An in vitro evaluation of Hypoxis hemerocallidea (African potato) corm, Helichrysum caespititium and Dicoma anomala effects on the proliferation of DU145 prostate cancer cell line

Abstract

Prostate cancer remains a significant health challenge globally, with growing interest in alternative treatment options. Once the safety and efficacy of alternative medicine are proven, it transitions from being “alternative” to mainstream. In Southern Africa, medicinal plants are widely available and form a crucial part of healthcare, with approximately 80% of the population relying on them for primary care. This rich botanical diversity offers potential for discovering novel treatments for prostate cancer, and the integration of such remedies into conventional medicine may provide safer, more holistic approaches to cancer care. The aim of this study was to evaluate the effectiveness of the corms of Hypoxis hemerocallidea (African potato), Helichrysum caespititium, and Dicoma anomala on the proliferation of DU145 prostate cancer cell line in vitro. Plants were collected, dried, ground, and extracted using methanol and distilled water as solvents. Extracts from the corms of H. hemerocallidea, H. caespititium, and D. anomala were screened for their phytochemicals using high-resolution mass spectrometry. For the identification of compounds, using the negative and positive ion modes analysis allowed for mass fragments and molecular formula peaks recognition. The anti-oxidant activities of the corms were determined using 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2, 2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), and Ferric reducing ability of plasma (FRAP) assays. The in vitro antiproliferative activity screening was evaluated using fluorescent stains, namely bisBenzamide H 33342 trihydrochloride and propidium iodide. Moreover, the antiproliferative effects mechanisms were studied by investigating the phosphatidylserine translocation and mitochondrial membrane depolarisation after treating the cells with the extracts. The extracts demonstrated 75% (DPPH) and 95% (FRAP) anti-oxidant activities, showing a strong positive correlation with the presence of phytochemicals such as phytosterols, phenolic acids, flavonoids, and terpenoids. D. anomala methanolic extracts exhibited an antiproliferative effect against the prostate cancer cell line DU145 with an IC50 value of 18.98 μg/mL. Cell cycle analysis showed DU145 prostate cancer cell death through cell arrest at the early M phase and S phase respectively. Depolarisation of mitochondrial membrane and cleaved caspase-3 increased after 48 hours of being exposed to D. anomala methanolic extracts. Cell cycle arrest, phosphatidylserine translocation, caspase activation, and mitochondrial membrane depolarisation suggested that the D. anomala methanolic extract can induce cell death through apoptosis observed from the Annexin V-FITC and propidium iodide stain, with melphalan as a positive control. The methanolic and aqueous extracts from H. hemerocallidea (African potato) and H. caespititium did not exhibit any cell proliferation. The extracts were thus not used for further investigation on the DU145 prostate cancer cell line. In conclusion, this study showed that D. anomala has the ability to induce apoptosis on the DU145 prostate cancer cell line. Conversely, H. hemerocallidea. and H. caespititium did not exhibit inhibitory effects on the DU145 prostate cancer cell line compared to D. anomala. Apoptotic activities and antioxidants properties of D. anomala highlight its potential as a therapeutic agent for treatment of prostate cancer. Further evaluation of D. anomala extracts on non-cancerous cell line and in vivo studies are recommended for safety profiling of the extract.