Dose-Dependent Cardioprotection of Pterocarpus indicus Extract in Rats With Myocardial Ischemia: Targeting Oxidative...

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.

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.

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 (EC₅₀ ∼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.

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.