Clerodane Diterpenoids from an Edible Plant Justicia insularis : Discovery, Cytotoxicity, and Apoptosis Induction in Human Ovarian Cancer Cells

• Published in: Molecules (Basel, Switzerland) Vol. 26; no. 19; p. 5933
• Main Authors: Fadayomi, Idowu E, Johnson-Ajinwo, Okiemute R, Pires, Elisabete, McCullagh, James, Claridge, Tim D W, Forsyth, Nicholas R, Li, Wen-Wu
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 30.09.2021; MDPI
• Subjects: Annexin V; Antineoplastic Agents, Phytogenic - pharmacology; Apoptosis; Apoptosis - drug effects; Bioassays; Calibration; Cancer therapies; Caspase-3; Caspase-8; Cell growth; Chemotherapy; Chromatography; Column chromatography; Cytotoxicity; Diterpenes; Diterpenes, Clerodane - pharmacology; diterpenoids; Drug Discovery; Drugs; Female; Flow cytometry; Herbal medicine; High performance liquid chromatography; Humans; induction of apoptosis; Justicia - chemistry; Justicia insularis; Liquid chromatography; Mass spectrometry; Medicinal plants; Natural products; NMR; Nuclear magnetic resonance; Ovarian cancer; Ovarian Neoplasms - drug therapy; Ovarian Neoplasms - pathology; Particle size; Plant extracts; Plant Extracts - pharmacology; Plant Leaves - chemistry; Proteins; Scientific imaging; Solvents; Sulforhodamine; target prediction; Tumor cell lines; Tumor Cells, Cultured; United Kingdom > UK; Nigeria; United States > US; induction of apoptosis; Justicia insularis; diterpenoids; target prediction; ovarian cancer; cytotoxicity
• ISSN: 1420-3049; 1420-3049
• DOI: 10.3390/molecules26195933

The toxicity of chemotherapeutic anticancer drugs is a serious issue in clinics. Drug discovery from edible and medicinal plants represents a promising approach towards finding safer anticancer therapeutics. T. Anderson (Acanthaceae) is an edible and medicinal plant in Nigeria. This study aims to discover cytotoxic compounds from this rarely explored and investigate their underlying mechanism of action. The cytotoxicity of the plant extract was evaluated in human ovarian cancer cell lines and normal human ovarian surface epithelia (HOE) cells using a sulforhodamine B assay. Bioassay-guided isolation was carried out using column chromatography including HPLC, and the isolated natural products were characterized using GC-MS, LC-HRMS, and 1D/2D NMR techniques. Induction of apoptosis was evaluated using Caspase 3/7, 8, and 9, and Annexin V and PI based flow cytometry assays. SwissADME and SwissTargetPrediction web tools were used to predict the molecular properties and possible protein targets of identified active compounds. Key finding: The two cytotoxic compounds were identified as clerodane diterpenoids: 16(α/β)-hydroxy-cleroda-3,13(14) -dien-15,16-olide ( ) and 16-oxo-cleroda-3,13(14) -dien-15-oic acid ( ) from the Acanthaceous plant for the first time. Compound was a very abundant compound (0.7% per dry weight of plant material) and was shown to be more potent than compound with IC values in the micromolar range against OVCAR-4 and OVCAR-8 cancer cells. Compounds and were less cytotoxic to HOE cell line. Both compounds induced apoptosis by increasing caspase 3/7 activities in a concentration dependent manner. Compound further increased caspase 8 and 9 activities and apoptosis cell populations. Compounds and are both drug like, and compound may target various proteins including a kinase. Clerodane diterpenoids ( and ) in were identified as cytotoxic to ovarian cancer cells via the induction of apoptosis, providing an abundant and valuable source of hit compounds for the treatment of ovarian cancer.