stilbenes and ethyl-acetate

Melanin plays an important role in protecting human skin, while excessive synthesis of melanin can cause abnormal pigmentation and induce skin diseases. Long-term use of commercial whitening agents in managing skin melanin such as kojic acid and arbutin can lead to some negative effects such as dermatitis and liver cancer. Although past studies have researched the melanin inhibitory effect of plant extracts, the effective dose and mechanisms are not well summarized and discussed. This study aims to explore the melanin inhibitory property of phytochemicals and tries to answer the following research questions: (1) Which plant extracts and phytochemicals could inhibit melanin biosynthesis in the skin? what is the mechanism of action? (2) Have human trials been conducted to confirm their melanin inhibitory effect? (3) If not, which phytochemicals are recommended for further human trials? This article would provide information for future research to develop natural and safe skin whitening products.. A preferred reporting items for systematic reviews and meta-analyses (PRISMA) systematic review method and OHAT risk-of-bias tool were applied to screen literature from 2000 to 2021 and 50 research articles met the selection criteria.. Flavonoids, phenolic acids, stilbenes and terpenes are main classes of phytochemicals responsible for the melanin inhibitory effects. The in vitro/in vivo melanin inhibitory effects of these plant extracts/phytochemicals are achieved via three main mechanisms: (1) the ethyl acetate extract of Oryza sativa Indica cv., and phytochemicals such as galangin and origanoside could manage melanin biosynthesis through competitive inhibition, non-competitive inhibition or mixed-type inhibition of tyrosinase; (2) phytochemicals such as ginsenoside F1, ginsenoside Rb1 and 4‑hydroxy-3-methoxycinnamaldehyde could inhibit melanogenesis through down-regulating microphthalmia-related transcription factor (MITF) gene expression via different signalling pathways; (3) the ethanolic extracts of Dimorphandra gardneriana, Dimorphandra gardneriana, Lippia microphylla and Schinus terebinthifolius have a good ultraviolet absorption ability and high sun protective factor (SPF) values, thereby inhibiting UV induced melanogenesis in the skin.. Although many plant extracts and phytochemicals have been found to inhibit melanin production, most of the results were only proved in cellular and/or animal models. Only the ethyl acetate extract of Oryza sativa Indica cv. panicle, and ginsenoside F1 were proved effective in human trials. Animal studies proved the effectiveness of galangin, origanoside, ginsenoside Rb1 and 4‑hydroxy-3-methoxycinnamaldehyde with effective dose below 3 mM, and therefore recommended for future human trial. In addition, cellular studies have demonstrated the effectiveness of oxyresveratrol, mulberroside A, kurarinol, kuraridinol, plumbagin, (6aR,11aR)-3,8-dihydroxy-9‑methoxy pterocarpan, ginsenoside Rh4, cardamonin, nobiletin, curcumin, β-mangostin and emodin in inhibiting melanin synthesis at low concentrations of 20 µM and proved the low SPF values of Dimorphandra gardneriana, Dimorphandra gardneriana, Lippia microphylla and Schinus terebinthifolius extracts, and therefore recommended for further animal and human trials.

Topics: Acetates; Acrolein; Animals; Arbutin; Bleaching Agents; Cell Line, Tumor; Curcumin; Emodin; Flavonoids; Ginsenosides; Glucosides; Humans; Hydroxybenzoates; Melanins; Microphthalmia-Associated Transcription Factor; Monophenol Monooxygenase; Phytochemicals; Plant Extracts; Pterocarpans; Stilbenes; Transcription Factors

The currently accepted paradigm is that fruits and vegetables should be consumed fresh and that their quality deteriorates during storage; however, there are indications that some metabolic properties can, in fact, be improved. We examined the effects of low temperature and high-CO

Topics: Acetates; Anaerobiosis; Benzofurans; Carbon Dioxide; Cold Temperature; Food Storage; Metabolomics; Pyruvic Acid; Signal Transduction; Stilbenes; Transcription Factors; Transcriptome; Up-Regulation; Vitis

