn cycle approach, we refactor the raspberry ketone pathway from a low level of productivity (0.2 mg/L), to achieve a 65-fold (12.9 mg/L) improvement in production. We perform this optimisation at the prototype level (using microtiter plate cultures) with E. coli DH10β, as a routine cloning host. The use of E. coli DH10β facilitates the Golden Gate cloning process for the screening of combinatorial libraries. In addition, we also newly establish a novel colour-based phenotypic screen to identify productive clones quickly from solid/liquid culture. Conclusions: Our findings provide a stable raspberry ketone pathway that relies upon a natural feedstock (L-tyrosine) and uses only constitutive promoters to control gene expression. In conclusion we demonstrate the capability of EcoFlex for fine-tuning a model fine chemical pathway and provide a range of newly characterised promoter tools gene expression in E. coli. [ABSTRACT FROM AUTHOR]

Morphological and floral chemical components are both important cues used by plants to attract pollinators. Two local ecotypes named 'Nabawan' and 'Apin-Apin' produced by the tropical orchid, Bulbophyllum ecornutum subspecies verrucatum, exhibit different morphology and scents to attract males of certain Bactrocera and Zeugodacus fruit fly species in the tribe Dacini as potential pollinators. Flowers of the Nabawan-ecotype possess a narrow-shaped lip (= labellum) structure and emit a characteristic fragrance of raspberry ketone along with smaller amounts of rhododendrol, whereas those of Apin-Apin-ecotype possess a broad-shaped lip and emit zingerone and zingerol as major components. Nevertheless, the structure of stiff hamulus appears similar and acts as a 'crowbar' during pollinarium removal by a fruit fly, indicating the basic mechanics of the movable see-saw lip structure to trap a fly is essentially the same. The changes in both morphology and chemistry, despite no significant difference in chloroplast DNA sequences, shown by the two ecotypes, might have occurred as part of a coevolutionary process involving both the Dacini fruit fly pollinators and the Bulbophyllum orchids in their natural habitats. [ABSTRACT FROM AUTHOR]

Raspberry ketone is a widely used flavor compound in food and cosmetic industry. Several processes for its biocatalytic production have already been described, but either with the use of genetically modified organisms (GMOs) or incomplete conversion of the variety of precursors that are available in nature. Such natural precursors are rhododendrol glycosides with different proportions of (R)- and (S)-rhododendrol depending on the origin. After hydrolysis of these rhododendrol glycosides, the formed rhododendrol enantiomers have to be oxidized to obtain the final product raspberry ketone. To be able to achieve a high conversion with different starting material, we assembled an alcohol dehydrogenase toolbox that can be accessed depending on the optical purity of the intermediate rhododendrol. This is demonstrated by converting racemic rhododendrol using a combination of (R)- and (S)-selective alcohol dehydrogenases together with a universal cofactor recycling system. Furthermore, we conducted a biocatalytic cascade reaction starting from naturally derived rhododendrol glycosides by the use of a glucosidase and an alcohol dehydrogenase to produce raspberry ketone in high yield. Key points: • LB-ADH, LK-ADH and LS-ADH oxidize (R)-rhododendrol • RR-ADH and ADH1E oxidize (S)-rhododendrol • Raspberry ketone production via glucosidase and alcohol dehydrogenases from a toolbox [ABSTRACT FROM AUTHOR]

Aim: Obesity is a continually growing pandemic leading to many diseases that affect the overall quality of life. The widely marketed Garcinia cambogia (GC) and Raspberry ketone (RK) were used in this study. Despite their known dietetic effect, however, the metabolomic/signaling pathways involved in this effect are not fully elucidated. Hence, our study comprehends the possible trajectories of their combination against obesity and insulin resistance in addition to exploring their combination merit. Materials and methods: Adult male Wistar rats were divided into 5 groups; viz., normal diet (ND), high fat fructose diet (HFFD), HFFD+GC (600mg/kg), HFFD+RK (55mg/kg) and HFFD+GC+RK. To assess our aim, we determined their effect on body weight, IPGTT, glucose homeostasis (glucose, insulin, HOMA IR), lipid profile parameters and SREBP-1c, oxidative stress markers, insulin and leptin signaling pathways (p-IRS-1/p-AKT/GLUT-4, and leptin/STAT-3), as well as liver and adipose tissue histopathology. Results: GC/RK combinationcaused weight loss, corrected the disturbed glucose and insulin homeostasis, raised serum levels of HDL anddecreased all other lipid profile parameters. They also increased Nrf-2 expression, ad GSH, as well as p-IRS-1/p-Akt/GLUT-4 cue, while they decreased MDA, leptin/STAT-3 and SREBP-1c content compared to the HFFD group. Furthermore, the GC/RK combination abolished apoptosis, fatty changes and inflammation in hepatocytes and decreased sclerotic blood vessels and congestion in adipose tissue. Conclusion: Our study highlights the involvement ofp-IRS-1/p-Akt/GLUT-4, leptin/STAT-3 and SREBP-1c signaling trajectories in the beneficial combination of GC and RK, besides, the efficient rebalance of the redox status, insulin resistance and tissue fat deposition confirmed histopathologically.

