Antioxidant properties of Thonningianin A, isolated from the African medicinal herb, Thonningia sanguinea

Activity of thonningianin A against Candida albicans in vitro and in vivo

Fungal infections are increasing rapidly, and antifungal agents used in clinics are limited. Therefore, novel antifungal agents with high efficiency are urgently required. In this study, we investigated the antifungal activity of thonningianin A (THA), a natural compound that is widely found in plants. We first determined the activity of THA against Candida albicans, one of the most common fungal pathogens, and found that THA showed antifungal activity against all C. albicans tested, including several fluconazole-resistant isolates. THA also inhibits the growth of non-Candida albicans species. In addition, THA displayed antibiofilm activity and could not only inhibit biofilm formation but also destroy mature biofilms. The in vivo antifungal efficacy of THA was confirmed in a Galleria mellonella infection model. Further studies revealed that THA could enhance intracellular reactive oxygen species (ROS) production and regulate the transcription of several redox-related genes. Specifically, caspase activity and expression of CaMCA1, a caspase-encoding gene in C. albicans, were remarkably increased upon THA treatment. Consistent with this, in the presence of THA, the Camca1 null mutant displayed higher survival rates and reduced caspase activity compared to the wild-type or CaMCA1-reintroduced strains, indicating an important role of CaMCA1 in the antifungal activity of THA. Taken together, our results indicate that THA possesses excellent antifungal activity and may be a promising novel antifungal candidate. KEY POINTS: • THA exhibits activity against Candida species, including fluconazole-resistant isolates • THA inhibits biofilm formation and destroys mature biofilm • Elevated ROS production and CaMCA1-mediated caspase activity are involved in the antifungal mechanisms of THA.

Phytochemicals targeting Alzheimer's disease via the AMP-activated protein kinase pathway, effects, and mechanisms of action

Alzheimer's disease (AD), characterized by cognitive dysfunction and other behavioral abnormalities, is a progressive neurodegenerative disease that occurs due to aging. Currently, effective drugs to mitigate or treat AD remain unavailable. AD is associated with several abnormalities in neuronal energy metabolism, such as decreased glucose uptake, mitochondrial dysfunction, and defects in cholesterol metabolism. Amp-activated protein kinase (AMPK) is an important serine/threonine protein kinase that regulates the energy status of cells. AMPK is widely present in eukaryotic cells and can sense and regulate energy metabolism to maintain energy supply and demand balance, making it a promising target for energy metabolism-based AD therapy. Therefore, this review aimed to discuss the molecular mechanism of AMPK in the pathogenesis of AD to provide a theoretical basis for the development of new anti-AD drugs. To review the mechanisms of phytochemicals in the treatment of AD via AMPK pathway regulation, we searched PubMed, Google Scholar, Web of Science, and Embase databases using specific keywords related to AD and phytochemicals in September 2023. Phytochemicals can activate AMPK or regulate the AMPK pathway to exert therapeutic effects in AD. The anti-AD mechanisms of these phytochemicals include inhibiting Aβ aggregation, preventing Tau hyperphosphorylation, inhibiting inflammatory response and glial activation, promoting autophagy, and suppressing anti-oxidative stress. Additionally, several AMPK-related pathways are involved in the anti-AD mechanism, including the AMPK/CaMKKβ/mTOR, AMPK/SIRT1/PGC-1α, AMPK/NF-κB/NLRP3, AMPK/mTOR, and PERK/eIF2α pathways. Notably, urolithin A, artemisinin, justicidin A, berberine, stigmasterol, arctigenin, and rutaecarpine are promising AMPK agonists with anti-AD effects. Several phytochemicals are effective AMPK agonists and may have potential applications in AD treatment. Overall, phytochemical-based drugs may overcome the barriers to the effective treatment of neurodegenerative diseases.

Tellimagrandin-I and camptothin a exhibit chemopreventive effects in Salmonella enterica serovar Typhimurium strains and human lymphocytes

Tellimagrandin-I (TL) and camptothin A (CA) are ellagitannins widely found in diverse plant species. Numerous studies demonstrated their significant biological activities, which include antitumor, antioxidant, and hepatoprotective properties. Despite this protective profile, the effects of TL and CA on DNA have not been comprehensively investigated. Thus, the aim of this study was to determine the mutagenic and antimutagenic effects attributed to TL and CA exposure on Salmonella enterica serovar Typhimurium strains using the Ames test. In addition, the cytotoxic and genotoxic effects were examined on human lymphocytes, employing both trypan blue exclusion and CometChip assay. The antigenotoxic effect was determined following TL and CA exposure in the presence of co-treatment with doxorubicin (DXR). Our results from the Ames test indicated that TL or CA did not display marked mutagenic activity. However, TL or CA demonstrated an ability to protect DNA against the damaging effects of the mutagens 4-nitroquinoline-1-oxide and sodium azide, thereby exhibiting antimutagenic properties. In relation to human lymphocytes, TL or CA did not induce significant cytotoxic or genotoxic actions on these cells. Further, these ellagitannins exhibited an ability to protect DNA from damage induced by DOX during co-treatment, indicating their potential beneficial usefulness as antigenotoxic agents. In conclusion, the protective effects of TL or CA against mutagens, coupled with their absence of genotoxic and cytotoxic effects on human lymphocytes, emphasize their potential therapeutic value in chemopreventive strategies.

A review on anti-nutritional factors: unraveling the natural gateways to human health

Humans are constantly facing multiple health challenges from both communicable and non-communicable diseases that significantly affect their health. Additionally, drug resistance or failure has made the situation even worse and poses serious challenges for researchers to develop new drugs. Hence, to address these problems, there is an urgent need to discover and develop timely and long-term-based therapeutic treatments from different sources. One such approach is harnessing the potential of plant secondary metabolites. Plants have been utilized for therapeutic purposes in addition to being used for nutritional benefits. In the last two decades, plant-based drug developments have been one of the effective means of treating human diseases owing to their multiple functions. More recently, anti-nutritional factors (ANFs) have emerged as one of the important targets for novel plant-based drug development due to their multifaceted and potential pharmacological properties. However, their anti-nutritional properties have been the major setback for their limited success in the pharmacological sector. In this review, we provide an overview of ANFs and their beneficial roles in preventing human diseases with multiple case studies. We also highlight the recent developments and applications of ANFs in the food industry, agriculture, and pharmaceutics with future perspectives. Furthermore, we evaluate meta-analyses on ANFs from the last 30 years in relation to their function in human health benefits. This review is an endeavor to reevaluate the merit of these natural compounds and explore their potential for both human and animal health.

