Mutagenicity assessment of Salacia chinensis by bacterial reverse mutation assay using histidine dependent Salmonella typhimurium tester strains

Abstract

Background and objective: Genotoxicity analysis is one of the most important non-clinical environmental safety investigations required for pharmaceutical and agrochemical product registration. Any medicinal product must undergo a risk evaluation to determine its mutagenicity and carcinogenicity.

Materials and methods: The Ames test is a commonly used in vitro test for determining a test chemical's mutagenic activity. Histidine-dependent Salmonella typhimurium strains with a defective gene that causes the bacteria to synthesis the necessary amino acid histidine for life were tested for mutagenic potential. In order to reveal pro-mutagens and mutagens, the mutagenic potential of both plate integration and pre-incubation techniques was examined in the presence and absence of metabolizing system. Salacia chinensis has been widely used in ayurveda to treat various ailments. However, the information of mutagenicity of Salacia chinensis is scarce as per available literature.

Results: The mutagenicity of a Salacia chinensis root extract was investigated utilizing the Ames assay with plate incorporation and pre-incubation protocols using the appropriate Salmonella typhimurium tester strains: TA98, TA100, TA1537, TA1535, and TA102 in the presence and absence of S9. The concentrations used were 0.3123, 0.625, 1.25, 2.5 and 5 mg/plate. The extract of Salacia chinensis root did not show any mutagenic effect in any of the Salmonella typhimurium strains at the concentrations tested in the absence or presence of metabolic activation.

Conclusion: The root of Salacia chinensis was hence confirmed to be non-mutagenic and at least according to the results of this genotoxicity evaluation can be regarded as being safe for human use.

Keywords: Ames test; Mangiferin; Mutagenecity; Salacia chinensis; Salmonella typhimurium.

Fig. 1

Graphical representation of dose response curve of Plate incorporation method. In the absence of metabolic activation, the mean revertant colonies of all tested doses of S. Chinensis extract (0.3125, 0.625, 1.25, 2.5, and 5 mg/plate) were equivalent to those of VC (Vehicle control- DMSO).

Fig. 2

Graphical representation of dose response curve of Plate incorporation method. The graph indicates that the mean revertant colonies of all the tested concentrations of S. chinensis extract (0.3125, 0.625, 1.25, 2.5 and 5 mg/plate) were comparable with that of VC (Vehicle control- DMSO) in the presence of metabolic activation.

Fig. 3

Graphical representation of dose response curve of Pre incubation method. In the absence of metabolic activation, the mean revertant colonies of all tested doses of S. chinensis extract (0.3125, 0.625, 1.25, 2.5, and 5 mg/plate) were equivalent to those of VC (Vehicle control- DMSO).

Fig. 4

A graphical depiction of the Pre incubation method's dosage response curve. In the presence of metabolic activity, the mean revertant colonies of all tested doses of S. chinensis extract (0.3125, 0.625, 1.25, 2.5, and 5 mg/plate) were equivalent to those of VC (Vehicle control-DMSO).

Fig. 5

Photograph of the plates of genotypic confirmation of Salmonella typhimurium tester strains TA98, TA100, TA1535, TA1537 and TA102. a.No zone of inhibition observed in the strains TA98, TA100, TA102 which carries plasmid pKM101 (Ampicillin resistance).b. No zone of inhibition observed in the strains TA102 which carries plasmid pAQ1 (Tetracycline resistance).c. Due to the deletion of bio-uvrB region, no growth was observed in the UV exposed area except TA102.d. Since, rfa mutation is present; all Salmonella strains have shown a zone of growth inhibition surrounding the Crystal Violet disk.