α-Glucosidases have been a major target in controlling and managing postprandial blood glucose and therefore diabetes treatment. This study aims to further identify and purify active compounds from the most active ethyl acetate fraction collected previously in Tinta Cão grape pomace extract (TCEE) using a newly developed and highly effective immobilization method, including obtaining compounds previously shown to inhibit the enzyme. Purification used crosslinked chitosan beads with α-glucosidases bound to polymer, which acted as immobilized enzyme vehicle to collect inhibitors. Compounds absorbed into the beads were eluded using methanol, where collected fraction was subjected to UHPLC-MS analysis to identify active compounds. Results presented 5 major compounds: viniferifuran (amurensin H), p-coumaroyl-6-O-D-glucopyranoside, p-coumaroyl-6-O-hexoside, (epi)catechin-hexoside, 10-carboxyl-pyranopeonidin 3-O-(6''-O-p-coumaroyl)-glucoside. These findings indicated the particular molecules can be utilized as potent α-glucosidases inhibitors, and may be further tested for postprandial glucose control.. A potential approach enriched and identified α-glucosidase inhibitors of grape pomace. Set-up of UHPLC/MS detection and identification of active compounds provide qualify assessment in developing grape pomace extract into potent dietary supplement and new drug for diabetes.

Topics: Acetates; alpha-Glucosidases; Benzofurans; Catechin; Chitosan; Chromatography, High Pressure Liquid; Coumarins; Enzymes, Immobilized; Glucosides; Glycoside Hydrolase Inhibitors; Hypoglycemic Agents; Mass Spectrometry; Plant Extracts; Polymers; Stilbenes; Vitis

This work provides a platform for the rapid generation of superstructure assemblies with a wide range of lengths that can be used to access a variety of metal-organic complex-based soft superstructures. Metallacage-based microneedles that are nanometers in diameter and millimeters in length were generated in dichloromethane and ethyl acetate; their size could be controlled by adjusting the ratio of the two solvents. Interestingly, microflower structures could be formed by further assembly of the microneedles during solvent evaporation. Our study establishes a feasible method designed to broaden the range of suprastructures with emissions from blue and green to red through the co-assembly of lysine-modified perylene. Similar to the co-assembly of lysine-modified perylene with microflowers, chlorophyll-a and vitamin B

Topics: Acetates; Adsorption; Chlorophyll A; Coordination Complexes; Dicarboxylic Acids; Macromolecular Substances; Methylene Chloride; Microtechnology; Particle Size; Perylene; Platinum; Pyridines; Stilbenes; Vitamin B 12

High efficiency and less solvent consumption are the essential requirements of high-speed countercurrent chromatography (HSCCC), especially for the large-scale preparation. In this study, an efficient HSCCC strategy with consecutive sample injection was successfully developed to rapidly separate and purify rhaponticin and rhapontigenin from the seeds of the Chinese medicinal herb fenugreek (Trigonella foenum-graecum L.). The effective separation was achieved using n-hexane-ethyl acetate-methanol-water (1:4:2:6, v/v/v/v) as the two-phase solvent system, in which the mobile phase was eluted at an optimized flow rate of 2.2 mL/min and a revolution speed of 850 rpm. After consecutively loading four identical fenugreek samples, each containing 120 mg, HSCCC separation yielded 146.4 mg of rhaponticin and 174.8 mg of rhapontigenin with purities of 98.6 and 99.1%, respectively, as determined by high-performance liquid chromatography at 320 nm. Their chemical structures were identified using UV spectroscopy, (1)H-NMR and (13)C-NMR. The HSCCC method with consecutive sample injection allowed faster separation and produced less solvent waste, suggesting that it is an efficient way to rapidly separate and purify natural products on a large scale.

Topics: Acetates; Chromatography, High Pressure Liquid; Countercurrent Distribution; Flow Injection Analysis; Hexanes; Liquid-Liquid Extraction; Methanol; Plant Extracts; Seeds; Solvents; Stilbenes; Trigonella; Water

Polygonum cuspidatum is a potent anti-oxidant herb that is well known for its various bioactivities. The current study investigates which compound group is most effective, to establish the key compound groups for quality assessment, especially in terms of neuroprotective effects. The roots of P. cuspidatum were extracted with 85% methanol and fractionated with hexane, ethyl acetate, n-butanol and water. Each fraction was applied to an in vitro radical scavenging assay, a lipid peroxidation assay in brain homogenates and an in vivo assay using a transient focal cerebra ischemia model induced by a middle cerebral artery occlusion in a Sprague-Dawley rat. The ethyl acetate fraction was the most effective fraction in both in vitro and in vivo assays, having the highest stilbene and anthraquinone contents. These results suggest that stilbenes and anthraquinones may be key compound groups for the quality assessment of the anti-oxidative and neuroprotective effects of P. cuspidatum.