An Updated Review on Efficiency of Penthorum chinense Pursh in Traditional Uses, Toxicology, and Clinical Trials

Traditional Chinese medicines (TCM) play an important role in the control and treatment of several animal diseases. Penthorum chinense Pursh (PCP) is a famous plant for its use in traditional medication practice and therapeutic effects in numerous pathological conditions. In China, PCP is utilized for both food and medication due to numerous bioactivities. PCP is widely administered in prevention and treatment of traumatic injury, edema, and liver diseases with functions of reducing swelling, support diuresis, blood stasis, and mitigation symptoms of excessive alcohol intake. Recently, PCP highlighted for research trials in various fields including pharmacology, pharmacognosy, cosmeceuticals, nutraceuticals, and pharmaceuticals due to medicinal significance with less toxicity and an effective ethnomedicine in veterinary practice. PCP contains diverse important ingredients such as flavonoids, organic acids, coumarins, lignans, polyphenols, and sterols that are important bioactive constituents of PCP exerting the therapeutic benefits and organ-protecting effects. In veterinary, PCP extract, compound, and phytochemicals/biomolecules significantly reversed the liver and kidney injuries, via antioxidation, oxidative stress, apoptosis, mitochondrial signaling pathways, and related genes. PCP water extract and compounds also proved in animal and humans' clinical trial for their hepatoprotective, antiaging, nephroprotective, anti-inflammatory, antidiabetic, antibacterial, antiapoptotic, immune regulation, and antioxidative stress pathways. This updated review spotlighted the current information on efficiency and application of PCP by compiling and reviewing recent publications on animal research. In addition, this review discussed the toxicology, traditional use, comparative, and clinical application of PCP in veterinary practices to authenticate and find out new perspectives on the research and development of this herbal medicine.

Evaluation of the Chemical Composition, Antioxidant and Antidiabetic Activity of Rhaponticoides iconiensis Flowers: Effects on Key Enzymes Linked to Type 2 Diabetes In Vitro, In Silico and on Alloxan-Induced Diabetic Rats In Vivo

Diabetes mellitus (DM) is one of the globally worst killer diseases. In this study, the in vitro and in vivo antidiabetic activity and antioxidant capacity were determined and the phytochemical analyses were carried out on flower extract and sub-extracts of Rhaponticoides iconiensis. The in vitro antidiabetic activity was tested with α-amylase and α-glucosidase enzyme inhibition methods and an in vivo OGTT test in healthy and alloxan-induced rats. Although, the antioxidant activity was investigated with DPPH●, ABTS●+ and FRAP tests, the phytochemical composition analysis was carried out by LC-MS/MS. The highest α-glucosidase and α-amylase activity even from positive control acarbose were found in the ethyl acetate sub-extract of R. iconiensis (IC50 = 11.737 ± 0.823 µg/mL and 84.247 ± 0.721 µg/mL, respectively). This sub-extract also was active according to the results of in vivo tests. Moreover, the highest antioxidant activity on DPPH● (IC50 = 0.126 ± 0.002 mg/mL), FRAP (at a concentration of 1 mg/mL equivalent to 3112.052 ± 2.023 mmol Fe2+) and ABTS+● (at a concentration of 0.5 mg/mL equivalent to 0.608 ± 0.005 µM Trolox) tests. In addition, LC-MS/MS analyses of the active sub-extract revealed mainly the presence of patuletin, patuletin 3,7-diglucoside, naringin and 3,4-dicaffeoylquinic acid detected in the active sub-extract. In silico molecular docking and dynamics simulations studies were performed on these compounds with α-amylase and α-glucosidase enzymes for protein-ligand interactions and stability.

Quantification of thonningianin a in rat plasma by liquid chromatography tandem mass spectrometry and its application to a pharmacokinetic study

CONTEXT

Thonningianin A is an ellagitannin substance and displays multiple pharmacological activities.

OBJECTIVE

This study investigated the pharmacokinetic characteristics of thonningianin A after oral administration in rats using a fully validated liquid chromatography tandem mass spectrometry (LC-MS/MS) method.

MATERIALS AND METHODS

A sensitive and selective LC-MS/MS assay was developed for quantifying thonningianin A. Eighteen Wistar rats were randomly divided into three groups (n = 6), which were given at a single dose of 10, 20, or 40 mg/kg thonningianin A by gavage. Blood samples (200 µL) were collected from the orbit vein at designated time points and analyzed using the LC-MS/MS method to measure the levels of thonningianin A.

RESULTS

Thonningianin A and internal standard (IS) were eluted at 1.5 and ∼3.0 min, respectively. The selected reaction mode transitions monitored were m/z 873.2 > 300.3 and 819.3 > 610.6 for thonningianin A and the IS, respectively. The calibration range was 10-1200 ng/mL. The intra- and the inter-day accuracy and precision met the acceptance criteria. No carryover and matrix effect were observed. The plasma concentrations of thonningianin A increased rapidly after oral administration of three dosages and reached the mean peak concentrations (C_max) within 0.61-0.83 h. Meanwhile, AUC_0-t/AUC_0-∞ of the three dosage groups was more than 89.0% (10 mg/kg), 95.7% (20 mg/kg), and 97.0% (40 mg/kg).

DISCUSSION AND CONCLUSIONS

The present method is the first report in terms of the simple precipitation procedure, high sensitivity, and high-throughput efficiency. This validated assay was successfully applied to determine the pharmacokinetic behaviours of thonningianin A in rats. This study should be helpful for providing references for understanding the action mechanism and further application of Penthorum chinense.

Natural Products and Extracts as Xantine Oxidase Inhibitors - A Hope for Gout Disease?

