The in vitro cytotoxic and apoptotic activity of Triphala--an Indian herbal drug

A study on cytotoxic effect of acetone extract of "Triphala" whose antimutagenicity has already been tested. The in vitro antimutagenic activity of Triphala--an Indian herbal drug. Food Chemistry and Toxicology 40, 47-54) was extended to test its cytotoxic effects on cancer cell-lines using Shionogi 115 (S115) and MCF-7 breast cancer cells and PC-3 and DU-145 prostate cancer cells as models. The results revealed that acetone extract of "Triphala" showed a significant cytotoxic effect on these cancer cell-lines and the effect was similar on all cancer cell lines used in this study. The major phenolic compounds in the most potent acetone extracts were isolated and purified. Structural analysis was conducted using spectroscopic techniques including mass spectroscopy, nuclear magnetic resonance (NMR) and infrared (IR) which showed gallic acid as the major component. The suppression of the growth of cancer cells in cytotoxic assays may be due to the gallic acid-a major polyphenol observed in "Triphala".     

Phytochemical profiling and phase II enzyme-inducing properties of Thunbergia laurifolia Lindl. (RC) extracts

Thunbergia laurifolia Lindl. (Acanthaceae) or Rang Chuet (RC) is described in traditional medicine for protection against dietary and environmental toxicants. This work, therefore, investigated RC's phytochemical profile, antimutagenic activity, and xenobiotic detoxification potential in its extracts. RC extracts were prepared by infusion with water, ethanol, acetone and subsequently assayed for major phytochemical constituents. Total phenolic content was 24.33, 5.65, and 1.42microg gallic acid equivalent (GAE) per mL for water, ethanol and acetone extract, respectively. HPLC analysis identified caffeic acid and apigenin as primary constituents of water extracts. Acetone and ethanol extracts contained primarily chlorophyll a and b, pheophorbide a, pheophytin a, and lutein. Treatment of Hepa 1C1C7 cells with standardized RC extracts resulted in a dose-dependent increase in QR specific activity for all extracts. Acetone extract (92microg GAE/mL) increased QR activity 2.8-fold, while ethanol (120microg GAE/mL) and water (1000microg GAE/mL) extracts increased QR activity by 1.35- and 1.56-fold, respectively. The RC extracts were subsequently assayed for mutagen and antimutagenic activity by bacterial reverse mutagenesis assay. All three RC extracts exhibited strong dose-dependent antimutagenic activity inhibiting 2-aminoanthracene induced mutagenesis up to 87% in Salmonella typhimurium TA 98. These results support the traditional medicinal use of RC for detoxification and suggest the potential role of both phenolic acids and natural chlorophyll constituents in modulating these effects.     

Cancer prevention and therapy with kiwifruit in Chinese folklore medicine: a study of kiwifruit extracts

Kiwi gold fruits were extracted successively with hexane, acetone, methanol and 70% methanol, and further fractionated by silica gel and ODS column chromatographies for the assays of various biological activities. Five fractions H1, H2 (hexane extract), Al, A2 (acetone extract) and M2 (methanol extract) showed selective cytotoxic activity against human oral tumor cell lines, which was more sensitive than human gingival fibroblasts. More hydrophilic fractions [70M3, 70M4, 70M5] of 70% methanol extract displayed higher anti-HIV activity, radical generation and O2- scavenging activity. The antibacterial activity of 70% methanol extracts [70M0, 70M1, 70M2, 70M3, 70M4] was generally lower than that of more lipophilic fractions (hexane, acetone, methanol extracts), although each fraction did not show any specific antimicrobial action. All fractions were inactive against Helicobacter pylori. These results demonstrate that gold kiwifruit extracts contain valuable, various bioactive materials, which can be separated with each other.     

