Phytochemical Profiles, Antiproliferative and Antioxidant Activities of Carissa Edulis (Forssk.) Vahl) and Pappea Capensis (L.) Extracts
Muruthi, W. Carolyn
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Cancer mortality is a global concern. In Kenya, cancer is ranked third cause of death. Incidence rates for breast and prostate cancers exceed those of other forms of cancer. Reactive species are implicated in all aspect of cancer, that is, initiation, promotion progreesion. With the increased changes in lifestyle and environmental pollutants; the burden caused by cancer will continue to have an upward trajectory. The current therapeutic approaches despite showing efficacy are characterized by several limitations such as adverse effects, prohibitive costs and sturdy resistance. This drives the need to explore alternative anticancer drugs. Several studies have evaluated anticancer and antioxidant effects of diverse plant extracts. In addition, toxicity effect of herbal plants has been evaluated using various assays including brine shrimp (Artemia salina) lethality assay. C. edulis and P. capensis are used as traditional therapy among the African communities to manage cancer and oxidative stress-related ailments. However, there is limited research on the antiproliferative and antioxidant effects of these medicinal plants. The current study, therefore, sought to evaluate the phytochemical profile, antiproliferative, antioxidant and in vivo cytotoxicity activities of C. edulis and P. capensis extracts. Samples were collected from Embu County, Kenya. Phytochemical profiles were determined using Liquid Chromatography Mass Spectrophotometer (LCMS) and Gas Chromatography Mass Spectrophotometer (GC-MS) analyses. Antiproliferative activity of the plant extracts against breast cancer (HCC 1395), prostate cancer (DU145) and Vero (normal) cell lines was determined using MTT assay. Effect of the extracts on expression of apoptotic genes (p53, bax and HOXB13) was evaluated using quantitative Real Time Polymerase Chain Reaction (qRTPCR). In vitro antioxidant properties of the extracts were evaluated through ferric reduction, Iron chelating, hydroxyl radical, and I, I-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activities. Activities of catalase, superoxide dismutase and glutathione reductases of the extracts were further determined. Toxicity of the extracts against was determined using the brine shrimp lethality test (BSLA). The results indicated that ethyl acetate extracts of C. edulis and P. capensis had the highest activity against cancer cells with IC50 values of 2.12±0.02, and 6.57±0.03μg/ml on HCC 1395 and 2.92±0.17 and 5.00±0.17μg/ml on DU145, respectively. Moreover, all the extracts exhibited relatively less cytotoxic activities against Vero cell lines (IC50>20μg/ml). The extracts also exhibited selectivity againt the cancer cells (SI>3). Further, mRNA expression of p53 in the treated HCC 1395 was increased by 7 and 3-fold, whereas by 3 and 2-fold in DU145 cells, upon treatment with ethyl acetate extracts of C. edulis and P. capensis, respectively. Similarly, severalfold increases were observed in the number of transcripts of Bax in HCC 1395 and HOXB13 in DU145 cells. The extracts had antioxidant activities whereby IC50 values were less than 50mg/ml, indicating strong scavenging activities. BSLA assay indicated that the extracts were non-toxic (LC50≥1000μg/ml) and had low toxicity (LC50≥500- 1000μg/ml) effects against A. salina. Phytochemical analyses revealed presence of compounds which are associated with antiproliferative and antioxidant activities including flavonoids, phenolics, tocopherols and terpenoids. The findings provide a scientific validation for the folklore use of C. edulis and P. capensis in management of cancer and oxidative stress. Nevertheless, there is a need for further purification and characterization of phytochemicals associated with anticancer and antioxidant activities. In addition, further toxicity assays should be conducted to explore effects of extracts on organs weight, body weight, haematological and biochemical parameters.