Background/Objectives: Honokiol (HK), a bioactive phenolic compound, exhibits significant anti-cancer properties. This study aimed to investigate the anti-cancer effects of HK in colorectal cancer (CRC) cells by focusing on its direct interaction with heat shock protein 27 (Hsp27) as a molecular target, and to elucidate the underlying mechanisms involved. Methods: HK was isolated via silica/ODS chromatography. Anchorage-independent growth of CRC cells was quantified using a soft agar assay with increasing HK concentrations. Apoptosis and cell cycle were analyzed by flow cytometry, and cell viability by MTS assay. Hsp27 binding to HK was validated by pull-down assay with HK-conjugated Sepharose 4B beads. Hsp27 knockdown was performed using lentiviral shRNA in CRC cells. Molecular docking of HK-Hsp27 interaction employed Schrödinger Suite 2016. Protein expressions, including chaperone and apoptotic proteins, were evaluated by Western blotting. Results: HK dose-dependently suppressed anchorage-independent growth of CRC cells and induced G₀/G₁ arrest. It triggered apoptosis through cytochrome c release, PARP cleavage, and Bcl-2 downregulation. HK directly bound to the α-crystallin domain of Hsp27 at Asn102 and His103 residues, confirmed by computational molecular docking and site-directed mutagenesis. Hsp27 knockdown in CRC cells dramatically reduced anchorage-independent growth. HK markedly decreased Hsp27 protein levels while having less effect on other heat shock proteins in CRC cells. Conclusions: HK exerts anti-cancer effects in CRC cells, associated with Hsp27 inhibition, resulting in suppressed cell growth and increased apoptosis. This interaction between HK and Hsp27 may support a mechanistic foundation supporting the potential utility of HK as a natural therapeutic agent for CRC.

Sarcopenia, an age-related muscle atrophy disease, is a major health concern in aging societies and is closely associated with severe chronic diseases. Its primary pathogenesis involves oxidative stress-induced apoptosis in muscle cells and an imbalance in protein metabolism. This study evaluated the potential of Rhododendron mucronulatum branch extract (RMB) and its major flavonoids, taxifolin-3-O-arabinopyranoside (Tax-G) and taxifolin (Tax-A), as natural therapeutic agents for sarcopenia. Phytochemical analyses were performed using TLC, HPLC, LC-MS/MS, and NMR, and Tax-G and Tax-A were isolated from RMB. In vitro models of apoptosis and muscle atrophy were established in C2C12 cells using H₂O₂ and dexamethasone (DEX), respectively. Cell viability, myotube diameter, and protein expression related to apoptosis and muscle differentiation were assessed. All three substances reduced H₂O₂-induced apoptosis by increasing Bcl-2 and inhibiting cleaved caspase-3 and PARP. They also attenuated DEX-induced muscle atrophy by suppressing Atrogin-1, MuRF1, and FoxO3α while promoting MyoD, Myogenin, Akt, and mTOR. Although Tax-A showed the highest activity, Tax-G exhibited comparable effects with lower cytotoxicity. These findings demonstrate that RMB and its active compounds protect muscle cells by regulating apoptosis and muscle metabolism, suggesting their potential as safe and functional natural materials for the prevention of sarcopenia.