Identification of antiplasmodial triterpenes from Keetia species using NMR-based metabolic profiling

Abstract

Introduction The increase in multidrug resistance and lack of efficacy in malaria therapy has propelled the urgent discovery of new antiplasmodial drugs, reviving the screening of secondary metabolites from traditional medicine. In plant metabolomics, NMR-based strategies are considered a golden method providing both a holistic view of the chemical profiles and a correlation between the metabolome and bioactivity, becoming a corner stone of drug development from natural products. Objective Create a multivariate model to identify antiplasmodial metabolites from 1 H NMR data of two African medicinal plants, Keetia leucantha and K. venosa . Methods The extracts of twigs and leaves of Keetia species were measured by 1 H NMR and the spectra were submitted to orthogonal partial least squares (OPLS) for antiplasmodial correlation. Results Unsupervised 1 H NMR analysis showed that the effect of tissues was higher than species and that triterpenoids signals were more associated to Keetia twigs than leaves. OPLS–DA based on Keetia species correlated triterpene signals to K. leucantha , exhibiting a higher concentration of triterpenoids and phenylpropanoid-conjugated triterpenes than K. venosa . In vitro antiplasmodial correlation by OPLS, validated for all Keetia samples, revealed that phenylpropanoid-conjugated triterpenes were highly correlated to the bioactivity, while the acyclic squalene was found as the major metabolite in low bioactivity samples. Conclusion NMR-based metabolomics combined with supervised multivariate data analysis is a powerful strategy for the identification of bioactive metabolites in plant extracts. Moreover, combination of statistical total correlation spectroscopy with 2D NMR allowed a detailed analysis of different triterpenes, overcoming the challenge posed by their structure similarity and coalescence in the aliphatic region. Electronic supplementary material The online version of this article (10.1007/s11306-019-1487-4) contains supplementary material, which is available to authorized users.

NMR-Based Metabolite Profiling and the Application of STOCSY toward the Quality and Authentication Assessment of European EVOOs

“…Even if it is used in human metabolomics [ 32 ], its employment in food analysis and generally in natural products is limited. To our knowledge, it has been used in the study of medicinal plants [ 44 , 45 , 46 , 47 ], whisky [ 48 ], and table olives and honey samples from our group [ 33 , 34 ].…”

NMR-Based Metabolic Profiling of Edible Olives—Determination of Quality Parameters

“…[ 45 ], Isatis tinctorial [ 46 ] and Keetia sp. [ 47 ], and a couple of other cases [ 48 , 49 , 50 ], while there is a recent study by Kew et al involving Scotch whisky [ 51 ].…”

Bioactivity-Guided Fractionation and NMR-Based Identification of the Immunomodulatory Isoflavone from the Roots of Uraria crinita (L.) Desv. ex DC

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