黄连素抗Tg和Fuc诱导的小鼠巨噬细胞凋亡的实验研究

目的 研究黄连素抗小鼠巨噬细胞凋亡的作用,初步确定其抗凋亡的浓度,探讨其治疗动脉粥样硬化(athemsclemsis,As)的机制.方法 以0.5 μmol/L的毒胡萝卜素(Tg)和50 μg/ml的墨角藻聚糖(Fuc)诱导RAW264.7巨噬细胞凋亡为实验模型,通过细胞毒性试验(MTT)法检测细胞存活率,Annexin V-FITC/P1流式细胞术检测细胞凋亡率.结果 浓度为800 μg/ml的黄连素组与正常对照组细胞存活率相比差异有统计学意义(P<0.01);随着黄连素浓度的下降,细胞凋亡率旱现下降的趋势,黄连素(0.02～0.63 μg/ml)能有效抑制Tg和Fuc诱导的小鼠巨噬细胞凋亡.结论 黄连素对RAW267.4细胞的增殖影响不大.黄连素能有效抑制Tg和Fuc诱导的小鼠巨噬细胞凋亡.     

Antibacterial efficacy of new commercially manufactured disinfectant substances against Salmonella typhimurium

The antibacterial effect of 19 new commercially manufactured disinfectant substances on a Salmonella typhimurium strain was studied. The substances tested represent 9 quaternary ammonium salts (QAT) and 11 combinated QAT with other ingredients. The antimicrobial efficacy was characterized by influencing the growth and reproduction of bacterial cells expressed either by MIC and ED₅₀ values (ED50 values represent concentration of substance in μ/ml which cause inhibition of growth by 50%), as well as by the inhibition of incorporation rate of [¹⁴C] adenine and [¹⁴C] leucine. The disinfectants are divided into three groups according to their efficacy. The first group comprises substances with strong inhibitory effect (MIC 0.04–0.19 μ/ml) such as Neoquat S, Antibacteric P, Divoquat forte, Sokrena and Diesin forte (sole from the group belonging to multicomponent substances). QAT except Antibacteric P interfere with energy metabolism (R values ～1). The second group represents substances with good antibacterial efficacy (MIC values up 1.56 μg/ml), and the third group substances with MIC values up 12.5 μg/ml. Cutasept G was found ineffective also in the concentration 100 μg/ml. The method of inhibition of [¹⁴C] precursors is suitable as one from possible criterion in evaluation of antibacterial efficacy of various synthetic substances.     

Sensitivity of monoclonal antibody, 5-D-4, for the detection of aggrecan,aggrecan fragments,and keratan sulfate

Bovine nasal septum aggrecan and selected proteinase-digested products of aggrecan were evaluated in an inhibition ELISA using the anti-keratan sulfate (KS) monoclonal antibody 5-D-4 (5D4). Undegraded aggrecan was recognized with an IC₅₀ of 0.27 μg/ml. When aggrecan was treated with human stromelysin (SLN), human leukocyte elastase (HLE), or papain, the degradation fragments had different hydrodynamic sizes. Treatment with SLN produced the largest fragments, HLE generated intermediate fragments, and papain the smallest fragments. Whereas degradation of aggrecan by SLN had little effect on recognition of proteoglycan in the ELISA (IC₅₀-0.5 μg/ml), degradation by both HLE and papain significantly decreased the sensitivity for detection of KS epitope (IC₅₀-170 and 215 μg/ml, respectively). In addition, 5D4 detected single chain costal and corneal KS with much less sensitivity (IC₅₀-21 and 469 μg/ml, respectively) than undegraded aggrecan (IC₅₀-0.27 μg/ml).

     

Biological Activities of Asparagus Racemosus

Cytotoxic, antioxidant, tyrosinase inhibitory, antimicrobial activities of the crude ethanol extract of dry powdered roots of Asparagus racemosus (Liliaceae) were investigated. The LC₅₀ to brine shrimp was 2189.49 µg/ml; the EC₅₀ for DPPH radical scavenging was 381.91 µg/ml; the IC₅₀ for tyrosinase inhibition was 7.98 mg/ml. The extract was active at 5–20 mg/ml against various pathogenic microbial (16 species, 18 strains) using the agar dilution assay, with the minimum inhibitory concentration (MIC) between 10–20 mg/ml for enteropathogens, the MIC between 5–20 mg/ml for dermatopathogens, and MIC = 10 mg/ml for a pneumonia causing bacteria Klebsiella pneumoniae. TLC and HPLC finger printing showed the presence of steroids-terpenes, alkaloids and flavonoids.     

