Urinary metabolites of gallic acid in rats and their radical-scavenging effects on 1,1-diphenyl-2-picrylhydrazyl radical

Exploring the underlying pharmacological, immunomodulatory, and anti-inflammatory mechanisms of phytochemicals against wounds: a molecular insight

BACKGROUND

Numerous cellular, humoral, and molecular processes are involved in the intricate process of wound healing.

PHARMACOLOGICAL RELEVANCE

Numerous bioactive substances, such as ß-sitosterol, tannic acid, gallic acid, protocatechuic acid, quercetin, ellagic acid, and pyrogallol, along with their pharmacokinetics and bioavailability, have been reviewed. These phytochemicals work together to promote angiogenesis, granulation, collagen synthesis, oxidative balance, extracellular matrix (ECM) formation, cell migration, proliferation, differentiation, and re-epithelialization during wound healing.

FINDINGS AND NOVELTY

To improve wound contraction, this review delves into how the application of each bioactive molecule mediates with the inflammatory, proliferative, and remodeling phases of wound healing to speed up the process. This review also reveals the underlying mechanisms of the phytochemicals against different stages of wound healing along with the differentiation of the in vitro evidence from the in vivo evidence There is growing interest in phytochemicals, or plant-derived compounds, due their potential health benefits. This calls for more scientific analysis and mechanistic research. The various pathways that these phytochemicals control/modulate to improve skin regeneration and wound healing are also briefly reviewed. The current review also elaborates the immunomodulatory modes of action of different phytochemicals during wound repair.

Screening and characterization of xenobiotics in rat bio-samples after oral administration of Shen-Wu-Yi-Shen tablet using UPLC-Q-TOF-MS/MS combined with a targeted and non-targeted strategy

Shen-Wu-Yi-Shen tablet (SWYST), a well-known traditional Chinese medicine prescription (TCMP), has been effectively used for treating chronic kidney disease (CKD) in clinically. However, an in-depth study of in vivo metabolism of SWYST is lacking. In this study, a targeted and non-targeted strategy based on ultra-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry (UPLC-Q-TOF-MS/MS) was developed to screen and characterize SWYST-related xenobiotics in rats. Based on the in-house library, a chemical database of SWYST including 215 constituents was constructed through "find by formula" and further verified by characteristic fragmentations or the literatures. Then the constructed chemical database was applied for the targeted screening of prototypes. As for metabolites, the non-targeted screening was achieved combined the peak picking using the function "find by auto-MS/MS" and peak filtration of the prototypes and endogenous components, while the targeted screening was performed using Metabolite ID according to the possible metabolic reactions. Furthermore, the potential metabolites were preliminarily identified by comparison of the parent compounds or references to the literatures. As a result, 201 exogenous components (87 prototypes and 121 metabolites) were characterized in rats after administration of SWYST, including 55 (17 prototypes and 38 metabolites) in plasma, 151 (52 prototypes and 99 metabolites) in urine, and 121 (74 prototypes and 47 metabolites) in feces. Finally, their possible metabolic pathways were summarized, and the metabolic reactions mainly involved phase I reactions (hydroxylation, deoxygenation, hydrogenation, methylation, oxidation, hydrolysis and esterification) and phase II reactions (glucuronidation and sulfation). The findings of this research reveal the potential active ingredients of SWYST, providing an important material basis for the pharmacokinetics and pharmacodynamics of SWYST.

Ethnopharmacology of Rubus idaeus Linnaeus: A critical review on ethnobotany, processing methods, phytochemicals, pharmacology and quality control

ETHNOPHARMACOLOGICAL RELEVANCE

Rubus idaeus Linnaeus (RI) is a Chinese herbal medicine that has been widely used in China for a long time to reinforce the kidney, nourish the liver, improve vision, and arrest polyuria.

AIM OF THE STUDY

This work aims to evaluate the recent progress of the chemical composition, pharmacological activity, pharmacokinetics, metabolism, and quality control and of Rubus idaeus, which focuses on the insufficiency of existing research and will shed light on future studies of Rubus idaeus.

METHODS

Literatures about "Rubus idaeus","Red raspberry" and "Fupenzi"are retrieved by browsing the database, such as Web of Science (http://www.webofknowledge.com/wos), Pubmed (https://pubmed.ncbi.nlm.nih.gov/), CNKI (http://www.cnki.net/), and Wanfang Data (http://www.wanfangdata.com.cn). In addition, related textbooks and digital documents are interrogated to provide a holistic and critical review of the topic. The period of the literature covered from 1981 to 2022.

RESULTS

Approximately 194 compounds have been isolated from Rubus idaeus, which is rich in phenols, terpenoids, alkaloids, steroids, and fatty acids. Numerous investigations have demonstrated that Rubus idaeus exhibits many pharmacological activities, including hypoglycemic and hypolipidemic, anti-Alzheimer effect, anti-osteoporosis, hepatoprotective, anti-cancer, neuroprotective, anti-bacteria and skin care, etc. However, it is worth noting that most of the research is not associated with the conventional effect, such as reducing urination and treating opacity of the cornea.

CONCLUSION

The effectiveness of Rubus idaeus has been proved by its long-term clinical application. The research on the pharmacological activity of Rubus idaeus has flourished. In many pharmacological experiments, only the high-dose group can achieve the corresponding efficacy, so the efficacy of Rubus idaeus needs to be further interrogated. Meanwhile, the relationship between pharmacological activity and specific compounds of Rubus idaeus has not been clarified yet. Last but not least, studies involving toxicology and pharmacokinetics are very limited. Knowledge of bioavailability and toxicological behavior of Rubus idaeus can help understand the herb's pharmacodynamic and safety profile.

Effect of gallic acid on the reproduction of adolescent male Brandt’s voles (Lasiopodomys brandtii)

Gallic acid (GA), a phenol that is present in various plants, potentially contains antioxidant properties. This study aimed to investigate the effects of GA on the reproduction of adolescent male Brandt’s voles (Lasiopodomys brandtii (Radde, 1861)). Antioxidant levels and apoptosis in the testis, as well as reproductive physiology, were evaluated in adolescent males treated with GA. The results showed that a low dose of GA enhanced relative epididymis mass and the sperm density in the epididymis, increased the mRNA levels of steroidogenic acute regulatory protein in the testis, and reduced the percentages of abnormal and dead sperm. In addition, a low dose of GA significantly increased the levels of superoxide dismutase, catalase, and glutathione peroxidase, and decreased the level of malondialdehyde in the testis, as well as the mRNA and protein levels of the apoptosis-related gene, caspase-3. However, a high dose of GA sharply reduced the mean diameter of the seminiferous tubules compared with a low dose. Collectively, these findings demonstrate that GA treatment during puberty affects the reproductive responses of male Brandt’s voles in a dose-dependent manner by regulating antioxidant levels and apoptosis.