Potential cytotoxic activity of some Brazilian seaweeds on human melanoma cells

In vitro screening of the crude extracts of some Brazilian coastal seaweeds for cytotoxic activity against a cultured human melanoma cancer cell line using the sulphorhodamine B assay was performed. The crude dichloromethane:chloroform extract of Stypopodium zonale showed good cytotoxic activity against the C32 cell line. The crude acetone extract and aqueous phase of Lobophora variegata did not show any activity, but semi-purified fractions XAD LOB I and II could inhibit the growth of melanoma cells. The crude acetone extract of Caulerpa racemosa showed some cytotoxicity, but caulerpin isolated from this extract did not show any such activity. The crude acetone extract of Spatoglossum schroederi was not able to inhibit the growth of C32 melanoma cells.     

Crown gall -- a plant tumour with biological activities

Petroleum ether, acetone, 80% MeOH and water extracts of crown gall, a plant tumour, obtained from Eucalyptus globulus tree were screened for cytotoxic, antioxidant, antiinflammatory, embryotoxic, antitumour-promoting and antimicrobial activities.In terms of bioactivity the 80% MeOH extract was most effective followed by the acetone extract. The petroleum ether extract showed weak to moderate cytotoxic activity in dose-dependent manner against PC12 cells, mouse L fibroblasts and 1321N1 glia cells, whereas the hydroalcohol extract had no or a weak cytotoxic effect. The 80% MeOH extract exhibited strong antioxidant activity. Based on the in vitro HET-CAM assay all the extracts were effective against inflammation. The extracts did not show any embryotoxic effect at the concentrations tested. Antitumour-promoting activity (100% inhibition; 100 microg/mL) was observed in the 80% MeOH and acetone extracts. In the antimicrobial screening all extracts displayed predominantly antifungal activity against Candida sp. The extracts also showed various levels of antibacterial activity against E. faecalis, Ps. aeruginosa, Bac. subtilis and Staph. epidermidis.From the results of the investigations it can be concluded that crown gall is a valuable plant tumour tissue having interesting biological activities.     

Biological activity of persimmon (Diospyros kaki) peel extracts

Fractionated extracts of persimmon (Diospyros kaki) peels were studied for cytotoxic activity, multidrug resistance (MDR) reversal activity, anti-human immunodeficiency virus (HIV) activity and anti-Helicobacter pylori (H. pylori) activity. The potent cytotoxic activity against human oral squamous cell carcinoma cells (HSC-2) and human submandibular gland tumor (HSG) cells was found in the acetone fractions (A4 and A5) with IC(50) ranging from 21 to 59 micro g/mL. However, the cytotoxic activity was not correlated with the radical intensity of the fractions. Three 70% MeOH extract fractions (70M2-4) produced radical and efficiently scavenged the O(2)(-) produced by hypoxanthine and xanthine oxidase reaction. All of the fractions tested were not effective for anti-H. pylori and anti-HIV. Fractions H3 and H4 of hexane extract, and M2 and M3 of MeOH extract showed a remarkable MDR reversal activity comparable with that of (+/-)-verapamil (a positive control). These results indicate the therapeutic value of persimmon peel extracts as potential antitumor and MDR-reversing agents.     

Antioxidant, anti-inflammatory, anti-nociceptive activities and composition of Lythrum salicaria L. extracts

Lythrum salicaria (purple loosestrife) known as "Tibbi hevhulma" in Turkish is used for its several beneficial health effects against as diarrhea, chronic intestinal catarrh, hemorrhoid and eczema in the form of a decoction or a fluid extract and to treat varicose veins, bleeding of the gums, hemorrhoid and eczema, externally. Dried herbal parts of Lythrum salicaria L. (Lythraceae) were sequentially extracted with different solvents such as petroleum ether, ethyl acetate, methanol and 50% aqueous methanol. Water extract of Lythrum salicaria was also prepared under reflux. Antioxidant, anti-inflammatory and anti-nociceptive activities of all the extracts were investigated using in vitro and in vivo methods, respectively. Free radical scavenging activity (1,1-diphenyl-2-picrylhydrazyl, DPPH* assay), iron(III) reductive activity, capacity of the inhibition of linoleic acid peroxidation and MDA formation, anti-nociceptive activity (p-benzoquinone-induced abdominal constriction test) and anti-inflammatory activity (carrageenan-induced hind paw edema model) were used for all the extracts. In addition, the content of total phenolics, flavonoids and flavonols in all the extracts were determined with spectrophotometric methods. Results were compared with reference antioxidants via ascorbic acid, butylated hydroxytoluene, and gallic acid. Qualitative and quantitative compositions of all the extracts were analysed using a HPLC-PDA system. Polar fractions were found to be rich in flavonoids such as isovitexin and isoorientin.     

