Homogentisic Acid and Gentisic Acid Biosynthesized Pyomelanin Mimics: Structural Characterization and Antioxidant Activity.

Pyomelanin mimics from homogentisic acid (HGA) and gentisic acid (GA) were biosynthesized by the oxidative enzyme T. versicolor laccase at physiological pH to obtain water soluble melanins. The pigments show brown-black color, broad band visible light absorption, a persistent paramagnetism and high antioxidant activity. The EPR approach shows that at least two different radical species are present in both cases, contributing to the paramagnetism of the samples. This achievement can also shed light on the composition of the ochronotic pigment in the Alkaptonuria disease. On the other hand, these soluble pyomelanin mimics, sharing physico-chemical properties with eumelanin, can represent a suitable alternative to replace the insoluble melanin pigment in biotechnological applications.

Marine Fungus Aspergillus chevalieri TM2-S6 Extract Protects Skin Fibroblasts from Oxidative Stress.

The strain Aspergillus chevalieri TM2-S6 was isolated from the sponge Axinella and identified according to internal transcribed spacer (ITS) molecular sequence homology with Aspergillus species from the section Restricti. The strain was cultivated 9 days on potato dextrose broth (PDB), and the medium evaluated as antioxidant on primary normal human dermal fibroblasts (NHDF). The cultivation broth was submitted to sterile filtration, lyophilized and used without any further processing to give the Aspergillus chevalieri TM2-S6 cultivation broth ingredient named ACBB. ACCB contains two main compounds: tetrahydroauroglaucin and flavoglaucin. Under oxidative stress, ACCB showed a significant promotion of cell viability. To elucidate the mechanism of action, the impact on a panel of hundreds of genes involved in fibroblast physiology was evaluated. Thus, ACCB stimulates cell proliferation (VEGFA, TGFB3), antioxidant response (GPX1, SOD1, NRF2), and extracellular matrix organization (COL1A1, COL3A1, CD44, MMP14). ACCD also reduced aging (SIRT1, SIRT2, FOXO3). These findings indicate that Aspergillus chevalieri TM2-S6 cultivation broth exhibits significant in vitro skin protection of human fibroblasts under oxidative stress, making it a potential cosmetic ingredient.

A review on gentisic acid as a plant derived phenolic acid and metabolite of aspirin: Comprehensive pharmacology, toxicology, and some pharmaceutical aspects.

Beneficial therapeutic effects of phenolic acids have been proven in various research projects including in vivo and in vitro studies. Gentisic acid (GA) is a phenolic acid that has been associated with useful effects on human health, such as antiinflammatory, antigenotoxic, hepatoprotective, neuroprotective, antimicrobial, and especially antioxidant activities. It is an important metabolite of aspirin and also widely distributed in plants as a secondary plant product such as Gentiana spp., Citrus spp., Vitis vinifera, Pterocarpus santalinus, Helianthus tuberosus, Hibiscus rosa-sinensis, Olea europaea, and Sesamum indicum and in fruits such as avocados, batoko plum, kiwi fruits, apple, bitter melon, black berries, pears, and some mushrooms. This study was undertaken to review the pharmacological effects, pharmacokinetic properties as well as toxicity and pharmaceutical applications of GA.

In vitro antioxidant and inhibitory activity of water decoctions of carob tree (Ceratonia siliqua L.) on cholinesterases, α-amylase and α-glucosidase.

This work reports the in vitro inhibitory activity of water decoctions of leaves, germ flour, pulp, locust bean gum and stem bark of carob tree on α-amylase, α-glucosidase, acetylcholinesterase and butyrylcholinesterase. The antioxidant activity and the chemical characterisation of the extracts made by spectrophotometric assays and by high-performance liquid chromatography are also reported. Leaves and stem bark decoctions strongly inhibited all the enzymes tested, had significant antioxidant activity and the highest total phenolics content. The major compounds were identified as gallic acid in the leaves and gentisic acid in the stem bark.

Enhancement of soluble dietary fibre, polyphenols and antioxidant properties of chapatis prepared from whole wheat flour dough treated with amylases and xylanase.

