The influence of tannins purified from Eastern Mediterranean Region plants (Pinus brutia Ten. and Quercus coccifera L.) on carbon mineralization: Antimicrobial and antimutagenic evaluation

Tannins, which are polyphenols with a wide variety of quality-quantity that control the carbon and nitrogen cycle in forest ecosystems, are very interesting because of their protein binding abilities and forming a complex structure with other compounds. In this study, the purified tannin content of Pinus brutia Ten. and Quercus coccifera L., the two dominant plant species of the Eastern Mediterranean region, and the effect of these tannins on C dynamics in a forest soil (O and A horizon) were evaluated. In addition, antimicrobial effects of tannin extracts on Bacillus subtilis, Staphylococcus aureus and Proteus mirabilis bacteria by disc diffusion method and antimutagenic effects on Allium cepa root tip cells were evaluated. Total phenol (TP) and condense tannins (CT) concentrations of P. brutia and Q. coccifera leaves ranged from 0.78–1.33 ?g/100mg DW and 4.68–1.35 ?g/100mg DW, respectively. With the addition of tannin extract to the soils, C mineralization (27th day) was significantly reduced compared to the control group. Both P. brutia tannin extract (PTE) and Q. coccifera tannin extract (QTE) exhibited antibacterial activity in the range of 8±0.2–35±1.1 mm zone diameter by inhibiting their microbial growth against test microorganisms. In addition, tannin treatments caused a dose-dependent mitotic index decrease in onion root tip cells and a serious inhibition by showing toxic effects on mitotic division stages. As a result, our data showed that C mineralization in soil is affected by different tannin sources and these tannin extracts have significant antimicrobial activity against pathogens and cytotoxic activity in A. cepa root tip cells.