Evaluation of Antibacterial Activities of Medicinal Plants

Plant and plant products are used as medicine from the beginning of human civilization. This study compares the antibacterial activity of crude hexane, ethylacetate and methanol extracts of nine different medicinal plants used in traditional Nepalese medicine, tested against 10 species of bacteria: Staphylococcus aureus (ATCC 25923), Escherichia coli (ATCC 25922), Klebsiella pneumoniae (ATCC 20063), Klebsiella oxytoca, Proteus mirabilis (ATCC 49132), Proteus vulgaris, Pseudomonas aeruginosa (ATCC 27853), Salmonella typhi, Salmonella paratyphi and Shigella dysenteriae by agar well diffusion method. The selected parts of these medicinal plants namely Acorus calamus (Rhizome), Aegle marmelos (Fruit), Asparagus racemosus (Tuberous root), Mimosa pudica (Root), Terminalia bellirica (Fruit), Terminalia chebula (Fruit), Tinospora cordifolia (Stem), Woodfordia fruticosa (Flower) and Holarrhena antidysenterica (Seed) were taken for study.The result showed that out of nine tested plants, four plant extracts (44%) showed activity against at least five or more tested bacteria and five plant extracts (56%) were active against three or less than three bacteria. None of the tested plant extracts was active against all the tested bacteria. A. racemosus was the least effective against bacterial species. S. aureus was the most susceptible bacteria being sensitive to 18 extracts from 9 medicinal plants. P. vulgaris was the most resistant bacteria being resistant to all selective plants. The MBC value ranges from 3.12 mg/ml to >50 mg/ml. Lowest MBC was shown by ethylacetate extract of T. bellirica against E. coli and ethylacetate extract of W. fruticosa against S. dysenteriae. Largest ZOI (31 mm) was produced by ethylacetate extract of T. bellirica. Nepal Journal of Science and Technology Vol. 13, No. 2 (2012) 209-214 DOI: http://dx.doi.org/10.3126/njst.v13i2.7738

Identification of plant extracts sensitizing breast cancer cells to TRAIL

Triple-negative breast cancer (TNBC) is an aggressive heterogeneous cancer subgroup with a higher rate of distant recurrence and a poorer prognosis compared to other subgroups. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is an attractive molecule that induces cell death in various tumor cells without causing cytotoxicity to normal cells; however, primary or acquired resistance to TRAIL often limits its efficacy in cancer patients. To develop combination therapies to improve TRAIL efficacy and/or to overcome the resistant mechanism, we screened 138 medicinal plant extracts against TRAIL-sensitive and -insensitive TNBC cell lines, MDA-MB-231 and MDA-MB-468. Among them, 5 plant extracts, Uvaria dac, Artemisia vulgaris, Cortia depressa, Dichasia bengalensis and Cinnamomum obtusifolium did not cause apparent cytotoxicity (<20%) as a single regimen, but showed significant synergistic effects in combination with TRAIL against both cell lines. Moreover, Uvaria dac, Artemisia vulgaris and Cinnamomum obtusifolium were found to suppress the phosphorylation of p65 that is involved in TRAIL-resistant mechanisms. These observations suggest that the identified plant extracts in combination with TRAIL could lead to potential therapeutic benefits for cancer patients in the clinical setting.

Phytochemical studies and in vitro activity of Asparagus racemosus

Phytochemical and biological screening of root of Asparagus racemosus was studied. The brine shrimp bioassay of its various extracts showed that the methanol (MeOH) extract was biologically active. The column chromatography of hexane, acetone and methanol extracts resulted in the isolation of 9- hexadecanoic acid-9-octadecenylester (Z,Z), ?-Sitosterol, stigmasterol-3-O-?-D-glucopyranoside and diosgenin. The estimation of saponin in the root of Asparagus racemosus has also been carried out.DOI: http://dx.doi.org/10.3126/jnpa.v26i1.6632JNPA. XXVI(1) 2012 48-53

