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The discovery of a green extraction solvent for natural plants could promote related research. In this study, deep eutectic solvents (DES) were used as green solvents coupled with an ultrasound-assisted extraction method (UAE) to extract flavonoids from lotus leaves. Thirty-four different DES were performed and choline chloride/urea with 40% water was chosen as the most promising one, and the related parameters in the procedures were optimized, resulting in the highest extraction amount of flavonoids in lotus leaves. D-101 was selected from four macroporous resins to separate the flavonoids from DES. Moreover, DES could be recycled and efficiently reused four times with satisfactory performances. In addition, the lotus leaf flavonoids from the DES extract exhibited antioxidant activities in five kinds of assays including DPPH, ABTS, Fe3+ reducing, FRAP, and Fe2+ chelating. It also showed antibacterial activities on Staphylococcus aureus and Escherichia coli bacterial strains with minimal inhibitory concentrations at 1666 μg/mL and 208 μg/mL, respectively. In the HPLC analysis, the three main components in the DES extract were identified as astragalin, hyperoside, and isoquercitrin. In conclusion, the developed UAE-DES followed by macroporous resin treatment could become an efficient and environmentally friendly extraction and enrichment method for flavonoids from lotus leaves and other natural products.

This study aimed to determine optimal extraction parameters by using response surface methodology, examining the effect of microencapsulation on crocin retention, and evaluating the temperature and pH stability of crocin microcapsules. The effect of process variables on the crocin yield was successfully determined by quadratic models (R 2 > 0.99 and adj R 2 > 0.98). All variables significantly affected the crocin yield (P < 0.1). The process parameters, namely extraction time (4.40 min), temperature (55 °C), amplitude level (94%), and liquid to solid ratio (L/S) (1000) were determined as optimum extraction points. Safranal was shown to be a compound with major volatility in both the saffron and microcapsule extracts. Safranal, 2,4,4-trimethyl-3-carboxaldehyde-5-hydroxy-2,5-cyclohexadiene-1-one, 4-hydroxy-2,6,6-trimethyl-1-cyclohexene-1-carboxaldehyde (HTCC), and isophorone were other major volatile compounds of saffron extract. The encapsulation process affected volatile percentage distribution insignificantly (P > 0.05). The thermal and pH stability of the crocin was determined at different temperatures (60, 70, 80, and 90 °C) and pH levels (2, 4.5, and 6). The crocin degradation showed first order kinetic, and degradation rate constant (k) were significantly affected by pH and temperature (P < 0.05). A high temperature and low pH showed higher degradation (k) in crocin content. This study suggested that crocin from saffron stigmas should be preserved by spray drying encapsulation and should only be used as a natural food colorant in low or moderate acid food. © 2019, Springer Science+Business Media, LLC, part of Springer Nature.

This study aims to demonstrate a simple and rapid “green” method for the ultrasound-assisted synthesis of t-aliphatic esters by reacting t -butanol with saturated (capric, lauric, palmitic) and unsaturated (oleic and undecylenic) acids. The spectral characterization of esters was performed by IR and NMR spectroscopies. The impact of ultrasonic irradiation on the reaction in comparison with the conventional method was analyzed based on the reaction time and the yield of the resulting esters. After spectroscopic studies, the synthesis of the corresponding esters after the ultrasound-assisted irradiation was proven. The yields of the t-butyl fatty acid esters increased between 2 and 10% in comparison with the conventional method for their synthesis. It was also established that the application of ultrasonic irradiation intensifies the esterification process significantly compared to the conventional method. The advantages of the ultrasound-assisted esterification include shortening the reaction time; the process is carried out at room temperature instead of at the conventional reaction temperature 67-70oC. The application of ultrasonic-assisted irradiation for esterification is a suitable and promising method to reduce energy consumption, shortening the reaction time, and increasing the yield of t -butyl fatty acid esters.