Xanthine oxidase (EC 1.17.3.2) (XO) is one of the main enzymatic sources that create reactive oxygen species (ROS) in the living system. It is a dehydrogenase enzyme that performs electron transfer to nicotinamide adenine dinucleotide (NAD+), while oxidizing hypoxanthin, which is an intermediate compound in purine catabolism, first to xanthine and then to uric acid. XO turns into an oxidant enzyme that oxidizes thiol groups under certain stress conditions in the tissue. The last metabolic step, in which hypoxanthin turns into uric acid, is catalyzed by XO. Uric acid, considered a waste product, can cause kidney stones and gouty-type arthritis as it is crystallized, when present in high concentrations. Thus, XO inhibitors are one of the drug classes used against gout, a purine metabolism disease that causes urate crystal storage in the joint and its surroundings caused by hyperuricemia. Urate-lowering therapy includes XO inhibitors that reduce uric acid production as well as uricosuric drugs that increase urea excretion. Current drugs that obstruct uric acid synthesis through XO inhibition are allopurinol, febuxostat, and uricase. However, since the side effects, safety and tolerability problems of some current gout medications still exist, intensive research is ongoing to look for new, effective, and safer XO inhibitors of natural or synthetic origins for the treatment of the disease. In the present review, we aimed to assess in detail XO inhibitory capacities of pure natural compounds along with the extracts from plants and other natural sources via screening Pubmed, Web of Science (WoS), Scopus, and Google Academic. The data pointed out to the fact that natural products, particularly phenolics such as flavonoids (quercetin, apigenin, and scutellarein), tannins (agrimoniin and ellagitannin), chalcones (melanoxethin), triterpenes (ginsenoside Rd and ursolic acid), stilbenes (resveratrol and piceatannol), alkaloids (berberin and palmatin) have a great potential for new XO inhibitors capable of use against gout disease. In addition, not only plants but other biological sources such as microfungi, macrofungi, lichens, insects (silk worms, ants, etc) seem to be the promising sources of novel XO inhibitors.

Characterization of a new blackberry cultivar BRS Xingu: Chemical composition, phenolic compounds, and antioxidant capacity in vitro and in vivo

The cultivar BRS Xingu was launched by EMBRAPA in 2015 with the intention of presenting higher productivity. Due to the lack of studies on this cultivar, the objective was to present the physical-chemical, centesimal, and phenolic composition of the BRS Xingu blackberry, its antioxidant capacity, protection against ROS generation, and compare it with other commercialized cultivars such as Guarani, Tupy, and Xavante. The BRS Xingu was prominent regarding anthocyanin and condensed tannin content and superior to the other cultivars. Moreover, BRS Xingu presented higher antioxidant capacity, protection of C. elegans from ROS generation, and soluble solid content when compared to Tupy, which is the most cultivated variety in the world. In the new cultivar, five anthocyanins, five phenolic acids, and ten non-anthocyanin flavonoids were identified. BRS Xingu is presented as an alternative blackberry with potential for industrialization and in natura consumption.

Phytochemical characteristics of aerial part of Cissus quadrangularis (L) and its in-vitro inhibitory activity against leukemic cells and antioxidant properties

BACKGROUND AND OBJECTIVES

Cissus quadrangularis Linn, is a rich bioresource for folk and traditional medicines from ancient times till date. The present study aimed to investigate the free radical scavenging and anticancer efficacy in vitro of the ethanolic and methanolic extract from the aerial parts of Cissus quadrangularis (L).

MATERIAL AND METHODS

In vitro cell-free antioxidant analyses were performed for the ethanolic extract of Cissus quadrangularis (L). (EECQ) and methanolic extract of Cissus quadrangularis (L). (MECQ) using different free radical scavenging assays includes DPPH, nitric oxide, superoxide, metal chelation, and hydrogen peroxide radical scavenging assays. In vitro leukemic cytotoxic assessment by MTT assay was performed both EECQ and MECQ extract against HL-60 cell lines.

RESULTS

Strong antioxidant effects were recorded in EECQ and MECQ in all the cell-free models. The ethanolic extract exhibited a significant dose-dependent free radical activity in comparison with methanolic extracts. The EECQ and MECQ possess pronounced anticancer efficacy against leukemic cells HL-60 with an IC50 value of 36 μg/mL and 40 μg/mL respectively.

CONCLUSION

Present data indicates the presence of marked antioxidant and anticancer behaviors in the extracts of aerial portions of Cissus quadrangularis (L). extracts. Thus, Cissus quadrangularis (L). poses as a promising safe chemopreventive plant to combat cancer.

Bioactivity Evaluation of Pinocembrin Derivatives From Penthorum chinense Pursh Stems

The extract of Penthorum chinense Pursh (PCP), a well-known Miao herb medicine, has been used as a key component for a Chinese patented drug to treat several kinds of liver-related diseases. In this work, 3 pinocembrin derivatives, S1, S2, and S3, were isolated from PCP stems and identified with high-performance liquid chromatography and electrospray ionization mass spectrometer. The molecular masses of S1, S2, and S3 were identical to Pinocembrin-7-O-[4″,6″-hexahydroxydiphenoyl (HHDP)]-β-D-glucose, Pinocembrin-7-O-[3″-O-galloyl-4″,6″-(s)-HHDP)-β-D-glucose, and Thonningianin A, respectively. Their free radical scavenging capability was evaluated with the 2,2-diphenyl-1-picrylhydrazyl assay. The half-maximal effective concentrations of S1, S2, and S3 were 26.75, 9.06, and 5.50 μg/mL, respectively. In vitro AML-12 assays demonstrated that S1 (5-20 μg/mL), S2 (10-40 μg/mL), and S3 (10-40 μg/mL) not only protected cells from H2O2-induced oxidation and alcohol-induced cell damages, but also reduced oleic acid (OA)-induced triglyceride accumulations in a dose-dependent manner. However, the 3 compounds potently exhibited similar cytotoxicity effect at high concentrations. The half-maximal inhibitory concentrations of S1, S2, and S3 to AML-12 cells were 74.19, 85.86, and 80.43 μg/mL. In addition, the 3 compounds also showed antibacterial activity on Escherichia coli, Staphylococcus aureus, Enterococcus faecalis, Lactobacillus rhamnosus, and Bacillus subtilis.

African Herbal Remedies with Antioxidant Activity: A Potential Resource Base for Wound Treatment

The use of traditional herbal remedies as alternative medicine plays an important role in Africa since it forms part of primary health care for treatment of various medical conditions, including wounds. Although physiological levels of free radicals are essential to the healing process, they are known to partly contribute to wound chronicity when in excess. Consequently, antioxidant therapy has been shown to facilitate healing of such wounds. Also, a growing body of evidence suggests that, at least, part of the therapeutic value of herbals may be explained by their antioxidant activity. This paper reviews African herbal remedies with antioxidant activity with the aim of indicating potential resources for wound treatment. Firstly, herbals with identified antioxidant compounds and, secondly, herbals with proven antioxidant activity, but where the compound(s) responsible for the activity has not yet been identified, are listed. In the latter case it has been attempted to ascribe the activity to a compound known to be present in the plant family and/or species, where related activity has previously been documented for another genus of the species. Also, the tests employed to assess antioxidant activity and the potential caveats thereof during assessment are briefly commented on.

