Phan Ke Loc

Ethnobotanical approach versus random approach in the search for new bioactive compounds: Support of a hypothesis

Context: Whether natural product drug discovery programs should rely on wild plants collected “randomly” from the natural environment, or whether they should also include plants collected on the basis of use in traditional medicine remains an open question. Objective: This study analyzes whether plants with ethnomedical uses from Vietnam and Laos have a higher hit rate in bioassay testing than plants collected from a national park in Vietnam with the goal of maximizing taxonomic diversity (“random” collection). Materials and Methods: All plants were extracted and subjected to bioassay in the same laboratories. Results of assays of plant collections and plant parts (samples) were scored as active or inactive based on whether any extracts had a positive result in a bioassay. Contingency tables were analyzed using χ2 statistics. Results: Random collections had a higher hit rate than ethnomedical collections, but for samples, ethnomedical plants were more likely to be active. Ethnomedical collections and samples had higher hit rates for tuberculosis, while samples, but not collections, had a higher hit rate for malaria. Little evidence was found to support an advantage for ethnomedical plants in HIV, chemoprevention and cancer bioassays. Plants whose ethnomedical uses directly correlated to a bioassay did not have a significantly higher hit rate than random plants. Discussion: Plants with ethnomedical uses generally had a higher rate of activity in some drug discovery bioassays, but the assays did not directly confirm specific uses. Conclusions: Ethnomedical uses may contribute to a higher rate of activity in drug discovery screening.

An unusual new species of Trevesia from Vietnam and its implications on generic delimitation in Araliaceae

Trevesia vietnamensis J. Wen & P.K. L?c (Araliaceae) is described as an unusual new species from northwestern Vietnam. This species has 4?5-merous flowers with a 4-5-locular ovary and palmately compound leaves and would thus fit well within Brassaiopsis morphologically. Phylogenetic analysis using the nuclear ribosomal ITS and the chloroplast ndhF and trnL-F sequences, however, clearly places the new taxon in Trevesia, defined to include species with 6-16-merous flowers with 6-16-locular ovaries, and palmately lobed simple leaves. The discovery of Trevesia vietnamensis thus blurs the generic boundary between Trevesia and Brassaiopsis. The phylogenetic analysis suggests a sister-species relationship between Trevesia vietnamensis and T. lateospina from northern Thailand, a finding supported by a shared morphological character?the presence of setose hairs on the inflorescences and young stems. Trevesia vietnamensis is restricted to two localities in northwestern Vietnam. It grows in limestone areas in valleys and on shady mountain slopes at 500-700 m in primary, tropical, monsoon, broad-leaved forests.