ANTIOXIDANT AND SELECTIVE CYTOTOXIC ACTIVITIES ON CANCER CELL LINES BY BIOACTIVATABLE COMPOUNDS IN EXTRACTS OF TERMITOMYCES SCHIMPERI (LYOPHYLLACEAE)

ABSTRACT

BACKGROUND: Termitomyces schimperi (TS) is an edible mushroom that is known to possess

certain therapeutic properties. Anecdotal report from La Cote d’Ivoire suggests that the

mushroom is traditionally used in combination with kaolin, to manage a number of cancers.

There is, however, a dearth of information on its antioxidant and anticancer properties with or

without kaolin.

AIMS: The aims of this study were to determine the antioxidant and cytotoxic potential of

aqueous and ethanolic extracts of TS, and elucidate the effect of microsome-dependent

bioactivation of these extracts in combination with kaolin on cancer cell lines.

METHODOLOGY: Aqueous and ethanolic (20:80, v/v) extracts of TS were prepared from the

dried mushroom in combination with kaolin (TSK), and extracts of kaolin alone (K) was also

prepared, giving 6 extracts in all. The six extracts were screened for secondary metabolites. Total

phenolic and flavonoid content of the extracts were determined by Folin Ciocalteu and

Aluminum Chloride methods, respectively. The antioxidant properties of all extracts (0 - 10

mg/ml) were evaluated, using 2, 2 diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and

reducing power assays. Cytotoxic activity of increasing concentrations of the extracts (0, 62.5,

125, 250, 500 and 1000 μg/ml) were ascertained, using 3-(4,5-Dimethylthiazol-2-yl)-2,5-

diphenyltetrazolium bromide (MTT) assay on a panel of six human cancer cell lines Jurkat

(blood), PC-3, LNCaP (prostate), MCF-7 (breast), HMV II (vaginal malignant epithelial cells),

and Hep G2 (liver), and a non-cancerous Chang liver cell line. Rat liver microsomes were

prepared and used in bioactivation studies.

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RESULTS:

Secondary metabolites screening: Both aqueous and ethanolic extracts of TS contained phenols,

terpenoids, saponins and cardiac glycosides. Flavonoids were present in the ethanolic but not the

aqueous extract of TS. Similar results were obtained for the aqueous and ethanolic extracts of the

mixture of the TS and kaolin (TSK). None of the secondary metabolites were found in the

extracts of kaolin only. Alkaloids were found to be absent in all the extracts.

Antioxidant activity: The aqueous and ethanolic extracts of TS and TSK exhibited

concentration-dependent scavenging activities. The ethanolic extract of TS exhibited a higher

free radical scavenging potential than the aqueous extract, as shown by EC50 values; 1.285 ±

0.038 and 1.971 ± 0.231 mg/ml, respectively (p