Immunomodulatory activity of the water extract from acanthus ebracteatus vahl. ROOT

Abstract

Acanthus ebracteatus (Ngueak Plaa Mo) is a Thai medicinal plant used for treatment of cancer and skin diseases, and used in health promotion and anti-aging. Previous study report that the water extract of A. ebracteatus (AE) roots contained polysaccharides and had no chronic toxicities in animals. Several polysaccharides have been demonstrated to exhibit immunomodulatory activities. Since there has been no evidence on the immunomodulatory activities of A. ebracteatus, this study aimed to study the in vitro immunomodulating effects of the water extract of A. ebracteatus root. The effects of the extract on proliferation of lymphocytes in human PBMCs isolated from whole blood and on functions of cells in the innate immunity including macrophages and natural killer (NK) cells were evaluated. The results demonstrated that the water extract activated macrophage, J774A.1, functions. It clearly increased zymosan phagocytosis of these cells, at all concentration use, and significantly at 62.5-500 µg/ml. It significantly stimulated NO production, at all concentrations (31.25-500 µg/ml). This result was correlated with the increase of the mRNA expression of inducible nitric oxide synthase (iNOS), which involves in NO production, by the extract. The extract also significantly induced the mRNA expression of activated macrophage markers, TNF- and IL-1. It didn’t stimulate NK cell function to kill target cells via antibody-dependent cellular cytotoxicity and had very weak mitogenic activity on lymphocyte proliferation in culture. This study reveals that the water extract of A. ebracteatus root exhibited the immunostimulatory effect on the innate immunity. The results from this study provide basic information for further studies about the immunomodulating activities of this plant on immune cells both in vivo and in vitro which may lead to development this medicinal plant to immunomodulating agents in the future.