Nonspecific immunostimulatory effects of hexane fraction and subfractions of Moringa oleifera Lam. in cyclophosphamide-treated mice

Traditional medicine is based on the use of herbal extracts in the treatment of health problems and diseases. However, scientific validation on the efficacy and safety of these products are needed, since these could provide leads in drug development. Natural products have been identified with various medicinal effects, including immunomodulation [1]. Reports on the immunomodulatory effects of Moringa oleifera are very few and results are not consistent [2,3,4]. Thus, this study was done to verify the immune effects of M. oleifera. Preliminary in vivo trial showed that the hexane fractions at 50 mg/kgbw significantly increased phagocytosis and ameliorated the effect of the immunosuppressant cyclophosphamide at 30 mg/kgbw after 9 days. After 17 days, significant proliferation of splenic lymphocytes in immunosuppressed mice was detected when treated with the hexane fraction as compared to the mice injected with cyclophosphamide only. A bio-assay guided process was done on the hexane fraction until immunoactive subfractions were obtained through HPLC. Subfractions SF1 and SF2 were used in in vivo trials at 2 mg/kgbw and 20 mg/kgbw for 14 days. Negative control mice were treated with PBS only while positive control mice were treated with cyclophosphamide only. Phagocytosis was significantly higher at days 7 and 15 in mice treated with both dosages of SF1 and SF2 compared with the positive control mice. At day 15, SF2 at 20 mg/kgbw significantly induced splenic lymphocyte proliferation while SF1 at 2 mg/kgbw increased splenic lymphocyte proliferation but it was not significantly different from the positive control mice. Subsequently, SF2 was used in a 21-day in vivo experiment at 2 mg/kgbw and 20 mg/kgbw that showed significantly higher reactive oxygen superoxide (ROS) level in macrophages from mice treated with 20 mg/kgbw of SF2. These data showed that an immunoactive compound could be obtained from the SF2 hexane subfraction. Further bio-assay guided purification could be done to characterize the immunostimulatory compound from M. oleifera.

Acknowledgements: The authors are grateful to the Department of Science and Technology- Philippine Council for Health Research and Development (DOST-PCHRD) for the financial assistance and Ms. Ma. Rexie R. Jimenez for her technical assistance.

Keywords: Immunostimulation, Moringa oleifera, cyclophosphamide, lymphocyte proliferation, phagocytosis.

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