Antioxidant, Enzyme and Molecular Docking Tyrosinase Inhibitory Activities of Major Polyphenols in Boscia coriacea Graells, Grewia erythraea (Schweinf.) Chiov., Ochradenus baccatus Delile, and Orthosiphon pallidus Royle Ex Benth.

Boscia coriacea Graells (BC), Grewia erythraea (Schweinf.) Chiov. (GE), Ochradenus baccatus Delile (OB), and Orthosiphon pallidus Royle ex Benth. (OP) are medicinal plants used in Djibouti. They were evaluated to determine their total phenolic content (TPC), flavonoid content (TFC), and phytochemical profile using HPLC–MS/MS. Additionally, their antioxidant capacity was assessed through five various methods. Enzymatic activities were also measured, focusing on acetylcholinesterase (AChE), butyrylcholinesterase (BChE), α-amylase, α-glucosidase, and tyrosinase. OP extract had the highest TPC and exhibited the best antioxidant capacity, whereas OB and BC extracts had the highest TFC. Twenty-seven compounds were identified and quantified by LCMS. GE extract demonstrated the highest AChE activity, whereas OP extract had the highest BChE activity. BC was most active against α-amylase and α-glucosidase, and only GE and OP extracts showed tyrosinase inhibition in vitro. In silico analysis, the compounds were optimized and docked to the human tyrosinase-related protein 1 using AutoDock Vina, with absorption, distribution, metabolism, and elimination to evaluate their suitability based on key therapeutic criteria. Chlorogenic, neochlorogenic, gallic acids, and quercetin emerged as promising tyrosinase inhibitors. These plants can be a viable source in the prevention and treatment related to tyrosinase enzyme inhibition.