Effect of oregano (<Emphasis Type="Italic">Origanum vulgare</Emphasis> L.) and thyme (<Emphasis Type="Italic">Thymus vulgaris</Emphasis> L.) essential oils on <Emphasis Type="Italic">Trypanosoma cruzi</Emphasis> (Protozoa: Kinetoplastida) growth and ultrastructure

In the present work, we have investigated the effect of essential oils obtained from Origanum vulgare L. (oregano) and Thymus vulgaris L. (thyme) on growth and ultrastructure of diverse evolutive forms of Trypanosoma cruzi. Culture epimastigotes and bloodstream trypomastigotes were incubated for 24 h with different concentrations of oregano or thyme essential oils and with thymol (the main constituent of thyme), and the inhibitory concentration (IC)₅₀ was determined by cell counting. Crude extract of oregano essential oil inhibited epimastigote growth (IC₅₀/24 h = 175 μg/ml) and also induced trypomastigote lysis (IC₅₀/24 h = 115 μg/ml). Thyme essential oil presented IC₅₀/24 h values of 77 μg/ml for epimastigotes and 38 μg/ml for trypomastigotes, while treatment with thymol resulted in an IC₅₀/24 h of 62 μg/ml for epimastigotes and 53 μg/ml for trypomastigotes. Scanning electron microscopy of treated cells showed few morphological alterations at the plasma membrane. Observation by transmission electron microscopy showed cytoplasmic swelling with occasional morphological alterations in plasma and flagellar membrane. Our data indicate that oregano and thyme essential oils are effective against T. cruzi, with higher activity of thyme, and that thymol may be the main component responsible for the trypanocidal activity.     

Vernonia cinerea L. scavenges free radicals and regulates nitric oxide and proinflammatory cytokines profile in carrageenan induced paw edema model

In this study, we evaluated the anti-oxidant and anti-inflammatory activities of the medicinal plant, Vernonia cinerea L (Asteraceae) using in vitro as well as in vivo models. Methanolic extract of Vernonia cinerea was found to scavenge the hydroxyl radical generated by Fenton reaction (IC₅₀130 μg/ml), Superoxide generated by photo reduction of riboflavin (IC₅₀190 μg/ml) and inhibited lipid peroxidation significantly (IC₅₀130.5 μg/ml). The drug also scavenged nitric oxide (IC₅₀210 μg/ml). Intraperitoneal administration of Vernonia cinerea was found to inhibit the PMA induced Superoxide generation in mice peritoneal macrophages. The administration of Vernonia cinerea to mice significantly increased the levels of catalase, superoxide dismutase, glutathione, glutathione peroxidase and glutathione-S transferase in blood and liver, whereas lipid peroxidation activity was significantly decreased. It was also found that Vernonia cinerea extract significantly inhibited carrageenan induced inflammation, compared with control models. Down regulation of pro-inflammatory cytokine level and gene expression were also support the above result.     

The anti-amoebic activity of some medicinal plants used by AIDS patients in southern Thailand

The anti-amoebic activities of chloroform, methanol and water extracts from 12 Thai medicinal plants (39 extracts) commonly used by AIDS patients in southern Thailand were screened, at a concentration of 1,000 μg/ml, against Entamoeba histolytica strain HTH-56:MUTM and strain HM1:IMSS growing in vitro. The extracts were incubated with 2×10⁵ E. histolytica trophozoites/ml of medium at 37°C under anaerobic conditions for 24 h. The cultures were examined with an inverted microscope and scored (1–4) according to the appearance and numbers of the trophozoites. The extracts that caused inhibition were selected and retested using the same conditions but with concentrations that ranged from 31.25 to 1,000 μg/ml using E. histolytica strain HM1:IMSS, and the IC₅₀ values for each extract were calculated. The chloroform extracts from Alpinia galanga (IC₅₀ 55.2 μg/ml), Barleria lupulina (IC₅₀ 78.5 μg/ml), Boesenbergia pandurata (IC₅₀ 45.8 μg/ml), Piper betle (IC₅₀ 91.1 μg/ml) and Piper chaba (IC₅₀ 71.4 μg/ml) and the methanol extract from B. pandurata (IC₅₀ 57.6 μg/ml) were all classified as “active”, i.e. with an IC₅₀ of less than 100 μg/ml, whereas those from Murraya paniculata (IC₅₀ 116.5 μg/ml) and Zingiber zerumbet (IC₅₀ 196.9 μg/ml) were classified as being “moderately active”. The IC₅₀ of a standard drug, metronidazole, was 1.1 μg/ml.     