BACKGROUND: Chapati preparation involves various processing steps such as mixing the flour into dough, sheeting and baking. During these processing steps, flour components are likely to undergo changes in their nutrient and polyphenol composition and their antioxidant properties due to phenol-mediated crosslinking of proteins and carbohydrates. Therefore, in the present study, changes in nutritional, nutraceutical and antioxidant properties of chapatis prepared from doughs treated with amylases and xylanase were determined. RESULTS: An increase in insoluble dietary fibre content and a decrease in soluble polyphenol content were observed during preparation of control chapatis from whole wheat flours. However, significant increases in soluble dietary fibre and soluble polyphenol contents were observed in chapatis prepared from amylase-treated doughs compared with control chapatis. Extracts of chapatis prepared from amylase- and xylanase-treated doughs showed better antioxidant properties than extracts of control chapatis. Among these enzyme treatments, chapatis prepared from amylase-treated doughs showed better antioxidant properties than chapatis prepared from xylanase-treated doughs. High-performance liquid chromatography analysis of extracts of chapatis prepared from doughs treated with amylases showed the presence of potential antioxidant phenolic acids such as caffeic, gentisic and syringic acids in addition to the phenolic acids present in control chapatis. CONCLUSION: Treatment of doughs with amylases increased the contents of soluble dietary fibre and soluble polyphenols as well as improving the antioxidant properties of chapatis.

Nanoparticle-assisted MALDI-TOF MS combined with seed-layer surface preparation for quantification of small molecules.

Despite the advantages of simplicity and high-throughput detection that matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has over other methods, quantitative analysis of low-molecular-weight analyte is hampered by interference from matrix-derived background noise and signal fluctuation due to the inhomogeneous MALDI sample surface. Taking advantage of improved sample homogeneity through matrix-conjugated magnetic nanoparticles (matrix@MNP) and the seed-layer method, we report a new strategy for the rapid identification and quantification of drugs in urine samples, using morphine and 7-aminoflunitrazepam (7-aminoFM2) as model compounds. To our knowledge, this is the first attempt using the seed-layer method for small molecule analysis. By applying the proposed seed-layer method, which was specifically optimized for the 2,5-dihydroxybenzoic acid@MNP (DHB@MNP) matrix, homogeneous sample crystallization examined by microscopy analysis was obtained that generated reproducible MALDI signals (RSD<10.0%). For urine sample analysis, simple liquid-liquid extraction as a sample pretreatment step effectively reduced the ion suppression effect caused by the endogenous components in urine; good recoveries (82-90%) were obtained with a small ion suppression effect (<14% of signal decrease). This newly developed method demonstrated good quantitation linearity over a range of 50-2000 ng mL(-1) (R(2)>0.996) with reduced signal variation (RSD<10.0%). The detection limit is 30 ng mL(-1) with good precision (intra-day, 2.0-9.3%; inter-day, 5.0-10.0%) and accuracy (intra-day, 95.0-106.0%; inter-day, 103.0-115.5%). The nanoparticle-assisted MALDI-TOF MS combined with seed-layer surface preparation provides a rapid, efficient and accurate platform for the quantification of small molecules in urine samples.

Gentisides C-K: nine new neuritogenic compounds from the traditional Chinese medicine Gentiana rigescens Franch.

Nine new alkyl 2,3-dihydroxybenzoates, gentisides C-K, were isolated from the traditional Chinese medicine Gentiana rigescens Franch. Their structures and stereochemistry were elucidated by spectroscopic methods, and comparison of the specific rotation with that of the gentiside B. These metabolites are additional members of the gentisides which belong to a novel class of neuritogenic compounds. They are structurally different from one another because they possess varying alkyl chain lengths, with or without an isobutyl or isopropyl group at the end of the alkyl chain. These compounds are potent inducers of neurite outgrowth on PC12 cells. The gentiside C possessing the shortest alkyl chain length exhibited the highest neuritogenic activity among all of the gentisides. Gentiside C showed a significant neuritogenic activity at 1 µM against PC12 cells comparable to that seen for the best nerve growth factor (NGF) concentration of 40 ng/mL. In addition, evident neuritogenic activity was observed in the cells when treated with gentiside C at a concentration as low as 0.03 µM. The structure-activity relationships within the gentisides A-K revealed that alkyl chain length is important for the activity, but structure diversity at the end of the alkyl chain is not.

Evaluation of flavoglaucin, its derivatives and pyranonigrins produced by molds used in fermented foods for inhibiting tumor promotion.

Flavoglaucin, its derivatives, and pyranonigrins, which are antioxidants produced by the molds used in fermented foods, were examined for their inhibition of tumor promotion by the Epstein-Barr virus early antigen activation test. Flavoglaucin and its derivatives exhibited high activity. Flavoglaucin and such a derivative as isodihydroauroglaucin inhibited mouse skin tumor promotion in a two-stage carcinogenesis test and appear to be antitumor promoters.