Antioxidant potential and optimization of production of extracellular polysaccharide by Acinetobacter indicus M6

Background

Extracellular polysaccharides (ECPs) produced by biofilm-producing marine bacterium have great applications in biotechnology, pharmaceutical, food engineering, bioremediation, and bio-hydrometallurgy industries. The ECP-producing strain was identified as Acinetobacter indicus M6 species by 16S rDNA analysis. The polymer produced by the isolate was quantified and purified and chemically analyzed, and antioxidant activities have been studied. The face-centered central composite design (FCCCD) was used to design the model.

Results

The results have clearly shown that the ECP was found to be endowed with significant antioxidative activities. The ECP showed 59% of hydroxyl radical scavenging activity at a concentration of 500 μg/mL, superoxide radical scavenging activity (72.4%) at a concentration of 300 μg/mL, and DPPH˙ radical scavenging activity (72.2%) at a concentration of 500 μg/mL, respectively. Further, HPLC and GC-MS results showed that the isolated ECP was a heteropolymer composed of glucose as a major monomer, and mannose and glucosamine were minor monomers. Furthermore, the production of ECP by Acinetobacter indicus M6 was increased through optimization of nutritional variables, namely, glucose, yeast extract, and MgSO₄ by “Response Surface Methodology”. Moreover the production of ECP reached to 2.21 g/L after the optimization of nutritional variables. The designed model is statistically significant and is indicated by the R² value of 0.99. The optimized medium improved the production of ECP and is two folds higher in comparison with the basal medium.

Conclusions

Acinetobacter indicus M6 bacterium produces a novel and unique extracellular heteropolysaccharide with highly efficient antioxidant activity. GC-MS analyses elucidated the presence of quite uncommon (1→4)-linked glucose, (1→4)-linked mannose, and (→4)-GlcN-(1→) glycosidic linkages in the backbone. The optimized medium improved the production of ECP and is two folds higher in comparison with the basal medium. The newly optimized medium could be used as a promising alternative for the overproduction of ECP.

Biodegradable and biocompatible spherical dendrimer nanoparticles with a gallic acid shell and a double-acting strong antioxidant activity as potential device to fight diseases from "oxidative stress"

Gallic acid (GA) is a natural polyphenol with remarkable antioxidant power present in several vegetables and fruits. A normal feeding regime leads to a daily intake of GA which is reasonably regarded as "natural" and "safe" for humans. It owns strong potentials as alternative to traditional drugs to treat several diseases triggered by oxidative stress (OS), but poor gastrointestinal absorbability, pharmacokinetic drawbacks, and fast metabolism limit its clinical application. In this work, a fifth-generation polyester-based dendrimer was firstly prepared as a better absorbable carrier to protect and deliver GA. Then, by its peripheral esterification with GA units, a GA-enriched delivering system (GAD) with remarkable antioxidant power and high potential against diseases from OS was achieved. Scanning electron microscopy results and dynamic light scattering analysis revealed particles with an average size around 387 and 375 nm, respectively, and an extraordinarily spherical morphology. These properties, by determining a large particles surface area, typically favour higher systemic residence time and bio-efficiency. Z-potential of - 25 mV suggests satisfactory stability in solution with tendency to form megamers and low polydispersity index. GAD showed intrinsic antioxidant power, higher than GA by 4 times and like prodrugs, and it can carry contemporary several bioactive GA units versus cells. In physiological condition, the action of pig liver esterase (PLE), selected as a model of cells esterase, hydrolyses GAD to non-cytotoxic small molecules, thus setting free the bioactive GA units, for further antioxidant effects. Cytotoxicity studies performed on two cell lines demonstrated a high cell viability. Graphical Abstract Graphical Abstract.

Improved recovery of galloyl metabolites from mango (Mangifera indica L.) in human plasma using protein precipitation with sodium dodecyl sulfate and methanol

Extraction of polyphenolic metabolites from blood fractions can be challenging since compound recovery can be limited by chemical structure, polarity, and protein-binding affinity of analytes. Gallic acid and its metabolites exhibit particularly low recoveries from plasma and can lead to an underestimation of their bioavailability from foods. A modified method to extract free gallic acid and its metabolites from human plasma aided by sodium dodecyl sulfate and acidified methanol (SDS-MeOH) was applied to extract free gallic acid and its metabolites from human plasma after a single consumption of 400 g of mango (cv. Ataulfo) pulp by 10 healthy male and female subjects. The use of SDS-MeOH facilitated extraction of significantly (p < 0.05) more pyrogallol, free gallic acid, 4-O-methylgallic acid, and ethyl gallate with recovery rates exceeding 80% in standard recovery from human blood plasma when compared to conventional methods that rely on solvent extraction or solid phase extraction. The method was reproducible and precise for standards from 50 to 500 μg/L. In pharmacokinetic plasma samples five predominant metabolites of gallic acid were tentatively characterized by HPLC-MS and absorption kinetics evaluated over 8 h for catechol-O-sulfate, 4-O-methylgallic acid-3-O-sulfate, and pyrogallol-O-sulfate, methylpyrogallol-O-sulfate, and 4-O-methylgallic acid with AUC_0-8h of 9520 ± 3370, 6030 ± 1310, 5990 ± 1690, 4020 ± 1040, and 2790 ± 1190 μg/L h respectively. Plasma extraction was rapid and reproducible with superior recovery rates compared to conventional methods when evaluating polar phenolic metabolites.

Urinary Metabolites of Green Tea as Potential Markers of Colonization Resistance to Pathogenic Gut Bacteria in Mice

Background

The gut microbiome (GMB) generates numerous chemicals that are absorbed systemically and excreted in urine. Antibiotics can disrupt the GMB ecosystem and weaken its resistance to colonization by enteric pathogens such as Clostridium difficile. If the changes in GMB composition and metabolism are sufficiently large, they can be reflected in the urinary metabo-lome. Characterizing these changes could provide a potentially valuable biomarker of the status of the GMB. While preliminary studies suggest such a possibility, the high level of data variance presents a challenge to translational applications. Since many GMB-generated chemicals are derived from the biotransformation of plant-derived dietary polyphenols, administering an oral precursor challenge should amplify GMB-dependent changes in urinary metabolites.

Methods

A course of antibiotics (clindamycin, piperacillin/tazobactam, or aztreonam) was administered SC daily (days 1 and 2) to mice receiving polyphenol-rich green tea in drinking water. Urine was collected at baseline as well as days 3, 7, and 11. Levels of pyrogallol and pyrocatechol, two phenolic molecules unequivocally GMB-dependent in humans but that had not been similarly examined in mice, were quantified.

Results

In confirmation of our hypothesis, differential changes in murine urinary pyrogallol levels identified the treatments (clindamycin, piperacillin/tazobactam) previously associated with a weakening of colonization resistance to Clostridium difficile. The changes in pyrocatechol levels did not withstand corrections for multiple comparisons.