Biological Activities of Schefflera Leucantha

This study investigated various biological activities of the ethanolic extract of dried ground leaves of Schefflera leucantha Viguier (Araliaceae). The extract possessed very low cytotoxicity to brine-shrimp with the LC₅₀ of 4,111.15µg/ml; the significant antioxidant activity on DPPH with the EC₅₀ of 71.90µg/ml; the inhibitory activity on mushroom tyrosinase with the IC₅₀ of 10.53mg/ml using the dopachrome microplate-assay. The extract of 5–20mg/ml range in the agar dilution assay were active against various pathogenic microbial (11 species, 11 strains), with the minimum inhibitory concentration (MIC) of 5mg/ml against Clostridium spp.; MIC=10mg/ml against enteropathogens as Bacteroides spp., Enterococcus faecalis ATCC 29212, Lactobacillus spp., Peptococcus spp. and Streptococcus mutans; MIC=10mg/ml against a pneumonia causing bacteria Klebsiella pneumoniae and a dermatopathogen as Propionibacterium acnes; MIC=20mg/ml against dermatopathogens as Staphylococcus aureus ATCC 6538, Streptococcus spp. and Candida albicans ATCC 90028. TLC fingerprints of the specific extracts from the leaf powder exhibited zones of steroids-terpenes and flavonoids. HPLC fingerprint of the flavonoid extract was performed.     

Anti-leishmania activity of semi-purified fraction of <Emphasis Type="Italic">Jacaranda puberula</Emphasis> leaves

The crude methanolic extract from leaves of Jacaranda puberula showed activity against Leishmania (Leishmania) amazonensis. The extract presented active against promastigote forms with an inhibitory concentration 50% (IC₅₀) value of 88.0 μg/ml, but only moderated activity against amastigote forms; however in higher concentrations the extract showed cytotoxic effects. The bio-guided chromatographic fractionation the crude methanolic extract against amastigotes yielded a fraction with an IC₅₀ value of 14.0 μg/ml (without cytotoxic activity) in relation to the crude extract (IC₅₀ value, 359.0 μg/ml). These data indicate that J. puberula leaves contain active compounds, which should be further investigated for the development of new potential drugs against cutaneous leishmaniasis.     

Comparative activity of various compounds against clinical strains of herpes simplex virus

The following compounds were evaluated for their inhibitory activity against clinical strains of herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) in both primary rabbit kidney (PRK) and HeLa cell cultures: (S)-9-(3-hydroxy-2-phosphonylmethoxypropyl)adenine (HPMPA), 9-(2-phosphonylmethoxyethyl)adenine (PMEA), (S)-1-(3-hydroxy-2-phosphonylmethoxypropyl)cytosine (HPMPC), (RS)-9-(3-hydroxy-2-phosphonylmethoxypropyl)-2,6-diaminopurine (HPMPDAP), 5-(5-bromothien-2-yl)-2-deoxyuridine (BTDU), 5-(5-chlorothien-2-yl)-2-deoxyuridine (CTDU), 9-(2-deoxy-2-hydroxymethyl--D-erythro-oxetanosyl)guanine (OXT-G), pentosan polysulfate, heparin, dextran sulfate (MW 10,000), acyclovir, 9-(2-hydroxyethoxymethyl)guanine (ACV), (E)-5-(2-bromovinyl)-2-deoxyuridine (BVDU), 1--D-arabinofuranosyl-(E)-5-(2-bromovinyl)-uracil (BVaraU), vidarabine (9--D-arabinofuranosyladenine) (ara-A) and phosphonoformate (PFA). The most potent inhibitors of HSV-1 were (in order of decreasing activity in PRK cells) BVDU, ACV, BVaraU and OXT-G, their mean 50 % inhibitory concentration (IC₅₀) ranging from 0.02 µg/ml to 0.9 µg/ml. Then followed BTDU and CTDU (IC₅₀ 1–2 µg/ml), the sulfated polysaccharides (IC₅₀ 1.3–5.8 µg/ml), the phosphonylmethoxyalkyl derivatives (IC₅₀ 5.6–25 µg/ml), ara-A (IC₅₀ 11 µg/ml) and PFA (IC₅₀ 38.5 µg/ml). Except for BVDU, BVaraU, BTDU and CTDU, the compounds did not discriminate between HSV-2 and HSV-1. All the compounds studied could be considered specific anti-HSV agents. Their selectivity indexes varied from 3 (PFA) to 6400 (BVDU).     

