Safety evaluation of styrax liquidus from the viewpoint of genotoxicity and mutagenicity.

ETHNOPHARMACOLOGICAL RELEVANCE: Styrax liquidus is a resinous exudate (balsam) obtained from the wounded trunk of the Liquidambar orientalis Mill. (Hamamelidaceae). Styrax has been used for treatment of various ailments in Turkish folk medicine such as skin problems, peptic ulcers, nocturnal enuresis, parasitic infections, antiseptic or as expectorant. AIM OF STUDY: In spite of frequent use of styrax in Turkish folk medicine as well as once as a stabilizer in perfumery industry, negative reports have been noticed by the international authority for restriction its use based on some limited evidences from an in vitro study. The aim of the present study was to evaluate the genotoxic and cytotoxic potential of styrax and its ethanolic extract using in vivo and in vitro assays, as well as an antimutagenic assay and also to determine its phenolic constituents with chromatographic analysis. MATERIALS AND METHODS: In vitro mutagenicity and antimutagenicity of styrax and its ethanolic extract were evaluated by Ames test performed on Salmonella TA98 and TA100 strains with and without metabolic activation (10- 30,000µg/plate). The genotoxicity was also studied in vivo by chromosomal aberrations assay on bone marrow of Balb C mice with different its concentrations (500-2000mg/kg body weight). Cytotoxicity has been evaluated by the MTT assay using L929 cell line. Its phenolic constituents were determined by HPLC analysis. RESULTS: Genotoxicological investigations of styrax or its ethanolic extract showed that none of the tested concentrations induced a significant increase in the revertant number of TA98 and TA100 strains with or without metabolic activation, indicating no mutagenicity to the tested strains. Also results indicated that up to 2000mg/kg body weight, styrax is not genotoxic in mammalian bone marrow chromosome aberration test in vivo. In cytotoxicity study, the IC50 values of styrax and its ethanolic extract were found to be 50.22±1.80 and 59.69±11.77µg/mL, respectively. Among the studied reference standards the major phenolic acids in styrax balsam was found to be p-coumaric acid (2.95mg/g), while in its ethanolic extract not only p-coumaric acid (11.46mg/g), but also gallic acid (1.60mg/g) were found to the main components. CONCLUSION: The findings of the present study provide scientific basis to the safety of styrax from the viewpoint of genotoxicity risk, and in fact, it was found to be beneficial against genotoxicity.

The cysteine releasing pattern of some antioxidant thiazolidine-4-carboxylic acids.

Oxidative stress that corresponds to a significant increase in free radical concentration in cells can cause considerable damage to crucial biological macromolecules if not prevented by cellular defense mechanisms. The low-molecular-weight thiol glutathione (GSH) constitutes one of the main intracellular antioxidants. It is synthesized via cysteine, an amino acid found only in limited amounts in cells because of its neurotoxicity. Thus, to ensure an efficient GSH synthesis in case of an oxidative stress, cysteine should be provided extracellularly. Yet, given its nucleophilic properties and its rapid conversion into cystine, its corresponding disulfide, cysteine presents some toxicity and therefore is usually supplemented in a prodrug approach. Here, some thiazolidine-4-carboxylic acids were synthesized and evaluated for their antioxidant properties via the DDPH and CUPRAC assays. Then, the cysteine releasing capacity of the obtained compounds was investigated in aqueous and organic medium in order to correlate the relevant antioxidant properties of the molecules with their cysteine releasing pattern. As a result, the structures' antioxidative properties were not only attributed to cysteine release but also to the thiazolidine cycle itself.