Phytochemical Composition and Anticancer Properties of Haplophyllum tuberculatum Growing in Qatar and Oman Against Human Triple-Negative Breast Cancer Cells

Abstract

Introduction: Breast cancer ranks as the most frequently diagnosed cancer globally, with the triple-negative breast cancer (TNBC) subtype linked to a notably poor prognosis. The absence of optimal therapeutic regimens has prompted the search for more effective alternative TNBC treatments including therapeutics based on natural plant products. Haplophyllum tuberculatum (Forsskal) A. Juss (H. tuberculatum), belonging to the Rutaceae family, has been traditionally used to treat a wide variety of illnesses, and has been a subject of various recent pharmacological studies. However, its potential therapeutic effects in cancer in general and TNBC in particular are poorly investigated. Aim: This study aimed to compare the in vitro cytotoxic activity of H. tuberculatum extracts collected from Qatar and Oman and prepared in different polarity solvents against MDA-MB-231 human TNBC cells. Further the antimigratory effects and antioxidant capabilities were evaluated. The phytochemical compounds of the extracts were identified to examine any correlation between potential anticancer properties and phytochemical composition. Methods: H. tuberculatum extracts in water, methanol, or dichloromethane (DCM) were tested for cytotoxic effects on the MDA-MB-231 cells using the Alamar Blue and crystal violet assays. The extracts showing better cytotoxic activity were evaluated for their antimigratory and antioxidant properties using the scratch and the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assays, respectively. The total phenolic and flavonoid contents were measured using the Folin-Ciocalteu (FC) and aluminum chloride colorimetric methods, respectively. Additionally, the phytochemical constituents were identified through Gas Chromatography-Mass Spectrometry (GC/MS) and High-Performance Liquid Chromatography (HPLC). Results: Both the Qatari and the Omani extracts reduced the viability of MDA-MB-231 cells. Among the extracts tested, the Qatari H. tuberculatum DCM (HTQ-DCM) and methanolic (HTQ-M) extracts demonstrated higher cytotoxicity against MDA-MB-231 cells, with IC50 values of 40.5 µg/ml and 163.4 µg/ml, respectively. Both HTQ-DCM and HTQ-M inhibited MDA-MB-231 cell migration. HTQ-M extracts possessed a high antioxidant capacity, with an EC50 of 81.6925 µg/ml, while that of HTQ-DCM was minimal. Additionally, HTQ-M displayed high levels of phenolic (391.7± 19.7 µg gallic acid equivalents/g dry weight) and flavonoid (15.7± 0.36 µg quercetin equivalents/g dry weight) content, while HTQ-DCM had negligible amounts of these compounds. GC/MS and HPLC analyses indicated that both extracts contain various bioactive secondary metabolites, potentially explaining their anticancer effects.