Abstract:
Cancer is the leading cause of death worldwide. In Kenya, different cancer cases
have been witnessed all over the country. The emphasis of diseases like malaria,
Human Immunodeficiency Virus (HIV) and tuberculosis has resulted in the neglect
of non-communicable diseases like cancer. This is characterized by lack of
awareness, inadequate facilities, qualified personnel and financial shortages. Locally, majority of the population relies on traditional medicine as an alternative treatment
since the conventional health system provides for only 30% of the population. Although medicinal plants in Kenya have been used for treatment of cancer by the
traditional healers, there are no reports of studies carried out to verify their healing
claims as well as their safety. The objective of this study was to determine the safety
and anti-proliferative activity of Prunus africana, Warburgia stulhamannii and
Maytenus senegalensis extracts in breast (4T1 ATCC®CRL-2539TM) and colon
(ATCC® CRL-2638TM) cancer cell lines. The in vitro assays involved determination
of the cytotoxic concentration levels (CC50) of the plant extracts on Vero cells as
well as calculating the inhibitory concentration (IC50) of the plant extracts on breast
and colon cancer cell lines.The extracts with the highest selectivity index (SI) to have
low IC50 in the breast and colon cancer cell lines and high CC50 in Vero cells were
used in the in vivo assays which involved acute oral toxicity studies, conducted on 8
weeks old Swiss albino mice to calculate the median lethal dose (LD50). The safest
effective extracts were of leaf methanol extracts of leaves from Prunus africana
whose triplicate results showed an average IC50 of 164.64±4.14 (n=3) µg/ml in the
breast cancer cell lines and 21.33±0.5 (n=3) µg/ml in the colon cancer cell lines, as
well as the stem bark water extracts from Warburgia Stuhlmanniiwhose triplicate
results showed an average IC50 of 332.79±7.53 (n=3) µg/ml in the breast cancer cell
lines and 107.20±2.50(n=3) µg/ml in the colon cancer cell lines.
xiv
Both extracts had an average CC50 of >1000 (n=3) µg/ml in Vero cells. Based on
positive cytotoxicity results on the two extracts, acute oral toxicity studies were
conducted on 8 weeks old female Swiss albino mice. This revealed no signs of acute
toxicity after administration with LD50 of >5000mg/kg body weight, therefore the
extracts were considered to be practically non-toxic. The findings of this study may
form basis for the development of a candidate drug that is effective, less toxic and
more affordable.