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The Palm-pressed mesocarp is a by-product from the palm oil mill and is comprised of 5–7 % of residual oil, which could be further refined into red palm-pressed mesocarp olein (PPMO). This study aimed to obtain the chemical profile of PPMO and assess its eye health effects through retinoid metabolic and visual cycle pathways regulation. PPMO contains exceptionally high vitamin E (1819.0 ppm) and carotenoid (1113.8 ppm) contents with a similar fatty acid composition to palm olein. The rats fed with 2 g/kg PPMO daily for 84 days through oral gavage up-regulated the retinol and retinyl palmitate levels, as well as the mRNA and protein expression levels of RBP4 in blood, CRBP1 and LRAT in the liver, RPE65 and RDH5 in the eye. The outcomes showed that PPMO showed comparable regulation effects with β-carotene in the retinoid metabolic and visual cycle pathways, revealing it as a phytonutrient-rich edible oil with beneficial eye health effects.

Graduate Research Symposium 2021 (GRS2021) was held virtually via Zoom on the 30th of November 2021. The theme of the symposium was Scientific Research Today: Borderless, Collaborative and Innovative. The symposium aimed to highlight the various types of scientific research being conducted by postgraduates from different international and local institutions to expand participants’ field of knowledge as well as encourage networking. GRS2021 covers a wide range of topics, which include natural products, drug discovery and formulation, life sciences, pharmaceutical sciences, medical sciences, food sciences and technology. This special issue exhibits the latest research findings by postgraduates from various scientific background. The emphasis is on studies that will contribute to the current knowledge and understanding in the targeted field of study.

A new series of 3-O-substituted xanthone derivatives were synthesised and evaluated for their anti-cholinergic activities against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). The results indicated that the xanthone derivatives possessed good AChE inhibitory activity with eleven of them (5, 8, 11, 17, 19, 21-23, 26-28) exhibited significant effects with the IC50 values ranged 0.88 to 1.28 µM. The AChE enzyme kinetic study of 3-(4-phenylbutoxy)-9H-xanthen-9-one (23) and ethyl 2-((9-oxo-9H-xanthen-3-yl)oxy)acetate (28) showed a mixed inhibition mechanism. Molecular docking study showed that 23 binds to the active site of AChE and interacts via extensive π–π stacking with the indole and phenol side chains of Trp86 and Tyr337, besides the hydrogen bonding with the hydration site and π–π interaction with the phenol side chain of Y72. This study revealed that 3-O-alkoxyl substituted xanthone derivatives are potential lead structures, especially 23 and 28 which can be further developed into potent AChE inhibitors.

Cancer is a major health issue around the globe. Chemotherapy and radiation therapy are no longer the standard treatments for patients as these remedies lead to many adverse effects. Thus, the development of alternative effective drugs from lead compounds, especially natural products is necessary. This study aimed to isolate cytotoxic phytochemical constituents from a plant Calophyllum inophyllum, which has been used as traditional medicine since ancient time. The root of C. inophyllum was extracted and subjected for phytochemical constituent isolation. A coumarin, benjaminin (1) was isolated successfully from the chloroform extract and its structural elucidation was performed by spectroscopy analyses of MS, IR and NMR. The anti-proliferative effect of 1 on four cancer cell lines, leukemia (K562), stomach (SNU-1), liver (Hep-G2) and lung (NCI-H23) cancers were evaluated by using colorimetric MTT assay. Benjaminin (1) exhibited cytotoxic effects towards all cancer cells and showed the strongest inhibition towards SNU-1 cell proliferation with an IC50 value of 70.42 μM. The outcome of this study revealed that 1 is a potential cytotoxic lead compound that could be further developed into anti-cancer drug. Thus, the study on the structure-activity relationship of 1 is highly recommended in due course to improve its anti-proliferative effects on cancer cells.

