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Based on mass spectrometry(MS)-guided separation strategy, compound 1 was obtained from the roots of Rhus chinensis. By comprehensive analysis of high resolution-electrospray ionization-mass spectrometry(HR-ESI-MS), nuclear magnetic resonance(NMR) data, and quantum chemical calculation of NMR(qcc-NMR) parameters, compound 1 was elucidated as rhuslactone, a 17-epi-dammarane triterpenoid with a rare 17α-side chain. An HPLC-ELSD method for its quantification in R. chinensis was established and adopted for the quantification of rhuslactone in different batches of R. chinensis. Rhuslactone displayed a good linear relationship within the range of 0.021 3-1.07 μmol·mL~(-1 )(r=0.997 6), and the average recovery was 99.34% [relative standard deviation(RSD) 2.9%). Moreover, the results of the evaluation test of the preventive effects of rhusalctone on coronary heart disease(CHD) and thrombosis showed that rhuslactone(0.11 nmol·mL~(-1)) significantly alleviated heart enlargement and venous congestion and increased cardiac output(CO), blood flow velocity(BFV), and heart rate, thereby reducing thrombus formation in zebrafish with CHD. The effects of rhuslactone on CO and BFV were superior to that of digoxin(1.02 nmol·mL~(-1)), and its effect on improving heart rate was comparable to that of digoxin. This study provides experimental references for the isolation, identification, quality control, and application of rhuslactone from R. chinensis against CHD. It is worth mentioning that this study has discussed some omissions in the determination of the stereochemistry of C-17 in dammarane triterpenoids in the present coursebook Chemistry of Chinese Medicine and some research papers, that is, the compound may be 17-epi-dammarane triterpenoid. This paper has also proposed steps for the establishment of C-17 stereochemistry.
Assuntos
Animais , Peixe-Zebra , Rhus/química , Triterpenos/análise , Doença das Coronárias , TromboseRESUMO
Steroids are the most important class of natural products. In the history of the development of human beings, not only steroidal compounds have made the special contribution for human health, but also its special stereochemical structure plays an important role in the development of organic chemistry, especially organic chemistry theory, which could improve the stereochemical theory. In this paper, the discovery, biological activity, the stereochemical structure of important compounds, stereochemistry, and the synthesis of steroids are briefly introduced for the purpose to broaden their horizon and provide some ideas for young teachers in the teaching and scientific research.
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The difficulty in the structure elucidation of natural products is in the elucidation of stereochemistry, especially the determination of absolute configuration, which generally involves the key techniques of structure elucidation of natural products. This paper shows some examples of our work in elucidating the stereochemistry of new chiral natural products by the application of several physicochemical techniques, such as the dimolybdenum tetraacetate [Mo2(OAc)4] induced CD (ICD, Snatzke’s method), empirical rules of classical CD, modified Mosher’s method, theoretical ECD calculation and modified Marfey’s analysis. The fundamental rules of the techniques and our experiences in the application of these techniques are also described for related researcher’s reference in relevant studies.
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Structural identification of natural products is the foundation for biological activity evaluation and further targeting action research. However, exact and prompt solutions to the structures, in particular, for the stereochemical problems derived from inherent variability and complexity of natural products, have been faced with challenges. In recent years, the quantum chemistry calculation methods (ECD, VCD, 0R, NMR and others) on the basis of Gaussian software undoubtedly provide a powerful tool for the structure elucidation of complex natural products. This review summarizes some successful cases of Gaussian calculation on structure elucidation with a purpose of broadening research and applications of this method.
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The determination of the relative configuration of flexible natural molecules is still a challenge due to the geometrical uncertainty of their flexible moieties. Coupling constant based configuration analysis (jBCA) is a valid approach in elucidating the relative configuration of these flexible systems. The approach is suitable for 1,2- or 1, 3-dimethine systems. The final relative configuration assignment on chiral organic compounds stems from conformational analysis by combining proton-proton and/or proton-carbon coupling values and nuclear overhauser effect (NOE) correlations. This paper gives a brief review on the latest application of coupling constant based analysis in determining the relative configuration of flexible natural molecules, aiming to give a reference to natural product research regarding the stereochemistry.