We reported that raspberry ketone (RK) is produced from rhododendrol (RD) in excised mouse skin. We confirmed that RK is also produced from RD in human skin homogenates. We also observed more conversion of RD to RK when the oxidized form of nicotinamide adenine dinucleotide (NAD+), a coenzyme of alcohol dehydrogenase (ADH), was added to human skin homogenates. Chiral column analysis of the consumption of RD enantiomers in human skin homogenates also showed that more of the R enantiomers of RD remained than the S enantiomers of RD. This suggests that the S-enantiomer of RD is more easily oxidized in human skin. We confirmed that RD is partially metabolized to RK in human skin, thus suggesting that ADH in the skin may be the main cause of the appearance of this oxidation product.

Background: Phenylpropanoid including raspberry ketone, is a kind of important natural plant product and widely used in pharmaceuticals, chemicals, cosmetics, and healthcare products. Bioproduction of phenylpropanoid in Escherichia coli and other microbial cell factories is an attractive approach considering the low phenylpropanoid contents in plants. However, it is usually difficult to produce high titer phenylpropanoid production when fermentation using glucose as carbon source. Developing novel bioprocess using alternative sources might provide a solution to this problem. In this study, typical phenylpropanoid raspberry ketone was used as the target product to develop a biosynthesis pathway for phenylpropanoid production from fatty acids, a promising alternative low-cost feedstock. Results: A raspberry ketone biosynthesis module was developed and optimized by introducing 4-coumarate-CoA ligase (4CL), benzalacetone synthase (BAS), and raspberry ketone reductase (RZS) in Escherichia coli strains CR1–CR4. Then strain CR5 was developed by introducing raspberry ketone biosynthesis module into a fatty acids-utilization chassis FA09 to achieve production of raspberry ketone from fatty acids feedstock. However, the production of raspberry ketone was still limited by the low biomass and unable to substantiate whole-cell bioconversion process. Thus, a process by coordinately using fatty-acids and glycerol was developed. In addition, we systematically screened and optimized fatty acids-response promoters. The optimized promoter Pfrd3 was then successfully used for the efficient expression of key enzymes of raspberry ketone biosynthesis module during bioconversion from fatty acids. The final engineered strain CR8 could efficiently produce raspberry ketone repeatedly using bioconversion from fatty acids feedstock strategy, and was able to produce raspberry ketone to a concentration of 180.94 mg/L from soybean oil in a 1-L fermentation process. Conclusion: Metabolically engineered Escherichia coli strains were successfully developed for raspberry ketone production from fatty acids using several strategies, including optimization of bioconversion process and fine-tuning key enzyme expression. This study provides an essential reference to establish the low-cost biological manufacture of phenylpropanoids compounds. [ABSTRACT FROM AUTHOR]

Raspberry ketone (RK)—an aromatic compound found mostly in red raspberries (Rubus idaeus) is widely used as an over the counter product for weight loss. The present study was conducted to determine adverse effects associated with RK in obese and health-compromised obese mice. Two sets of experiments were conducted on normal obese and health-compromised obese mice treated with RK for a duration of 10 days. Obese conditions were induced by feeding mice a high fat diet for 10 weeks, while the health compromised obese mouse model was developed by a single intraperitoneal injection of a nontoxic dose of lipopolysaccharide (LPS) (6 mg/kg) to obese mice. Results showed that RK (165, 330, and 500 mg/kg) under obese as well as health-compromised condition retarded the gain in body weights as compared to the control groups. RK at doses 330 and 500 mg/kg resulted in 67.6 and 50% mortality, respectively in normal obese mice and 70% mortality was observed in health-compromised obese mice treated with RK at 500 mg/kg. At higher doses deaths were observed earlier than those given lower doses of RK. Significant elevations in blood alanine transaminase (ALT) were also observed with RK treatment in obese mice. Blood glucose levels were significantly elevated in all groups of mice treated with RK. This study suggests that higher doses of RK may cause adverse effects in health compromised conditions. Under these conditions, prolonged use of RK, especially in high doses, may pose a health hazard. [ABSTRACT FROM AUTHOR]

