Abstract
The standardized methanol extracts of Phyllanthus amarus and P. 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 Malaysian P. amarus showing the strongest inhibitory activity (IC50 value, 1.1 µg/mL). There was moderate inhibition by the extracts of the bacteria engulfment by the phagocytes with the Malaysian P. amarus exhibiting the highest inhibition (50.8% of phagocytizing cells). The Malaysian P. amarus and P. urinaria showed strong reactive oxygen species (ROS) inhibitory activity, with both extracts exhibiting IC50 value of 0.7 µg/mL. Phyllanthin and hypophyllanthin exhibited relatively strong activity against PMNs chemotaxis, with IC50 values slightly lower than that of ibuprofen (1.4 µg/mL). Phyllanthin exhibited strong inhibitory activity on the oxidative burst with an IC50 value 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.
Highlights
Phagocytosis is an important response of innate immunity which is mediated by professional phagocytes such as polymorphonuclear neutrophils (PMNs), peripheral blood mononuclear, and macrophage cells [1, 2]
Phyllanthin and hypophyllanthin were isolated from the whole plants of Phyllanthus amarus from Malaysia and Indonesia by various chromatographic techniques
The marker compounds were obtained in high yields from the crude methanol extracts of P. amarus from both countries
Summary
Phagocytosis is an important response of innate immunity which is mediated by professional phagocytes such as polymorphonuclear neutrophils (PMNs), peripheral blood mononuclear, and macrophage cells [1, 2]. At the earliest stage of immune response, active recruitment of neutrophils to sites of infection is fundamentally important. This process involves mobilizations of PMNs from circulation in response to host- and pathogen-derived chemotactic factors. Phagocytes pass through the capillary wall, surveying tissue, membranes, and lymphatic organs for signs of tissue distress and the presence of chemoattractant [4]. Endogenous substances such as interleukin 8 (IL-8), leukotriene B4 (LTB4), platelet-activating factor (PAF), and exogenous substances such as formyl methionylleucyl-phenylalanine (fMLP) derived from bacterial cell products are the important neutrophil chemoattractants [5]. The pathogens are destroyed by microbicidal mechanism that is often referred to as oxidative burst [5]
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