ANTIGENOTOXIC ACTIVITIES OF EXTRACTS OF SPONDIAS MOMBIN L.(ANACARDIACEAE) AND CHROMOLAENA ODORATA L. (ASTERACEAE)

Abstract

Spondias mombin (Anarcadiaceae) and Chromolaena odorata (Asteracea) are common tropical shrubs. Different parts of the plants are used locally as antibacterial, anthelmintic agents and in the treatment of ulcerative wounds in the southern part of Nigeria. However, there is dearth of information on their anticancer effects. This study was therefore aimed at investigating their antigenotoxic effects in human colon cancer cell (CaCo2) and wistar rats. Ethanolic extracts of the leaves were used and phytochemical screening conducted. Acute toxicity test was assessed by administering varying doses of the extracts (0.1 to 8.0 g/kg) orally to ninety male wistar rats (160-220g) in eight treatment groups per extract using distilled water and 10% propylene glycol as negative controls. Toxicological effects of the extracts were assessed by haematological indices and histopathology of the liver. Genotoxic effects were assessed by the in vivo micronucleus test in sodium arsenite and chromosomal damage measured as the percentage of Micronucleated Polychromatic Erythrocyte (mPCE) per 1000 PCE. Further studies were conducted on S. mombin based on its relatively higher potency. Flash, vacuum liquid and thin layer chromatographies of the extract were carried out. The chromatographic fractions were tested for cytotoxic activities on CaCo2 with cisplatin as the positive control. The mutagenic effect on S. typhymuruim TA98 was determined by Ames test. Statistical analysis was done using Student's t-test and ANOVA. Alkaloids, tannins, saponins, phlobatannin and flavonoids were present in both extracts. In addition, anthraquinones were present in S.mombin, while steroids and terpenes were in C. odorata. Administration of extracts up to 8.0 g/kg induced no mortality (L₅₀ > 8.0 g/kg). The rat liver did not show any visible lesion, genotoxicity or marked change in haematological parameters. S mombin had over 5 fold antigenotoxic activity (ED₅₀= 0.5 g/kg) compared to C. odorata (ED₅₀=0.1 g/kg) (p<0.001). Effect of dose on MnPCE induction was more significant (p <0.0001) in C. odorata (36 %), whereas in S. mombin it was 1.7% (p<0.05). However, exposure time was more critical in the activity of S.mombin (89.3%) than in Codarata (71.7 %). The interplay of dose and exposure time of extracts on the induction of MnPCE was 1.8% for S.mombin and 5.1% for C. odorata. Each of the chromatographic fractions (1-5) from S.mambo showed, cytotoxic effect on CaCo2 cells similar to that of cisplatin, with fraction 3 having the minimum 50% growth inhibition concentrations (IC₅₀). Further purification and separation of this fraction produced nine fractions (SI - S9). These fractions showed cytotoxicity in CaCo2 cells with least IC₅₀ of 0.1 ug/ml produced by fraction S4. Fractions S1- S9 showed antimutagenic activity when compared with a positive mutagen 2- amino- 3 methyl-- 3H- Imidazo (4, 5-F) quinoline with S4 showing the highest percentage of inhibition of mutagenicity of 98.3%. Phytochemistry of fraction S4 revealed the presence of polyphenols. Ethanolic extracts of Spondias mombin and Chromolaena odorata exhibited antigenotoxic activities and could be useful in the treatment of diseases involving genotoxic damage in addition to the present usage.