Cengiz Darici

The genotoxic and antigenotoxic effects of tannic acid in human lymphocytes.

The genotoxicity of tannic acid (TA, tannin) were investigated using chromosome aberration (CA), sister chromatid exchange (SCE), and micronucleus (MN) test systems in human peripheral lymphocytes. Also, the antigenotoxicity of TA against known mutagen EMS was also examined. The lymphocytes were treated with 1.74 × 10−5, 3.49 × 10−5, and 6.98 × 10−5 µM of TA for 24- and 48-hour treatment periods. For the antigenotoxicity of TA, the lymphocytes were treated with three different concentrations of TA and 2.71 µM of EMS. TA synergically induced the CA alone and with the mixture of EMS. However, TA did not induce the SCE alone, whereas TA and EMS as a mixture also synergically induced SCE. TA alone showed no clear effect on micronucleus formation, and it did not induce the MN when used with EMS as a mixture. In addition, TA showed a synergistic cytotoxic effect by decreasing the mitotic and nuclear division indices. The replication index was decreased at all concentrations for 48 hours of treatment time by TA and EMS as a mixture.

Priming effects of leaves of Laurus nobilis L. and 1,8-cineole on carbon mineralization

Plant secondary compounds can have stimulating effect on C cycling and change its rate in soils. We examined how leaves of bay laurel (Laurus nobilis L.; Lauraceae) and 1,8-cineole (CIN), one of its constituents, affect soil C mineralization and its rate. Leaves and soil samples of bay laurel were taken from Cukurova University Campus (Adana, Turkey) growing naturally under Mediterranean climate conditions. Leaves and CIN were considered as the two forms of organic C sources. After determining the level of 1,8-cineole in leaves by gas chromatography-mass spectrometry, soils were mixed with powdered leaves and 1,8-cineole based on their C contents at same and half doses of soil organic C level. Carbon mineralization of all soils was determined over 54 d (28 °C, 80% field capacity). While 1,8-cineole was found as a major constituent of leaves (65% of essential oil), all doses of leaves and CIN increased soil microbial activity. There were significant differences for C mineralization rate between control and all applications (P < 0.05). High C levels of all treatments decreased C mineralization rate compared to control soils. In summary, all treatments stimulated C mineralization and it is possible to conclude that soil microorganisms adapted to use CIN as an energy source.