Immunomodulatory Effect of Petroleum Ether Extract and Ethyl Acetate Fraction of Bengkoang <i>(Pachyrhizus erosus</i> (L.) Urban) <i>In Vitro</i>

Bengkoang (Pachyrhizus erosus (L.) Urban) contains phytosterol and the isoflavone daidzein, which are thought to have immunomodulatory activity. There have been no studies reporting on the immunomodulatory effects of bengkoang extract containing polar and semi-polar compounds, such as phytosterols and isoflavone-like compounds. The objective of this study was to evaluate the immunomodulatory effects of bengkoang extracts, including petroleum ether extract (PEE), methanol extract (ME), and the ethyl acetate fraction (EAF) of bengkoang, in vitro. The immunomodulatory effects of PEE, ME, and EAF of bengkoang were determined according to the phagocytic activity of macrophages based on phagocytosis of latex beads, lymphocyte proliferation, and detection of cytokine production of tumor necrosis factor-alpha (TNF-alpha) interleukin-6 (IL-6), and interleukin-10 (IL-10) levels. Results: The phagocytic index and phagocytic capacity of ME, PEE, and EAF of bengkoang on macrophage cells were significantly increased (p < 0.05), whereas on lymphocyte proliferation, ME showed a trend of increasing activity (p < 0.05). On the other hand, the PEE effect showed a decreasing trend of activity, and the others had no significant effect on lymphocyte proliferation (p > 0.05), and ME of bengkoang enhanced the levels of the cytokines TNF-alpha and IL-6. In contrast, PEE and EAF of bengkoang decreased TNF-alpha and IL-6 levels compared with the control group. All of the bengkoang extracts decrease the production of the anti-inflammatory cytokine IL-10. In conclusion, this study showed that PEE, ME, and EAF of bengkoang could increase the non-specific immune response (phagocytic activity) but had a lesser effect on the specific immune response (lymphocyte proliferation). The ME of bengkoang acts as an immunostimulant by increasing the levels of the inflammatory cytokines TNF-alpha and IL-6 and decreasing those of the antiinflammatory cytokine IL-10. Further investigation of in vivo immunomodulatory effects is needed to determine its effect on systemically innate and adaptive immune responses.