New Triterpenes from Maytenus robusta: Structural Elucidation Based on NMR Experimental Data and Theoretical Calculations

Molecules

Grasiely F. Sousa¹  Lucienir P. Duarte¹  Antônio F. C. Alcântara¹  Grácia D. F. Silva¹  Sidney A. Vieira-Filho¹  Roqueline R. Silva¹  Djalma M. Oliveira¹ 

[1] ¹Departamento de Química, Instituto de Ciências Exatas, Universidade Federal de Minas Gerais, 31270-901, Belo Horizonte, MG, Brazil ²Escola de Farmácia, Universidade Federal de Ouro Preto, 35400-000, Ouro Preto, MG, Brazil ³Departamento de Química e Exatas, Universidade Estadual do Sudoeste da Bahia, 45206-191, Jequié, BA, Brazil

关键词: Maytenus robusta;    pentacyclic triterpenes;    NMR;    DFT calculations;    acetylcholinesterase inhibitory activity;   

DOI  :  10.3390/molecules171113439

来源: mdpi

【 摘 要 】

Leaves of Maytenus robusta (Celastraceae) were subjected to phytochemical investigation mainly directed at the isolation of pentacyclic triterpenes. The compounds friedelin (1), β-friedelinol (2), 3-oxo-21β-H-hop-22(29)-ene (7), 3,4-seco-friedelan-3,11β-olide (8), 3β-hydroxy-21β-H-hop-22(29)-ene (9), 3,4-seco-21β-H-hop-22(29)-en-3-oic acid (10), 3,4-seco-friedelan-3-oic acid (11), and sitosterol were identified in the hexane extract of M. robusta leaves. Compounds 8 and 9 are described herein for the first time. The structure and stereochemistry of both compounds were experimentally established by IR, HRLC-MS, and 1D (¹H, ¹³C, and DEPT 135) and 2D (HSQC, HMBC and COSY) NMR data and supported by correlations with carbon chemical shifts calculated using the DFT method (BLYP/6-31G* level). Compounds 7 and 10 are also described for the first time, and their chemical structures were established by comparison with NMR data of similar structures described in the literature and correlations with BLYP/6-31G* calculated carbon chemical shifts. Compound 9, a mixture of 11 and sitosterol, and 3β,11β-dihydroxyfriedelane (4) were evaluated by the Ellman’s method and all these compounds showed acethylcholinesterase inhibitory properties.

【 授权许可】

CC BY   
This is an open access article distributed under the Creative Commons Attribution License (CC BY) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.