Conclusions

In the mouse, urinary pyrogallol and, in all likelihood, pyrocatechol levels, are GMB-dependent and, in combination with precursor challenge, deserve further consideration as potential metabolomic biomarkers for the health and dysbiotic vulnerability of the GMB.

Reshaped as polyester-based nanoparticles, gallic acid inhibits platelet aggregation, reactive oxygen species production and multi-resistant Gram-positive bacteria with an efficiency never obtained

Natural polyphenols such as Gallic Acid (GA) form an important class of bioactive chemical entities that, having innumerable biological properties, could represent a safer alternative to common drugs against several disorders, including platelet aggregation, radical oxygen species (ROS) hyperproduction, oxidative stress (OS) and bacterial infections. Unfortunately, their clinical uses are limited by pharmacokinetics drawbacks and high sensitivity to environmental factors. In order to overcome these problems and to exploit the GA curative potentials, it has been linked to a biodegradable nanospherical dendrimer matrix, capable of protecting it, thus obtaining a GA-enriched nanosized dendrimer (GAD) endowed with a strong antioxidant capacity. GAD activity as an inhibitor of platelet aggregation and ROS accumulation and its antibacterial efficiency are evaluated here and compared to those of free GA, obtaining outcomes never achieved. Regarding platelet aggregation induced by thrombin and collagen, the GAD proved to be stronger by 7.1 and 7.3 times, respectively. Furthermore, the GAD showed a ROS inhibitory activity higher than that of GA by 8.1 (thrombin) and 6.9 (collagen) times. Concerning the antibacterial activities, evaluated on eleven multi-resistant Gram-positive strains of clinical relevance, the GAD is far more potent than GA, by exerting a growth inhibitory activity at MIC (μM) concentrations lower by factors in the range 12-50.

Computational and biological investigation of the soybean lecithin-gallic acid complex for ameliorating alcoholic liver disease in mice with iron overload

Alcoholic liver disease (ALD) is associated with significant morbidity and mortality globally. In this study, the soybean lecithin-gallic acid complex was synthesized, and its physicochemical properties were evaluated, which confirmed the complex formation. Compared with the free state of the drug, gallic acid exhibited significantly different physicochemical properties after it was complexed with soybean lecithin. To clarify the binding mode between two monomers, computational investigation was performed. From the computational data, we deduced the structure of the compound and predicted that it has a high affinity for human phosphatidylcholine transfer protein and exhibits strong pharmacological activities in vivo. The complex not only effectively ameliorated liver fibrosis, lipid peroxidation, and oxidative stress, but also reduced liver iron overload in a mouse ALD model induced by alcohol (p < 0.05). Additionally, it regulated iron metabolism by inhibiting TfR1 expression (p < 0.05) and promoting hepcidin expression (p < 0.05). These results suggest that the soybean lecithin-gallic acid complex ameliorates hepatic damage and iron overload induced by alcohol and exert hepatoprotective effects.

Body Mass Index as a Determinant of Systemic Exposure to Gallotannin Metabolites during 6-Week Consumption of Mango (Mangifera indica L.) and Modulation of Intestinal Microbiota in Lean and Obese Individuals

SCOPE

This human clinical pilot trial investigated pharmacokinetics of gallotannin-metabolites and modulation of intestinal microbiota in healthy lean and obese individuals after 6 weeks of daily mango consumption.

METHODS AND RESULTS

Participants are divided into three groups: Lean Mango (LM: n = 12; BMI = 22.9 kg m^-2 ), Obese Mango (OM: n = 9; BMI = 34.6 kg m^-2 ), and Lean Control (LC: n = 11; BMI = 22.1 kg m^-2 ). LM and OM consumed 400 g of mango per day for 6 weeks. LC consumed mango only on Days 0 and 42. After 6 weeks, LM experienced increased systemic exposure (AUC_0-8h ) to gallotannin-metabolites, 1.4-fold (p = 0.043). The greatest increase is 4-O-methyl-gallic acid, 3.3-fold (p = 0.0026). Cumulative urinary excretion of gallotannin-metabolites significantly increased in LM and OM, but not LC. For OM, qPCR data show increased levels of tannase-producing Lactococcus lactis and decreased levels of Clostridium leptum and Bacteroides thetaiotaomicron, bacteria associated with obesity. LM experienced an increased trend of fecal levels of butyric (1.3-fold; p = 0.09) and valeric acids (1.5-fold; p = 0.056). Plasma endotoxins showed a decreased trend in LM and OM.

CONCLUSION

Continuous mango intake significantly increased systemic exposure to gallotannin- metabolites and induced an increased trend for fecal short-chain fatty acids in lean but not obese individuals. This pharmacokinetic discrepancy may result in BMI-associated reduced gallotannin-derived health benefits.

Gallic acid loaded PEO-core/zein-shell nanofibers for chemopreventive action on gallbladder cancer cells

Coaxial electrospinning was used to develop gallic acid (GA) loaded poly(ethylene oxide)/zein nanofibers in order to improve its chemopreventive action on human gallbladder cancer cells. Using a Plackett-Burman design, the effects of poly(ethylene oxide) and zein concentration and applied voltage on the diameter and morphology index of nanofibers were investigated. Coaxial nanofibers were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). GA loading efficiency as high as 77% was obtained under optimal process conditions. The coaxial nanofibers controlled GA release in acid and neutral pH medium. Cytotoxicity and reactive oxygen species (ROS) production on gallbladder cancer cell lines GB-d1 and NOZ in the presence of GA-nanofibers were assessed. GA-nanofibers triggered an increase in the cellular cytotoxicity compared with free GA on GB-d1 and NOZ cells. Statistically significant differences were found in ROS levels of GA-nanofibers compared with free GA on NOZ cells. Differently, ROS production on GB-d1 cell line was similar. Based on these results, the coaxial nanofibers obtained in this study under optimized operational conditions offer an alternative for the development of a GA release system with improved chemopreventive action on gallbladder cancer cells.

Comparative Pharmacokinetics of Gallic Acid After Oral Administration of Gallic Acid Monohydrate in Normal and Isoproterenol-Induced Myocardial Infarcted Rats

Gallic acid (GA) is a polyphenolic natural product widely distributed in food, beverage, and traditional Chinese herbs with beneficial effects on the cardiovascular system. In this research, a comparative study was conducted to investigate the possible difference of pharmacokinetic process in normal and isoproterenol-induced myocardial infarcted rats after oral administration of GA monohydrate with the dose of 50 and 100 mg/kg, respectively. Quantification of GA in rat plasma was achieved by using a simple and rapid high-performance liquid chromatographic method. The results revealed that pharmacokinetics of GA were greatly different between normal and pathological state. GA exhibited slower absorption into the bloodstream, and yielded 1.7-fold (50 mg/kg GA) and 1.3-fold (100 mg/kg GA) less values of area under concentration-time curve as well as 2.5-fold lower of maximum blood concentration (C_max) in MI rats than those in normal rats. In addition, significant prolonged T_1/2 and MRT as well as decreased CL were also registered in MI rats. Our findings suggest that myocardial infarction could alter the pharmacokinetic process of GA, and thus the potential pharmacokinetic differences of herbal preparations (or dietary nutrition) containing GA between normal and pathological conditions should be brought to the forefront seriously in clinical practice.

