Unveiling The Antioxidant and Anticancer Potential of Local Mediterranean Olive and Fig Extracts Against Breast Cancer

Abstract

Background: Breast cancer (BC) stands out as the fastest-growing cancer worldwide, posing a significant threat to public health. Lebanon has witnessed the highest age standardized rate (ASR) of breast cancer incidence in the eastern Mediterranean region. The Mediterranean diet (MD) has gained widespread recognition for its potential in mitigating various ailments including cancer. This positive effect was attributed to its rich array of bioactive compounds in its local produce including polyphenols, flavonoids, and phytosterols. Given the serious side effects of traditional chemotherapeutic drugs along with multidrug resistance, efforts are aiming to further investigate the effects of key components of the Mediterranean diet in the context of breast cancer prevention and management. Research has predominantly focused on olive oil and fig leaf and lumen extracts, with limited exploration of the potential anticancer properties of Ficus carica (FC) pulp and skin and Olea europea (OE) fruit extracts. Objective: The objective of this research is to evaluate the antioxidant and anticancer potential of extracts of three Lebanese FC varieties (Shatawi (Sh), Baqarati (Bq), Asali (As)) and two local OE varieties (green olive (GO), black olive (BO)) in single and combined treatment on decreasing viability of breast cancer cells and elucidating their mechanism of action in vitro. Methodology: Methanolic extraction of both FC and OE varieties was followed by quantification of key phytochemicals such as total polyphenols (using Folin-Ciocalteu assay) and anthocyanin content (using the total anthocyanin quantification assay). Extracts were tested for their antioxidant activity using DPPH and FRAP assays. The anticancer potential of extracts was assessed using MTT assay, where concentrations of FC extracts (2,5,7,10,20,30 mg/ml) and OE extracts (0.3, 0.6, 0.9, 1.2, 1.6, 2.4 mg/ml) were tested against FHs 74 non-tumorigenic intestinal epithelial cells, MDA-MB-231 and MCF-7 breast cancer cell lines; whereas their effect on cell cycle progression was tested by Guava EasyCyte8 Flow Cytometry-Millipore. Combination indices of combined treatment were reported based on calculations from Chou et al. (1984) to assess any synergistic effect on cell viability.

Results: Phytochemical analysis revealed that OE variety extracts exhibited significantly higher total polyphenolic content (TPC), particularly anthocyanins, with the black olive (BO) variety displaying the highest levels compared to FC variety extracts. This elevated TPC corresponded to a three-folds stronger antioxidant capacity in OE extracts. Furthermore, results from MTT supported the cytotoxic effect of the Lebanese olive and fig extracts on breast cancer cells. This effect was amplified for MCF-7, but not for MDA-MB-231cells. OE variety extracts showed stronger anticancer activity at 100- folds lower concentration than FC variety extracts. Combined treatment of both breast cancer cell lines with these extracts showed a strong synergism, while having no toxic effect on the non-cancerous FHs 74 cells, highlighting the selectivity of the extracts on decreasing breast cancer cell viability. Conclusion: Darker colored FC and OE variety extracts exhibited higher total polyphenolic content and greater antioxidant activity than lighter varieties. Extracts from these darker varieties have higher anticancer effects. The two dark extracts BO and Sh extracts have synergistic effect in decreasing breast cancer viability, but not in non-cancerous cells. Testing the mechanism of action of these extracts has shown that extracts lock up the cells in sub-G1 phase indicating apoptosis.