九牛造中总鞣质提取方法和没食子酸含量测定研究

目的:测定九牛造根中总鞣质和没食子酸含量。方法:以没食子酸为对照品,分别用紫外分光光度法及高效液相色谱法测定九牛造根中总鞣质和没食子酸含量。结果:九牛造根不同提取方法所得样品中总鞣质含量分别是水超声提取为4.375%;70%乙醇超声提取为7.24%;丙酮超声提取为3.958%;水回流提取为3.773%;70%乙醇回流提取为2.503%;丙酮回流提取为1.59%。九牛造根中没食子酸含量为0.047%。结论:采用70%乙醇超声提取所得样品中总鞣质含量最高,该方法可用于九牛造根中总鞣质的提取方法。     

Modulation of rat and human cytochromes P450 involved in PhIP and 4-ABP activation by an aqueous extract of Phyllanthus orbicularis

Phyllanthus orbicularis HBK (Euphorbiaceae) is a medicinal plant, endemic to Cuba, whose aqueous extract has proven antimutagenic effects against hydrogen peroxide and some promutagenic aromatic amines (AAs), in addition to its antiviral properties. In this paper, antimutagenesis of this extract against two carcinogenic AAs, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) and 4-aminobiphenyl (4-ABP) has been studied. Liver microsomal fractions from both induced rats and humans were used to metabolise both procarcinogenic compounds in the Salmonella assay. The plant extract was effective in reducing the mutagenesis of these AAs, activated by both kinds of fractions. The optimal antimutagenic effect was obtained when both AAs were metabolised by human enzymes, with an almost total reduction of 4-ABP mutagenesis and a decrease of about 75% of PhIP mutagenicity. Mutagenicity of both AAs, activated by induced rat fraction, was only decreased by about 50%. Inhibition by plant extract of alkoxyresorufin O-dealkylation activities, dependent on CYP1A, of both fractions was determined. In accordance with the results obtained, the inhibition or modulation of CYP1A subfamily activities, and possibly of CYP1A2, is thought to be the main mechanism of antimutagenesis of the aqueous extract of Phyllanthus orbicularis against 4-ABP and PhIP.     

Biological activity of barbados cherry (acerola fruits, fruit of Malpighia emarginata DC) extracts and fractions

Fractionation of barbados cherry (acerola fruit, a fruit of Malpighia emarginata DC.) extracts were performed by organic solvent extractions and column chromatographies, using two extraction methods. Higher cytotoxic activity was concentrated in fractions A4 and A6 (acetone extract), and H3 and HE3 (hexane extract). These four fractions showed higher cytotoxic activity against tumor cell lines such as human oral squamous cell carcinoma (HSC-2) and human submandibular gland carcinoma (HSG), when compared with that against normal cells such as human periodontal ligament fibroblasts (HPLF) and human gingival fibroblasts (HGF). HE2 (hexane extract), AE2 (ethyl acetate extract), AE3, AE4, AE5, A8, A9 and A10 showed some relatively higher anti-bacterial activity on the Gram-positive Staphylococcus epidermidis ATCC 1228 but were ineffective on the representative Gram-negative species E. coli and Ps. aeruginosa. The fractions were inactive against Helicobacter pylori, two representative Candida species, and human immunodeficiency virus (HIV). H3, H4 and HE3, which displayed higher tumor-specific cytotoxicity also showed higher multidrug resistance (MDR) reversal activity, than (+/-)-verapamil as positive control. ESR spectroscopy shows that the radical-mediated oxidation is not involved in the induction of tumor-specific cytotoxic activity. The tumor specific cytotoxic activity and MDR reversal activity of barbados cherry may suggest its possible application for cancer therapy.     

