Documentation Of Medicinal Plants In Sabah And The Characterization Of Biologically Active Natural Products

Author

Siraj Omar, Fasihuddin Ahmad and Ghazally Ismail

Proceeding

Seminar Kebangsaan IRPA (Intensification of Research in Priority Areas), Pulau Pinang, Malaysia.

Date

16/12/1991

Keyword

medicinal plants, Sabah, phytochemical screening , biologically active compounds, antibacterial screenings

Abstract

A concerted effort has been undertaken to study the abundant biological resources of Borneo for their natural products, especially those with medicinal values. For the last 5 years our main focus has been towards the study of medicinal plants in Sabah, their uses in traditional medical practices and their natural products; although the chemical potentials of other resources, such as seaweeds and marine sponges, are also being looked into. We have so far managed to document more than 450 species of plants from 150 families used in traditional medicine by various ethnic communities in the state, carefully noting their purported curative values and methods of utilization. The chemical and biological characteristics of these plants were assessed by phytochemical and antibacterial screenings of their crude methanol extracts. Phytochemical screening carried out on more than 500 plant specimens (mainly from families of higher plants), revealed that between 15-20% of the plant specimens contained alkaloids, the majority of which are those plants from the Annonaceae family; 60-65% of the specimens contained saponins in varying quantities, about 45% contained triterpenoids or steroids or both, but only less than 10% contained cardiac glycosides. About 150 specimens of medicinal plants were tested for antibacterial properties. The majority of the plant extracts exhibited antibacterial properties with varying significance, some exhibited selectivity against only Gram positive bacteria or Gram positive bacteria, but a few species belonging to the families Annonaceae, Apocynaceae, Euphorbiaceae, Leguminosae, Manispermaceae and Rubiaceae, showed strong inhibitory effects against a wide spectrum of bacteria. A number of plant samples which possess interesting chemicals and biological properties were chosen for extensive purification to isolate the active principles. From such work, Goniothalamus giganteus yielded 5 compounds, namely, goniothalenol, goniotriol, goniofufurone, goniopypyroneand pinocembrin. G. uvaroides yielded two major compounds, goniothalamin and 5-acetylgoniothalamin. G. velutinus yielded five aristolactam alkaloids in which fourwere new compounds. From Kopsia dasyrachiswe obtained three known indole alkaloids, kopsinine and kopsoffine, which have never been reported from this species before this. Finally, from Phaeanthus crassipetaluswe also isolated three known alkaloids, namely, phaeanthine, limacine and lanuginosine. With the exception of pinocembrin, all pure metabolites isolated possess strong antibacterial properties, as well as exhibited in vitro cytoxicity against certain leukemia cell lines, such as HeLa, HL-60, CEMC7 and L1210.