Gallic acid-PAMAM and gallic acid-phospholipid conjugates, physicochemical characterization and in vivo evaluation

Gallic acid (GA) is a naturally occurring compound with valuable antioxidant activity. Its oral bioavailability is limited by its high metabolism and rapid clearance. In this paper, GA was conjugated with two different materials, phosphatidylcholine (PC) and polyamidoamine (PAMAM) dendrimer. The prepared conjugates were characterized by FTIR, DSC, and SEM. Also, they were tested for drug content and in vitro drug release. It was found that GA conjugation with both materials have significantly prolonged its release up to 12 h. In vivo hepatoprotective activity of free and conjugated GA was studied in rats after carbon tetrachloride (CCl4)-induced oxidative damage in rat liver through measurement of different liver marker enzymes (aspartate aminotransferase (AST), alanine aminotransferase (ALT)), in addition to the total protein and albumin level in rat serum. Also, histopathological examination of liver cell of all rat groups was done. Results showed that both prepared conjugates have significantly reduced the hepatic marker enzymes accompanied by normalizing total protein and albumin levels in rat serum and with respect to CCl4-induced group (p < .05). Histopathological examination showed that pretreatment of rats with GA-PC or GA-PAMAM before CCL4 could reduce the induced cellular histopathological changes. It appears that conjugation of GA could enhance its bioavailability and increase its hepatoprotective effect.

Antioxidant properties and polyphenolic content in terrestrial cyanobacteria

Cell-free extracts of twenty terrestrial cyanobacteria were evaluated for their antioxidant properties in terms of free-radical scavenging (DPPH and ABTS) and metal chelating activity and deoxyribose protection. Extract of Anabaena constricta was the most prominent antioxidant agent (IC50 for DPPH activity 0.91 mg ml-1, ABTS 0.23 mg ml-1, deoxyribose protection 0.63 mg ml-1 and Fe+2-ion chelating 0.9 mg ml-1). The extracts of cyanobacterial species contained high quantity of total phenol and total flavonoid that were supposed to impart prominent antioxidant properties. Cyanobacterial species also showed fairly high PAL activity. We reported varied quantities of polyphenolics gallic, chlorogenic, caffeic, vanillic and ferulic acids and flavonoids rutin, quercetin and kaempferol in cyanobacterial extracts. The presence of these polyphenolics was linked with the free radical scavenging, metal chelating and antioxidative damage protecting properties of the organisms. Cyanobacteria are the most feasible, promising and alternative candidates for searching out new chemical leads for industrial applications in pharmaceuticals, neutraceuticals and biomolecules of importance. Presence of biomolecules such as polyphenolics and their connection with the prominent biological functions (e.g., antioxidant properties) make these organisms a potential source of secondary metabolites with predominant biological activities. Additionally, dominant presence of polyphenols as antioxidant agents in cyanobacterial species may reflect their adaptation strategies against abiotic stresses for their ecological success in different habitats.

A UPLC-MS/MS Method for Simultaneous Determination of Free and Total Forms of a Phenolic Acid and Two Flavonoids in Rat Plasma and Its Application to Comparative Pharmacokinetic Studies of Polygonum capitatum Extract in Rats

The principal active constituents of Polygonum capitatum are phenolic acids and flavonoids, such as gallic acid, quercitrin, and quercetin. The aim of this study was to develop and validate a method to determine the three constituents and the corresponding conjugated metabolites of Polygonum capitatum in vivo and to conduct pharmacokinetic studies on the herb, a well-known Miao medicinal plant in China. Gallic acid, quercitrin, and quercetin were analysed by ultra-performance liquid chromatography-electrospray ionization-tandem mass spectrometry (UPLC-ESI-MS/MS). Protein precipitation in plasma samples was performed using methanol. For the determination of total forms of analytes, an additional process of hydrolysis was conducted using β-glucuronidase and sulphatase. The analytes were separated on a BEH C₁₈ column (50 mm × 2.1 mm; i.d., 1.7 μm) and quantified by multiple reaction monitoring (MRM) mode. The linear regression showed high linearity over a 729-fold dynamic range for the three analytes. The relative standard deviations of intra- and inter-day measurements were less than 9.5%, and the method was accurate to within −11.1% to 12.5%. The extraction recoveries for gallic acid, quercitrin, and quercetin were 94.3%–98.8%, 88.9%–98.8%, and 95.7%–98.5%, respectively. All samples were stable under short- and long-term storage conditions. The validated method was successfully applied to a comparative pharmacokinetic study of gallic acid, quercitrin, and quercetin in their free and total forms in rat plasma. The study revealed significantly higher exposure of the constituents in total forms for gallic acid and quercetin, while quercitrin was detected mainly in its corresponding free form in vivo. The established method was rapid and sensitive for the simultaneous quantification of free and total forms of multiple constituents of Polygonum capitatum extract in plasma.

Semisynthetic flavonoid 7-O-galloylquercetin activates Nrf2 and induces Nrf2-dependent gene expression in RAW264.7 and Hepa1c1c7 cells

The natural flavonoid quercetin is known to activate the transcription factor Nrf2, which regulates the expression of cytoprotective enzymes such as heme oxygenase-1 (HO-1) and NAD(P)H:quinone oxidoreductase 1 (NQO1). In this study, a novel semisynthetic flavonoid 7-O-galloylquercetin (or quercetin-7-gallate, 3) was prepared by direct galloylation of quercetin, and its effect on the Nrf2 pathway was examined. A luciferase reporter assay showed that 7-O-galloylquercetin, like quercetin, significantly activated transcription via the antioxidant response element in a stably transfected human AREc32 reporter cell line. In addition, 7-O-galloylquercetin caused the accumulation of Nrf2 and induced the expression of HO-1 at both the mRNA and protein levels in murine macrophage RAW264.7 cells. The induction of HO-1 by 7-O-galloylquercetin was significantly suppressed by N-acetyl-l-cysteine and SB203580, indicating the involvement of reactive oxygen species and p38 mitogen-activated protein kinase activity, respectively. HPLC/MS analyses also showed that 7-O-galloylquercetin was not degalloylated to quercetin, but it was conjugated with glucuronic acid and/or methylated in RAW264.7 cells. Furthermore, 7-O-galloylquercetin was found to increase the protein levels of Nrf2 and HO-1, and also the activity of NQO1 in murine hepatoma Hepa1c1c7 cells. Taken together, we conclude that 7-O-galloylquercetin increases Nrf2 activity and induces Nrf2-dependent gene expression in RAW264.7 and Hepa1c1c7 cells.

