ABSTRACT
Pouteria ramiflora (Mart.) Radlk. (Sapotaceae) is a species used by inhabitants from the Cerrado for its edible fruits and medicinal value. Hexane crude extracts from leaves and fractions were evaluated for in vitro α-amylase inhibitory activity and antioxidant potential. The fraction with the highest α-amylase inhibitory activity was submitted to a phytochemical study. Three triterpenes were isolated, friedelin, epi-friedelanol, and taraxerol. This is the first report of these compounds isolated from P. ramiflora. Moreover, this is the first report of friedelin isolated from Pouteria sp. Epi-friedelanol was present in significant amounts, suggesting that this compound could be a candidate marker for this species.
Subject(s)
Plant Extracts/chemistry , Pouteria/chemistry , Triterpenes/chemistry , Animals , Antioxidants/chemistry , Antioxidants/isolation & purification , Enzyme Inhibitors/chemistry , Enzyme Inhibitors/isolation & purification , Molecular Structure , Oleanolic Acid/analogs & derivatives , Oleanolic Acid/chemistry , Oleanolic Acid/isolation & purification , Plant Extracts/isolation & purification , Plant Leaves/chemistry , Swine , Triterpenes/isolation & purification , alpha-Amylases/antagonists & inhibitors , alpha-Amylases/chemistryABSTRACT
This work aims at using theoretical calculations of shielding tensors (σ) through different methods [gauge-independent atomic orbital (GIAO), continuous set of gauge transformations (CSGT) and individual gauges for atoms in molecules (IGAIM)] and spin-spin coupling constants J using GIAO method to compare these methods and to corroborate the data obtained with the assignment of all of (1)H and (13)C NMR signals and the relative stereochemistry of the 1,6-epoxycarvone and the α-epoxypinene. All the (1)H and (13)C NMR signals were assigned unequivocally. The stereochemistry for the epoxides is trans and the B3LYP theory level with CSGT and IGAIM methods is the best choice to evaluate theoretical chemical shifts for compounds studied.
ABSTRACT
A conceptual analysis of the CLOPPA (Contributions from Localized Orbitals within the Polarization Propagator Approach) expressions that deconvolute NMR spin-spin coupling constants [Diz A. C.; Giribet C. G.; Ruiz de Azua, M. C.; Contreras, R. H. Int. J. Quantum Chem. 1990, 37, 663.] into orbital contributions can provide an in-depth insight into the features of the electronic molecular structure that originate a given 1JCH experimental trend. In this work, several 1-X-cyclopropane derivatives are taken as model compounds to apply such ideas to rationalize substituent effects on the Fermi contact term of 1JC1,H spin-spin coupling. It is shown that in this type of coupling, its experimental trend, as measured in this work, cannot be accounted for with only the "bond" and the "other bond" contributions, requiring the inclusion of "other antibonding contributions". Such effect is discussed in terms of hyperconjugative interactions.