Biological activity of ellagitannins: Effects as anti-oxidants, pro-oxidants and metal chelators

Ellagitannins are a subclass of hydrolysable tannins that have been suggested to function as defensive compounds of plants against herbivores. However, it is known that the conditions in the digestive tracts of different herbivores are variable, so it seems reasonable to anticipate that the reactivities and modes of actions of these ingested defensive compounds would also be different. A previous study on a few ellagitannins has shown that these polyphenolic compounds are highly oxidizable at high pH and that their bioactivity can be attributed to certain structural features. Herein, the activities of 13 ellagitannins using the deoxyribose assay were measured. The results provided information about the anti-oxidant, pro-oxidant and metal chelating properties of ellagitannins. Surprisingly, many of the tested ellagitannins exhibited pro-oxidant activities even at neutral pH and only moderate to low radical scavenging activities, although the metal chelating capacities of all tested ellagitannins were relatively high.

Antioxidant activity of various extracts of selected gourd vegetables

Study was conducted to evaluate the antioxidative activity of methanolic (ME), ethanolic (EE) and butanolic extracts (BE) of selected gourd vegetables. The antioxidant activity was investigated using different assays namely ferric thiocyanate test (FTC), thiobarbituric acid test (TBA), ferric reducing antioxidant power (FRAP) and DPPH free radicals scavenging test. A densitometric HPTLC analysis was performed for the analysis of phenolic acids and flavonoids. Different extracts of the selected gourd vegetables revealed different antioxidant activity. Different extracts of Lagenaria siceraria, Momordica charantia and Luffa cylindrica revealed significantly higher (p < 0.05) concentrations of total phenols, flavonids, tannins and carotenoids content and also the antioxidant activity in comparison to remaining vegetable extracts. Correlation studies indicated that FRAP test best described the antioxidant activity of phenols, flavonoids and carotenoids (r = 0.854, 0.692 and 0.915 respectively). HPTLC profiles revealed the presence of maximum number of phenolic acids and flavonoids in L. siceraria and M. charantia.

Neuroprotective Effects of Castanea sativa Mill. Bark Extract in Human Neuroblastoma Cells Subjected to Oxidative Stress

One of the major features of neurodegenerative disease is the selective vulnerability of different neuronal populations that are affected in a progressive and often stereotyped manner. Despite the susceptible neuronal population varies between diseases, oxidative stress is implicated as the major pathogenic process in all of them. Natural Extract of Castanea sativa Mill. bark (ENC), recently characterized in its phenolic composition, acts as antioxidant and cardioprotective agent. Its neuroprotettive properties, however, have never been investigated. The aim of this study was to assess neuroprotection of ENC in in vitro models of oxidative-stress-mediate injury. Human neuroblastoma SH-SY5Y cells treated with glutamate (50 mM for 24 h) or hydrogen peroxide (25 μM for 1 h followed by 24 with medium) were used. The results showed that the addition of ENC (1-50 μg/ml) to cell medium before the neuronal damage provided neuroprotection in both experimental models used, while its addition after the injury was ineffective. In conclusion, the present results suggest that ENC could be a valuable support as dietary supplement, combining beneficial preventive neuroprotettive effects with a high antioxidant activity.

Effects of thonningianin A in natural foods on apoptosis and cell cycle arrest of HepG-2 human hepatocellular carcinoma cells

The anti-cancer activities of Thonningianin A on the HepG-2 human hepatocellular carcinoma cell line were evaluated by MTT assay, flow cytometry, quantitative real-time PCR and western blotting. Results showed that Thonningianin A effectively inhibited the proliferation of HepG-2 cells by inducing apoptosis, as evidenced by increase in the sub-G1 cell population, DNA fragmentation, and increase in the content of reactive oxygen species. Activation of caspase-9 and the subsequent activation of caspase-3 indicated that Thonningianin A-induced apoptosis is caspase-dependent. Thonningianin A also disrupted the mitochondrial membrane potential (Δψm) and down-regulated the Bcl-xL mRNA expression in HepG-2 cells. Thonningianin A induced cell cycle arrest by changing the cyclin D1 and CDK4 mRNA expression levels. Moreover, western blotting showed that Thonningianin A significantly down-regulated the NF-kappa-B cell survival pathway, along with up-regulation of the expression level of phosphorylated P38 and down-regulation of the expression level of phosphorylated ERK. The anti-cancer activity of Thonningianin A was confirmed by the characteristic patterns of DNA fragmentation and cell cycle arrest, suggesting that Th A is an effective antitumor ingredient in natural plant foods, and is worthy of further study.

Traditional Chinese Herbal Medicine Penthorum chinense Pursh: A Phytochemical and Pharmacological Review

Penthorum chinense Pursh (ganhuangcao), a traditional Chinese medicine, is used for the prevention and treatment of liver diseases, including hepatitis B, hepatitis C, and alcoholic liver damage. A wide range of investigations have been carried out on this herbal medicine from pharmacognosy to pharmaceuticals, as well as pharmacology. The extract of P. chinense was reported to have significant liver protective effects through anti-oxidation, reduction of key enzyme levels, inhibition of hepatitis B virus DNA replication, and promotion of bile secretion. Based on the current knowledge, flavonoids and phenols are considered to be responsible for P. chinense's bioactivities. The main purpose of this review is to provide comprehensive and up-to-date knowledge of the phytochemical and pharmacological studies performed on P. chinense during the past few decades. Moreover, it intends to provide new insights into the research and development of this herbal medicine.

Sweet chestnut (Castanea sativa Mill.) bark extract: cardiovascular activity and myocyte protection against oxidative damage

This work was aimed at evaluating the cardioprotective effects of Castanea sativa Mill. (CSM) bark extract characterized in its phenolic composition by HPLC-DAD-MS analysis. The study was performed using primary cultures of neonatal rat cardiomyocytes to investigate the antioxidant and cytoprotective effects of CSM bark extract and isolated guinea pig left and right atria, left papillary muscle, and aorta to evaluate its direct effect on cholinergic and adrenergic response. In cultured cardiomyocytes the CSM bark extract reduced intracellular reactive oxygen species formation and improved cell viability following oxidative stress in dose-dependent manner. Moreover, the extract decreased the contraction induced by noradrenaline (1  μ M) in guinea pig aortic strips and induced transient negative chronotropic and positive inotropic effects without involvement of cholinergic or adrenergic receptors in the guinea pig atria. Our results indicate that CSM bark extract exhibits antioxidant activity and might induce cardioprotective effect.

