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Stability of tannins and stilbenes against UV-B radiation
Tannins function as powerful defensive biopolymers against herbivories or microbes by mainly precipitating proteins  while stilbenes have a role in plant disease resistance . They have shown to inhibit the growth of bacteria and fungi in vitro. The synthesis of tannins and stilbenes is increased by UV-B radiation in some species [2, 3]. The studies on pine seedlings have revealed that also ozone induces the synthesis of stilbenes in the needles. The aim of this study was to test the stability of tannins and stilbenes in UV radiation in vitro.
Standard curves were prepared for tannins (acid-butanol test) and stilbenes (RP-HPLC). The compounds were added in filter paper chips and recoveries were analyzed. The recovery percentage of tannins using an acid butanol test was 99,96±1,23%. Stilbenes were extracted from the paper chips and analyzed by RP-HPLC. Their recovery percentages were 80,95±1,02% and 81,29±0,95% to pinosylvin and pinosylvin monomethyl ether, respectively.
The stability tests of tannins and stilbenes will be started during ongoing spring by adding them on the filter paper chips, exposing the chips to UV radiation and analyzing the chips as described above. Results will be presented and discussed.
Acknowledgements:Åbo Akademi, Eckerman C & Holmbom B.
References: 1. Robbins, C.T., Hanley, T.A., Hagerman, A.E., Hjeljord, O., Baker, D.I., Schwartz, C.C. & Mautz, W.W. 1987. Role of tannins in defending plants against ruminants: reduction in protein availability. Ecology 68: 98–107.
2. Chong, J., Poutaraud, A. & Hugueney, P. 2009. Metabolism and roles of stilbenes in plants. Plant Science 177: 143–155.
3. Rozema, J., van de Staaij, J., Björn, L.O. & Caldwell, M. 1997. UV-B as an environmental factor in plant life: stress and regulation. Trends Ecol. Evol. 12: 22–28.