Alkaloids from Lepidium meyenii (Maca), structural revision of macaridine and UPLC-MS/MS feature-based molecular networking

UPLC-TQD-MS/MS Method Validation for Quality Control of Alkaloid Content in Lepidium meyenii (Maca)-Containing Food and Dietary Supplements

Lepidium meyenii Walp. (Brassicaceae), also known as Maca or Peruvian ginseng, is a common ingredient in food supplements with many claimed health benefits, such as improved endurance, increased energy level, and enhanced sexual properties. Due to potential toxicity of its chemicals, including alkaloids, some regulatory authorities, e.g., in Belgium, Germany, the United States, expressed concerns about the safe consumption of Maca root. However, due to the lack of commercial standards, no established analytical method currently exists for this purpose. The current project focuses on the quantitative determination of potentially toxic alkaloids from Maca. The current study presents the first analytical method for quality control of alkaloid content in Maca-containing food and dietary supplements, assessing the presence of 11 major compounds belonging to three different classes, i.e., imidazole, β-carboline, and pyrrole alkaloids. An accurate, rapid, and sensitive UPLC-TQD-MS/MS method is reported, which was fully validated according to the International Council for Harmonization of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH) and SANTE/11312/2021 guidelines. To ensure the method's applicability and practicability in the absence of primary standards, validation of secondary standards (SSs) alongside primary standards (PSs) was also conducted for imidazole alkaloids. As a result, in Maca raw powder, total alkaloid content was found to vary from 418 to 554 ppm (mg/kg). Furthermore, all quantified imidazole alkaloids were ascertained to be the major alkaloids with the total content from 323 to 470 ppm in Maca raw powder, followed by the β-carboline and pyrrole alkaloids. It was also observed that the commercial preparation of finished products affects the total alkaloid content, evidenced by the large variation from 56 to 598 ppm. Ultimately, from a regulatory point of view, it seems advisible not to request the complete absence of the alkaloids but to impose a maximum level based on safety considerations. In addition to the analytical method, a low-cost, simple, and scalable synthetic scheme of macapyrrolins A, C, and G was reported for the first time.

Heterologous expression of the cryptic mdk gene cluster and structural revision of maduralactomycin A

After conducting an in silico analysis of the cryptic mdk cluster region and performing transcriptomic studies, an integrative Streptomyces BAC Vector containing the mdk gene sequence was constructed. The heterologous expression of the mdk cluster in Streptomyces albus J1074 resulted in the production of the angucyclic product, seongomycin, which allowed for the assesment of its antibacterial, antiproliferative, and antiviral activities. Heterologous production was further confirmed by targeted knock-out experiments involving key regulators of the biosynthetic pathways. We were further able to revise the core structure of maduralactomycin A, using a computational approach.

Phytochemical Profiles and Biological Studies of Selected Botanical Dietary Supplements Used in the United States

Based on their current wide bioavailability, botanical dietary supplements have become an important component of the United States healthcare system, although most of these products have limited scientific evidence for their use. The most recent American Botanical Council Market Report estimated for 2020 a 17.3% increase in sales of these products when compared to 2019, for a total sales volume of $11,261 billion. The use of botanical dietary supplements products in the United States is guided by the Dietary Supplement Health and Education Act (DSHEA) from 1994, enacted by the U.S. Congress with the aim of providing more information to consumers and to facilitate access to a larger number of botanical dietary supplements available on the market than previously. Botanical dietary supplements may be formulated for and use only using crude plant samples (e.g., plant parts such as the bark, leaves, or roots) that can be processed by grinding into a dried powder. Plant parts can also be extracted with hot water to form an "herbal tea." Other preparations of botanical dietary supplements include capsules, essential oils, gummies, powders, tablets, and tinctures. Overall, botanical dietary supplements contain bioactive secondary metabolites with diverse chemotypes that typically are found at low concentration levels. These bioactive constituents usually occur in combination with inactive molecules that may induce synergy and potentiation of the effects observed when botanical dietary supplements are taken in their different forms. Most of the botanical dietary supplements available on the U.S. market have been used previously as herbal remedies or as part of traditional medicine systems from around the world. Their prior use in these systems also provides a certain level of assurance in regard to lower toxicity levels. This chapter will focus on the importance and diversity of the chemical features of bioactive secondary metabolites found in botanical dietary supplements that are responsible for their applications. Many of the active principles of botanical dietary substances are phenolics and isoprenoids, but glycosides and some alkaloids are also present. Biological studies on the active constituents of selected botanical dietary supplements will be discussed. Thus, the present chapter should be of interest for both members of the natural products scientific community, who may be performing development studies of the products available, as well as for healthcare professionals who are directly involved in the analysis of botanical interactions and evaluation of the suitability of botanical dietary supplements for human consumption.

