Immunostimulatory Activity of Opu-Opu (Crinum asiaticum L.) Leaf Extract on Lymphocyte Proliferation

Background: Opu-opu leaves (Crinum asiaticum L.) are medicinal plant materials containing various secondary metabolites with potential immunomodulatory activities. Immunostimulatory activity can be evaluated by examining lymphocyte responses, which play an essential role in adaptive immunity. Objective: This study aimed to evaluate the activity of ethanolic extract of opu-opu leaves (Crinum asiaticum L.) on lymphocyte proliferation as a potential immunostimulatory agent. Methods: This experimental study involved extracting opu-opu leaves by maceration using 96% ethanol. Phytochemical screening was performed using thin-layer chromatography (TLC), while lymphocyte proliferation-related activity was evaluated using the MTT assay. The extract was tested at concentrations of 3.125, 6.25, 12.5, and 25 µg/mL, with Imboost® serving as the positive control. Cellular activity was assessed based on absorbance measurements and the Effective Concentration (EC50) value. Results: Extraction of 500 g of dried plant material yielded 12.25 g of extract, corresponding to a yield of 2.45%. The reported EC50 values were 4.446 µg/mL for the opu-opu leaf extract and 4.282 µg/mL for Imboost®. Extract absorbance increased with concentration, reaching 0.234 ± 0.05, 0.261 ± 0.05, 0.341 ± 0.04, and 0.432 ± 0.01, respectively. The highest absorbance was observed at 25 µg/mL, compared with 0.234 ± 0.01 in the negative control. Conclusion: The ethanolic extract of opu-opu leaves demonstrated potential immunostimulatory activity, as indicated by increased lymphocyte metabolic activity measured using the MTT assay. However, direct confirmation of lymphocyte proliferation and further safety evaluation are required to support its development as an immunostimulatory agent.