Immunomodulatory and Cytotoxic Properties of Natural Triterpenoids Isolated from Grewia flavescens Juss

Objectives: The present investigation was undertaken to examine the immunomodulatory and cytotoxic properties of natural triterpenoids isolated from the stem bark of G. flavescens. Materials and Methods: The immunomodulatory activity was measured using oxidative burst chemiluminescence and phytohemagglutinin stimulated T‑cell proliferation assay. The cytotoxicity was measured using MTT assay. One new triterpenoid (29 [30]‑lupene‑3, 20‑diol; 3 β‑form, 29‑Aldehyde [4]) in addition to four known ones; lupeol (1), ß‑sitosterol (2), betulin (3), and ß‑sitosterol glucopyranoside (5), have been isolated from the stem bark of G. flavescens and identified using Fourier‑transform infrared spectroscopy, ultraviolet, and NMR techniques. Results: Chemiluminescence experiments showed that no compound exerted an inhibitory effect on reactive oxygen species production. However, 29 (30)‑lupene‑3, 20‑diol; 3 β‑form, 29‑Aldehyde (4) significantly repressed the cell proliferation activity with an IC50 of 8.7 µg/mL, whereas, ß‑sitosterol glucopyranoside (5) and ß‑sitosterol (2) showed moderate inhibitory activities (IC50 of 16.7 and 23.6 µg/mL, respectively) compared to the standard drug prednisolone (0.2 µg/mL). Betulin (3) revealed the highest cytotoxicity activity toward Hela cancer cells, followed by 29 (30)‑lupene‑3, 20‑diol; 3 β‑form, 29‑Aldehyde (4), and ß‑sitosterol (2) with IC50 11.10, 16.5 and 21.51 µg/ml respectively. Conclusion: The present investigation supports the traditional use of this plant in treating various diseases and it has a good potential for future studies based on animal model based, which could bring more mechanistic facts about this plant’s activity.