Gentisides A and B, two new neuritogenic compounds from the traditional Chinese medicine Gentiana rigescens Franch.

Two new alkyl 2,3-dihydroxybenzoates, gentisides A and B, were isolated from the traditional Chinese medicine Gentiana rigescens Franch. Their structures and stereochemistry were elucidated by spectroscopic methods and chemical derivatization. These compounds showed a significant neuritogenic activity at 30 microM against PC12 cells that was comparable to that seen for the best nerve growth factor (NGF) concentration of 40 ng/mL. Gentisides A and B showed parallel activity, indicating that the observed structural difference at the end of their alkyl chain did not affect neuritogenic activity.

[Studies on the chemical constituents of Sarcopyramis nepalensis].

OBJECTIVE: To study the chemical constituents of Sarcopyramis nepalensis. METHODS: The constituents were isolated and purified with chromatography and the structures were elucidated by spectral analysis. RESULTS: Ten compounds were isolated and their structures were identified as: (E)-1-(3,4-dihydroxy-phenyl) ethyl acrylate (I), stearic acid (II), palmitic acid (III), 4-hydroxybenzonic acid (IV), 3,4-dihydroxy benzoic acid (V), gentisic acid ( VI), gallic acid (VII), beta-sitosterol (VIII), daucosterol (IX), stigmasterolstearate (X). CONCLUSION: Compounds I , IV, V, VI, VII are isolated from this plant for the first time.

Radical-scavenging activity of hot water extract of Japanese rice bran--association with phenolic acids.

A strong radical-scavenging activity against a stable radical compound, 1,1-diphenyl-2-picrylhydrazyl (DPPH) was found in the hot water extract of Japanese rice bran. When the extract was treated with ethanol, a dominant radical-scavenging activity was observed in the ethanol-soluble (ES) fraction in a dose-dependent manner, but a weak radical-scavenging activity was detected in the ethanol-precipitable (EP) fraction. Their activities were proportional to the amounts of phenolic substances in each fraction. The phenolic substances in the ES fraction were efficiently separated by Amberlite XAD column chromatography and high performance liquid chromatography using an ODS column. The four major phenolic acids (ferulic, para-coumaric, para-hydroxybenzoic and vanillic acids) and four minor phenolic acids (caffeic, gentisic, protocatechuic and syringic acids) were detected in the HPLC system. Among these phenolic acids, protocatechuic, caffeic, ferulic and gentisic acids showed relatively strong radical scavenging activities (EC50: 8, 9, 29 and 75 microM, respectively) compared with the control antioxidants such as ascorbic acid and alpha-tocopherol (EC50: 93 and 134 microM). Para-coumaric, syringic and vanillic acids exhibited weak but significant radical-scavenging activities (EC50: 780, 2640 and 3250 microM). However, para-hydroxybenzoic acid did not show any significant effects even at 5 mM. Furthermore, a simulated mixture combined with these phenolic acids in comparable amounts in the ES fraction showed slightly weak radical-scavenging activity compared with that of rice bran extract. However, all the phenolic acids detected in the ES fraction did not show significant antioxidant activities against hydroperoxide generation in lipid peroxidation compared with that of a typical antioxidant such as ascorbic acid, which was estimated by the alminum chloride method. These results suggest that Japanese rice bran has a potent radical-scavenging activity against DPPH radical and this activity is associated with some phenolic acids in the ES fraction. The significance of this finding is discussed from the viewpoint of the protective role of rice bran against oxygen radical-induced chronic diseases.

Quantitation of patulin pathway metabolites using gas-liquid chromatography.

A gas-liquid chromatographic system which allows most of the metabolites of the patulin pathway to be separated and quantitated has been developed. The metabolites are mostly phenols, and after conversion to their trimethylsilyl derivatives they are efficiently separated on a 3.18 mm O.D. stainless-stell column of 10% QF-1 on Gas-Chrom Q using a temperature programme. The detection limits for the three phenolic acids, 6-methylsalicylic acid, m-hydroxybenzoic acid and gentisic acid are all markedly lower than those obtained in previous systems. The usefulness of the system has been assessed by quantitating the patulin pathway metabolites present in culture filtrates of Penicillium urticae NRRL 2159A.