Metabolite characterization, antioxidant, anti-proliferative and enzyme inhibitory activities of Lophira lanceolata Tiegh. ex Keay extracts

Lophira lanceolata Tiegh. ex Keay, a native tropical plant to west and central Africa, is a multifunctional plant used as timber and also exploited in traditional medicine in Africa. The present study present the pharmacological properties of Lophira lanceolata leaf and stem bark extracts prepared from different extraction procedures (infusion, homogenizer‐assisted extraction, maceration, soxhlet). The detailed phytochemical composition, in vitro antioxidant and antiproliferative assays, as well as the key enzyme (cholinesterases, tyrosinase, α‐amylase and α‐glucosidase) inhibitory potentials of the extracts were evaluated. Chemical profiling confirmed the presence of lanceolatins and lophirones in all analyzed plant parts. Higher levels of total phenolics (156.42 mg gallic acid equivalent (GAE)/g for maceration-water), phenolic acids (165.84 mg caffeic acid equivalent (CE)/g for maceration-water) and flavanols (101.51 mg catechin equivalent (CAE)/g for soxhlet-methanol (MeOH)) were observed in the stem bark extracts. Antioxidant assays showed remarkable free radical scavenging and reducing power activities for all extracts, among which stem bark showed the highest potential. Stem bark extracts (IC50 values: 57.55–93.10 μg/ml for colorectal adenocarcinoma (HT29) and 78.18–89.58 μg/ml for metastatic breast cancer cell line (MCF7)) also showed better antiproliferative effect than leaf (424.14–790.27 μg/ml for HT29 and 374.46–943.09 μg/ml for MCF7) on carcinoma cells while they induced proliferation in normal human cell lines (normal skin fibroblasts (HFF)). In the enzyme inhibitory assays, the methanol extracts of both plant parts were confirmed as effective against AChE, BChE (only stem barks extracts) and α-glucosidase enzymes. Regarding anti-tyrosinase effects, the methanol leaf extracts (122.21–131.17 mg kojic acid equivalent (KAE)/g) and all stem bark extracts (94.58–153.21 mg KAE/g) exhibited inhibitory effects. Findings amassed herein tend to validate the traditional uses of L. lanceolata and advocate for the development of phyto-medicaments based on its extracts.