Passiflora edulis f. flavicarpa Extract Prevents Muscle Atrophy and Insulin Resistance in High-Fat Diet-Induced Obese Rats via Regulating the Nrf2, NF-κB, and IRS-1/PI3K/AKT Signaling Pathways.

High-fat diets (HFDs) are a key contributor to obesity and promote oxidative stress and inflammation, which are associated with muscle atrophy and insulin resistance (IR). Passiflora edulis exhibits anti-obesity, antioxidant, and anti-inflammatory effects. The study aimed to investigate the potential benefit of P. edulis f. flavicarpa (PF) extract in preventing obesity-associated muscle atrophy and IR. The PF extract effectively inhibited cholesterol micelle solubility with an IC50 of 3431 µg/mL and decreased fat accumulation in 3T3-L1 adipocytes. Furthermore, this study investigated a model of HFD-induced IR and muscle atrophy in rats. Thirty-five male Sprague-Dawley (SD) rats were induced with obesity by HFD and were administered 250 and 500 mg/kg/day of PF extract. Rats fed with an HFD were associated with fat accumulation and oxidative stress, which promoted inflammation, muscle damage, muscle atrophy, and IR in obese rats. However, administration of PF extract effectively mitigated these effects. The PF extract decreased fat accumulation in white adipose tissues and gastrocnemius (GAS) muscle by inhibiting fat absorption and synthesis, particularly Cd36 and Hmgcr. The PF extract also notably reduced oxidative stress-induced muscle inflammation and damage via elevating nuclear factor erythroid 2-related factor 2 (Nrf2) and reducing nuclear factor kappa B (NF-κB) expressions. Additionally, PF extract was found to mechanistically prevent muscle atrophy by inhibiting Fbxo32, Trim63, and B-cell lymphoma 2 (BCL2)-associated X (Bax) expressions, while enhancing Bcl2 expression. We also found that PF extract mitigated muscle IR by upregulation of the insulin receptor substrate-1/phosphatidylinositol-3 kinase/protein kinase B (IRS-1/PI3K/AKT) pathway and Slc2a4 expression. The findings indicate that PF extract can prevent skeletal muscle loss and IR in obesity by modulating oxidative stress, inflammation, and activating IRS-1/PI3K/AKT signaling pathway.