Anticonvulsive activity of Albizzia lebbeck, Hibiscus rosa sinesis and Butea monosperma in experimental animals

The ethanolic extracts of leaves of Albizzia lebbeck and flowers of Hibiscus rosa sinesis and the petroleum ether extract of flowers of Butea monosperma exhibited anticonvulsant activity. The bioassay guided fractionation indicated that the anticonvulsant activity lies in the methanolic fraction of chloroform soluble part of ethanolic extract of the leaves of A. lebbeck, acetone soluble part of ethanolic extract of H. rosa sinesis flowers and acetone soluble part of petroleum ether extract of B. monosperma flowers. The fractions protected animals from maximum electro shock, electrical kindling and pentylenetetrazole-induced convulsions in mice. The fractions also inhibited convulsions induced by lithium-pilocarpine and electrical kindling. However, they failed to protect animals from strychnine-induced convulsions. The fractions antagonised the behavioral effects of D-amphetamine and potentiated the pentobarbitone-induced sleep. The fractions raised brain contents of gamma-aminobutyric acid (GABA) and serotonin. These fractions were found to be anxiogenic and general depressant of central nervous system.     

没食子酸抑制白念珠菌生物膜作用的研究

目的:研究没食子酸对体外白念珠菌生物膜的影响.方法:采用XTT减低法评价没食子酸对白念珠菌的生物膜及黏附性的影响;镜下观察没食子酸对白念珠菌生物膜的形态学影响;细胞毒试验检测该药的毒副作用.结果:没食子酸抑制白念珠菌生物膜最低药物浓度SMIC_(50),SMIC_(80)分别是500,1 000 mg·L~(-1);100,1 000 mg·L~(-1) 的没食子酸对白念珠菌的早期黏附及菌丝生长有抑制作用;没食子酸对人细胞毒性较弱.结论:没食子酸对体外白念珠菌生物膜有较强的抑制作用.     

Cytotoxic and multidrug resistance reversal activity of a vegetable, 'Anastasia Red', a variety of sweet pepper

The vegetable, Anastasia Red, Capsicum annuum L. var. angulosum Mill. (Solanaceae) was successively extracted with hexane, acetone, methanol and 70% methanol, and the extracts were further separated into a total of 21 fractions by silica gel or octadecylsilane (ODS) column chromatography. The biological activities of extracts and fractions were determined. These extracts showed relatively higher cytotoxic activity against two human oral tumor cell lines (HSC-2, HSG) than against normal human gingival fibroblasts (HGF), suggesting a tumor-specific cytotoxic activity. The cytotoxic activity of these extracts was enhanced by fractionation on silica gel [H2, A2, M1-M3] or ODS column chromatography [70M]. Several fractions [H2, H4, H5, A1, A2, A3, A5, A6, A7, M2] reversed the multidrug resistance (MDR) phenotype with L5178 mouse lymphoma T cells, more efficiently than (+/-)-verapamil. The extracts and fractions did not show any detectable anti-human immunodeficiency virus (HIV) or anti-Helicobacter pylori activity. Thus, this study suggests the effective and selective antitumor potential of 'Anastasia Red' of sweet pepper for further phytochemical and biological investigation.     