The interactions between Dacini male fruit flies and phytochemical male lures are unique. Lure response, fate and its effects after consumption on fruit fly mating behaviour are species- and lure-specific. Bactrocera frauenfeldi is known to respond to the phenylbutanoids raspberry ketone (RK) and cue lure (CL), anisyl acetone (AA), and zingerone (ZN), which are produced by some rainforest orchids. Here we compared the relative field responses of B. frauenfeldi males to these phenylbutanoids in two selected locations to determine the most attractive lure for this species. We also performed gas chromatographic-mass spectral analyses of male rectal pheromone glands to understand the fate of the ingested compounds. Results showed that B. frauenfeldi males were most responsive to CL, equally to RK and AA, while poorly to ZN in Cairns, a site with high population density. No significant difference was observed in Lockhart River which has a low population density of B. frauenfeldi. Chemical analyses showed that most of the ingested phenylbutanoids were sequestered into rectal glands, either unchanged or with minimal structural changes except for AA, which is converted to RK via a demethylation of the methoxy- to a hydroxy-moiety and reduced to 4-(4-methoxyphenyl)-2-butanol via the keto-moiety. This study provides both practical and ecological implications: it identified the most attractive lure, which is important for monitoring and management of B. frauenfeldi; and based on the relative responses, conversion and retention rates by B. frauenfeldi males, revealed the ecological significance of these phytochemical lures in plant-fruit fly co-evolution. [ABSTRACT FROM AUTHOR]

Annualy, helminthic diseases are one of the causes of economic losses in agriculture. Ruminantia are most often observed to be infected with nematodes of the gastrointestinal tract, including Strongyloides papillosus and the representatives of the Strongylida order. Identifying factors which could cause a decrease in the level of infection of agricultural animals with helminthiases would allow stock-raising facilities to regularly achieve high quality dairy and meat production in sufficient quantity. On the basis of this study, we determined the impact of flavourings and source materials approved for use in and on foods (isoamyl alcohol, isoamyl acetate, raspberry ketone, trilon B, methylparaben) on the survivability of larvae of Strongyloides papillosus and Haemonchus contortus, parasitic nematodes of Ruminantia animals. Among these substances, the lowest efficiency against the nematode larvae was found in isoamyl alcohol, isoamyl acetate and trilon B. A stronger effect was caused by methylparaben (for L3 S. papillosus LD50 = 0.67 ± 0.04%, L1 and L2 S. papillosus – LD50 = 0.0038 ± 0.0008%, L3 H. contortus – LD50 = 0.89 ± 0.15%). Minimum efficient dosage of the solutions was 10 g/l. Significant antihelminthic properties were manifested by raspberry ketone (for L3 S. papillosus LD50 = 1.00 ± 0.72%, L1 and L2 S. papillosus – LD50 = 0.07 ± 0.06%, L3 H. contortus – LD50 = 0.39 ± 0.26%). The results show that there is considerable potential for further studies on the antiparasitic properties of these substances against nematodes in the conditions of farming enterprises and agricultural complexes.

This paper reports a one-pot synthesis of 5-[2-(4-methoxyphenyl)ethyl]-1H-pyrazole-3-carboxylates via cyclocondensation of 1,1,1-trichloro-4-methoxy-6-(4-methoxyphenyl)hex-3-en-2-one with hydrazine hydrochloride in ROH (R = Me, Et, n-Pr, i-Pr, i-Bu, i-Am, hexadecyl) under conventional and microwave heating. Yields are comparable in both methods, but under MW heating the reaction proceeds faster. The antioxidant activity of the compounds was measured using DPPH radical scavenging assay. It was observed, that the increase of the alcohol chain length decreases the antioxidant potential of the raspberry ketone derived molecular system. [ABSTRACT FROM AUTHOR]