Skincare industries are growing rapidly around the globe but most products are formulated using synthetic chemicals and organic solvent extracted plant extracts, thus may be hazardous to the users and incur higher cost for purification that eventually leads to phytonutrient degradation. Therefore, this study aimed to formulate a stable natural formulation with antioxidant and antimicrobial activities by using supercritical carbon dioxide (SC-CO2) extracted palm-pressed fiber oil (PPFO) as an active ingredient with virgin coconut oil (VCO) as a formulation base. PPFO was extracted from fresh palm-pressed fiber (PPF) while VCO was from dried grated coconut copra using SC-CO2 before being subjected to the analyses of physicochemical properties, phytonutrient content and biological activities including antioxidant and antimicrobial. The nanoemulgel formulations were then developed and examined for their stability through accelerated stability study for 3 months by measuring their pH, particle size, polydispersity index and zeta potential. The results showed that PPFO contained a high amount of phytonutrients, especially total carotenoid (1497 ppm) and total tocopherol and tocotrienol (2269 ppm) contents. The newly developed nanoemulgels maintained their particles in nano size and showed good stability with high negative zeta potentials. Sample nanoemulgel formulated with 3% PPFO diluted in VCO as effective concentration showed significantly stronger antioxidant activity than the control which was formulated from 3% tocopheryl acetate diluted in mineral oil, towards DPPH and ABTS radicals, with IC50 values of 67.41 and 44.28 µL/mL, respectively. For the antibacterial activities, the sample nanoemulgel was found to inhibit Gram positive bacteria S. aureus and S. epidermidis growth but not the Gram negative strain E. coli. Overall, this study revealed the potential of SF-extracted PPFO as an active ingredient in the antioxidant topical formulations thus future study on in vitro skin cell models is highly recommended for validation. [ABSTRACT FROM AUTHOR]

The pathogenesis of skin inflammatory diseases such as atopic dermatitis, acne, psoriasis, and skin cancers generally involve the generation of oxidative stress and chronic inflammation. Exposure of the skin to external aggressors such as ultraviolet (UV) radiation and xenobiotics induces the generation of reactive oxygen species (ROS) which subsequently activates immune responses and causes immunological aberrations. Hence, antioxidant and anti-inflammatory agents were considered to be potential compounds to treat skin inflammatory diseases. A prime example of such compounds is xanthone (xanthene-9-one), a class of natural compounds that possess a wide range of biological activities including antioxidant, anti-inflammatory, antimicrobial, cytotoxic, and chemotherapeutic effects. Many studies reported various mechanisms of action by xanthones for the treatment of skin inflammatory diseases. These mechanisms of action commonly involve the modulation of various pro-inflammatory cytokines such as interleukin (IL)-1β, IL-6, IL-8, and tumor necrosis factor α (TNF-α), as well as anti-inflammatory cytokines such as IL-10. Other mechanisms of action include the regulation of NF-κB and MAPK signaling pathways, besides immune cell recruitment via modulation of chemokines, activation, and infiltration. Moreover, disease-specific activity contributed by xanthones, such as antibacterial action against Propionibacterium acnes and Staphylococcus epidermidis for acne treatment, and numerous cytotoxic mechanisms involving pro-apoptotic and anti-metastatic effects for skin cancer treatment have been extensively elucidated. Furthermore, xanthones have been reported to modulate pathways responsible for mediating oxidative stress and inflammation such as PPAR, nuclear factor erythroid 2-related factor and prostaglandin cascades. These pathways were also implicated in skin inflammatory diseases. Xanthones including the prenylated α-mangostin (2) and γ-mangostin (3), glucosylated mangiferin (4) and the caged xanthone gambogic acid (8) are potential lead compounds to be further developed into pharmaceutical agents for the treatment of skin inflammatory diseases. Future studies on the structure-activity relationships, molecular mechanisms, and applications of xanthones for the treatment of skin inflammatory diseases are thus highly recommended.

The Refined, Bleached and Deodorized (RBD) Coconut Oil (CO) and RBD Palm Oil (PO) are heavily consumed as cooking oils by Asians. Recently, Virgin Coconut Oil (VCO) and Palm-pressed Mesocarp Oil (PPMO) emerged into the market as functional oils. A number of studies were conducted to extract these edible oils by using different methods and conditions. Thus, this review focuses on the extraction methods of CO, VCO, CPO and PPMO, together with their yields and phytonutrient profiles. Phytonutrients such as carotenoids, tocopherol and tocotrienols, squalene, phytosterol and coenzyme Q10 were found in all the oils with various concentrations depending on their respective extraction methods. Supercritical Fluid Extraction (SFE) showed the highest efficiency in extracting VCO and PPMO among the extraction methods, in terms of yield and phytonutrient contents. VCO extracted by SFE contains higher medium chain fatty acids which promotes good digestibility when compared to other extraction methods. PPMO extracted by SFE is clean with a pleasant aroma without the presence of the gums and contains a lower amount of phospholipids. Furthermore, water soluble-phenolics were found to be present in the PPMO that contribute to its antioxidant activity. Thus, SFE is highly recommended for the extraction of VCO and PPMO.