Isolation and identification of compounds from Penthorum chinense Pursh with antioxidant and antihepatocarcinoma properties

Penthorum chinense Pursh, widely distributed in eastern Asia, has long been used in China for both food and medicine due to its various bioactivities. The aim of this study was to isolate its active compounds with antioxidant and antihepatocarcinoma properties. P. chinense was extracted with 95% ethanol, 70% ethanol, and water, respectively, and then the 70% ethanol extract was re-extracted, resulting in petroleum ether, ethyl acetate, n-butanol, and water fractions, subsequently. Results showed that the antioxidant and antihepatocarcinoma activities of ethanol extracts were stronger than those of aqueous extract, and the ethyl acetate fraction of 70% ethanol extract showed the highest activities. Four compounds, β-sitosterol, quercetin, pinocembrin-7-O-[3-O-galloyl-4″,6″-hexahydroxydiphenoyl]-β-glucose (PGHG), and thonningianins A (Th A), were isolated from the ethyl acetate fraction and identified by UV, MS, and NMR spectroscopic analysis. Th A was isolated from P. chinense for the first time. PGHG and Th A exhibited higher antioxidant and antihepatocarcinoma activities than did other isolated parts of P. chinense . The antihepatocarcinoma activity of Th A was much higher than that of positive control (5-fluorouracil). PGHG and Th A were suggested to be the active chemical compositions responsible for potent antioxidant and antihepatocarcinoma properties of P. chinense , which are worthy of further study.

Protective role ofPhyllanthus niruri against nimesulide induced hepatic damage

Present study aimed to evaluate the protective role of the aqueous extract of Phyllanthus niruri (P. niruri) against nimesulide-induced hepatic disoder in mice by determining levels of glutamate oxaloacetate transaminase (GOT), glutamate pyruvate transaminase (GPT) and alkaline phosphatase (ALP) in serum and also by measuring the hepatic content of the antioxidant enzymes, superoxide dismitase (SOD) and catalase (CAT); the free radical scavenger, reduced glutathione (GSH) and thiobarbituric acid reacting substances (TBARS). Aqueous extract of P. niruri was administered either orally or intraperitoneally in different doses and times as needed for the experiments. Intraperitoneal of the extract (100 mg/kg body weight for seven days) reduced nimesulide (750 mg/kg body weight for 3 days) induced increased levels of GOT (37.0±1.8 units/ml in control group vs. 91.8±2.0 units/ml in nimesulide treated group vs. 35.0±1.0 units/ml in extract treated group), GPT (30.0±2.1 units/ml in control group vs. 88.4±2.9 units/ml in nimesulide treated group vs. 34.1±1.8 units/ml in extract treated group), and ALP (7.86±0.47 KA units/ml in control group vs. 23.80±0.60 KA units/ml in nimesulide treated group vs. 7.30±0.40 KA units/ml, in extract treated group) to almost nomal. In addition, P. niruri restored the nimesulide induced alterations of hepatic SOD (550±20 units/mg total protein in control group vs. 310±13 units/mg total protein in nimesulide treated group vs. 515±10 units/mg total protein in extract treated group), CAT (99.5±2 units/mg total protein in control group vs. 25.0±1.5 units/mg total protein in nimesulide treated group vs. 81.0±0.8 units/mg total protein in extract treated group), GSH (90±3 nmoles/mg total protein in control group vs. 17±4.2 nmoles/mg total protein in nimesulide treated group vs. 81±1 nmoles/mg total protein in extract treated group) and TBARS (measured as MDA, 36.6±3.0 nmoles/g liver tissue in control group vs. 96.3±5.2 nmoles/g liver tissue in nimesulide treated group vs. 41.2±1.7 nmoles/g liver tissue in extract treated group) contents. Dose-dependent studies showed that the herb could protect liver even if the nimesulide-induced injury is severe. Intraperitoneal administration of the extract showed better protective effect than oral administration. Combining all, the data suggest that P. niruri possesses hepatoprotective activity against nimesulide-induced liver toxicity and probably acts via an antioxidant defense mechanism. To the best of our knowledge, this is the first report of the hepatoprotective action of P. niruri against nimesulide induced liver damage.

Protein Isolate from the Herb Phyllanthus niruri Modulates Carbon Tetrachloride-Induced Cytotoxicity in Hepatocytes

ABSTRACT Phyllanthus niruri is a well-known hepatoprotective herbal plant. In the present study, hepatoprotective potential of the protein isolate of P. niruri was investigated against carbon tetrachloride (CCl(4))-induced hepatoxicity in vitro. Isolated hepatocytes were treated with CCl(4) and also separately with various concentrations of the protein isolate of P. niruri along with CCl(4). Levels of different marker enzymes related to hepatic integrity and different antioxidant enzymes as well as lipid peroxidation products in hepatocytes were measured in normal, control (toxicity induced), and protein isolate-treated cells. Administration of CCl(4) increased the leakage of glutamate pyruvate transaminase (GPT) by four fold and lactate dehydrogenase (LDH) by 84% in cell suspension, along with increased lipid peroxidation (114%), and reduced the levels of antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) to almost 30% and 37% of the normal values, respectively. Treatment with the protein isolate of P. niruri significantly altered these changes. GPT value almost came down to normal levels and LDH value was reduced to 32% of normal values. Depletion of SOD and CAT activities were restored significantly to 75% and 87% of normal values, respectively. Lipid peroxidation was also reduced significantly. In the DPPH free radical scavenging activity, the protein isolate was also able to quench the free radical. Results suggest that the protein isolate of P. niruri protects hepatocytes against CCl(4)-induced oxidative damage and may be used as an effective cytoprotector against CCl(4)-induced hepatotoxicity.

Tannic acid is more effective than clofibrate for the elevation of hepatic β-oxidation and the inhibition of 3-hydroxy-3-methyl-glutaryl-CoA reductase and aortic lesion formation in apo E-deficient mice

The effects of tannic acid (TA) supplementation (0·02 %, wt/wt) were compared with the effects of clofibrate (CF) supplementation (0·02 %, wt/wt) in apo E-deficient (apo E(- / -)) mice fed a AIN-76 semi-synthetic diet (normal diet) over 20 weeks. The mice were monitored for the modulation of hepatic mRNA expression and the activities of lipid-regulating enzymes. Both TA and CF supplementation lowered hepatic 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMGR) activity and prevented atherosclerotic lesion formation in comparison with the control group. Hepatic carnitine palmitoyl transferase and β-oxidation activities were significantly higher in the TA and CF groups than in the control group. Both CF and TA supplementation resulted in significant decreases in hepatic HMGR mRNA levels in association with its enzyme activity. However, in contrast to CF supplementation, TA supplementation seemed to decrease the accumulation of hepatic lipids in the apo E(- / -) mice without increasing liver weight. These results suggest that the overall effect of TA is more desirable than CF for the alleviation of hepatic lipogenesis and atherogenesis in apo E(- / -) mice.

