Genotoxicity evaluation of freeze-dried Carica papaya leaf aqueous extract using in vitro and in vivo assays

Abstract

In Malaysia, Carica papaya is a common medicinal plant that can be found and also planted in housing areas. Traditionally, C. papaya is used to treat various ailments by using its fruit and other parts of the plant. The present study was designed to analyse the mutagenicity and cytotoxicity activities of freeze-dried Carica papaya leaves aqueous extract (CPLAE) using the Ames test and bone marrow micronucleus assay. The Ames test of CPLAE was performed on Salmonella typhimurium strains TA98, TA100, TA1535, TA1537 and Escherichia coli strain WP2 uvrA using the pre-incubation method in the presence and absence of an exogenous metabolic activation system (S9 mixture). The results showed the number of revertant colonies for all strains treated with the test item was at least 2-fold lower than that of the negative controls in the presence and absence of S9 mixture. The micronucleus assay was performed on groups of adult male Sprague Dawley rats, as follows: negative control (NC) – water alone; positive control (PC) – cyclophosphamide (20 mg/kg, ip); treatment group – Carica papaya (CP) (2000 mg/kg). Micronucleated Polychromatic Erythrocyte (MNPCE) numbers were also increased in the CPLAE group after 24 hours and 48 hours compared to the control group, but these changes were not significant (p>0.05). Based on the findings mentioned above, CPLAE is considered relatively Non-mutagenic at the highest dosage of 5000 μg/plate using the Ames test, and at a dosage of 2000 mg/kg in Sprague Dawley rats using the micronucleus assay.