Active-oxygen scavenging activity of traditional nourishing-tonic herbal medicines and active constituents of Rhodiola sacra

The active-oxygen scavenging activity of 70 traditional herbal medicines used in China and Japan as nourishing tonics were evaluated by electron spin resonance (ESR) technique, in order to evaluate their effectiveness for anti-aging and to search for new active-oxygen scavengers from natural resources. Most of the 70 herbal medicines showed scavenging activity with various intensities. Areca catechu (methanol extract), Dendrobium plicatile (methanol extract), Juglans regia (water extract), Paeonia lactiflora (methanol extract), Psychotria serpens (water and methanol extracts), Rhodiola sacra (water and methanol extracts) and Uncaria rhynchophylla (water extract) especially showed strong scavenging activity against superoxide anion radical (*O2-), while J. regia (water and methanol extracts), Morus alba (water extract) and Schisandra chinensis (water extract) revealed strong scavenging activity against hydroxyl radical (HO*). In addition, the active-oxygen scavenging activities of 19 compounds isolated from R. sacra were also examined, and hydroquinone (1), caffeic acid (3), protocatechuic acid (6), gallic acid (7), (-)-epigallocatechin 3-O-gallate (8), 3-O-galloylepigallocatechin-(4beta-->8)-epigallocatechin+ ++ 3-O-gallate (10), heterodendrin (17) and gallic acid 4-O-beta-D-glucopyranoside (19) were found to show mild or strong inhibitory activity against superoxide anion radical (*O2-), while 4-hydroxybenzoic acid (2), 3, 4-hydroxycinnamic acid (4), 6-8 and 19 inhibited hydroxyl radical (OH*). These active-oxygen scavengers may contribute, to different extents, to their anti-aging action.     

Polarity of extracts and fractions of four Combretum (Combretaceae) species used to treat infections and gastrointestinal disorders in southern African traditional medicine has a major effect on different relevant in vitro activities

Ethnopharmacological importance

Gastrointestinal disorders and infections are the major pathoaetiologies of diarrhoea causing many problems in human health and animal production. Many Combretum species are used in traditional medicine to treat infectious diseases including diarrhoea and many other ailments by rural people in Africa and Asia. Much of the work done to date on this genus was on the non-polar or intermediate polarity components. Some parameters that may cause diarrhoea and the evaluation of more polar extracts have apparently not been investigated.

Aims

The polar components were extracted and fractionated by solvent–solvent fractionation to yield fractions with different polarities. The activity of these fractions on different parameters that could be involved in factors associated with diarrhoea was investigated. The cytotoxic activities of the extracts were also determined to evaluate the potential of these extracts to combat diarrhoea in production animals.

Materials and methods

Phenolic-enriched leaf extracts of Combretum bracteosum (COB), Combretum padoides (COP), Combretum vendae (COV) and Combretum woodii (COW) were obtained by extracting with a mixture of 70% acetone acidified with 1% HCl and n-hexane. Acetone was removed from a portion of the 70% acetone extract and it was sequentially treated by solvent–solvent fractionation with dichloromethane, ethyl acetate, and butanol to yield fractions with a large variation in polarity. The phenolic constituents of the extracts and fractions were determined using standard procedures The antioxidant activities were determined using the 2,2-diphenyl-1-picrylhydrazyl (DPPH); 2,2′-azino-bis (3-ethylbenzothiazoline)-6-sulphonic acid (ABTS⁺) radical scavenging, ferric reducing antioxidant power (FRAP) methods and lipid peroxidation inhibitory capacity standard methods. The ferric reducing antioxidant activities of the fractions were also determined. The minimum inhibitory concentrations (MICs) of the crude extracts and fractions against four bacterial and three fungal strains were assessed with a microplate serial dilution method. Cyclooxygenase (COX) and lipoxygenase (LOX) enzyme inhibitory assays and cytotoxicity studies against Vero cells were also carried out.

