Phytochemical Extract from Syzygium cumini Leaf: Maximization of Compound Extraction, Chemical Characterization, Antidiabetic and Antibacterial Activity, and Cell Viability

This work aimed to obtain a phytochemical extract from jambolan leaf using a hydroethanolic solvent and ultrasound-assisted extraction. For this purpose, an experimental design was applied to analyze the effect of process variables related to temperature (30–60 °C), time (10–30 min), and solvent to leaf ratio (5–15 mL g−1), on the extraction mass yield (EMY) and on the yield of phenolic compounds (PCY). The effect of extractor solvent, AE (absolute ethanol), 75E (75% v·v−1 ethanol) and 50E (50% v·v−1), on the chemical characterization of the extracts, antidiabetic and antimicrobial activity, and cell viability, were also evaluated. The application of the highest values of process variables resulted in obtaining the maximum of the response variables (EMY = 9.94 wt% and PCY = 13.01 mg GAE g−1 leaf). A higher content of phenolic compounds and flavonoids was obtained with 50E, which is mainly composed of sinapic, vanillic, trans-caffeic, and quinic acids, which were responsible for the greatest antioxidant potential, antibacterial activity (against Staphylococcus aureus and Pseudomonas aeruginosa), and inhibition of α-amylase. On the other hand, the use of AE allowed us to obtain extracts with higher concentrations of squalene, α-tocopherol, β-sitosterol, and friedelin. From cell viability tests, the extracts are not considered toxic at the concentration tested (100 µg mg−1).