Aims: Cabraleadiol (1), Ocotilone (2) and Odoratone (3) are three triterpenes isolated from Cabralea canjerana (Vell.) Mart. (Meliaceae). They were chemically characterized, and their effect was tested on the light re...Aims: Cabraleadiol (1), Ocotilone (2) and Odoratone (3) are three triterpenes isolated from Cabralea canjerana (Vell.) Mart. (Meliaceae). They were chemically characterized, and their effect was tested on the light reaction of photosynthesis. Study Design: Natural products were used as models to find new models for inhibitors of photosynthesis. Place and Duration of Study: Departmento de Química, Universidade Federal de São Carlos and Departmento de Bioquímica, Facultad de Química, Universidad Nacional Autonoma de México, between May 2013 and January 2014. Methodology: The natural products had their effect on the light reaction of photosynthesis studied by pollarography and Chlorophyll a (Chl a) fluorescence transients. Results: The compounds inhibited ATP synthesis and electron transport rate (basal, phosphorylating and uncoupled). Therefore, they act as Hill reactions inhibitors. Their inhibition site were located in the range of electron flow from OEC complex and between P680 to QA of PS II, and inhibited the photosystem II (PS II) by inducing the appearance of a K-band which is an indicative that the photochemical apparatus is failing at the donor side of PS II interacting at the OEC complex and by transforming active reaction centers to “heat sinks” or the formation of silent reaction centers unable to reduce QA. Conclusion: Furthermore, these triterpenes inhibit PS II and induce the appearance of small G band which is related with the decreased plastoquinone (PQ) pool reduction.展开更多
基金financial support of the DGAPA-UNAM IT102012-3#FAPESP(Fundacao de Amparo a Pesquisa do Estado de Sao Paulo)+1 种基金#CNPq(Conselho Nacional de Pesquisa e Desenvolvimento)CAPES(Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior).
文摘Aims: Cabraleadiol (1), Ocotilone (2) and Odoratone (3) are three triterpenes isolated from Cabralea canjerana (Vell.) Mart. (Meliaceae). They were chemically characterized, and their effect was tested on the light reaction of photosynthesis. Study Design: Natural products were used as models to find new models for inhibitors of photosynthesis. Place and Duration of Study: Departmento de Química, Universidade Federal de São Carlos and Departmento de Bioquímica, Facultad de Química, Universidad Nacional Autonoma de México, between May 2013 and January 2014. Methodology: The natural products had their effect on the light reaction of photosynthesis studied by pollarography and Chlorophyll a (Chl a) fluorescence transients. Results: The compounds inhibited ATP synthesis and electron transport rate (basal, phosphorylating and uncoupled). Therefore, they act as Hill reactions inhibitors. Their inhibition site were located in the range of electron flow from OEC complex and between P680 to QA of PS II, and inhibited the photosystem II (PS II) by inducing the appearance of a K-band which is an indicative that the photochemical apparatus is failing at the donor side of PS II interacting at the OEC complex and by transforming active reaction centers to “heat sinks” or the formation of silent reaction centers unable to reduce QA. Conclusion: Furthermore, these triterpenes inhibit PS II and induce the appearance of small G band which is related with the decreased plastoquinone (PQ) pool reduction.
