Cytotoxic phytochemicals from the crude extract of Tetrapleura tetraptera fruits towards multi-factorial drug resistant cancer cells

• Published in: Journal of ethnopharmacology 2021-03, Vol.267, p.113632, Article 113632
• Main Authors: Mbaveng, Armelle T., Chi, Godloves F., Bonsou, Idrios N., Ombito, Japheth O., Yeboah, Samuel O., Kuete, Victor, Efferth, Thomas
• Format: Article
• Language: English
• Subjects: Antineoplastic Agents, Phytogenic - isolation & purification; Antineoplastic Agents, Phytogenic - pharmacology; Apoptosis; Apoptosis - drug effects; Cancer; Caspases - metabolism; Cytotoxicity; Dose-Response Relationship, Drug; Drug Resistance, Multiple; Drug Resistance, Neoplasm; Fabaceae; Fruit - chemistry; HCT116 Cells; Hep G2 Cells; Humans; Inhibitory Concentration 50; Membrane Potential, Mitochondrial - drug effects; Multi-drug resistance; Neoplasms - drug therapy; Neoplasms - metabolism; Neoplasms - pathology; Oxidative Stress - drug effects; Phytochemicals - isolation & purification; Phytochemicals - pharmacology; Plant Extracts - isolation & purification; Plant Extracts - pharmacology; Reactive Oxygen Species - metabolism; Signal Transduction; Tetrapleura - chemistry; Tetrapleura tetraptera
• ISSN: 0378-8741; 1872-7573
• DOI: 10.1016/j.jep.2020.113632

Tetrapleura tetraptera is an African medicinal spice used in traditional medicine to treat several ailments including cancer. The present study was designed to evaluate the cytotoxicity of the dichloromethane-methanol (1:1) extract of the fruits of Tetrapleura tetraptera (TTF) and its constituents: (3R, 4S)-3,4-dimethyloxetan-2-one (1), luteolin (2), stigmasterol (4), 3-O-[6′-O-undecanoyl-β-D-glucopyranosyl]stigmasterol (6), olean-12-en-3-β-O-D-glucopyranoside (7), 3-O-β-D-glucopyranosyl-(1 → 6)-β-D-glucopyranosylurs-12-en-28-oic acid (8), 3-O-β-D-glucopyranosyl-(1 → 3)-β-D-glucopyranosyl-27-hydroxyolean-12-ene-28-oic acid (9), methyl-O-β-D-glucopyranoside (10), β-D-fructofuranosyl-(2 → 1)-β-D-glucopyranoside (11) towards a panel of cancer cell lines including MDR phenotypes. The cellular mode of induction of apoptosis by TTF and compound 7 was further investigated. The resazurin reduction assay (RRA) was applied to determine the cytotoxicity of the studied samples. The cell cycle (PI staining), apoptosis (annexin V/PI staining), mitochondrial membrane potential (MMP; JC-1) and reactive oxygen species (ROS; H2DCFH-DA) were measured by flow cytometry. Column chromatography was used for the purification of TTF, whilst nuclear magnetic resonance (NMR) spectroscopic analysis was applied for structural elucidation. The botanical, TTF and the phytochemicals, 2, 7, 8 and 9 as well as doxorubicin exerted cytotoxicity against 9 cancer cell lines including drug-sensitive and drug resistant phenotypes. TTF, compound 7 and doxorubicin were the most active samples, and displayed IC50 values ranging from 10.27 μg/mL (in CCRF-CEM leukemia cells) to 23.61 μg/mL (against HCT116 p53−/− colon adenocarcinoma cells) for TTF, from 4.76 μM (against CCRF-CEM cells) to 12.92 μM (against HepG2 hepatocarcinoma cells) for compound 7, and from 0.02 μM (against CCRF-CEM cells) to 122.96 μM (against CEM/ADR5000 cells) for doxorubicin. TTF induced apoptosis in CCRF-CEM cells through MMP alteration and increased ROS production while compound 7 induced apoptosis mediated by caspases activation, MMP alteration and increased ROS production. Tetrapleura tetraptera and some of its constituents, mostly compound 7 are good cytotoxic natural products that should be explored in depth to develop new drugs to fight cancers. The botanical, TTF and the phytochemicals, 2, 7, 8 and 9 had cytotoxic effect against the nine cancer cell lines tested including drug-sensitive and drug resistant phenotypes. TT