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Uncoupling and inhibition properties of 3,4-seco-friedelan-3-oic acid isolated from Maytenus imbricata |
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| Authors: | Silvia Ribeiro de Souza e Silva,Luiz Claú dio de Almeida Barbosa,Beatriz King-Diaz,Blas Lotina-Hennsen |
| Affiliation: | a NEPLAM Departamento de Química, ICEx, Universidade Federal de Minas Gerais, Avenida Presidente Antonio Carlos, 6627, Pampulha, CEP 31270-901, Belo Horizonte, Minas Gerais, Brazil b LASA, Departamento de Química, CCE, Universidade Federal de Viçosa, Avenida PH Rolfs, s/n, Campus UFV, CEP 36570-000, Viçosa, Minas Gerais, Brazil c Departamento de Bioquímica, Facultad de Química, Universidad Nacional Autónoma de México (UNAM), Ciudad Universitaria, Coyoacan, México DF 04510, Mexico |
| Abstract: | 3,4-Seco-friedelan-3-oic acid was isolated from Maytenus imbricata (Celastraceae). At low concentrations it inhibited non-cyclic electron transport and ATP synthesis in spinach chloroplasts, i.e., it behaved as a Hill reaction inhibitor, and at high concentrations it acts as an uncoupler by enhancing uncoupled electron transport and Mg2+-ATPase activity. 3,4-Seco-friedelan-3-oic acid did not inhibit PSII electron transport from DPC to DCPIPox and photosystem I activity, but it enhanced from TMQH2 to MV, corroborating its action as uncoupler. It inhibits electron flow through PSII from water to sodium silicomolybdate. The whole results indicate that the 3,4-seco-friedelan-3-oic acid target is at the OEC complex enzyme, the donor side of PSII. The fluorescence decay data shows the formation of the K-band, which match this result, acting as inhibitor at the donor side of PSII and it as an uncoupler. |
| Keywords: | Maytenus imbricata Triterpenes Photosystem II Uncoupler-inhibitor 3,4-Seco-friedelan-3-oic acid |
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