The Profiling and Identification of the Absorbed Constituents and Metabolites of Guizhi Decoction in Rat Plasma and Urine by Rapid Resolution Liquid Chromatography Combined with Quadrupole-Time-of-Flight Mass Spectrometry

Guizhi decoction (GZD), a well-known traditional Chinese medicine (TCM) prescription consisting of Ramulus Cinnamomi, Radix Paeoniae Alba, Radix Glycyrrhizae, Fructus Jujubae and Rhizoma Zingiberis Recens, is usually used for the treatment of common colds, influenza, and other pyretic conditions in the clinic. However, the absorbed ingredients and metabolic compounds of GZD have not been reported. In this paper, a method incorporating rapid resolution liquid chromatography (RRLC) with quadrupole-time-of-flight mass spectrometry (Q-TOF-MS) was used to identify ingredients after oral administration of GZD. Identification of the primary components in GZD, drug-containing serum and urine samples was carried out in order to investigate the assimilation and metabolites of the decoction in vivo. By comparing the total ion chromatograms (TICs) of GZD, a total of 71 constituents were detected or characterized. By comparing TICs of blank and dosed rat plasma, a total of 15 constituents were detected and identified as prototypes according to their retention time (tR) and MS, MS/MS data. Based on this, neutral loss scans of 80 and 176 Da in samples of rat plasma and urine helped us to identify most of the metabolites. Results showed that the predominant metabolic pathways of (epi) catechin and gallic acid were sulfation, methylation, glucuronidation and dehydroxylation; the major metabolic pathways of flavone were hydrolysis, sulfation and glucuronidation. Furthermore, degradation, oxidation and ring fission were found to often occur in the metabolism process of GZD in vivo.

Phytochemical, antioxidant and hepatoprotective effects of Alnus nitida bark in carbon tetrachloride challenged Sprague Dawley rats

BACKGROUND

Alnus nitida (Spach) Endl. is traditionally used for inflammatory disorders. Diarylheptanoids constituents having diverse therapeutically importance including hepato-protective was reported in A. nitida. The aim of this study was to explore the antioxidant and hepato-protective profile of A. nitida stem bark's crude methanol extract (ANM).

METHODS

Crude methanol extract of A. nitida stem bark and its derived fractions were assessed for phytochemical classes and in vitro antioxidant profiling by multidimensional assays. Hepato-protective assessment of ANM was investigated on rats, which were made hepatotoxic using carbon tetrachloride (CCl4). Additionally HPLC-DAD analysis of ANM, and its derived ethyl acetate and aqueous fraction was carried out to determine the presence of active constituents.

RESULTS

Qualitative analysis of crude extract-and its fractions depicted the presence of terpenoids, saponins, coumarins, phenols and flavonoids. Maximum quantity of total phenolic content (TPC) and total flavonoid content (TFC) was recorded in ANM and its derived fractions; n-hexane (ANH), chloroform (ANC), ethyl acetate (ANE) and the residual aqueous (ANA). ANM exhibited the best total antioxidant capacity, total reducing power, and scavenging of DPPH and OH radicals. ANE and ANA exhibited strong scavenging potential for iron chelation, nitric oxide and β-carotene bleaching assay. ANM treatment converse the activities of serum-marker enzymes and lipid profile, altered by CCl4 treatment in rat. CCl4 induced hepatic-cirrhosis in rat resulted in decrease of antioxidant enzyme activities such as catalase, peroxidase, superoxide dismutase, glutathione peroxidase, glutathione-S-transferase and glutathione reductase-which were restored towards the normal level with ANM. Similarly diminished level of reduced glutathione while enhanced level of lipid peroxides, hydrogen peroxide and nitrite in liver of cirrhotic rats was normalized by treatment of ANM. The histopathological studies of liver tissues also represented that ANM possessed the hepato-protective activity. HPLC-DAD analysis against eight known standards confirmed the presence of gallic acid, catechin and rutin in ANM and in ANA while in ANE gallic acid was only detected.

CONCLUSION

Based on the results of antioxidants, restoration of various antioxidant enzymes and histopathological studies, the recent study concludes that antioxidant potential of A. nitida bark might protect the liver damages.

Urinary metabolites from mango (Mangifera indica L. cv. Keitt) galloyl derivatives and in vitro hydrolysis of gallotannins in physiological conditions

SCOPE

The absorption, metabolism, and excretion of mango galloyl derivatives (GD) has not yet been investigated in humans, and studies investigating repeated dosages of polyphenols are limited.

METHODS AND RESULTS

In this human pilot trial, healthy volunteers (age = 21-38 y, n = 11) consumed 400 g/day of mango-pulp (cv. Keitt) for 10 days, and seven metabolites of gallic acid (GA) were characterized and quantified in urine excreted over a 12 h period. Pyrogallol-O-sulfate and deoxypyrogallol-O-sulfate were found to be significantly more excreted between days 1 and 10 (p < 0.05) from 28.5 to 55.4 mg and 23.6 to 47.7 mg, respectively. Additionally, the in vitro hydrolysis of gallotannins (GTs) was monitored at physiological pH and temperature conditions, and after 4 h a significant (p < 0.05) shift in composition from relativity high to low molecular weight GTs was observed.

CONCLUSION

Seven metabolites of GA were identified in the urine of healthy volunteers, and two microbial metabolites were found to be significantly more excreted following 10 days of mango consumption. Mango GTs were also found to release free GA in conditions similar to the intestines. GTs may serve as a pool of pro-GA compounds that can be absorbed or undergo microbial metabolism.

Factors Influencing Oral Bioavailability of Thai Mango Seed Kernel Extract and Its Key Phenolic Principles

Mango seed kernel extract (MSKE) and its key components (gallic acid, GA; methyl gallate, MG; and pentagalloyl glucopyranose, PGG) have generated interest because of their pharmacological activities. To develop the potential use of the key components in MSKE as natural therapeutic agents, their pharmacokinetic data are necessary. Therefore, this study was performed to evaluate the factors affecting their oral bioavailability as pure compounds and as components in MSKE. The in vitro chemical stability, biological stability, and absorption were evaluated in Hanks' Balanced Salt Solution, Caco-2 cell and rat fecal lysates, and the Caco-2 cell model, respectively. The in vivo oral pharmacokinetic behavior was elucidated in Sprague-Dawley rats. The key components were unstable under alkaline conditions and in Caco-2 cell lysates or rat fecal lysates. The absorptive permeability coefficient followed the order MG > GA > PGG. The in vivo results exhibited similar pharmacokinetic trends to the in vitro studies. Additionally, the co-components in MSKE may affect the pharmacokinetic behaviors of the key components in MSKE. In conclusion, chemical degradation under alkaline conditions, biological degradation by intestinal cell and colonic microflora enzymes, and low absorptive permeability could be important factors underlying the oral bioavailability of these polyphenols.