Antioxidant and antidiabetic properties of condensed tannins in acetonic extract of selected raw and processed indigenous food ingredients from Kenya

Recently, tannins have received considerable attention as health-promoting component in various plant foods and several studies have reported on its nutraceutical properties. However, no study has established the role of condensed tannins in indigenous foods of Kenya. Therefore, this study was designed to evaluate the antioxidant activity (DPPH and FRAP) and antidiabetic effects (α-amylase and α-glucosidase inhibition activities) of condensed tannins in some selected raw and traditionally processed indigenous cereals, legumes, oil seeds, and vegetables. The condensed tannin content of the grains and vegetables ranged between 2.55 and 4.35 g/100 g DM and 1.53 and 5.73 g/100 g DM, respectively. The scavenging effect of acetonic extract on DPPH radical ranged from 77% to 90% while the reducing power was found to be 31 to 574 mmol Fe(II)/g DM in all the investigated food ingredients. The condensed tannin extracts of the analyzed samples showed promising antidiabetic effects with potential α-amylase and α-glucosidase inhibition activities of 23% to 44% and 58% to 88%, respectively. Condensed tannins extracted from the amaranth grain, finger millet, field bean, sunflower seeds, drumstick, and amaranth leaves exerted significantly higher antioxidant and antidiabetic activities than other food ingredients. Among the traditional processing methods, roasting of grains and cooking of vegetables were found to be more suitable mild treatments for preserving the tannin compound and its functional properties as opposed to soaking + cooking and blanching treatments. The identified elite sources of optimally processed indigenous food ingredients with promising results could be used as health-promoting ingredients through formulation of therapeutic diets.

Tannins: current knowledge of food sources, intake, bioavailability and biological effects

Tannins are a unique group of phenolic metabolites with molecular weights between 500 and 30 000 Da, which are widely distributed in almost all plant foods and beverages. Proanthocyanidins and hydrolysable tannins are the two major groups of these bioactive compounds, but complex tannins containing structural elements of both groups and specific tannins in marine brown algae have also been described. Most literature data on food tannins refer only to oligomeric compounds that are extracted with aqueous-organic solvents, but a significant number of non-extractable tannins are usually not mentioned in the literature. The biological effects of tannins usually depend on their grade of polymerisation and solubility. Highly polymerised tannins exhibit low bioaccessibility in the small intestine and low fermentability by colonic microflora. This review summarises a new approach to analysis of extractable and non-extractable tannins, major food sources, and effects of storage and processing on tannin content and bioavailability. Biological properties such as antioxidant, antimicrobial and antiviral effects are also described. In addition, the role of tannins in diabetes mellitus has been discussed.

In vitro antioxidant and free radical scavenging activity of Cyperus rotundus

Cyperus rotundus (Family Cyperaceae) is used both as a functional food and as a drug. In this study, the antioxidative potential of a hydroalcoholic extract of C. rotundus (CRE) was evaluated by various antioxidant assays, including antioxidant capacity by the phosphomolybdenum method, total antioxidant activity in linoleic acid emulsion systems, 1,1-diphenyl-2-picrylhydrazyl (DPPH), superoxide, hydroxyl radicals, and nitric oxide (NO) scavenging. We further evaluated the reducing potential of the extract as well as Fe(2+)/ascorbate-induced lipid peroxidation in rat liver homogenate. These various antioxidant activities were compared to standard antioxidants such as butylated hydroxytoluene, tocopherol, L-ascorbic acid, and catechin. Total phenolic and flavonoid content of CRE was also determined by a colorimetric method. The extract exhibited high reduction capability and powerful free radical scavenging, especially against DPPH and superoxide anions as well as a moderate effect on NO. CRE also showed inhibited lipid peroxidation in rat liver homogenate induced by Fe(2+)/ascorbate and prevented deoxyribose degradation in both non-site-specific and site-specific assays showing the hydroxyl radical scavenging and metal chelating activity of the hydroalcoholic extract. Moreover, the peroxidation inhibiting activity of CRE was demonstrated in the linoleic acid emulsion system. These results clearly established the antioxidative potency of C. rotundus, which may account for some of the medical claims attributed to this plant.

Antimicrobial activity of some important Adiantum species used traditionally in indigenous systems of medicine

Adiantum Linn. of Adiantaceae family is one of the most common and widely distributed species. Ethnomedicinally, the genus is important and popularly known as "Hansraj" in Ayurvedic System of Medicine. It has been used in cold, tumors of spleen, liver and other viscera, skin diseases, bronchitis and inflammatory diseases. It is also considered as tonic and diuretic. In the present study its four important species, i.e. Adiantum capillus-veneris, Adiantum peruvianum, Adiantum venustum and Adiantum caudatum were collected and extracted with methanol. These extracts were tested for their antimicrobial agents against five gram positive, six gram negative (including multiresistant bacteria Staphylococcus aureus) and eight fungal strains using standard microdilution assay. The maximum activity was exhibited by the methanolic extract of Adiantum venustum followed by Adiantum capillus-veneris, Adiantum peruvianum and Adiantum caudatum. The methanolic extract of Adiantum capillus-veneris had very low MIC value (0.48 microg/ml) against Escherichia coli whereas, Adiantum venustum extract against Aspergillus terreus with MIC of 0.97 microg/ml. Total phenolic constituents of Adiantum species viz. Adiantum venustum, Adiantum capillus-veneris, Adiantum peruvianum and Adiantum caudatum were 0.81% (w/w), 0.83% (w/w), 0.71% (w/w) and 0.52% (w/w), respectively (as gallic acid equivalent); implying that the observed activity could be related to the amount of phenolics.

