| Summary: | Information about the medicinal uses of forty-two plant species was
collected from traditional healers and knowledgeable villagers from a variety of
different ethnic groups in Nepal. Illnesses for which these plants are used are
those perceived in western style medicine to be caused by bacterial, fungal or
viral pathogens. Methanol extracts of the species were screened for activity
against a variety of bacteria, fungi and viruses, under various light conditions to
test for photosensitizers. Thirty-seven extracts showed activity against bacteria
and thirty-five showed activity against fungi. Only eight were active against
Gram-negative bacteria. The exposure to UV-A light had a considerable effect
on the activities of some extracts, with eight extracts being active only when
exposed to light. The antibacterial and antifungal effects of fifteen extracts were
enhanced upon exposure to light. Fifteen extracts showed 100% inactivation of
at least one virus, and fifteen showed partial activity. Eight extracts were active
only when exposed to light, and the antiviral effect of eight extracts was
enhanced upon exposure to light.
A species showing antibacterial activity, Centipeda minima
(Asteraceae), and one showing antiviral activity, Carissa carandas
(Apocynaceae) were the focus of bioactivity guided fractionation. Centipeda
minima was found to contain three sesquiterpene lactones, identified as
6-O-methylacrylylplenolin, 6-O-isobutyroylplenolin, and 6-O-angeloylplenolin.
6-O-Methylacrylylplenolin had not been previously isolated from C. minima. All
three of these sesquiterpene lactones had activity against Bacillus subtilis and
Staphylococcus aureus. A fraction from the methanol extract of Carissa
carandas was quite active against herpes simplex virus. This fraction was
found to contain a derivative of 3,4,5-trimethoxycinnamic acid.
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