Antiplasmodial activity of ineupatorolides A from Carpesium rosulatum

Samples of Carpesium genus used as traditional remedies for the treatment of parasite infections were collected, and methanol extracts were obtained by sonication. The ethylacetate-, n-butanol- and H₂O-soluble fractions exhibited weak antiplasmodial activity (IC₅₀ > 100 μg/ml; IC₅₀, 50% inhibitory concentration). However, the chloroform fraction exhibited more impressive antiplasmodial activity (IC₅₀ = 8.2 μg/ml). The antiplasmodial activity of the chloroform fractions was evaluated in vitro against the chloroquine-resistant D10 strain of Plasmodium falciparum. Bioactivity-guided isolation of the chloroform fractions of the whole plants of Carpesium rosulatum has led to the isolation of a sesquiterpene lactone, ineupatorolides A, displaying high antiplasmodial activity (IC₅₀ = 0.007 μg/ml). This is the first report of the isolation of ineupatorolides A from this species and of its remarkable antiplasmodial activity.     

The use of microfluorometric method for activity-guided isolation of antiplasmodial compound from plant extracts

In vitro antiplasmodial activity of methanolic extracts of 16 medicinal plants was evaluated by fluorometric assay using PicoGreen. The IC50s, as determined by parasite DNA concentration, ranged from <11 to >200 and <13 to >200 μg/ml for Plasmodium falciparum 3D7 and K1, respectively; and the most active extracts were those from Anogeissus leiocarpus and Terminalia avicennoides (<11–≥14 μg/ml). Aqueous, butanolic, ethyl acetate, and methanolic fractions of these two extracts revealed butanolic fraction to have a relatively better activity (IC₅₀, 10–12 μg/ml). Activity-guided chromatographic separation of the butanolic fraction on Sephadex LH-20 followed by nuclear magnetic resonance and correlation high-performance liquid chromatography revealed the presence of known hydrolysable tannins and some related compounds—castalagin, ellagic acid, flavogallonic acid, punicalagin, terchebulin, and two other fractions. The IC₅₀s of all these compounds ranged between 8–21 μg/ml (8–40 μM) against both the strains. Toxicity assay with mouse fibroblasts showed all the extracts and isolated compounds to have IC₅₀ ≥ 1500 μg/ml, except for Momordica balsamina with <1500 μg/l. All the extracts and isolated compounds did not affect the integrity of human erythrocyte membrane at the observed IC₅₀s. However, adverse effects manifest in a concentration-dependent fashion (from IC₅₀ ≥ 500 μg/ml).     

Dual inhibition of 5-lipoxygenase/cyclooxygenase by a reconstituted homeopathic remedy; possible explanation for clinical efficacy and favourable gastrointestinal tolerability

Objective: In order to elucidate potential anti-inflammatory activities of Zeel comp. N and its constituents, the inhibition of the synthesis of Leukotriene B₄ (LTB₄) and Prostaglandin (PGE₂) by 5-lipoxygenase (5-LOX) and cyclo-oxygenase 1 and 2 (COX 1 and 2) respectively were examined in vitro.Materials: Human HL-60 cells, differentiated for 6–8 days with DMSO (1.2% v/v) were used for the 5-LOX assay. The COX activity assays were carried out with purified enzymes, COX 1 (ram seminal vesicles), COX 2 (sheep placenta) and with human THP-1 cells, differentiated for 24 h with PMA (50 nM).Methods: LTB₄ and PGE₂ production in the 5-LOX and COX assays respectively were determined by enzyme linked immunoassays.Results: A reconstituted Zeel comp. N combination as well as its constituent mother tinctures of Arnica montana, Sanguinaria canadensis and Rhus toxicodendron (Toxicodendron quercifolium) showed distinct inhibitory effects on the production of LTB₄ by 5-LOX (IC₅₀ values of 10, 20, 2 and 5 µg/ml respectively) and on the synthesis of PGE₂ by COX 1 (IC₅₀ values of 50, 80, 40 and 20 µg/ml respectively) and COX 2 enzymes (IC₅₀ values of 60, 110, 50 and 20 µg/ml respectively). The mother tincture of Solanum dulcamara inhibited the production of PGE₂ by COX 1 (IC₅₀ 40 µg/ml) and COX 2 (IC₅₀ 150 µg/ml) but not production of leukotriene LTB₄ by 5-LOX.Conclusions: The observed dual inhibition of both LOX- and COX-metabolic pathways may offer an explanation for the reported clinical efficacy and the favorable gastrointestinal tolerability of the original remedy Zeel comp. N.Received 10 April 2003; returned for revision 27 May 2003; accepted by W. B. van den Berg 24 November 2003     