Result

Some of the fractions had much higher antioxidant activity than the positive controls. The average EC₅₀ values of the extracts for the DPPH and ABTS antioxidant assays were 0.21–12 µg/ml (COP), 0.25–16 µg/ml (COV), 0.33–9.41 µg/ml (COW) and 4.97–85 µg/ml (COB) respectively while the mean EC₅₀ values for the positive controls ascorbic acid and trolox were 1.28–1.51 and 1.02–1.19 µg/ml respectively. All the crude extracts inhibited lipid peroxidation of linoleic acid by more than 80% at a concentration of 64 µg/ml. COP had the highest antibacterial activity with MICs ranging between 19–2500 µg/ml, followed by COV with MICs ranging between 39–625 µg/ml; COW and COB had similar MICs ranging between 39–2500 µg/ml. COP also had the highest antifungal activity with MICs between 19–625 µg/ml. The MIC for COW and COV ranged from 19 to 1250 µg/ml. COB had the lowest antifungal activity (MIC values were between 39 and 625 µg/ml). In general non-polar fractions had a high antimicrobial activity and polar fractions had a high antioxidant activity. The extracts had no activity against COX 1 and 2 enzymes in the anti-inflammatory assay but had good lipoxygenase inhibition. The crude extracts had high concentration of hydrolysable tannin (gallotannin). A good correlation (R²= 0.99) was found between the antioxidant activity and total tannin content indicating that, gallotannins may be responsible for the antioxidant activity.

Conclusion

The results obtained in this study with more polar extracts indicate that the use of extracts of these plant species as antidiarrhoeal agents may have a scientific basis. The extractant used here extracted a much higher percentage of the phytochemicals than acetone. It was better for isolating antioxidant compounds (polar) but not good for isolating antimicrobial compounds (non-polar) from the same species compared to acetone, ethyl acetate, dichloromethane, and hexane.     

The pharmacological screening of Pentanisia prunelloides and the isolation of the antibacterial compound palmitic acid.

The uses of Pentanisia prunelloides in Zulu traditional medicine indicate that the plant is believed to be effective in relieving inflammation, bacterial and viral infections and also stimulating uterine contraction. Aqueous, ethanolic and ethyl acetate extracts of leaves and roots were screened for prostaglandin-synthesis inhibitors and antibacterial and antiviral activity. In the results of the anti-inflammatory assay all the extracts showed cyclooxygenase-1 inhibition. The ethanolic and ethyl acetate extracts showed greater antibacterial activity than the aqueous extracts against Gram-positive (Bacillus subtilis, Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli, Klebsiella pneumoniae). Both root and leaf extracts were found to inhibit viral replication of the Influenza A virus. The ethyl acetate extract was fractionated by silica vacuum liquid chromatography and anti-inflammatory activity was found to be most pronounced in the more polar fractions. The presence of antibacterial activity was confirmed by running the fractions on a thin layer chromatography (TLC) plate and performing a bioautographic assay. The active fraction was further purified by TLC and the major antibacterial compound in the ethyl acetate root extract was identified by GC/MS as palmitic acid.     

Gallic acid is partially responsible for the antiangiogenic activities of Rubus leaf extract

An aqueous extract of leaves from Rubus suavissimus S. Lee (Rosaceae) or sweet leaf tea was tested for antiangiogenic activity in a human tissue-based fibrin-thrombin clot angiogenesis assay. Further fractionation of this crude extract was performed and the antiangiogenic effect of individual fractions was assessed. The extract was also tested for its oral bioavailability by using the serum of normal rats gavaged with the extract in the assay. At a 0.1% w/v concentration, the extract inhibited initiation of the angiogenic response and subsequent neovessel growth from samples that had already initiated an angiogenic response. Two subfractions of the extract showed significant inhibition of angiogenesis at 0.1% w/w. Gallic acid was elucidated as one of the active angiogenesis inhibitors in one fraction. A 1 mm concentration of gallic acid totally inhibited angiogenesis. In the form of leaf extract, a one-tenth concentration produced the same total inhibition as pure gallic acid. The 10-fold difference in potency suggests the presence of other active compounds contributing to the overall antiangiogenic effect of the extract. The oral absorption of this extract was tested by using serum from rats given the extract orally (gavage) in the angiogenesis assay system. The serum of rats orally administered the sweet leaf tea extract at doses of 0.1% w/w and 0.3% w/w did not significantly inhibit angiogenesis. However, the serum of rats injected intraperitoneally at a dose of 0.1% w/w caused a 41% inhibition of angiogenesis compared with saline injected controls. These preliminary results warrant further bioassay directed identification of other responsible compounds.     

