Heterophyllin B

Diabetic cardiomyopathy (DCM), a major cause of diabetic mortality, lacks effective therapies. This study investigated the cardioprotective role of Heterophyllin B (HET-B), a natural compound and its underlying mechanisms in DCM. Using streptozotocin-induced DCM mice and high glucose (HG)-treated H9C2/neonatal cardiomyocytes, we assessed cardiac function, mitochondrial homeostasis, and apoptosis. HET-B significantly improved cardiac function, indicated by increased ejection fraction (EF) and fractional shortening (FS). It also reduced cardiomyocyte apoptosis (in vivo/vitro), and ameliorated HG-induced mitochondrial damage, characterized by dysfunction, fragmentation, and excessive reactive oxygen species (ROS) production. HET-B enhanced mitochondrial fusion protein OPA1 expression and reduced Bax/Bcl2, cytochrome C (Cyt C) release and caspase-3 cleavage. Molecular docking and cellular thermal shift assays identified mitochondrial antiviral-signaling protein (MAVS) as a potential target of HET-B. HET-B reversed MAVS downregulation induced by HG/DCM in vitro and in vivo. Importantly, MAVS knockdown via siRNA abolished HET-B's protection against HG-induced apoptosis and mitochondrial damage. Furthermore, HET-B restored HG-impaired autophagic flux, reducing autolysosome accumulation and normalizing LC3-II. Collectively, HET-B, a natural compound, attenuates diabetic myocardial injury by targeting MAVS, thereby enhancing autophagy, preserving mitochondrial homeostasis, and inhibiting apoptosis, positioning it as a promising DCM therapeutic candidate.

Heterophyllin B is a natural occurring cyclic peptide with diverse attributed bioactivities. NMR‐based conformational analysis of cyclic peptides often poses a challenge due to limited isotropic solution‐state NMR data. In this study, we combined isotropic and anisotropic NMR observables including J‐coupling, NOEs, amide proton temperature coefficients, and residual dipolar couplings (RDCs), which enabled the determination of a minimal conformational ensemble of heterophyllin B in methanol at density functional theory (DFT) accuracy. For conformational sampling of a cyclic peptide with a high degree of conformational freedom, we proposed a computational strategy that combines the Conformer–Rotamer Ensemble Sampling Tool (CREST) with the Commandline Energetic SOrting (CENSO). This combined computational and NMR‐based approach offers a robust framework for the conformational analysis of cyclic peptides.