The compounds 2-(1-benzofuran-2-yl)-2-oxoethyl 2-nitrobenzoate, C17H11NO6 (I), and 2-(1-benzofuran-2-yl)-2-oxoethyl 2-aminobenzoate, C17H13NO4 (II), were synthesized under mild conditions. Their molecular structures were characterized by both spectroscopic and single-crystal X-ray diffraction analysis. The molecular conformations of both title compounds are generally similar. However, different ortho-substituted moieties at the phenyl ring of the two compounds cause deviations in the torsion angles between the carbonyl group and the attached phenyl ring. In compound (I), the ortho-nitrophenyl ring is twisted away from the adjacent carbonyl group whereas in compound (II), the ortho-aminophenyl ring is almost co-planar with the carbonyl group. In the crystal of compound (I), two C—H...O hydrogen bonds link the molecules into chains propagating along the c-axis direction and the chains are interdigitated, forming sheets parallel to [20-1]. Conversely, pairs of N—H...O hydrogen bonds in compound (II) link inversion-related molecules into dimers, which are further extended by C—H...O hydrogen bonds into dimer chains. These chains are interconnected by π–π interactions involving the furan rings, forming sheets parallel to the ac plane.

Context: Sida (Malvaceae) has been used as a traditional remedy for the treatment of diarrhoea, malarial, gastrointestinal dysentery, fevers, asthma and inflammation. Objectives: This study evaluates the anti-inflammatory, cytotoxic and anti-cholinergic activities of Sida rhombifolia Linn. whole plant for the first time. Materials and methods: S. rhombifolia whole plant was extracted by n-hexane, ethyl acetate and methanol using Soxhlet apparatus. The plant extracts were evaluated for their antioxidant (DPPH, FIC and FRAP), anti-inflammatory (NO and protein denaturation inhibitions), cytotoxic (MTT) and anti-cholinesterase (AChE) properties in a range of concentrations to obtain IC50 values. GC-MS analysis was carried out on the n-hexane extract. Results and discussion: The ethyl acetate extract exhibited the most significant antioxidant activities by scavenging DPPH radicals and ferrous ions with EC50 of 380.5 and 263.4 μg/mL, respectively. In contrast, the n-hexane extract showed the strongest anti-inflammatory activity with IC50 of 52.16 and 146.03 μg/mL for NO and protein denaturation inhibition assays, respectively. The same extract also revealed the strongest effects in anti-cholinesterase and cytotoxic tests at the concentration of 100 μg/mL, AChE enzyme inhibition was 58.55% and human cancer cells, SNU-1 and Hep G2 inhibition was 68.52% and 47.82%, respectively. The phytochemicals present in the n-hexane extract are palmitic acid, linoleic acid and γ-sitosterol. Conclusions: The present study revealed that the n-hexane extract possessed relatively high pharmacological activities in anti-inflammation, cytotoxicity and anti-cholinesterase assays. Thus, further work on the detail mechanism of the bioactive phytochemicals which contribute to the biological properties are strongly recommended.

Adamantyl-based compounds are commercially important in the treatments for neurological conditions and type-2 diabetes, aside from their anti-viral abilities. Their values in drug design are chronicled as multi-dimensional. In the present study, a series of 2-(adamantan-1-yl)-2-oxoethyl benzoates, 2(a–q), and 2-(adamantan-1-yl)-2-oxoethyl 2-pyridinecarboxylate, 2r, were synthesized by reacting 1-adamantyl bromomethyl ketone with various carboxylic acids using potassium carbonate in dimethylformamide medium at room temperature. Three-dimensional structures studied using X-ray diffraction suggest that the adamantyl moiety can serve as an efficient building block to synthesize 2-oxopropyl benzoate derivatives with synclinal conformation with a looser-packed crystal packing system. Compounds 2a, 2b, 2f, 2g, 2i, 2j, 2m, 2n, 2o, 2q and 2r exhibit strong antioxidant activities in the hydrogen peroxide radical scavenging test. Furthermore, three compounds, 2p, 2q and 2r, show good anti-inflammatory activities in the evaluation of albumin denaturation.

