An evaluation of antioxidant properties and development of anticancer ingredients from Sclerocarya birrea fruits exocarp and Terminalia prunoides pods

Abstract

Oxidative stress has been implicated as one of the causes of cancer. Cancer ranks top amongst diseases with a high mortality rate. Conventional drugs are expensive and have been reported to have sever side effects. This creates a need to come up with a solution that is inexpensive with less or no side effects. Therefore, this study aimed to evaluate antioxidant properties and formulate anticancer ingredients from Sclerocarya birrea fruit exocarp and Terminalia prunoides pods. Hexane, chloroform, ethyl acetate and methanol extracts from Sclerocarya birrea fruit exocarp, and Terminalia prunoides pods underwent phytochemical screening, qualitative phytochemical analyses, potential antioxidant activity. Furthermore, three anticancer ingredients were formulated from the 2 plants, and then evaluated for their antiproliferative effects on HeLa cells. Two individual extracts; Sclerocarya birrea fruit exocarp methanol extracts (M1) and Terminalia prunoides pods methanol extracts (M2), and two ingredients; Sclerocarya birrea fruit exocarp methanol extracts + Terminalia prunoides pods methanol extracts (M1M2), and methanol + ethyl acetate extracts from Sclerocarya birrea fruit exocarp + methanol + ethyl acetate from Terminalia prunoides pods (M1E1M2E2) with the lowest IC50 values on HeLa cells were evaluated for their effects on the expression of cervical cancer markers; Epidermal Growth Factor Receptor (EGFR), Metastasis-Associated in Colon Cancer 1 (MACC1), Vascular Endothelial Growth Factor (VEGF), Cytokeratin Fragment (CYFRA 21-1), and Cluster differentiation 95 (CD95). Methanol and ethyl acetate extracts from both plants tested positive for saponins, tannins, flavonoids, phenols, terpenoids, cardiac glucoside and steroids. Methanol extracts from both plants recorded total flavonoid content (TFC) of 55.2± 3.8mg QE/g and 67.8 ±10.4 mg QE/g for Sclerocarya birrea fruit exocarp and Terminalia prunoides pods respectively, and total phenolic contents (TPC) of 105.4 ± 1.4 mg GAE/g and 113.2 ± 7.6 mg GAE/g for Sclerocarya birrea fruit exocarp and Terminalia prunoides pods respectively. Methanol extracts from Sclerocarya birrea fruit exocarp recorded IC50 values of 0.12 mg/mL, 0.09 mg/mL, and 0.2mg/mL of 2, 2-diphenyl-1-picryl hydrazyl (DPPH), Ferric reducing antioxidant power (FRAP), and 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid (ABTS) assays respectively. Methanol xiii extracts from Terminalia prunoides pods recorded IC50 values of 0.06 mg/mL, 0.07 mg/mL, and 0.24 mg/mL after DPPH, FRAP and ABTS assays respectively. Ethyl acetate and methanol extracts of both plants significantly increased Catalase (CAT), reduced glutathione (GSH), and Superoxide Dismutase (SOD) activities. For antiproliferative effects, the IC50 values of methanol extracts of Sclerocarya birrea fruit exocarp and Terminalia prunoides pods were 75 µg/mL and 190 µg/mL respectively. The M1E1M2E2 and M1M2 ingredients had IC50 values of 77 µg/mL and 83 µg/mL respectively. All treatments: M1E1M2E2, M1M2, M1 and M2 inhibited the growth of HeLa cells by significantly downregulating the expression of EGFR, MACC1, VEGF, CYFRA 21-1 genes, and upregulating the Cluster differentiation 95 (CD95) gene. Ingredients were more effective through effectively regulating gene expression. However, extracts need to be isolated and studied more.