Background: The phenylbutanoid 4-(4-hydroxyphenyl)butan-2-one, commonly known as raspberry ketone, is responsible for the typical scent and flavor of ripe raspberries. Chemical production of nature-identical raspberry ketone is well established as this compound is frequently used to flavor food, beverages and perfumes. However, high demand for natural raspberry ketone, but low natural abundance in raspberries, render raspberry ketone one of the most expensive natural flavoring components. Results: In this study, Corynebacterium glutamicum was engineered for the microbial synthesis of the character impact compound raspberry ketone from supplemented p-coumaric acid. In this context, the NADPH-dependent curcumin/dihydrocurcumin reductase CurA from Escherichia coli was employed to catalyze the final step of raspberry ketone synthesis as it provides a hitherto unknown benzalacetone reductase activity. In combination with a 4-coumarate: CoA ligase from parsley (Petroselinum crispum) and a monofunctional benzalacetone synthase from Chinese rhubarb (Rheum palmatum), CurA constitutes the synthetic pathway for raspberry ketone synthesis in C. glutamicum. The resulting strain accumulated up to 99.8 mg/L (0.61 mM) raspberry ketone. In addition, supplementation of other phenylpropanoids allowed for the synthesis of two other naturally-occurring and flavoring phenylbutanoids, zingerone (70 mg/L, 0.36 mM) and benzylacetone (10.5 mg/L, 0.07 mM). Conclusion: The aromatic product portfolio of C. glutamicum was extended towards the synthesis of the flavoring phenylbutanoids raspberry ketone, zingerone and benzylacetone. Key to success was the identification of CurA from E. coli having a benzalacetone reductase activity. We believe, that the constructed C. glutamicum strain represents a versatile platform for the production of natural flavoring phenylbutanoids at larger scale. [ABSTRACT FROM AUTHOR]

Natural raspberry ketone has a high value in the flavor, fragrance and pharmaceutical industries. Its extraction is costly, justifying the search for biosynthetic routes. We hypothesized that cytochrome P450 BM3 (P450 BM3) could be engineered to catalyze the hydroxylation of 4‐phenyl‐2‐butanone, a naturally sourceable precursor, to raspberry ketone. The synthesis of indigo by variants of P450 BM3 has previously served as a predictor of promiscuous oxidation reactions. To this end, we screened 53 active‐site variants of P450 BM3 using orthogonal high‐throughput workflows to identify the most streamlined route to all indigo‐forming variants. Among the three known and 13 new indigo‐forming variants, eight hydroxylated 4‐phenyl‐2‐butanone to raspberry ketone. Previously unreported variant A82Q displayed the highest initial rates and coupling efficiencies in synthesis of indigo and of raspberry ketone. It produced the highest total concentration of raspberry ketone despite producing less total indigo than previously reported variants. Its productivity, although modest, clearly demonstrates the potential for development of a biocatalytic route to raspberry ketone. In addition to validating indigo as a robust predictor of this promiscuous activity, we demonstrate that monitoring rapid NADPH consumption serves as an alternative predictor of a promiscuous reactivity in P450 BM3. [ABSTRACT FROM AUTHOR]

Chemical leukoderma is a patchy hypopigmentation in the skin. Phenol derivatives such as raspberry ketone have been reported to cause the development of occupationally induced leukoderma. Recently, 2% (w/w) rhododenol, a reduced form of raspberry ketone used in a skin-lightning agent, also caused the development of leukoderma in >16,000 users, about 2% of all users, in Asian countries including Japan. However, a method for assessing the risk of leukoderma caused by 2% rhododenol has not been established despite the fact that the development of leukoderma caused by 30% rhododenol was previously shown in animal experiments. Establishment of a novel technique for risk assessment of leukoderma in humans caused by external treatment with chemicals is needed to prevent a possible future chemical disaster. This study demonstrated that external treatment with 2% rhododenol and the same concentration of raspberry ketone caused the development of leukoderma in murine tail skin without exception with significant decreases in the amount of melanin and number of melanocytes in the epidermis. Thus, a novel in vivo technique that can assess the risk of leukoderma caused by 2% rhododenol was developed. The unique technique using tail skin has the potential to prevent chemical leukoderma in the future. Image 1 • 2% rhododenol caused leukoderma in >16,000 users in Asian countries. • Establishment of a technique for risk assessment of leukoderma is an urgent task. • A system to assess the risk of leukoderma caused by 2% rhododenol was developed. • 2% rhododenol caused decreases in the levels of melanin and melanocytes. • Our risk assessment technique has the potential to prevent chemical leukoderma. [ABSTRACT FROM AUTHOR]

