Abstract Introduction Metabolic disorders such as obesity, type 2 diabetes (T2DM), and metabolic dysfunction–associated steatotic liver disease (MASLD) are major contributors to cardiovascular risk. Dysregulated glucose and lipid metabolism drive atherosclerosis and inflammation. While SGLT2 inhibitors improve steatosis and metabolic health, flavonoids, abundant in Malus pumila extract, have emerged as promising modulators of glucose and lipid metabolism due to their antioxidant and anti-inflammatory properties. Methodology A botanical extract from Malus pumila was characterized by mass spectrometry (MS) and tested for metabolic effects in human hepatocytes (HepG2 cells). The extract’s influence on glucose uptake, lipid accumulation, mitochondrial mass, lysosomal content, and cytosolic calcium was assessed after 24 h of treatment with extract on the cells previously incubated for 6 days with oleate (200 µM) and palmitate (100 µM). Via western blot analysis we evaluated ETC complexes, CD36, LDL-R, AMPK, LC3, and mTOR. Furthermore, the impact of ammonium chloride (10 µM) on lysosomal activity and lipid uptake was evaluated to further investigate the involvement of lysosomal pathways in lipid metabolism. Results The extract was non-cytotoxic and significantly enhanced glucose uptake while reducing lipid accumulation and mitochondrial mass. The extract induced a significant activation of AMPK and suppression of mTOR, together with upregulation of LC3, CD36, LDL-R, and ETC complexes I, II, and V, indicating stimulation of autophagy, enhanced fatty acid and cholesterol uptake, and improved mitochondrial function. Cytosolic calcium levels were elevated, suggesting calcium-dependent signaling involvement. Malus pumila extract increased lysosomal mass, whereas ammonium chloride abolished this effect and further reduced lysosomal integrity, confirming the importance of lysosomal pH in its mechanism. Conclusion Malus pumila extract likely increases cytosolic calcium via inhibition of sodium–glucose transporters, activating AMPK, inhibiting mTOR, and stimulating autophagy. This promotes removal of damaged mitochondria and enhances the function of remaining ones through calcium-driven activation of ETC complexes, supporting metabolic homeostasis via coordinated regulation of calcium signaling, autophagy, and mitochondrial function.
F Kuci (Fri,) studied this question.