Bioactive Neolignans and Other Compounds from Magnolia grandiflora L.: Isolation and Antiplasmodial Activity

Naturally occurring phenylethanoids and phenylpropanoids: antimalarial potential

Malaria as an infectious disease is one of the world's most dangerous parasitic diseases. There is an urgent need for the development of new antimalarial drugs. Natural products are a very rich source of new bioactive compounds. Our research aims to shed light on the recent studies which demonstrated the antimalarial potential of phenylpropanoids as a major natural-products class. This study involves an in silico analysis of naturally-occurring phenylpropanoids and phenylethanoids which showed 25 compounds with moderate to strong binding affinity to various amino acid residues lining the active site; P. falciparum kinase (PfPK5), P. falciparum cytochrome bc1 complex (cyt bc1), and P. falciparum lysyl-tRNA synthetase (PfKRS1); of Plasmodium falciparum parasite, a unicellular protozoan which causes the most severe and life-threatening malaria. Furthermore, the study was augmented by the assessment of antiplasmodial activity of glandularin, a naturally occurring dibenzylbutyrolactolic lignan, against chloroquine-sensitive 3D7 strain of P. falciparum using SYBR green I-based fluorescence assay, which showed high antimalarial activity with IC50 value of 11.2 μM after 24 hours of incubation. Our results highlight phenylpropanoids and glandularin in particular as a promising chemical lead for development of antimalarial drugs.

Bis((5-allyl-2-(benzo[d][1,3]dioxol-5-yl)benzofuran-7-yl)oxy)methane: An Unusual Nor-Neolignan Dimer from Magnolia grandiflora L

An unreported and unusual nor-neolignan dimer, namely bis((5-allyl-2-(benzo[d][1,3]dioxol-5-yl)benzofuran-7-yl)oxy)methane (1), was isolated from the bark-derived chloroform extract of Magnolia grandiflora L. Compound 1 was structurally elucidated through the detailed analysis of the spectroscopic data (one- and two-dimensional nuclear magnetic resonance, infrared, and high-resolution mass spectrometry). The effect of compound 1 on the mycelial growth of Fusarium oxysporum was also determined, affording moderate antifungal activity.

GC-MS-based Fingerprinting Reveals Two Chemotypes in the Leaf Essential Oils from Magnolia grandiflora Trees within The Urban Forestry of a Colombian Andean Plateau

Magnolia grandiflora is an aromatic plant widely distributed around the world. In Colombia, and more specifically in Bogotá, M. grandiflora has been introduced as part of urban forestry programs, and their specimens are therefore subjected to several environments. Nevertheless, there are no previous studies on the chemical composition of such plants. Hence, the characterization of the essential oil from 20 specimens of M. grandiflora from Bogotá, Colombia, by GC-MS was carried out here. Two different chemotypes were found. While one was characterized by monoterpenes α-pinene, β-pinene, and limonene, the other contained mainly sesquiterpenes β-elemene, bicyclogermacrene, and germacrene D. Multivariate statistical analyses confirmed their existence and helped to identify variations within and between chemotypes. Furthermore, differential expression of genes encoding the terpene synthases Mg 25 and Mg 17 could arguably be responsible for the characteristic compositions of both chemotypes, as suggested by rational biosynthetic analysis of the most contrasting metabolites.

Antiplasmodial natural products: an update

Background

Malaria remains a significant public health challenge in regions of the world where it is endemic. An unprecedented decline in malaria incidences was recorded during the last decade due to the availability of effective control interventions, such as the deployment of artemisinin-based combination therapy and insecticide-treated nets. However, according to the World Health Organization, malaria is staging a comeback, in part due to the development of drug resistance. Therefore, there is an urgent need to discover new anti-malarial drugs. This article reviews the literature on natural products with antiplasmodial activity that was reported between 2010 and 2017.

Methods

Relevant literature was sourced by searching the major scientific databases, including Web of Science, ScienceDirect, Scopus, SciFinder, Pubmed, and Google Scholar, using appropriate keyword combinations.

Results and Discussion

A total of 1524 compounds from 397 relevant references, assayed against at least one strain of Plasmodium, were reported in the period under review. Out of these, 39% were described as new natural products, and 29% of the compounds had IC₅₀ ≤ 3.0 µM against at least one strain of Plasmodium. Several of these compounds have the potential to be developed into viable anti-malarial drugs. Also, some of these compounds could play a role in malaria eradication by targeting gametocytes. However, the research into natural products with potential for blocking the transmission of malaria is still in its infancy stage and needs to be vigorously pursued.

Lignans and Neolignans: Plant secondary metabolites as a reservoir of biologically active substances

Lignans and neolignans are plant secondary metabolites derived from the oxidative coupling of phenylpropanoids. Biological activity of these phenolic compounds ranges from antioxidant, antitumor (terminaloside P, IC₅₀ = 10 nM), anti-inflammatory, anti-neurodegenerative (schibitubin B, IC₅₀ = 3.2 nM) and antiviral (patentiflorin A, IC₅₀ = 14-23 nM) to antimicrobial. In addition, it was observed that several members of this group, namely enterolactone and its biochemical precursors also known as phytoestrogens, possess important protective properties. Most of these lignans and neolignans are presented in reasonable amounts in one's diet and thus the protection they provide against the colon and breast cancer, to name a few, is even more important to note. Similarly, neuroprotective properties were observed (schisanwilsonin G, IC₅₀ = 3.2 nM) These structural motives also serve as an important starting point in the development of anticancer drugs. Presumably the most famous members of this family, etoposide and teniposide, synthetic derivatives of podophyllotoxin, are used in the clinical treatment of lymphocytic leukemia, certain brain tumors, and lung tumors already for nearly 20 years. This review describes 413 lignans and neolignans which have been isolated between 2016 and mid-2018 being reported in more than 300 peer-reviewed articles. It covers their source, structure elucidation, and bioactivity. Within the review, the structure-based overview of compounds as well as the bioactivity-based overview of compounds are described.

The value of universally available raw NMR data for transparency, reproducibility, and integrity in natural product research

Covering: up to 2018With contributions from the global natural product (NP) research community, and continuing the Raw Data Initiative, this review collects a comprehensive demonstration of the immense scientific value of disseminating raw nuclear magnetic resonance (NMR) data, independently of, and in parallel with, classical publishing outlets. A comprehensive compilation of historic to present-day cases as well as contemporary and future applications show that addressing the urgent need for a repository of publicly accessible raw NMR data has the potential to transform natural products (NPs) and associated fields of chemical and biomedical research. The call for advancing open sharing mechanisms for raw data is intended to enhance the transparency of experimental protocols, augment the reproducibility of reported outcomes, including biological studies, become a regular component of responsible research, and thereby enrich the integrity of NP research and related fields.