A facile synthesis of hitherto unreported 3-(2-benzofuroyl)carbazoles 3a–k, 3,6-bis(2-benzofuroyl)carbazoles 5a–k, and naphtho[2,1-b]furoylcarbazoles 3l and 5l is described. The synthesis mainly relies on the ultrasound-assisted Rap–Stoermer reaction of 3-chloroacetyl- (1) or 3,6-dichloroacetyl-9-ethyl-9H-carbazole (4) with various salicylaldehydes 2a–k as well as 2-hydroxy-1-naphthaldehyde (2l) in CH3CN with the presence of PEG-400 as catalyst. The procedure offers easy access to benzofuroylcarbazoles in short reaction times and the products are obtained in moderate to good yields.

The 19th International Electronic Conference on Synthetic Organic Chemistry session Bioorganic, Medicinal and Natural Products Chemistry In the category of microorganism, fungi are considered as the special class of microbes responsible for opportunistic pathogenic infections in humans species. Due to the side effects of commercially available antifungal drugs and the emergence of new drug resistant fungal species in the past few years has forced the researchers to search for novel and efficient antifungal drug molecules. The 1,3,4-oxadiazoles scaffold is associated with diverse biological activities. The multipurpose use of the Mannich bases in pharmaceutical chemistry provoked us to prepare a new series of 1,3,4-oxadiazole Mannich bases derivatives, as antifungal agents. Herein we report Molecular sieves and Ultrasound assisted synthesis of novel series of Mannich bases of the 5-substituted 1,3,4-oxadiazole-2-thiones by amino methylation with paraformaldehyde and substituted primary / secondary amines and their evaluation for antifungal activity .The structures of the newly synthesized compounds were determined by IR, NMR and Mass spectral study. The synthesized compounds exhibited interesting moderate to excellent antifungal activity against Candida albicans (NCIM 3557),Candida albicans(NCIM3471), Candida glabrata(NCIM3237), Cryptococcus neoformans (NCIM 3542),Cryptococcus neoformans(NCIM 3378),Aspergillus fumigates(NCIM 902), Aspergillus niger( NCIM 628) using Flucanazole as a standard reference drug. The synthesised compounds 6d, 6f ,6g, 6h and 6j exhibited promising antifungal activity as fungi static agents

© 2015 Elsevier Ltd. Herein, we developed a novel integrated device to perform phase separation based on ultrasound-assisted, salt-induced, liquid-liquid microextraction for determination of five fluoroquinones in meats by HPLC analysis. The novel integrated device consisted of three simple HDPE (high density polyethylene) parts that were used to separate the solvent from the aqueous solution prior to retrieving the extractant. The extraction parameters were optimized using the response surface method based on central composite design: 589μL of acetone solvent, pH2.1, 4.1min extraction time and 3.5g of Na2SO4. The limits of detection were 0.056-0.64μgkg-1 and recoveries were 87.2-110.6% for the five fluoroquinones in muscle tissue from fish, chicken, pork and beef. This method is easily constructed from inexpensive materials, extraction efficiency is high, and the approach is compatible with HPLC analysis. Thus, it has excellent prospects for sample pre-treatment and analysis of fluoroquinones in meat samples.

Background Extraction prior to component analysis is the primary step in the recovery and isolation of bioactive phytochemicals from plant materials. Methods Response surface methodology was applied to optimize ultrasound-assisted extraction conditions followed by ultra high performance liquid chromatography (UHPLC) to achieve high catechin, myricetin, and quercetin contents, and high antioxidant and anticancer activities in the curry leaf extracts. The antioxidant and anticancer activities of the leaf extracts were determined by the 1,1-diphenyl-2-picryl-hydrazyl (DPPH) and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays, respectively. The central composite experimental design (3-level, 3-factorial) was employed to consider the effects of ultrasonic power (80–150 W), temperature (40–80°C), and methanol dilution (40–80%) on the properties of the curry leaf extracts. Results It was found that ultrasonic power of 145.49 W at 55.9°C with 80% methanol was the most appropriate set of conditions for the extraction of catechin, myricetin, and quercetin from curry leaves with the consequent high antioxidant activity. Using the optimum extraction conditions, the extraction yields of catechin, myricetin, and quercetin were 0.482, 0.517, and 0.394 mg/g DW, respectively, and the antioxidant activity was enhanced to 83%. The optimized extract showed more distinct anticancer activity against HeLa cancer cells in a concentration of 67.2 μg/mL (P