Isolation, Identification and Antimicrobial Activity of a Withanolide [WS-1] from the Roots of Withania somnifera

Column chromatographic purification of the organic extract obtained from the roots of Withania somnifera yielded a biologically active withanolide compound WS-1 whose structure was established on the basis of spectroscopic evidences. Potent antibacterial activity was observed in this compound.DOI: http://dx.doi.org/10.3126/njst.v12i0.6497 Nepal Journal of Science and Technology 12 (2011) 179-186 

Identification of arctigenin as an antitumor agent having the ability to eliminate the tolerance of cancer cells to nutrient starvation

Tumor cells generally proliferate rapidly and the demand for essential nutrients as well as oxygen always exceeds the supply due to the unregulated growth and the insufficient and inappropriate vascular supply. However, cancer cells show an inherent ability to tolerate extreme conditions, such as that characterized by low nutrient and oxygen supply, by modulating their energy metabolism. Thus, targeting nutrient-deprived cancer cells may be a novel strategy in anticancer drug development. Based on that, we established a novel screening method to discover anticancer agents that preferentially inhibit cancer cell viability under the nutrient-deprived condition. After screening 500 medicinal plant extracts used in Japanese Kampo medicine, we found that a CH(2)Cl(2)-soluble extract of Arctium lappa exhibited 100% preferential cytotoxicity under the nutrient-deprived condition at a concentration of 50 microg/mL with virtually no cytotoxicity under nutrient-rich condition. Further bioassay-guided fractionation and isolation led to the isolation of arctigenin as the primary compound responsible for such preferential cytotoxicity; the compound exhibited 100% preferential cytotoxicity against nutrient-deprived cells at a concentration of 0.01 microg/mL. Furthermore, arctigenin was also found to strongly suppress the PANC-1 tumor growth in nude mice, as well as the growth of several of the tested pancreatic cancer cell lines, suggesting the feasibility of this novel antiausterity approach in cancer therapy. Further investigation of the mechanism of action of arctigenin revealed that the compound blocked the activation of Akt induced by glucose starvation, which is a key process in the tolerance exhibited by cancer cells to glucose starvation.

Angelmarin, a novel anti-cancer agent able to eliminate the tolerance of cancer cells to nutrient starvation

The CH(2)Cl(2)-soluble extract of Angelica pubescens was found to kill PANC-1 cancer cells preferentially under nutrition starvation at a concentration of 50 microg/ml, with virtually no cytotoxicity under nutrient-rich conditions. Further bioassay-guided fractionation and isolation led to the isolation of a novel compound named angelmarin as the primary compound responsible for the preferential cytotoxicity; the compound exhibited 100% preferential cytotoxicity against PANC-1 cells at a concentration of 0.01 microg/ml.

Cassane- and norcassane-type diterpenes from Caesalpinia crista of Indonesia and their antimalarial activity against the growth of Plasmodium falciparum

The CH2Cl2 extract of the seed kernels of Caesalpinia crista, which exhibited promising antimalarial activity against Plasmodium berghei-infected mice in vivo, was examined and resulted in the isolation of seven new furanocassane-type diterpenes [caesalpinins C-G (1-5) and norcaesalpinins D and E (6, 7)] together with norcaesalpinins A-C (8-10) and 11 known compounds (norcaesalpinins A-C, 2-acetoxy-3-deacetoxycaesaldekarin e, caesalmin B, caesaldekarin e, caesalpin F, 14(17)-dehydrocaesalpin F, 2-acetoxycaesaldekarin e, 7-acetoxybonducellpin C, and caesalmin G). Their structures were determined on the basis of spectroscopic analysis. The isolated diterpenes showed significant dose-dependent inhibitory effects on Plasmodium falciparum FCR-3/A2 growth in vitro. Their IC50 values ranged from 90 nM to 6.5 microM, and norcaesalpinin E (7) showed the most potent inhibitory activity (IC50, 90 nM).