Epimeric Mixture Analysis and Absolute Configuration Determination Using an Integrated Spectroscopic and Computational Approach-A Case Study of Two Epimers of 6-Hydroxyhippeastidine

Structural elucidation has always been challenging, and misassignment remains a stringent issue in the field of natural products. The growing interest in discovering unknown, complex natural structures accompanies the increasing awareness concerning misassignments in the community. The combination of various spectroscopic methods with molecular modeling has gained popularity in recent years. In this work, we demonstrated, for the first time, its power to fully elucidate the 2-dimensional and 3-dimensional structures of two epimers in an epimeric mixture of 6-hydroxyhippeastidine. DFT calculation of chemical shifts was first performed to assist the assignment of planar structures. Furthermore, relative and absolute configurations were established by three different ways of computer-assisted structure elucidation (CASE) coupled with ORD/ECD/VCD spectroscopies. In addition, the significant added value of OR/ORD computations to relative and absolute configuration determination was also revealed. Remarkably, the differentiation of two enantiomeric scaffolds (crinine and haemanthamine) was accomplished via OR/ORD calculations with cross-validation by ECD and VCD.

Lepidium meyenii (Maca) Roots: UPLC-HRMS, Molecular Docking, and Molecular Dynamics

Lepidium meyenii or Maca is widely cultivated as a health care food supplement due to its nutritional and medicinal properties. Although there are a few in-depth studies evaluating Maca antihypertensive effects, the correlations between the chemical constituents and bioactivity of the plant have not been studied before. Thus, the roots were extracted using different solvents (aqueous, methanol, 50% methanol, and methylene chloride) and investigated for their antihypertensive and antioxidant activities through several in vitro assays. The methanolic extract exhibited the best renin and angiotensin converting enzyme (ACE) inhibitory activities with IC₅₀ values of 24.79 ± 1.3 ng/mL and 22.02 ± 1.1 ng/mL, respectively, along with the highest antioxidant activity. In total, 120 metabolites from different classes, e.g., alkylamides, alkaloids, glucosinolates, organic acids, and hydantoin derivatives, were identified in the methanolic extract using ultrahigh-performance liquid chromatography/high-resolution mass spectrometry (UPLC/HRMS). Molecular docking simulations were used to investigate the potential binding modes and the intermolecular interactions of the identified compounds with ACE and renin active sites. Glucotropaeolin, β-carboline alkaloids, succinic acid, and 2,4-dihydroxy-3,5-cyclopentyl dienoic acid showed the highest affinity to target the ACE with high docking scores (S ranging from -35.32 to -22.51 kcal mol^-1) compared to lisinopril (S = -36.64 kcal mol^-1). Interestingly, macamides displayed the greatest binding affinity to the active site of renin with docking scores (S ranging from -22.47 to -28.25 kcal mol^-1). Further, β-carbolines achieved docking scores comparable to that of the native ligand (S ranging from -13.50 to -20.06 kcal mol^-1). Molecular dynamics simulations and MMPBSA were also carried out and confirmed the docking results. Additionally, the computational ADMET study predicted that the compounds attaining promising docking results had proper pharmacokinetics, drug-likeness characteristics, and safe toxicological profiles. Ultimately, our findings revealed that Maca roots could be considered a promising candidate as an antihypertensive drug.

Simultaneous determination of Allium compounds (Propyl propane thiosulfonate and thiosulfinate) in animal feed using UPLC-MS/MS

Propyl-propane-thiosulfonate (PTSO) and Propyl-propane-thiosulfinate (PTS) are organosulfur compounds used to supplement the diet of livestock because of their beneficial effects on feed palatability, their antibacterial, anti-inflammatory, and antimethanogenic activities. Besides, antibiotic residues in the environment can be reduced by using these natural bioactive compounds. The objective of this study was to optimize the extraction parameters for the analysis of PTSO and PTS in feed matrices by performing a solid-liquid extraction and quantification by Ultra performance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS). Optimization was performed using the Response Surface Methodology on a Box-Behnken experimental design, optimizing the following parameters: solvent:sample ratios and evaporation temperature set for the rotary evaporator. The method was validated for 3 concentration levels for both PTSO (100, 500, 1000 ng g^-1) and PTS (500, 1150, 2300 ng g^-1). The highest recoveries of PTSO and PTS were obtained using 12.5 mL of 100% acetonitrile, stirring for 15 min, and an evaporation temperature of 20 °C. The validated method was further applied to detect and quantify these compounds in different feed matrices. In conclusion, this is the first study to simultaneously analyze PTSO and PTS at low concentrations, employing a sensitive technique such as UPLC-MS/MS.