An Investigation Into The Antineoplastic Properties Of Schinziophyton Rautanenii And Colophospermum Mopane

ABSTRACT 

Cancer incidences are on the rise in Namibia, because of late diagnosis, cancer cases often have poor prognosis and treatment options are limited especially in resource poor rural settings. Ethnomedicinal plants present a treatment option which is used in such settings, is accessible and inexpensive. However evidence on safety and efficacy of these traditional medicinal plants is lacking, which prevents mainstream use. This study evaluated two Namibian indigenous plants, Schinziophyton rautanenii and Colophospermum mopane used medicinally in Zambezi region, for their phytochemical content and anti-protease activity. Furthermore, phytochemicals where quantified as percentage yields of dry plant material, antioxidant activity measured and plants were evaluated in vitro for anti-cancer activity against breast, renal and melanoma cancer cell models. Additionally, plant extracts were screened against a human fetal lung fibroblast cell line to determine cytotoxicity. Extracts were also assayed in vivo in Planaria, for toxicity. Alkaloids, coumarins, flavonoids and triterpenes were found in all plant extracts, except anthraquinones which were only found in the root extract of S. rautanenii. Antioxidant activity shown by plant extracts was in correlation with the observed alkaloid content of plants, (correlation =0.58, n=12, p=0.048). The highest in vitro anticancer activity was exhibited by the organic root extract of C. mopane, with IC50 48.2 µg/ml although it also showed mild cytotoxicity against fibroblast cells, IC50 162.4 µg/ml.  In vivo toxicity evaluation further revealed the strong toxicity level of the organic C. mopane root extract against the freshwater flatworm planaria at 20 µg/ml. The aqueous bark and root extracts of C. mopane showed some anticancer activity towards the breast cancer model (IC50 86.8 µg/ml  and 87.9 µg/ml respectively) while the organic bark and root extracts of C. mopane showed anticancer activity against a melanoma (IC50 92.5 µg/ml    and 64.1  µg/ml), breast (IC5070.2 µg/ml    and 48.2 µg/ml ) cancer models respectively. The melanoma cell line UACC-62 displayed sensitivity towards the aqueous bark and root extracts of S. rautanenii  with low IC50 values of 116.7 µg/ml    and 128.7 µg/ml respectively. The organic root extract of S. rautanenii also showed sensitivity towards the UACC-62 melanoma cell line at high extract concentration  although IC50 102.6 µg/ml, was similar to that obtained against MCF-7 breast cancer cells, 102.4 µg/ml. The organic and aqueous root extracts of S. rautanenii displayed the highest IC50 values of 315.5 µg/ml and 444.8 µg/ml against the human fetal lung fibroblast cell. In conclusion, the use of C. mopane and S. rautanenii within the traditional settings is rational and a readily accessible alternative. However, further studies are required to assess the extent of toxicity before the extracts can be recommended for mainstream usage.