Effect of myricetin, pyrogallol, and phloroglucinol on yeast resistance to oxidative stress

The health beneficial effects of dietary polyphenols have been attributed to their intrinsic antioxidant activity, which depends on the structure of the compound and number of hydroxyl groups. In this study, the protective effects of pyrogallol, phloroglucinol, and myricetin on the yeast Saccharomyces cerevisiae were investigated. Pyrogallol and myricetin, which have a pyrogallol structure in the B ring, increased H2O2 resistance associated with a reduction in intracellular oxidation and protein carbonylation, whereas phloroglucinol did not exert protective effects. The acquisition of oxidative stress resistance in cells pretreated with pyrogallol and myricetin was not associated with an induction of endogenous antioxidant defences as assessed by the analysis of superoxide dismutase and catalase activities. However, myricetin, which provided greater stress resistance, prevented H2O2-induced glutathione oxidation. Moreover, myricetin increased the chronological lifespan of yeast lacking the mitochondrial superoxide dismutase (Sod2p), which exhibited a premature aging phenotype and oxidative stress sensitivity. These findings show that the presence of hydroxyl groups in the ortho position of the B ring in pyrogallol and myricetin contributes to the antioxidant protection afforded by these compounds. In addition, myricetin may alleviate aging-induced oxidative stress, particularly when redox homeostasis is compromised due to downregulation of endogenous defences present in mitochondria.

Phenolic sulfates as new and highly abundant metabolites in human plasma after ingestion of a mixed berry fruit purée

Bioavailability studies are vital to assess the potential impact of bioactive compounds on human health. Although conjugated phenolic metabolites derived from colonic metabolism have been identified in the urine, the quantification and appearance of these compounds in plasma is less well studied. In this regard, it is important to further assess their potential biological activityin vivo. To address this gap, a cross-over intervention study with a mixed fruit purée (blueberry, blackberry, raspberry, strawberry tree fruit and Portuguese crowberry) and a standard polyphenol-free meal was conducted in thirteen volunteers (ten females and three males), who received each test meal once, and plasma metabolites were identified by HPLC–MS/MS. Sulfated compounds were chemically synthesised and used as standards to facilitate quantification. Gallic and caffeic acid conjugates were absorbed rapidly, reaching a maximum concentration between 1 and 2 h. The concentrations of sulfated metabolites resulting from the colonic degradation of more complex polyphenols increased in plasma from 4 h, and pyrogallol sulfate and catechol sulfate reached concentrations ranging from 5 to 20 μmat 6 h. In conclusion, phenolic sulfates reached high concentrations in plasma, as opposed to their undetected parent compounds. These compounds have potential use as biomarkers of polyphenol intake, and their biological activities need to be considered.

On the benefit of galls of Quercus brantii Lindl. in murine colitis: the role of free gallic acid

INTRODUCTION

In this study we investigated the effect of gall of Quercus brantii Lindl., a traditional Iranian medicine, in a murine model of experimental colitis induced in male rats by rectal administration of 2,4,6-trinitrobenzene sulfonic acid (TNBS).

MATERIAL AND METHODS

Quantification of the main active components was done for estimation of total phenolic content and free gallic acid. Gall of Quercus brantii Lindl. in two forms (gall powder and gall hydro alcoholic extract) was gavaged for 10 days (500 mg/kg). Ten days after induction of colitis, colonic status was examined by macroscopic, microscopic and biochemical analyses. Colonic tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) were analyzed as biomarkers of inflammatory condition. To determine the role of oxidative stress (OS) in colitis, the levels of cellular lipid peroxidation (LPO), total antioxidant power (TAP) and myeloperoxidase (MPO) were measured in colon tissues.

RESULTS

TNBS-induced colitis exhibited a significant increase in colon MPO activity and concentrations of cellular LPO, TNF-α and IL-1β, while TAP was significantly reduced. Microscopic evaluations of the colonic damage in the colitis group revealed multifocal degenerative changes in the epithelial lining and areas of necrosis, extensive mucosal and sub-mucosal damage with congested blood vessels, edema and hemorrhages along with extensive infiltration of inflammatory cells. Parameters including macroscopic and microscopic scores, TNF-α, IL-1β, LPO, TAP and MPO improved by both gall extract and gall powder of Quercus brantii Lindl. and reached close to normal levels. The level of total phenols (GAE/100 g of sample) and free gallic acid were estimated to be 88.43 ±7.23 (mean ± SD) and 3.74% of dry weight, respectively.

CONCLUSIONS

The present study indicates that the gall of Quercus brantii Lindl. is able to exert antioxidative and anti-inflammatory effects on the biochemical and pathological parameters of colitis.

The gallic acid-phospholipid complex improved the antioxidant potential of gallic acid by enhancing its bioavailability

Gallic acid (GA) is well known for its antioxidant and hepatoprotective activity, though its effectiveness is restricted due to rapid metabolism and elimination. To overcome these problems, gallic acid-phospholipid complex was prepared and the effect of phospholipid complexation was investigated on carbon tetrachloride (CCl4)-induced oxidative damage in rat liver. The complex significantly reduced the hepatic marker enzymes in rat serum and restored the antioxidant enzyme levels with respect to CCl4-induced group (P < 0.05 and P < 0.01). Also, the complex improved the pharmacokinetics of GA by increasing the relative bioavailability and elimination half-life. The study therefore suggests that phospholipid complexation has enhanced the therapeutic efficacy of GA which may be due to its improved absorption and increased bioavailability in rat serum.

The gallic acid-phospholipid complex improved the antioxidant potential of gallic acid by enhancing its bioavailability

Gallic acid (GA) is well known for its antioxidant and hepatoprotective activity, though its effectiveness is restricted due to rapid metabolism and elimination. To overcome these problems, gallic acid-phospholipid complex was prepared and the effect of phospholipid complexation was investigated on carbon tetrachloride (CCl4)-induced oxidative damage in rat liver. The complex significantly reduced the hepatic marker enzymes in rat serum and restored the antioxidant enzyme levels with respect to CCl4-induced group (P < 0.05 and P < 0.01). Also, the complex improved the pharmacokinetics of GA by increasing the relative bioavailability and elimination half-life. The study therefore suggests that phospholipid complexation has enhanced the therapeutic efficacy of GA which may be due to its improved absorption and increased bioavailability in rat serum.