Antioxidant and hepatoprotective actions of medicinal herb, Terminalia catappa L. from Okinawa Island and its tannin corilagin

The antioxidant and hepatoprotective actions of Terminalia catappa L. collected from Okinawa Island were evaluated in vitro and in vivo using leaves extract and isolated antioxidants. A water extract of the leaves of T. catappa showed a strong radical scavenging action for 1,1-diphenyl-2-picrylhydrazyl and superoxide (O(2)(.-)) anion. Chebulagic acid and corilagin were isolated as the active components from T. catappa. Both antioxidants showed a strong scavenging action for O(2)(.-) and peroxyl radicals and also inhibited reactive oxygen species production from leukocytes stimulated by phorbol-12-myristate acetate. Galactosamine (GalN, 600 mg/kg, s.c.,) and lipopolysaccharide (LPS, 0.5 microg/kg, i.p.)-induced hepatotoxicity of rats as seen by an elevation of serum alanine aminotransferase, aspartate aminotransferase and glutathione S-transferase (GST) activities was significantly reduced when the herb extract or corilagin was given intraperitoneally to rats prior to GalN/LPS treatment. Increase of free radical formation and lipid peroxidation in mitochondria caused by GalN/LPS treatment were also decreased by pretreatment with the herb/corilagin. In addition, apoptotic events such as DNA fragmentation and the increase in caspase-3 activity in the liver observed with GalN/LPS treatment were prevented by the pretreatment with the herb/corilagin. These results show that the extract of T. catappa and its antioxidant, corilagin are protective against GalN/LPS-induced liver injury through suppression of oxidative stress and apoptosis.

Quercus infectoria galls possess antioxidant activity and abrogates oxidative stress-induced functional alterations in murine macrophages

The present study reports the antioxidant activity of ethanolic extract of Quercus infectoria galls. The antioxidant potency of galls was investigated employing several established in vitro model systems. Their protective efficacy on oxidative modulation of murine macrophages was also explored. Gall extract was found to contain a large amount of polyphenols and possess a potent reducing power. HPTLC analysis of the extract suggested it to contain 19.925% tannic acid (TA) and 8.75% gallic acid (GA). The extract potently scavenged free radicals including DPPH (IC(50)~0.5 microg/ml), ABTS (IC(50)~1 microg/ml), hydrogen peroxide (H(2)O(2)) (IC(50)~2.6 microg/ml) and hydroxyl (*OH) radicals (IC(50)~6 microg/ml). Gall extract also chelated metal ions and inhibited Fe(3+) -ascorbate-induced oxidation of protein and peroxidation of lipids. Exposure of rat peritoneal macrophages to tertiary butyl hydroperoxide (tBOOH) induced oxidative stress in them and altered their phagocytic functions. These macrophages showed elevated secretion of lysosomal hydrolases, and attenuated phagocytosis and respiratory burst. Activity of macrophage mannose receptor (MR) also diminished following oxidant exposure. Pretreatment of macrophages with gall extract preserved antioxidant armory near to control values and significantly protected against all the investigated functional mutilations. MTT assay revealed gall extract to enhance percent survival of tBOOH exposed macrophages. These results indicate that Q. infectoria galls possess potent antioxidant activity, when tested both in chemical as well as biological models.

Phytomedicinal activity of Terminalia arjuna against carbon tetrachloride induced cardiac oxidative stress

Chronic and acute overproduction of reactive oxygen species (ROS) plays a positive role in the development of cardiovascular diseases under pathophysiological conditions. However, very little is known about carbon tetrachloride (CCl(4)) induced cardiac oxidative stress. The present study was conducted to find out CCl(4) induced oxidative insult in cardiac tissue and the cardioprotective effect of the 70% ethanol extractable active constituents of the bark of Terminalia arjuna (TA) against that stress in mice. Oral administration of CCl(4) at a dose of 1ml/kg body weight for 2 days significantly reduced the activities of antioxidant enzymes, superoxide dismutase (SOD), catalase (CAT) and glutathione-S-transferase (GST), as well as depleted the level of reduced glutathione (GSH) in the cardiac tissue. In addition, extent of lipid peroxidation and the level of oxidized glutathione (GSSG) were increased under the same experimental conditions. Oral treatment of the active constituents of TA at a dose of 50mg/kg body weight for 7 days prior to CCl(4) administration significantly restored the activities of all antioxidant enzymes as well as increased the level of GSH and decreased the level of lipid peroxidation end products. In addition, FRAP assay showed that the active constituents of TA enhanced the cardiac intracellular antioxidant activity. Histological studies also supported the cardioprotective role of the active constituents. The active constituents-induced protective effect was compared with a known antioxidant, vitamin C. To the best of our knowledge, this is the first report describing the CCl(4) induced cardiac oxidative stress and cardioprotective action of the active phytoconstituents of Terminalia arjuna against that oxidative insult.

Antioxidative and oxidative changes in the digestive gland cells of freshwater mussels Unio tumidus caused by selected phenolic compounds in the presence of H2O2 or Cu2+ ions

Research on biomarkers as early bioindicators of perturbation in populations and individuals has received increasing interest during recent decades. These ecotoxicity studies allow us to measure the impact of environmental stressors and to monitor and evaluate the degradation or restoration of systems. In the present study we used bivalve molluscs (mussels), which are sensitive biomarkers of aquatic ecosystem pollution, to assess the effects of three polyphenols: tannic acid, ellagic acid and gallic acid. These compounds were used in the 1-60 microM concentration range, alone and in the presence of H(2)O(2) (40 and 100 microM) or Cu(2+) ions (50 microM). The fluorescence probe dichlorofluorescein-diacetate (DCFH-DA) was used to measure reactive oxygen species (ROS). The oxidation of DCFH-DA to the fluorescent DCF (dichlorofluorescein) by the phenolic compounds was investigated spectrofluorimetrically. The results showed that the polyphenols tested can act as antioxidants against the ROS present in the digestive gland cells, but their activity is decreased after incubation with hydrogen peroxide or copper ions. SH-groups were determined spectrophotometrically using Ellman's reagent. The results showed that oxidative modification of proteins increased in a concentration-dependent manner in cells incubated with polyphenols (above 15 microM) alone. Incubation of the cells with phenolic acids and H(2)O(2) or Cu(2+) ions revealed that the phenolic acids had prooxidant properties in all concentrations used except for 1 microM tannic and ellagic acid and 40 microM H(2)O(2). DNA fragmentation was estimated by a fluorescence method using Hoechst 33258/propidium iodine binding. The data showed that the phenolic acids alone and in the presence of hydrogen peroxide or copper ions can induce apoptosis and necrosis. The methods used and results obtained indicate that the polyphenols selected can act not only as antioxidants but also as prooxidants in digestive gland cells of Unio tumidus.

