Inhibitory Effects of Standardized Extracts ofPhyllanthus amarusandPhyllanthus urinariaand Their Marker Compounds on Phagocytic Activity of Human Neutrophils

Abstract

The standardized methanol extracts ofPhyllanthus amarusandP. urinaria, collected from Malaysia and Indonesia, and their isolated chemical markers, phyllanthin and hypophyllanthin, were evaluated for their effects on the chemotaxis, phagocytosis and chemiluminescence of human phagocytes. All the plant extracts strongly inhibited the migration of polymorphonuclear leukocytes (PMNs) with the MalaysianP. amarusshowing the strongest inhibitory activity (IC50value, 1.1 µg/mL). There was moderate inhibition by the extracts of the bacteria engulfment by the phagocytes with the MalaysianP. amarusexhibiting the highest inhibition (50.8% of phagocytizing cells). The MalaysianP. amarusandP. urinariashowed strong reactive oxygen species (ROS) inhibitory activity, with both extracts exhibiting IC50value of 0.7 µg/mL. Phyllanthin and hypophyllanthin exhibited relatively strong activity against PMNs chemotaxis, with IC50values slightly lower than that of ibuprofen (1.4 µg/mL). Phyllanthin exhibited strong inhibitory activity on the oxidative burst with an IC50value comparable to that of aspirin (1.9 µg/mL). Phyllanthin exhibited strong engulfment inhibitory activity with percentage of phagocytizing cells of 14.2 and 27.1% for neutrophils and monocytes, respectively. The strong inhibitory activity of the extracts was due to the presence of high amounts of phyllanthin and hypophyllanthin although other constituents may also contribute.