1 H qNMR Quantification of Annonaceous Acetogenins in Crude Extracts of Annona muricata L. Fruit Pulp

Dereplication of Acetogenins from Annona muricata by Combining Tandem Mass Spectrometry after Lithium and Copper Postcolumn Cationization and Molecular Networks

Annonaceous acetogenins are natural products held responsible for atypical Parkinsonism due to chronic consumption in traditional medicine or as food, leading to the development of analytical strategies for their complete chemical characterization in complex mixtures. Characterization by tandem mass spectrometry (MS/MS) of acetogenins using collision-induced dissociation from lithium adducts provides additional structural information compared to protonated or sodiated species such as ketone location on the acetogenin backbone. However, very low intensity diagnostic ions together with the lack of extensive structural information regarding position of OH and THF substituents limit this approach. Copper adducts led to diagnostic fragment ions that allow us to identify the position of oxygen rings and hydroxyl substituents. Fragmentation rules were established on the basis of acetogenin standards allowing the identification of 45 over the 77 analogues observed in an extract of Annona muricata by LC-MS/MS using postcolumn infusion of copper sulfate (CuSO₄) solution. Molecular networks that were generated thanks to specific fragmentations obtained with copper led to the distinction of THF ring position or to the identification of hydroxylated lactone, for instance.

NMR technique and methodology in botanical health product analysis and quality control

Botanicals have played an important role in maintaining human health and well-being throughout history. During the past few decades in particular, the use of botanical health products has gained more popularity. Whereas, quality, safety and efficacy concerns have continuously been critical issues due to the intrinsic chemical complexity of botanicals. Chemical analytical technologies play an imperative role in addressing these issues. Nuclear magnetic resonance (NMR) spectroscopy has proven to be a powerful and useful tool for the investigation of botanical health products. In this review, NMR techniques and methodologies that have been successfully applied to the research and development of botanical health products in all stages, from plants to products, are discussed and summarized. Furthermore, applications of NMR together with other analytical techniques in a variety of domains of botanical health products investigation, such as plant species differentiation, adulteration detection, and bio-activity evaluation, are discussed and illustrated with typical examples. This article provides an overview of the potential uses of NMR techniques and methodologies in an attempt to further promote their recognition and utilization in the field of botanical health products analysis and quality control.

Multinuclear NMR screening of pharmaceuticals using standardization by 2H integral of a deuterated solvent

NMR standardization approach that uses the ²H integral of deuterated solvent for quantitative multinuclear analysis of pharmaceuticals is described. As a proof of principle, the existing NMR procedure for the analysis of heparin products according to US Pharmacopeia monograph is extended to the determination of Na⁺ and Cl^- content in this matrix. Quantification is performed based on the ratio of a ²³Na (³⁵Cl) NMR integral and ²H NMR signal of deuterated solvent, D₂O, acquired using the specific spectrometer hardware. As an alternative, the possibility of ¹³³Cs standardization using the addition of Cs₂CO₃ stock solution is shown. Validation characteristics (linearity, repeatability, sensitivity) are evaluated. A holistic NMR profiling of heparin products can now also be used for the quantitative determination of inorganic compounds in a single analytical run using a single sample. In general, the new standardization methodology provides an appealing alternative for the NMR screening of inorganic and organic components in pharmaceutical products.

Lactose quantification in bovine milk by nuclear magnetic resonance without deuterated solvent (No-D qNMR)

Milk is a homogeneous mixture of substances such as lactose, proteins, and glycerides. Among carbohydrates, lactose is a disaccharide composed of glucose and galactose, and it is present in bovine milk at a level of 4.6%. According to resolution no. 135 of the National Health Surveillance Agency (ANVISA) from Brazil, dairy products labeled "lactose-free" must contain 1.0 mg mL-1 or less of this disaccharide. Thus, this work aims to develop and validate a method for quantifying the lactose content by quantitative nuclear magnetic resonance without the use of deuterated solvent (No-D qMNR). The validation of the developed method followed the norms provided by ANVISA resolution RDC no. 166, based on the figures of merit such as selectivity, linearity, the limit of detection (LOD) and quantification (LOQ), accuracy, precision, and robustness. The obtained results validated the method due to excellent linearity, demonstrated by the value of R > 0.990 and the homoscedasticity of the results, as well as precision, accuracy, and robustness values lower than 5%. Furthermore, LOD and LOQ values around 0.1345 mg mL-1 and 0.4076 mg mL-1, respectively, were obtained, which are lower than those required by legislation. The No-D qNMR technique was also able to quantify lactose content in commercial lactose-free milk.

Mass spectrometry-based metabolomics approach in the isolation of bioactive natural products

Metabolomics is a powerful tool in the analysis and identification of metabolites responsible for biological properties. Regarding natural product chemistry, it constitutes a potential strategy to streamline the classic and laborious process of isolating natural products, which often involves the re-isolation and identification of known compounds. In this contribution, we establish a mass spectrometry-based metabolomics strategy to discover compounds with larvicidal activity against Aedes aegypti. We analyse the Brazilian plant Annona crassiflora using different platforms to annotate the active compounds in different extracts/fractions of various plant parts. The MetaboAnalyst and GNPS platforms, which consider LC-MS and LC-MS/MS data, respectively, were chosen to identify compounds that differentiate active and inactive samples. Bio-guided isolation was subsequently performed to confirm compound activity. Results proved the capacity of metabolomics to predict metabolite differences between active and inactive samples using LC-MS and LC-MS/MS data. Moreover, we discuss the limitations, possibilities, and strategies to have a broad view of vast data.

A feasible and practical 1H NMR analytical method for the quality control and quantification of bioactive principles in Lycii Fructus

Lycii Fructus, a solanaceous drug, is widely used as functional foods and in Traditional Chinese Medicine. Samples collected from different regions of China have been found to be not identical in chemical compositions which might affect the biological activities. Although many chromatographic and spectrometric methods have been reported to determine the concentration of betaine and other bioactive amino acids, disturbance resulted from other polar substances with low UV-absorbance and expensive mass facilities reduced the applicability of these techniques. In the present study, the strong cation exchange solid phase extraction procedure incorporated with ¹H NMR was successfully developed as a rapid and reliable method that can simultaneously determine betaine, citric acid, threonine, alanine, and proline in various Lycii Fructus. In addition, ERETIC 2 method based on PULCON principle was also applied and compared with conventional method. This feasible and practical method offers a very powerful tool for the quality control of commercial Lycii Fructus from different sources.