三叶人字草抗氧化活性研究

目的 研究三叶人字草不同溶剂提取物的抗氧化活性.方法 用冷浸法得到三叶人字草乙醇、丙酮和醋酸乙酯提取物.测定了3种提取物的总酚含量,并通过测定其对DPPH自由基的清除能力和还原能力来研究其抗氧化能力.结果三叶人字草不同溶剂提取物均表现出很强的抗氧化性能,其中醋酸乙酯提取物具有最优异的抗氧化能力.结论 三叶人字草提取物具有作为天然抗氧化剂和功能性食品进行研究和开发的潜力.     

Antimutagenic effect of broccoli flower head by the ames salmonella reverse mutation assay

A study was performed to investigate the antimutagenic effect of broccoli flower head by the Ames Salmonella reverse mutation assay. Broccoli flower head being the most highly edible part in the plant was analysed for its antimutagenic effect. Without isolating the phytomolecules, the crude ethanol extract of broccoli flower head was tested for suppressing the mutagenic effect induced by certain chemical mutagens. Three strains - TA 98, TA102 and TA 1535 were used in the study. The tester strains were challenged with their respective mutagens. These were challenged with the ethanol extract of broccoli flower head at concentrations of 23 and 46 mg/plate. The plates were incubated for 72 h and the revertant colonies were counted. The crude extract did not prove to be promutagenic. The ethanol extract of the broccoli flower head at 46 mg/plate suppressed the mutagenic effect induced by the corresponding positive mutagens on all the three tester strains used in this study. The crude extract of broccoli flower head alone was not cytotoxic even at the maximum concentration tested (46 mg/plate). In conclusion, the ethanol extract of broccoli at 46 mg/plate suggests their diverse antimutagenic potential against the mutagenic chemicals employed in this study.     

Antiviral activity against human immunodeficiency virus type 1 (HIV-1) and type 2 (HIV-2) of ethnobotanically selected Ethiopian medicinal plants

Ethiopian medicinal plants used for the treatment of a variety of ailments including infectious diseases were screened for activity against human immunodeficiency virus type 1 (HIV-1) and type 2 (HIV-2). Seventy-one polar and nonpolar extracts derived from 21 plants belonging to 14 families were tested for inhibition of viral replication using HIV-1 (III(B)) and HIV-2 (ROD) strains. Selective inhibition of viral growth was assessed by the simultaneous determination of the in vitro cytotoxicity of each of the extracts against MT-4 cells. Six extracts made from the root bark of Bersama abyssinica Fresen, the leaves of Combretum paniculatum Vent., and Dodonaea angustifolia L.f., and the stem bark of Ximenia americana L. displayed antiviral activity at concentrations that were nontoxic to MT-4 cells. The highest selective inhibition of HIV-1 replication was observed with the acetone fraction of C. paniculatum and the methanol fraction of D. angustifolia which showed selectivity indices (ratio of 50% cytotoxic concentration to 50% effective antiviral concentration) of 6.4 and 4.9, and afforded cell protection of viral induced cytopathic effect of 100% and 99%, respectively, when compared with control samples. The greatest degree of antiviral activity against HIV-2 was achieved with the acetone extract of C. paniculatum (EC(50): 3 microg/mL), which also showed the highest selectivity index (32). The 50% cytotoxic concentration ranged from 0.5 microg/mL for the hexane extract of D. angustifolia L.f., the most cytotoxic of the extracts tested, to >250 microg/mL for some extracts such as the methanol fraction of Alcea rosea L., the least toxic tested. Only the polar extracts that were obtained by extraction with hydroalcohol, methanol or acetone exhibited inhibition of viral growth at subtoxic concentrations. The results obtained in this study enable the selection of extracts which show some specificity of action and support the further investigation of these extracts for their potential as new lead antiretroviral compounds.