In Vitro Immunomodulatory and Cytotoxic Potentials of Faloak (Sterculia quadrifida R.Br.) Bark

Faloak (Sterculia quadrifida R.Br., Sterculiaceae) is an Indonesia indigenous plant widely used as a traditional remedy for various health complaints. This study aimed to explore the immunomodulatory and cytotoxicity potentials of Faloak bark by using in vitro techniques. Barks was extracted using water, ethanol and ethanol: water (1:1) separately. Colorimetric analysis was used for the determination of the total phenolic and the total flavonoid contents. Immunomodulator activities of the extracts were evaluated by studying their effects on mice macrophages and lymphocytes using in vitro methods, while the cytotoxicity potential was evaluated against Vero and HepG2 cell lines. The active extract was further fractionated and tested using different cell lines by the MTT method. Data were analyzed using one-way ANOVA and LSD tests, with a 95% confidence level (p<0.05). All extracts significantly increased the phagocytosis of macrophages compared to that of control in a concentration-dependent manner. However, all the extracts exhibited the Stimulation Index value of < 2, which indicated no effect on lymphocyte proliferation. The ethyl acetate fraction showed the highest activity against T47D, MCF7 and HepG2 cells with IC50 9.56; 7.62; 3.24 µg/mL and the Selectivity Index (against Vero cells) as follows, 2.01; 2.52; 5.94, respectively. Faloak bark extracts can stimulate macrophage phagocytosis activity in vitro, which positively correlates to the contents of flavonoids and other phenolic compounds. The ethyl acetate fraction exhibited the highest activity, which supports its potency as cancer chemopreventive herbal medicine.