Chemical Composition of Tunisian Ziziphus lotus, In Vitro Biological Activities, and In Silico Computational...

Ziziphus lotus, valued in traditional medicine, is characterized by its rich bioactive compounds that confer nutritional and therapeutic properties. The present study aimed to prepare two types of extracts using hexane (HZL) and ethyl acetate (EAZL) from Z. lotus leaves and evaluate their phytochemical composition, antioxidant capacity, enzyme inhibitory, and antimicrobial activities, complemented by in silico computational analysis. The EAZL extract exhibited higher levels of total phenolic (551.83 ± 5.7 mg gallic acid equivalent [GAE/g]), flavonoid (251.90 ± 7.6 mg QE/g), and tannins (219.70 ± 2.7 mg CE/g) content compared to the HZL extract. Notably, the EAZL extract demonstrated significant antioxidant capacity and significant inhibition of α-amylase (IC₅₀ = 0.087 ± 0.005 mg/mL) and acetylcholinesterase (IC₅₀ = 0.218 ± 0.019 mg/mL). Both extracts showed antibacterial activity against Escherichia coli and methicillin-resistant Staphylococcus aureus (minimum inhibitory concentration [MIC] = 5 mg/mL), as well as notable antibiofilm activity. LC-MS analysis of EAZL identified eight phytoconstituents, including major flavonoids such as quercetin-O-dihexoside, isorhamnetin-3-O-rutinoside, quercetin-3-O-rutinoside, luteolin-7-O-rutinoside, and quercetin-3-O-rutinoside-O-rhamnoside, which likely contribute to its bioactive effects. Molecular docking simulations revealed high-affinity interactions between these compounds and the active sites of SarA and CtrM proteins from S. aureus, which could explain their antibiofilm and anti-virulence activities. These findings uniquely integrate in vitro and in silico approaches to explore the bioactive compounds of Z. lotus, unveiling their nutraceutical uses and providing new insights as therapeutic candidates.