In vitro activity of phyllanthus (Euphorbiaceae) species against the DNA polymerase of hepatitis viruses: Effects of growing environment and inter- and intra-specific differences

Abstract

Extracts of Phyllanthus amarus (Euphorbiaceae) are known to reduce or eliminate detectable hepatitis B virus surface antigen in humans or surface antigen of woodchuck hepatitis virus in woodchucks. The objectives of the experiments in this paper were to evaluate the in vitro inhibicion of viral DNA polymerase (DNAp) among (1) different species of Phyllanthus; (2) within the most promising species; and (3) to evaluate differences in activity that might be correlated with environmental effects. The ultimate goal of our studies is to develop a system for producing high quality plants for large scale extraction. Inhibitory activity varied significantly among species. InP. urinaria there were also significant differences among intraspecific accessions. Accessions ofP. amarus from various locations did not differ significantly. Experiments with one seedlot showed highly significant plant-to-plant differences in anti-viral activity, but clear-cut heritable differences were not established among progeny of the plants at extremes in the distribution. Differences in general soil fertility, soil moisture, pH or Ca generally did not significantly affect inhibicion of viral DNAp but temperature differences did. Except for temperature, the detectable environmental effects were generally less than the size of the genetic differences among species.P. amarus was successfully grown as a row crop with inputs of fertilizer and irrigation and showed no loss of activity when compared to samples from the wild. Thus, once an accession of Phyllanthus with potent inhibicion of viral DNAp is identified, it can be grown under cultivated conditions for extraction without a loss of activity.