Liquid Chromatography/Quadrupole Time-of-Flight Mass Spectrometry for Identification of In Vitro and In Vivo Metabolites of Bornyl Gallate in Rats

Bornyl gallate (BG) is a potential drug candidate synthesized by the reaction of two natural products, gallic acid and borneol. Previous studies have strongly suggested that BG is worthy of further investigation due to antioxidant, antiatherosclerosis activities, and obvious activity of stimulating intersegmental vessel growth in zebrafish. This work was designed to elucidate the metabolic profile of BG through analyzing its metabolites in vitro and in vivo by a chromatographic separation coupled with a mass spectrometry. The metabolites of BG were characterized from the rat liver microsome incubation solution, as well as rat urine and plasma after oral administration. Chromatographic separation was performed on an Agilent TC-C18 column (250 mm × 4.6 mm, 5  μ m) with gradient elution using methanol and water containing 0.2% (V : V) formic acid as the mobile phase. Metabolites identification involved analyzing the retention behaviors, changes of molecular weights and MS/MS fragment patterns of BG and the metabolites. Five compounds were identified as isomers of hydroxylated BG metabolites in vitro. The major metabolites of BG in rat urine and plasma proved to be BG-O-glucuronide and O-methyl BG-O-glucuronide. The proposed method confirmed to be a reliable and sensitive alternative for characterizing metabolic pathways of BG.

Identification of metabolites of Si-Ni-San, a traditional Chinese medicine formula, in rat plasma and urine using liquid chromatography/diode array detection/triple-quadrupole spectrometry

Si-Ni-San (SNS) is a widely used traditional Chinese medicine formula (TCMF) in treating various diseases. However, the in vivo integrated metabolism of its multiple components remains unknown. In this paper, a liquid chromatography coupled with diode array detection and triple-quadrupole spectrometry (LC-DAD-MS/MS) method was developed for detection and identification of SNS metabolites in rat plasma and urine at a normal clinical dosage. Accurate structural elucidation was performed using MS/MS, UV data and n-octanol/water partition coefficient. Based on the proposed strategy, 36 absorbed compounds and 29 metabolites in plasma and 33 metabolites in urine were detected by a highly sensitive MRM method. Our results indicated that phase II reactions (e.g., methylation, glucuronidation and sulfation) were the main metabolic pathways of gallic acid and flavanones, while phase I reactions (e.g., hydroxylation) were the major metabolic reaction for triterpenoid saponins. The metabolite profile analysis of SNS provided a comprehensive understanding of the in vivo metabolic fates of constituents in SNS. Moreover, the results in this work demonstrated the present strategy based on the combination of chromatographic, spectrophotometric, mass-spectrometric, and software prediction to detect and identify metabolites was effective and reliable. And such a strategy may also be extended to investigate the metabolism of other TCMF.

Bioavailability of gallic acid and catechins from grape seed polyphenol extract is improved by repeated dosing in rats: implications for treatment in Alzheimer's disease

The present study explored the bioavailability and brain deposition of a grape seed polyphenolic extract (GSPE) previously found to attenuate cognitive deterioration in a mouse model of Alzheimer's disease (AD). Plasma pharmacokinetic response of major GSPE phenolic components was measured following intragastric gavage of 50, 100, and 150 mg GSPE per kg body weight. Liquid chromatography-mass spectrometry (LC-MS) analysis identified gallic acid (GA), catechin (C), and epicatechin (EC) in plasma of rats gavaged acutely with GSPE. Additionally, 4-methylgallic acid (4-OMeGA), 3'-methylcatechin (3'-OMeC), and 3'-methylepicatechin (3'-OMeEC) were identified as circulating metabolites of GSPE phenolic constituents. Cmax for individual GSPE constituents and their metabolites increased in a dose-dependent fashion (with increasing GSPE oral dose). Repeated daily exposure to GSPE was found to significantly increase bioavailability (defined as plasma AUC0-8h) of GA, C, and EC by 198, 253, and 282% relative to animals receiving only a single acute GSPE dose. EC and C were not detectable in brain tissues of rats receiving a single GSPE dose but reached levels of 290.7 +/-45.9 and 576.7 +/- 227.7 pg/g in brain tissues from rats administered GSPE for 10 days. This study suggests that brain deposition of GA, C, and EC is affected by repeated dosing of GSPE.

Novel metabolic routes during the oxidation of hydroxylated aromatic acids by the yeast Arxula adeninivorans

AIM

To complete our study on tannin degradation via gallic acid by the biotechnologically interesting yeast Arxula adeninivorans as well as to characterize new degradation pathways of hydroxylated aromatic acids.

METHODS AND RESULTS

With glucose-grown cells of A. adeninivorans, transformation experiments with hydroxylated derivatives of benzoic acid were carried out. The 12 metabolites were analysed and identified by high performance liquid chromatography and GC/MS. The yeast is able to transform the derivatives by oxidative and nonoxidative decarboxylation as well as by methoxylation. The products of nonoxidative decarboxylation of protocatechuate and gallic acid are substrates for further ring fission.

CONCLUSION

Whereas other organisms use only one route of transformation, A. adeninivorans is able to carry out three different pathways (oxidative, nonoxidative decarboxylation and methoxylation) on one hydroxylated aromatic acid. The determination of the KM-values for protocatechuate and gallic acid in crude extracts of cells of A. adeninivorans cultivated with protocatechuate and gallic acid, respectively, suggests that the decarboxylation of protocatechuate and gallic acid may be catalysed by the same enzyme.

SIGNIFICANCE AND IMPACT OF THE STUDY

This transformation pathway of protocatechuate and gallic acid via nonoxidative decarboxylation up to ring fission is novel and has not been described so far. This is also the first report of nonoxidative decarboxylation of gallic acid by a eukaryotic micro-organism.

Antioxidant effects of different extracts from Melissa officinalis, Matricaria recutita and Cymbopogon citratus

Considering the important role of oxidative stress in the pathogenesis of several neurological diseases, and the growing evidence of the presence of compounds with antioxidant properties in the plant extracts, the aim of the present study was to investigate the antioxidant capacity of three plants used in Brazil to treat neurological disorders: Melissa officinalis, Matricaria recutita and Cymbopogon citratus. The antioxidant effect of phenolic compounds commonly found in plant extracts, namely, quercetin, gallic acid, quercitrin and rutin was also examined for comparative purposes. Cerebral lipid peroxidation (assessed by TBARS) was induced by iron sulfate (10 microM), sodium nitroprusside (5 microM) or 3-nitropropionic acid (2 mM). Free radical scavenger properties and the chemical composition of plant extracts were assessed by 1'-1' Diphenyl-2' picrylhydrazyl (DPPH) method and by Thin Layer Chromatography (TLC), respectively. M. officinalis aqueous extract caused the highest decrease in TBARS production induced by all tested pro-oxidants. In the DPPH assay, M. officinalis presented also the best antioxidant effect, but, in this case, the antioxidant potencies were similar for the aqueous, methanolic and ethanolic extracts. Among the purified compounds, quercetin had the highest antioxidant activity followed by gallic acid, quercitrin and rutin. In this work, we have demonstrated that the plant extracts could protect against oxidative damage induced by various pro-oxidant agents that induce lipid peroxidation by different process. Thus, plant extracts could inhibit the generation of early chemical reactive species that subsequently initiate lipid peroxidation or, alternatively, they could block a common final pathway in the process of polyunsaturated fatty acids peroxidation. Our study indicates that M. officinalis could be considered an effective agent in the prevention of various neurological diseases associated with oxidative stress.