Biphenyl-based compounds are clinically important for the treatments of hypertension and inflammatory, while many more are under development for pharmaceutical uses. In the present study, a series of 2-([1,1'-biphenyl]-4-yl)-2-oxoethyl benzoates, 2(a-q), and 2-([1,1'-biphenyl]-4-yl)-2-oxoethyl pyridinecarboxylate, 2(r-s) were synthesized by reacting 1-([1,1'-biphenyl]-4-yl)-2-bromoethan-1-one with various carboxylic acids using potassium carbonate in dimethylformamide at ambient temperature. Single-crystal X-ray diffraction studies revealed a more closely packed crystal structure can be produced by introduction of biphenyl moiety. Five of the compounds among the reported series exhibited significant anti-tyrosinase activities, in which 2p, 2r and 2s displayed good inhibitions which are comparable to standard inhibitor kojic acid at concentrations of 100 and 250 μg/mL. The inhibitory effects of these active compounds were further confirmed by computational molecular docking studies and the results revealed the primary binding site is active-site entrance instead of inner copper binding site which acted as the secondary binding site.

The cytotoxic structure-activity relationships among a series of xanthone derivatives from Mesua beccariana, Mesua ferrea and Mesua congestiflora were studied. Eleven xanthone derivatives identified as mesuarianone (1), mesuasinone (2), mesuaferrin A (3), mesuaferrin B (4), mesuaferrin C (5), 6-deoxyjacareubin (6), caloxanthone C (7), macluraxanthone (8), 1,5-dihydroxyxanthone (9), tovopyrifolin C (10) and α-mangostin (11) were isolated from the three Mesua species. The human cancer cell lines tested were Raji, SNU-1, K562, LS-174T, SK-MEL-28, IMR-32, HeLa, Hep G2 and NCI-H23. Mesuaferrin A (3), macluraxanthone (8) and α-mangostin (11) showed strong cytotoxicities as they possess significant inhibitory effects against all the cell lines. The structure-activity relationship (SAR) study revealed that the diprenyl, dipyrano and prenylated pyrano substituent groups of the xanthone derivatives contributed towards the cytotoxicities.

An investigation on biologically active secondary metabolites from the stem bark of Mesua beccariana was carried out. A new cyclodione, mesuadione (1), along with several known constituents which are beccamarin (2), 2,5-dihydroxy-1,3,4-trimethoxy anthraquinone (3), 4-methoxy-1,3,5-trihydroxyanthraquinone (4), betulinic acid (5) and stigmasterol (6) were obtained from this ongoing research. Structures of these compounds were elucidated by extensive spectroscopic methods, including 1D and 2D-NMR, GC-MS, IR and UV techniques. Preliminary tests of the in vitro cytotoxic activities of all the isolated metabolites against a panel of human cancer cell lines Raji (lymphoma), SNU-1 (gastric carcinoma), K562 (erythroleukemia cells), LS-174T (colorectal adenocarcinoma), HeLa (cervical cells), SK-MEL-28 (malignant melanoma cells), NCI-H23 (lung adenocarcinoma), IMR-32 (neuroblastoma) and Hep-G2 (hepatocellular liver carcinoma) were carried out using an MTT assay. Mesuadione (1), beccamarin (2), betulinic acid (5) and stigmasterol (6) displayed strong inhibition of Raji cell proliferation, while the proliferation rate of SK-MEL-28 and HeLa were strongly inhibited by stigmasterol (6) and beccamarin (2), indicating these secondary metabolites could be anti-cancer lead compounds in drug discovery.

Our continuing studies on secondary metabolites from the stem bark of Calophyllum soulattri has led to the isolation of another new diprenylated xanthone, phylattrin (1), in addition to five other xanthones and two common sterols. The xanthones are soulattrin (2), caloxanthone C (3), macluraxanthone (4), brasixanthone B (5) and trapezifolixanthone (6) while the sterols are stigmasterol (7) and β-sitosterol (8). The structures of these compounds were determined on the basis of spectroscopic analyses such as 1D and 2D-NMR, HRESIMS, IR and UV. Compounds 1–7 exhibited moderate cytotoxic activities against SNU-1, HeLa, Hep G2, NCI-H23, K562, Raji, LS174T, IMR-32 and SK-MEL-28 cells.