Topics: 1-Butanol; Acetates; Animals; Anthraquinones; Cerebrovascular Disorders; Chemical Fractionation; Chromatography, High Pressure Liquid; Fallopia japonica; Hexanes; Lipid Peroxidation; Male; Neuroprotective Agents; Phytotherapy; Plant Extracts; Plant Roots; Plants, Medicinal; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Rotarod Performance Test; Stilbenes

Resveratrol (3,5,4'-trihydroxy-trans-stilbene, 3,5,4'-THS) is a well-known natural antioxidant and cancer chemopreventive agent that has attracted much interest in the past decade. To find a more active antioxidant and investigate the antioxidative mechanism with resveratrol as the lead compound, we synthesized 3,5-dihydroxy-trans-stilbene (3,5-DHS), 4-hydroxy-trans-stilbene (4-HS) 3,4-dihydroxy-trans-stilbene (3,4-DHS), 4,4'-dihydroxy-trans-stilbene (4,4'-DHS), 4-hydroxy-3-methoxy-trans-stilbene (3-MeO-4-HS), 4-hydroxy-4'-methoxy-trans-stilbene (4'-MeO-4-HS), 4-hydroxy-4'-methyl-trans-stilbene (4'-Me-4-HS), 4-hydroxy-4'-nitro-trans-stilbene (4'-NO(2)-4-HS), and 4-hydroxy-4'-trifluoromethyl-trans-stilbene (4'-CF(3)-4-HS). The radical-scavenging activity and detailed mechanism of resveratrol and its analogues (ArOHs) were investigated by the reaction kinetics with galvinoxyl (GO(*)) and 2,2-diphenyl-1-picrylhydrazyl (DPPH(*)) radicals in ethanol and ethyl acetate at 25 degrees C, using UV-vis spectroscopy. It was found that the reaction rates increase with increasing the electron-rich environment in the molecules, and the compound bearing o-dihydroxyl groups (3,4-DHS) is the most reactive one among the examined resveratrol analogues. The effect of added acetic acid on the measured rate constant for GO(*)-scavenging reaction reveals that in ethanol that supports ionization solvent besides hydrogen atom transfer (HAT), the kinetics of the process is partially governed by sequential proton loss electron transfer (SPLET). In contrast to GO(*), DPPH(*) has a relatively high reduction potential and therefore enhances the proportion of SPLET in ethanol. The relatively low rate constants for the reactions of ArOHs with GO(*) or DPPH(*) in ethyl acetate compared with the rate constants in ethanol prove that in ethyl acetate these reactions occur primarily by the HAT mechanism. The contribution of SPLET and HAT mechanism depends on the ability of the solvent to ionize ArOH and the reduction potential of the free radical involved. Furthermore, the fate of the ArOH-derived radicals, i.e., the phenoxyl radicals, was investigated by the oxidative product analysis of ArOHs and GO(*) in ethanol. The major products were dihydrofuran dimers in the case of resveratrol, 4,4'-DHS, and 4-HS and a dioxane-like dimer in the case of 3,4-DHS. It is suggested from the oxidative products of these ArOHs that the hydroxyl group at the 4-position is much easier to subject to oxidation t

Topics: Acetates; Antioxidants; Ethanol; Free Radicals; Kinetics; Molecular Structure; Resveratrol; Solvents; Stilbenes; Structure-Activity Relationship

Preparative high-speed counter-current chromatography (HSCCC) was successfully applied to the isolation and purification of three stilbene oligomers from Vitis chunganeniss using stepwise elution with a pair of two-phase solvent systems composed of n-hexane-ethyl acetate-methanol-water at (2:5:2:5, v/v) and (1:2:1:2, v/v). The preparative HSCCC separation was performed on 800 mg of crude sample yielding hopeaphenol (21.1 mg), amurensin G (37.2 mg) and vitisin A (95.6 mg) in a one-step separation, with purities over 95% as determined by HPLC. The structures of these three compounds were identified by MS, (1)H NMR and (13)C NMR. In addition, their antioxidant activities were screened by DPPH assay, where vitisin A showed strong antioxidant activity. Further EPR experiments with spin-trapping technique demonstrated that vitisin A is a potent and selective singlet oxygen quencher, which may be used in singlet oxygen-mediated diseases as a pharmacological agent.

Topics: Acetates; Antioxidants; Chromatography, High Pressure Liquid; Countercurrent Distribution; Hexanes; Methanol; Molecular Conformation; Solvents; Stilbenes; Time Factors; Vitis; Water