Dose-Dependent Cardioprotection of Pterocarpus indicus Extract in Rats With Myocardial Ischemia: Targeting Oxidative Stress, Inflammation, and Apoptosis.

BACKGROUND AND AIM: This study investigated the dose-dependent cardioprotective effects of Pterocarpus indicus extract (P.indicus; LD: 27, MD: 54, HD: 108 mg/kg) against isoproterenol (ISO)-induced myocardial ischemia in rats, focusing on oxidative stress, apoptosis, inflammation, and fibrosis. EXPERIMENTAL PROCEDURE: Rats were pretreated for 14 days and divided into control, ISO, propranolol, and P.indicus (LD, MD, HD) groups. Myocardial injury was assessed via ECG, histopathology, serum biomarkers (CK-MB, LDH, cTnT, IL-6, IL-1β, TNF-α), oxidative markers (SOD, MDA, GSH-Px), and apoptosis-related proteins (Bax, Bcl-2, Caspase-3). Nrf2/HO-1 expression was analyzed by western blot. Phytochemical profiling was performed via UPLC-MS/MS and HPLC. Pharmacokinetics, safety, and therapeutic-regimen efficacy were also evaluated. RESULTS: P.indicus at MD and HD significantly attenuated ISO-induced ECG abnormalities, histopathological damage, serum injury markers, inflammatory cytokines, and fibrosis (all P < 0.01). Treatment suppressed oxidative stress (restored SOD/GSH-Px, reduced MDA) via Nrf2/HO-1 activation and inhibited apoptosis via Bax/Bcl-2/Caspase-3 modulation. The efficacy of MD (EC(50) ∼50 mg/kg) was confirmed by dose-response analysis. Pharmacological inhibition established that both Nrf2 activation and caspase-3 inhibition are necessary for P.indicus's effects. PK studies showed systemic exposure to key compounds (quercetin-3-O-glucoside, ferulic acid, linoleic acid), and a 14-day safety assessment revealed no hepatorenal toxicity. Post-injury therapeutic administration also conferred significant protection. CONCLUSION: P. indicus extract confers dose-dependent cardioprotection against ISO-induced myocardial injury through dual modulation of the Nrf2/HO-1 and Bax/Bcl-2/Caspase-3 pathways, with the medium dose (54 mg/kg) identified as optimally effective and well-tolerated.