Nepalese Medicinal Plants Research Articles

Medicinal plants from Nepal: evaluation as inhibitors of leukotriene biosynthesis

The methanolic extracts of 25 different Nepalese medicinal plants were tested for their activity to inhibit the biosynthesis of leukotriene B 4 in bovine polymorphonuclear leukocytes. The selected indigenous plants are used in traditional herb remedies to treat inflammatory diseases such as asthma, bronchitis, rheumatism, and skin disorders presumed to be mediated by leukotrienes. The leaves of Zanthoxylum nepalensis were shown to be the most potent inhibitor with an IC 50 value of 11 μg/ml. The extracts obtained from Astercantha longifolia and Hedychium ellipticum also exhibited potent inhibitory action with IC 50 values of 20 and 22 μg/ml, respectively.

Medicinal plants from Nepal; II. Evaluation as inhibitors of lipid peroxidation in biological membranes

In an ethnopharmacological screening of selected Nepalese medicinal plants, the inhibitory effect on lipid peroxidation of 36 methanolic extracts of 28 different plant species were evaluated using bovine brain phospholipid liposomes as model membranes. The most potent inhibitor with an IC 50 value of 0.93 μg/ml was the extract obtained from the bark of Clerodendrum indicum. The extracts obtained from Aglaia roxburghiana fruits, Euonymus pendulus barks and Emblica officinalis fruits were also active and inhibited lipid peroxidation with IC 50 values of 10, 12 and 13 μg/ml, respectively. The most active extracts were from indigenous plants traditionally used to treat inflammatory diseases.

Antiviral activities of Nepalese medicinal plants

In a screening of plants used traditionally in Nepal to treat diseases that could be caused by viruses, methanol extracts from 21 species were assayed for activity against three mammalian viruses: herpes simplex virus, Sindbis virus and poliovirus. Assays were performed in UV-A or visible light, as well as dark. Individual species of Hypericum, Lygodium, and Maesa exhibited impressive antiviral activities, although their selective effects on the three viruses suggested that the antiviral ingredients were different in each extract. In addition, many of the other extracts showed partial inactivation of one or more test viruses.

Antimicrobial activities of southern Nepalese medicinal plants

In an ethnopharmacological screening of selected medicinal plants used in Nepal, methanol extracts from 20 plant species were assayed for activity against eleven strains of bacteria and four strains of fungi. Duplicate assays were conducted with and without exposure to ultraviolet (UV)-A radiation to test for light-activated or light-enhanced activity. Fifteen of the extracts showed activity against bacteria and fourteen showed activity against fungi. Five extracts were active only when exposed to UV-A light, and the antibiotic or antifungal effect of five extracts was enhanced upon exposure to light. Two of the most active extracts were from plants used to treat diarrhoea and dysentery. Bark from both Terminalia alata (Combretaceae) and Mallotus phillppensis (Euphorbiaceae) was active against Gram-positive and Gram-negative bacteria.

Phytochemical screening and antimicrobial assay of some Nepalese medicinal plants

Medicinal plants constitute several bioactive compounds that are antimicrobial. Due to the extensive need of the new antimicrobial compounds of plant origin the study was conducted. The present paper deals with the qualitative phytochemical analysis and antimicrobial assay of methanolic extracts of four medicinal plants namely Butea monosperma (seed), Cissampelos pareira (root), Myrica esculenta (bark) and Selinum tenuifolium (root). The standard phytochemical test of the extracts revealed the presence of polyphenols, glycosides and coumarins in all the plant extracts. For the in-vitro antimicrobial assay, agar well diffusion method was employed against human pathogenic bacteria (11) and phytopathogenic fungi (5). The extracts of C. pareira, M. esculenta were effective against all the tested bacteria and fungi which indicated their broad spectrum antimicrobial potential. The extract of B. monosperma was effective against B. subtilis, S. typhi, Acinetobacter species, F. oxysporum, F. moniliformie, E. turticum and S. roulfsii. But the extract of S. tenuifolium was ineffective against all the tested bacteria but was effective against all the fungal strains revealing it to have more antifungal potential. The antimicrobial properties of these plant extracts may be due to the presence of various secondary metabolites. The results provided evidence that the studied plants might indeed be employed in the management of microbial infections. Key words: Plant extract; Phytochemicals; Antibacterial; Antifungal DOI: http://dx.doi.org/10.3126/sw.v9i9.5526 SW 2011; 9(9): 90-92

Biological Activities of Some Nepalese Medicinal Plants Used in Treating Bacterial Infections in Human Beings

In continuation of Nepalese medicinal plant screening research, we have examined the antibacterial property of 40 methanol crude extracts in vitro using disc diffusion method against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Bacillus subtilis. Overall, 95 % of the extracts showed antibacterial activity against at least one Gram-negative bacteria and 90 % of the extracts against at least one Gram-positive bacteria examined. Twenty-one extracts including Artemisia caruifolia, Dicranostigma lactucoides, Rauvolfia serpentina, and other plants showed antibacterial activity with all the tested bacterial species. The laboratory results are promising because several plants showed broad-spectrum antibacterial property. It is hoped that this scientific research will aware the related partners in Nepal to search for safe, efficacious, cheap alternative antibacterials of plant origin and may create an opportunity for biological conservation of the medicinal plants and cultural diversity conservation.Key words: Antibacterial activity; In vitro; Ethnomedicinal plantsDOI: 10.3126/njst.v10i0.2830Nepal Journal of Science and Technology Volume 10, 2009 December Page: 83-90