Here, we aimed to elucidate the mechanism of rhododendrol (RD)-induced leukoderma. We investigated the skin permeability of RD in an aqueous solution and in different cosmetic formulations (lotion and emulsion) in an in vitro skin permeation study. The samples were analyzed using high-performance liquid chromatography (HPLC), and an unknown substance appeared on the spectrum. For identification, we analyzed various possible substances, such as raspberry ketone (RK) and rhododendrol quinone, using HPLC and then compared the detected absorption spectra and further verified the matched components using liquid chromatography–mass spectrometry. The unknown substance was found to be RK. To clarify the mechanism of formation of RK, we conducted a 24-h skin permeation test on heat-treated skin. By quantifying the RK in the samples using HPLC, we observed that an enzyme in the skin seemed to be the cause of RK generation and that the components of the emulsion formulation could also be a cause. To investigate the enzyme, we reacted alcohol dehydrogenase with RD and observed that it was one of the converting enzymes. As RK has been reported to be a substance that causes leukoderma, the intraepidermal metabolism of RD to RK may be one of the mechanisms of susceptibility to leukoderma.

Raspberry ketone (RK) is an aromatic phenolic compound naturally occurring in red raspberries, kiwifruit, peaches, and apples and reported for its potential therapeutic and nutraceutical properties. Studies in cells and rodents have suggested an important role for RK in hepatic/cardio/gastric protection and as an anti-hyperlipidemic, anti-obesity, depigmentation, and sexual maturation agent. Raspberry ketone-mediated activation of peroxisome proliferator-activated receptor-α (PPAR-α) stands out as one of its main modes of action. Although rodent studies have demonstrated the efficacious effects of RK, its mechanism remains largely unknown. In spite of a lack of reliable human research, RK is marketed as a health supplement, at very high doses. In this review, we provide a compilation of scientific research that has been conducted so far, assessing the therapeutic properties of RK in several disease conditions as well as inspiring future research before RK can be considered safe and efficacious with limited side effects as an alternative to modern medicines in the treatment of major lifestyle-based diseases.

Oxidative stress is closely linked to various diseases, and many studies have been conducted to determine how to reduce this stress. In particular, efforts are being made to find potential antioxidants from natural products. Studies have shown that raspberry ketone (RK; 4-(4-hydroxyphenyl)-2-butanone) has various pharmacological activities. This review summarizes the antioxidant activities of RK and their underlying mechanisms. In several experimental models, it was proven that RK exhibits antioxidant properties through increasing total antioxidant capacity (TAC); upregulating antioxidant enzymes, such as superoxide dismutase (SOD) and catalase (CAT); and improving lipid peroxidation. In conclusion, research about RK’s antioxidant activities is directly or indirectly related to its other various physiological activities. Further studies at the clinical level will be able to verify the value of RK as an effective antioxidant, functional health food, and therapeutic agent.

Raspberry ketone (RK) is the characteristic aromatic compound in raspberry (Rubus idaeus L.) with wide applications as food additive and anti-obesity agent. However, quantification of RK has presented difficulties in MS detection and reliable LC-MS method for RK analysis in literature is in limit to date. In order to facilitate quality control of raspberry derived products and RK metabolomics study, this study aimed to develop a validated and sensitive UHPLC-MS/MS method. Strong in-source fragmentation was noted and the fragmental ion of 107 m/z produced was selected as the precursor ion for MRM detection, and as such the electrospray ionization performance was optimized by fractional factorial design to accommodate such ion-source dissociation behavior as well as its moderate volatility. A pathway involving the formation of quinone-like structure with strong conjugation was proposed to explain the intense in-source fragmentation. The MRM transition was optimized with product ion of 77 m/z selected as the quantifier ion. The method featured low limit of quantification of ~2 ng/mL and allowed for rapid detection of RK in fresh raspberries following direct sample preparation. RK contents were found to be higher from locally grown and harvested farm sources compared to commercial products shipped into the state, and higher in those at late-stage compared with early-stage maturity. No correlations in RK content between organic and non-organic labels were noted. [ABSTRACT FROM AUTHOR]