The extracts of the stem bark of Calophyllum soulattri gave a new pyranocoumarin, soulamarin (1), together with five other xanthones caloxanthone B (2), caloxanthone C (3), macluraxanthone (4), trapezifolixanthone (5) and brasixanthone B (6) one common triterpene, friedelin (7), and the steroidal triterpene stigmasterol (8). The structures of these compounds were established based on spectral evidence (1D and 2D NMR).

Our ongoing investigations on the stem bark of Mesua beccariana afforded a novel cyclodione coumarin, beccamarin, together with two known xanthones, mesuarianone, mesuasinone, two anthraquinones, 4-methoxy-1,3,5-trihydroxy-anthraquinone and 2,5-dihydroxy-1,3,4-trimethoxyanthraquinone and one coumarin, mammea A/AB. The structures were elucidated by 1D and 2D NMR and MS techniques.

Our phytochemical studies on the root bark extracts of Mesua ferrea have led to the isolation of two new pyranoxanthones, mesuaferrin A (1) and mesuaferrin B (2). Five other compounds – caloxanthone C (3), 1,8-dihydro-3-methoxy-6-methylanthraquinone (4), β-sitosterol (5), friedelin (6) and betulinic acid (7) – were also successfully isolated. Structural elucidations of these compounds were achieved using 1D and 2D NMR and MS techniques.

Our interest on xanthones from the Calophyllum genus has led us to a detailed study on the chemistry of the stem bark of Calophyllum soulattri. This gave one new pyranoxanthone, soulattrin (1), together with three other xanthones, caloxanthone B (2), caloxanthone C (3), macluraxanthone (4), the triterpene friedelin (5) and the steroid stigmasterol (6). The identities of these compounds were established using analyses of 1D and 2D NMR data.

Our recent study on the stem bark extracts of Mesua beccariana has led to the isolation of two new pyranoxanthones, mesuarianone (1) and mesuasinone (2), two anthraquinones, 4-methoxy-1,3,5-trihydroxyanthraquinone (3) and 2,5-dihydroxy-1,3,4-trimethoxyanthraquinone (4), one coumarin, mammea A/AB (5) and three common triterpenes, stigmasterol (6), friedelin (7) and betulinic acid (8). Structural elucidations of these compounds were achieved using 1D and 2D NMR and MS techniques. This is the first report on the phytochemistry of Mesua beccariana.

The phenolic constituents in Piper betle are well known for their antioxidant potential; however, current literature has very little information on their stability under the influence of storage factors. Present study evaluated the stability of total phenolic content (TPC) and antioxidant activity together with individual phenolic constituents (hydroxychavicol, eugenol, isoeugenol and allylpyrocatechol 3,4-diacetate) present in dried Piper betle’s extract under different storage temperature of 5 and 25 °C with and without light for a period of six months. Both light and temperature significantly influenced TPC and its corresponding antioxidant activity over time. More than 95% TPC and antioxidant activity was retained at 5 °C in dark condition after 180 days of storage. Hydroxychavicol demonstrated the best stability with no degradation while eugenol and isoeugenol displayed moderate stability in low temperature (5 °C) and dark conditions. 4-allyl-1,2-diacetoxybenzene was the only compound that underwent complete degradation. A new compound, 2,4-di-tert-butylphenol, was detected after five weeks of storage only in the extracts exposed to light. Both zero-order and first-order kinetic models were adopted to describe the degradation kinetics of the extract’s antioxidant activity. Zero-order displayed better fit with higher correlation coefficients (R2 = 0.9046) and the half-life was determined as 62 days for the optimised storage conditions (5 °C in dark conditions).

The title compound congestiflorone, C28H32O4, which was isolated from the stem bark of Mesua congestiflora, consists of a benzophenone skeleton with two attached pyran rings to which a cyclohexane ring and a C6 side chain are bonded. The benzene ring is significantly distorted from planarity (r.m.s. deviation = 0.0007 Å) due to the constraints imposed by junctions with the two pyran rings. The cyclohexane ring is in a chair conformation, one pyran ring is in a boat conformation, while the other is a distorted chair. The phenyl and benzene rings make a dihedral angle of 55.85 (9)°. An intramolecular O—H...O hydrogen bond is observed. In the crystal, molecules are linked via C—H...O interactions.