Identification of urinary and intestinal bacterial metabolites of ellagitannin geraniin in rats

Hydrolyzable tannins, including ellagitannins, occur in foods such as berries and nuts. Various biological activities, including antioxidant, antiviral, and antitumor activities, have been noted and reported for ellagitannins, but the absorption and metabolism of purified ellagitannins are poorly understood. We describe herein the characterization of urinary and intestinal microbial metabolites in rats after the ingestion of ellagitannins. Urine samples were collected after oral administration of ellagitannins such as geraniin ( 1), corilagin ( 2), and their related polyphenols. The suspension of rat intestinal microflora was anaerobically incubated with ellagitannins. Each sample was separated by column chromatography and/or preparative HPLC to give seven metabolites, M1- M7. The structures of these metabolites were determined on the basis of spectroscopic data and chemical evidence. These compounds, except for M1, were characterized as ellagitannin metabolites for the first time. Furthermore, among four major metabolites ( M1- M4) in urine, M2 showed an antioxidant activity comparable to intact geraniin and related polyphenols.

Evaluation of antioxidant potential of ethyl acetate extract/fractions of Acacia auriculiformis A. Cunn

The present study estimates the free radical scavenging activity of the ethyl acetate extract/fractions of Acacia auriculiformis A. Cunn in different assays viz. 1'-1' diphenyl-2'picrylhydrazyl (DPPH), deoxyribose (site specific and non-site specific), relative reducing power, chelating power and lipid peroxidation. The bark powder of the plant was extracted with different solvents by maceration method in the order of increasing and decreasing polarity. The crude ethyl acetate extract was partitioned with ethyl acetate and water (Flow Chart 1 and 2). The scavenging activity of fractions was found to be more as compared to the crude extract. The percent inhibition with water fraction of ethyl acetate extract was observed to be 71.2%, 73.66%, 83.37%, 75.63% and 72.92% in DPPH, chelating power, lipid peroxidation, site specific and non-site specific deoxyribose scavenging assays respectively at maximum concentration tested. l-ascorbic acid and BHT were used as reference compounds for comparing the activity of plant extract/fractions. Studies are in progress to evaluate the effect of extract/fractions in other antioxidant assays and identify the factors responsible for the activity.

Biotransformation of gallic acid by Beauveria sulfurescens ATCC 7159

Preparative-scale fermentation of gallic acid (3,4,5-trihydroxybenzoic acid) (1) with Beauveria sulfurescens ATCC 7159 gave two new glucosidated compounds, 4-(3,4-dihydroxy-6-hydroxymethyl-5-methoxy-tetrahydro-pyran-2-yloxy)-3-hydroxy-5-methoxy-benzoic acid (4), 3-hydroxy-4,5-dimethoxy-benzoic acid 3,4-dihydroxy-6-hydroxymethyl-5-methoxy-tetrahydro-pyran-2-yl ester (7), along with four known compounds, 3-O-methylgallic acid (2), 4-O-methylgallic acid (3), 3,4-O-dimethylgallic acid (5), and 3,5-O-dimethylgallic acid (6). The new metabolite genistein 7-O-beta-D-4''-O-methyl-glucopyranoside (8) was also obtained as a byproduct due to the use of soybean meal in the fermentation medium. The structural elucidation of the metabolites was based primarily on 1D-, 2D-NMR, and HRFABMS analyses. Among these compounds, 2, 3, and 5 are metabolites of gallic acid in mammals. This result demonstrated that microbial culture parallels mammalian metabolism; therefore, B. sulfurescens might be a useful tool for generating mammalian metabolites of related analogs of gallic acid (1) for complete structural identification and for further use in investigating pharmacological and toxicological properties in this series of compounds. In addition, a GRE (glucocorticoid response element)-mediated luciferase reporter gene assay was used to initially screen for the biological activity of the 6 compounds, 2-6 and 8, along with 1 and its chemical O-methylated derivatives 9-13. Among the 12 compounds tested, 11-13 were found to be significant, but less active than the reference compounds of methylprednisolone and dexamethasone.

Protection of DNA and membrane from gamma radiation induced damage by gallic acid

Gallic acid (3,4,5-trihydroxybenzoic acid, GA) is a naturally occurring plant phenol. In vitro and in vivo studies have shown that this phytochemical protected DNA and membranes against ionizing radiation. Rat liver microsomes and plasmid pBR322 DNA were exposed to various doses of gamma radiation in presence and absence of GA. Exposure of the microsomes to gamma radiation resulted in the formation of peroxides of membrane lipids measured as thiobarbituric acid reactive substances and presence of GA during irradiation prevented the formation of lipid peroxidation. Gamma irradiation of plasmid DNA resulted in induction of strand breaks in DNA resulting in disappearance of the supercoiled (ccc) form. Presence of GA during irradiation protected the DNA from undergoing the strand breaks. In in vivo studies it was found that whole body exposure of mice to gamma radiation (4 Gy) increased the formation of lipid peroxides in various tissues and damage to cellular DNA (as measured by alkaline comet assay) in peripheral blood leucocytes. Administration of GA to mice prior to whole body radiation exposure reduced the peroxidation of lipids and the damage to the cellular DNA indicating in vivo radiation protection of membranes and DNA by GA.

Synthesis of a novel plant growth promoter from gallic acid

Gallic acid has been modified to naphthophenone derivatives with esterified fatty acid side chain. Compound 12, an ethyl crotonate ester of naphthophenone derivative has shown potent auxin like growth promoter activity. This is the first example of naphthophenone derivatives with plant growth promoting activity.

Free radical scavenging active components from Cedrus deodara

An activity-directed fractionation and purification process was used to identify the antioxidant components of Cedrus deodara. Dried heartwood powder of C. deodara was first defatted with petroleum ether and then extracted with chloroform. The chloroform extract showed strong antioxidant activity on 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical. This fraction was then subjected to separation and purification using silica gel column chromatography. Three compounds with potent antioxidant activity were isolated in significant yields and identified by spectroscopic methods ((1)H NMR, (13)C NMR, IR, and MS). They were identified as (-)-matairesinol, (-)-nortrachelogenin, and a dibenzylbutyrolactollignan (4,4',9-trihydroxy-3,3'-dimethoxy-9,9'-epoxylignan). This is the first report of the occurrence of these compounds in C. deodara.