Hibiscus macrophyllus Roxb. (Malvaceae) is traditionally used in Southeast Asia for the management of gastrointestinal disorders, pain, and fever; however, scientific evidence supporting the pharmacological potential of its bark remains limited. The present study aimed to evaluate the pharmacological properties of bark extracts of H. macrophyllus and to characterize major phytoconstituents. Dried bark material was extracted with methanol and fractionated into n ‐hexane, chloroform, ethyl acetate, and methanolic fractions. In vitro antioxidant, thrombolytic, membrane stabilizing, and cytotoxic activities were evaluated, while in vivo antidiarrheal, analgesic, antipyretic, and hypoglycemic activities were assessed using Swiss albino male mice. Among the extracts, the methanolic extract exhibited the highest concentration of total phenol (162.571 ± 3.293 mg/g GAE), flavonoid (5.541 ± 0.669 mg/g QE), and antioxidant capacity (66.65 ± 1.74 mg/g AAE) content. Ethyl acetate extract exhibited the highest DPPH and nitric oxide free radical scavenging activity, with IC 50 values of 79.111 μg/mL and 9.945 μg/mL, respectively. The highest membrane‐stabilizing potential was exhibited by the methanolic extract. The chloroform extract demonstrated notable inhibition of defecation (78.26%, p ≤ 0.01), while the n ‐hexane extracts exhibited significant analgesic effects of 74.528% ( p ≤ 0.001) and 57.89% ( p ≤ 0.001) in peripheral writhing and tail immersion test. Each extract reduced blood glucose levels significantly, with the methanolic extract exhibiting the highest reduction (50.923%, p ≤ 0.01) after 3 rd hour of glucose administration. Three bioactive compounds, namely, hibiscus acid, gossypetin‐3′‐O‐β‐glucoside, and naringenin, were isolated from the methanolic extract of bark.
Chowdhury et al. (Thu,) studied this question.