腺病毒介导胞嘧啶脱氨酶基因联合黄连素对直肠癌细胞的杀伤作用

目的:探讨黄连素联合腺病毒介导的胞嘧啶脱氨酶自杀基因(Ad-CD)对直肠癌细胞的体外杀伤作用.方法:用重组腺病毒介导外源CD基因转染到人直肠癌细胞株HR-8348,检测病毒的转导效率和CD基因表达.用四甲基偶氮唑盐(MTT法)检测黄连素联合Ad-CD基因对HR-8348细胞存活率及体外旁观者效应的影响.结果:在250μg/ml 5-氟胞嘧啶(5-FC)浓度下,0 1、 0 3、 3 0、 30 0μmol/L浓度的黄连素联合5-FC对直肠癌细胞生长抑制率分别为27 7%、 42 4%、 52 3%、 56 3%.3 0μmol/L浓度的黄连素可作为参考用药浓度.在转染和未转染CD基因的HR-8348混合体系中,黄连素联合CD/5-FC对直肠癌细胞具有更强的抑制作用.结论:黄连素可以增强自杀基因系统对直肠癌细胞的杀伤作用,可作为一种增效剂应用于直肠癌的治疗.     

Inhibitory Activity of Drynariae rhizoma Extracts on Cathepsin Having Bone Resorption Activity

Effects of traditional Korean (Hanbang) medicine, Drynariae rhizoma (DR), on the protease activity of bone loss‐initiation in rats and mice were investigated. Ethanol extracts‐DR (EE‐DR) and water extracts‐DR (WE‐DR) were identified as potent inhibitor of cathepsins K and L. The original WE‐DR inhibits cathepsins K and L with IC₅₀ values of 3.7 µg/ml and 4.5 µg/ml, respectively. EE‐DR was more potent than that of WE‐DR, because the inhibitions of cathepsin K and L increased to 0.5 µg/ml and 0.8 µg/ml, respectively. The EE‐DR was proved to be the most potent. EE‐DR was found to be a potent inhibitor of cathepsins K with a Ki value of 5.0 µg/ml for cathepsin K. The activity was increased by 10‐fold when the assay is performed in the presence of glutathione at pH 7.0, which favors the formation of a GSH thiolate anion. Thus, it is suggested that this increase in potency is probably due to an enhanced chemical reactivity of the extract mixtures toward the thiolate of the active site of the enzyme. WE‐DR exhibited time‐dependet inhibition which allowed us to determine the association and dissociation rate constants with cathepsin K. Finally, EE‐DR inhibits bone resorption in an in vitro assay involving mouse osteoclasts and bovine bone with an IC₅₀ value of 70 µg/ml. WE‐DR represents a new herbal formulation inhibiting cathepsin K and L activity and proteolysis of bone collagen. These results strongly suggest that DR is effective for preventing the development of bone loss induced by cathepsin K. This result also suggested that the DR is effective for bone resorptive action in bone cells.     

Antibacterial,antioxidant and anticancer activities of biphenyls from Streptomyces sp. BO-07: an endophyte in Boesenbergia rotunda (L.) Mansf A.

Strain BO-07 was isolated from the root tissue of Boesenbergia rotunda (L.) Mansf A. and identified as Streptomyces sp. on the basis of morphology, chemotaxonomy and 16S rDNA sequencing. The fractionation of the crude extract from strain BO-07 cultures led to the isolation of two biphenyls: 3′-hydroxy-5-methoxy-3,4-methylenedioxybiphenyl (1) and 3′-hydroxy-5,5′-dimethoxy-3,4-methylenedioxybiphenyl (2); these compounds and the crude extract had potent antibacterial activity against Gram-positive bacteria, and antioxidant and anticancer activities. These compounds showed the highest activity against Staphylococcus aureus ATCC25932, Bacillus cereus ATCC7064 and Bacillus subtilis ATCC6633 with a minimum inhibitory concentration value of 0.5?µg/ml and minimum bactericidal concentration of 2–8?µg/ml. Compounds 1 and 2 showed the highest (1, 1diphenyl-2-picryl hydrazyl) DPPH antioxidant activity with a scavenging concentration (SC₅₀) value of 85.84 and 88.26?µg/ml, respectively, and also showed strong cytotoxicity against all the three cancer cell lines (HeLa, HepG2 and Huh7) at an IC₅₀ value of 3.04–20.30?μg/ml. Both the compounds were less toxic on normal cells (L929) than on the investigated cancer cell lines.     

