RESUMO
Betulinic acid (BA) is a naturally occurring pentacyclic triterpene that is widely distributed throughout the plant kingdom. A variety of pharmacological activities have been ascribed to BA, including antitumor, anti-HIV, immunomodulatory, anti-oxidative, antimicrobial, anti-inflammatory, and antihelmintic activities. BA is a very promising new chemotherapeutic agent for the treatment of HIV infection and cancer due to the greater potencies and better therapeutic indices than some clinically used drugs. Notably, BA may play an increasingly important role in immune regulation and against oxidative damage as an immunomodulator and anti-oxidant. The pharmacological activities of BA are reviewed which provide a reference for the future research and utilization of BA.
RESUMO
The objective of this study was to explore the immunomodulatory effects of betulinic acid (BA) extracted from the bark of white birch on mice. Female mice were orally administered BA for 14 days in doses of 0, 0.25, 0.5, and 1 mg/kg body weight. We found that BA significantly enhanced the thymus and spleen indices, and stimulated lymphocyte proliferation induced by Concanavalin A and lipopolysaccharide as shown by MTT assay. Flow cytometry revealed that BA increased the percentage of CD4+ cells in thymus as well as the percentage of CD19+ and the ratios of CD4+/CD8+ in spleen. BA increased the number of plaque-forming cell and macrophage phagocytic activity as indicated by a neutral red dye uptake assay, and the peritoneal macrophages levels of TNF-alpha were also increased. In contrast, serum levels of IgG and IgM and serum concentrations of IL-2 and IL-6 were significantly decreased in BA-treated mice compared to the control as assayed by haemagglutination tests and ELISA, respectively. Taken together, these results suggest that BA enhances mouse cellular immunity, humoral immunity, and activity of macrophages. Thus, BA is a potential immune stimulator and may strengthen the immune response of its host.