Protein isolate from the herb, Phyllanthus niruri L. (Euphorbiaceae), plays hepatoprotective role against carbon tetrachloride induced liver damage via its antioxidant properties

Phyllanthus niruri L. (Euphorbiaceae) (P. niruri) is a well-known hepatoprotective herbal plant. In the present study, hepatoprotective potential of the protein isolate of P. niruri was investigated against carbon tetrachloride (CCl(4)) induced liver damage in vivo. Protein isolate of P. niruri was intraperitoneally injected in mice either prior to (preventive) or after the induction of toxicity (curative). Levels of different liver marker enzymes in serum and different anti-oxidant enzymes, as well as lipid peroxidation products and glutathione (GSH) in liver homogenates were measured in normal, control (toxicity induced) and protein isolate treated mice. Administration of CCl(4) increased the serum glutamate pyruvate transaminase (GPT) and alkaline phosphatase (ALP) levels of mice sera along with increased lipid peroxidation and reduced levels of antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) in the liver. Treatment with the protein isolate of P. niruri significantly altered these changes to almost normal. The protein isolate also showed protective properties as was evidenced in histopathological studies. Results suggest that the protein isolate of P. niruri protects liver tissues against oxidative damage and somehow helps stimulating repair mechanism present in liver. It could be used as an effective hepatoprotector against CCl(4) induced liver damage.

Evaluation of free radical scavenging and antityrosinase activities of standardized longan fruit extract

The protective effects of fruits and vegetables against chronic diseases have been attributed to the antioxidant properties of some secondary metabolites present in these foods. Plant polyphenols have been reported to exhibit bioactive properties, and in particular antioxidant activities. Longan seeds are found to contain high levels of some beneficial polyphenolic compounds such as corilagin, gallic acid and ellagic acid. The present study examined the free radical scavenging activity of longan seed extract by using three different assay methods. Longan extracts contained corilagin ranging from zero to 50.64 mg/g DW, gallic acid from 9.18 to 23.04 mg/g DW, and ellagic acid from 8.13 to 12.65 mg/g DW depending on the cultivars. Dried longan seed extracts of cultivar Edor contained high levels of gallic acid and ellagic acid and also exhibited the highest radical scavenging activities when comparing fresh seed and dried pulp extracts. For scavenging activity of DPPH and superoxide radicals, longan seed extract was found to be as effective as Japanese green tea extract while dried longan pulp and mulberry green tea extracts showed the least scavenging activities. In the ORAC assay, both fresh and dried longan seed also had higher activity than dried pulp and whole fruit. However, the results demonstrate that three polyphenolics may not be the major contributors of the high antioxidant activity of longan water extracts but this high activity may be due to other phenolic/flavonoid glycosides and ellagitannins present in longan fruit. In addition, longan seed also showed tyrosinase inhibitory activity with IC(50) values of 2.9-3.2 mg/ml. Therefore, the preliminary observations suggest that longan seed extract could be another potential source of potent natural dietary antioxidants and also in an application as a new natural skin-whitening agent.

Antiulcer and antimicrobial activity of Anogeissus latifolia

Ethnobotanically, the bark of Anogeissus latifolia (Roxb. ex DC.) Wall. ex Guill. and Perr.(Combretaceae) has been reported to be used in the treatment of various disorders including stomach and skin diseases. We studied the antiulcer potential and antimicrobial activity of the 50% aqueous alcoholic extract in order to validate ethnobotanical claims regarding the plant use in the above-mentioned disorders. Gastroprotective potential of the Anogeissus latifolia extract (ALE) (100 and 200mg/kg/body weight) was studied on aspirin, cold-resistant stress (CRS), pylorus ligated (PL) and ethanol-induced ulcers. Status of the antioxidant enzymes superoxide dismutase (SOD) and catalase along with lipid peroxidation (LPO) was also studied in CRS-induced ulcers. The results of the present study showed for the first time that the ALE possessed gastroprotective activity as evidenced by its significant inhibition in the formation of ulcers induced by physical and chemical agents with a maximum of 84.16% curation (200mg/kg body weight) in CRS-induced ulcers. ALE decreased LPO and SOD with concomitant increase in catalase activity in CRS-induced ulcers. Moderate antibacterial activity and antifungal activity was also observed. High performance thin layer chromatography (HPTLC) showed the presence of gallic acid and ellagic acid (0.95%, w/w, 0.25%, w/w, respectively) in the plant. These findings could justify, at least partially, the inclusion of this plant in the management of gastric disorders in traditional medicine.

Antioxidant properties of minocycline: neuroprotection in an oxidative stress assay and direct radical-scavenging activity

Minocycline is neuroprotective in animal models of a number of acute CNS injuries and neurodegenerative diseases. While anti-inflammatory and anti-apoptotic effects of minocycline have been characterized, the molecular basis for the neuroprotective effects of minocycline remains unclear. We report here that minocycline and a number of antioxidant compounds protect mixed neuronal cultures in an oxidative stress assay. To evaluate the role of minocycline's direct antioxidant properties in neuroprotection, we determined potencies for minocycline, other tetracycline antibiotics, and reference antioxidant compounds using a panel of in vitro radical scavenging assays. Data from in vitro rat brain homogenate lipid peroxidation and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assays show that minocycline, in contrast to tetracycline, is an effective antioxidant with radical scavenging potency similar to vitamin E. Our findings suggest that the direct antioxidant activity of minocycline may contribute to its neuroprotective effects in some cell-based assays and animal models of neuronal injury.

Inhibition of glutathione S-transferases by thonningianin A, isolated from the African medicinal herb, Thonningia sanguinea, in vitro

There is evidence that increased expression of glutathione S-transferase (EC: 2.5.1.18, GST) is involved in resistance of tumor cells against chemotherapeutic agents. In this study we investigated the inhibitory effects of thonningianin A (Th A), a novel antioxidant isolated from the medicinal herb, Thonningia sanguinea on uncharacterized rat liver GST and human GST P1-1. Using 1-chloro-2,4-dinitrobenzene (CDNB) as substrate, rat liver cytosolic GST activity was inhibited by Th A in a concentration dependent manner with 50% inhibition concentration (IC50) of 1.1 microM. When Th A was compared with known potent GST inhibitors the order of inhibition was tannic acid>cibacron blue>hematin>Th A>ethacrynic acid with CDNB as substrate. Th A also exhibited non-competitive inhibition towards both CDNB and glutathione. Furthermore, using 1,2-dichloro-4-nitrobenzene, ethacrynic acid and 1,2-epoxy-3-(p-nitrophenoxy) propane as substrates Th A at 1.0 microM inhibited cytosolic GST by 2%, 12% and 36% respectively. Human GST P1-1 was also inhibited by Th A with an IC50 of 3.6 microM. While Th A showed competitive inhibition towards CDNB it exhibited non-competitive inhibition towards GSH of the human GST P1-1. These results suggest that Th A represents a new potent GST in vitro inhibitor.