Determination of minimum inhibitory concentrations of itraconazole,terbinafine and ketoconazole against dermatophyte species by broth microdilution method

Purpose: Various antifungal agents both topical and systemic have been introduced into clinical practice for effectively treating dermatophytic conditions. Dermatophytosis is the infection of keratinised tissues caused by fungal species of genera Trichophyton, Epidermophyton and Microsporum, commonly known as dermatophytes affecting 20–25% of the world’s population. The present study aims at determining the susceptibility patterns of dermatophyte species recovered from superficial mycoses of human patients in Himachal Pradesh to antifungal agents; itraconazole, terbinafine and ketoconazole. The study also aims at determining the minimum inhibitory concentrations (MICs) of these agents following the recommended protocol of Clinical and Laboratory Standards Institute (CLSI) (M38-A2). Methodology: A total of 53 isolates of dermatophytes (T. mentagrophyte-34 in no., T. rubrum-18 and M. gypseum-1) recovered from the superficial mycoses were examined. Broth microdilution method M38-A2 approved protocol of CLSI (2008) for filamentous fungi was followed for determining the susceptibility of dermatophyte species. Results: T. mentagrophyte isolates were found more susceptible to both itraconazole and ketoconazole as compared to terbinafine (MIC₅₀: 0.125 μg/ml for itraconazole, 0.0625 μg/ml for ketoconazole and 0.5 μg/ml for terbinafine). Three isolates of T. mentagrophytes (VBS-5, VBSo-3 and VBSo-73) and one isolate of T. rubrum (VBPo-9) had higher MIC values of itraconazole (1 μg/ml). Similarly, the higher MIC values of ketoconazole were observed in case of only three isolates of T. mentagrophyte (VBSo-30 = 2 μg/ml; VBSo-44, VBM-2 = 1 μg/ml). The comparative analysis of the three antifungal drugs based on t-test revealed that ‘itraconazole and terbinafine’ and ‘terbinafine and ketoconazole’ were found independent based on the P < 0.005 in case of T. mentagrophyte isolates. In case of T. rubrum, the similarity existed between MIC values of ‘itraconazole and ketoconazole’ and ‘terbinafine and ketoconazole’. Conclusion: The MIC values observed in the present study based on standard protocol M38-A2 of CLSI 2008 might serve as reference for further studies covering large number of isolates from different geographic regions of the state. Such studies might reflect on the acquisition of drug resistance among isolates of dermatophyte species based on MIC values.     

Inhibition of Microsomal Lipid Peroxidation and Protein Oxidation by Extracts from Plants Used in Bamun Folk Medicine (Cameroon) Against Hepatitis

The antioxidant activities of 53 medicinal plants used in Bamun Folk Medicine for the management of jaundice and hepatitis were investigated. The studies were done using rat hepatic microsomes for lipid peroxidation and bovine serum albumin (BSA) for carbonyl group formation. Silymarine was used as reference compound. Fifteen different extracts were effective at a dose of 200µg/ml in both experiments. Specifically, 25 extracts inhibited lipid peroxidation initiated non-enzymatically by ascorbic acid while 18 inhibited peroxidation as determined by reduced Nicotinamide Adenine Dinucleotide Phosphate (NADPH). The inhibitory concentration 50 (IC₅₀) of 23 different plant extracts was lower than 200µg/ml in the microsomal lipid peroxidation inhibition study. Fifteen of the 23 extracts were active in preventing protein oxidation by inhibiting the formation of the carbonyl group on BSA with an IC₅₀ value less than 200µg/ ml. The results suggest that the antioxidant activity of the extracts, may be due to their ability to scavenge free radicals involved in microsomal lipid peroxidation or in protein oxidation. These biochemical processes are involved in the aetiology of toxic hepatitis.