Cassane- and norcassane-type diterpenes of Caesalpinia crista from Myanmar

From the CH(2)Cl(2) extract of seed kernels of Caesalpinia crista from Myanmar, five new cassane-type diterpenes, caesalpinins MA-ME (1-5), and three new norcassane-type diterpenes, norcaesalpinins MA-MC (6-8), have been isolated, together with 12 known cassane-type diterpenes, 14(17)-dehydrocaesalmin F, caesaldekarin e, caesalmin B, caesalmin C, caesalmin E, 2-acetoxy-3-deacetoxycaesaldekarin e, 2-acetoxycaesaldekarin e, caesalpinin C, 7-acetoxybonducellpin C, caesalpinin E, norcaesalpinin B, and 6-acetoxy-3-deacetoxycaesaldekarin e. The structures of the isolated compounds were elucidated by analysis of their spectroscopic data.

New cholinesterase inhibiting steroidal alkaloids from the leaves of Sarcococca coriacea of Nepalese origin

From the leaves of Sarcococca coriacea two new steroidal alkaloids, epoxynepapakistamine-A [(20S)-20-(N-methylamino)-3beta-(tigloylamino)-5alpha-pregna-16alpha,17alpha-epoxy-2beta,4beta-di-O-acetate] (1), and epoxysarcovagenine-D [(20S)-20-(N-methylamino)-3beta-(tigloylamino)-5alpha-pregna-2-en-16alpha,17alpha-epoxy-4-one] (2), and two known compounds funtumafrine C [(20S)-20-(N,N-dimethylamino)-5alpha-pregna-3-one] (3) and N-methylfuntumine (4) were isolated. Their structures were elucidated on the basis of their spectral properties. The compounds 1, 3 and 4 were found to have cholinesterase inhibitory activity when tested for the inhibition of electric eel acetylcholinesterase and horse serum butyrylcholinesterase. They inhibited both enzymes in a concentration dependent fashion.

Steroidal alkaloids from the leaves of Sarcococca coriacea of Nepalese origin

Two new steroidal alkaloids, (-)-vaganine D (1) [(20S)-20-(N,N-dimethylamino)-3 beta-(senecioylamino)-5 alpha-pregn-16-en-4 beta-yl acetate], and (+)-nepapakistamine A (2) [(20S)-20-(N-methylamino)-3 beta-(tigloylamino)-5 alpha-pregn-16-en-2 beta,4 beta-diacetate], were isolated from the leaves of Sarcococca coriacea. Their structures were elucidated on the basis of their spectral properties. Compounds 1 and 2 were found to be cholinesterase inhibitors.

Phytochemical Constituents of the Bark of Vitex negundo L

p-Hydroxybenzoic acid (1) and β-sitosterol (2) were isolated, and identified from the methanol and hexane extracts of Vitex negundo. The structure of the compounds were established on the basis of spectral analysis.Keywords: p-hydroxybenzoic acid, β-sitosterol,  vitex negundo.DOI: 10.3126/jncs.v23i0.2101Journal of Nepal Chemical Society, Vol. 23, 2008/2009Page: 89-92

Chemical constituents from Oroxylum indicum (L.) Kurz of Nepalese Origin

From the stem bark of Oroxylum indicum, three flavones namely baicalein (1), oroxylin (2) and pinostrobin (3) along with one sterol, Stigmast-7-en-3-ol (4) were isolated and their structures were established by the use of spectroscopic techniques. Baicalein (1) and oroxylin (2) were found to be active against brine shrimp with LC50 value 10.0 μg/ml and 36.0 μg/ ml and also exhibited the antimicrobial activity on both Gram-positive and Gram-negative bacteria with MIC value 4.0 mg/ml and 8.0 mg/ml respectively. Key words: Oroxylum indicum; Flavones; Baicalein; Brine-shrimp bioassay. DOI: 10.3126/sw.v8i8.3852 Scientific World Vol.8(8) 2010 pp.66-68