Lindenane sesquiterpenoid dimers from Chloranthus japonicus inhibit HIV-1 and HCV replication

Lindenane sesquiterpenoid dimers with NLRP3 inflammasome inhibitory activities from Chloranthus holostegius var. shimianensis

Thirteen previously undescribed lindenane sesquiterpenoid dimers (LSDs), named chlorahololides G-S (1-13), were isolated from the whole plants of Chloranthus holostegius var. shimianensis, along with ten known analogues (14-23). The structures and absolute configurations of compounds 1-13 were elucidated through comprehensive spectroscopic analysis, NMR and electronic circular dichroism (ECD) calculations, and X-ray single-crystal diffraction. Chlorahololide G (1) represents the first instance of LSDs formed via a C-15-C-9' carbon-carbon single bond, whose plausible biosynthetic pathway was also proposed. Chlorahololides I and J (3 and 4) were deduced to be rare 8,9-seco and 9-deoxy LSDs with C-11-C-7' carbon-carbon bond, respectively. The inhibitory activity against NLRP3 inflammasome activation was evaluated for all isolates, with six compounds (5, 7, 8, 17, 22, and 23) exhibiting significant effects, and IC50 values ranging from 2.99 to 8.73 µM. Additionally, a preliminary structure-activity relationship analysis regarding their inhibition of NLRP3 inflammasome activation was summarized. Compound 17 exhibited dose-dependent inhibition of nigericin-induced pyroptosis in J774A.1 cells. Molecular docking studies suggested a strong interaction between compound 17 and NLRP3.

Terpenoids of plants from Chloranthaceae family: chemistry, bioactivity, and synthesis

Covering: 1976 to December 2023Chloranthaceae is comprised of four extant genera (Chloranthus, Sarcandra, Hedyosmum, and Ascarina), totaling about 80 species, many of which have been widely used as herbal medicines for diverse medical purposes. Chloranthaceae plants represent a rich source of structurally interesting and diverse secondary metabolites, with sesquiterpenoids and diterpenoids being the predominant structural types. Lindenane sesquiterpenoids and their oligomers, chemotaxonomical markers of the family Chloranthaceae, have shown a wide spectrum of bioactivities, attracting significant attention from organic chemists and pharmacologists. Recent achievements also demonstrated the research value of two unique structural types in this plant family, sesquiterpenoid-monoterpenoid heterodimers and meroterpenoids. This review systematically summarizes 682 structurally characterized terpenoids from 22 Chloranthaceae plants and their key biological activities as well as the chemical synthesis of selected terpenoids.

Chemistry and bioactivity of lindenane sesquiterpenoids and their oligomers

Covering: 1925 to July 2023Among the sesquiterpenoids with rich structural diversity and potential bioactivities, lindenane sesquiterpenoids (LSs) possess a characteristic cis, trans-3,5,6-carbocyclic skeleton and mainly exist as monomers and diverse oligomers in plants from the Lindera genus and Chloranthaceae family. Since the first identification of lindeneol from Lindera strychnifolia in 1925, 354 natural LSs and their oligomers with anti-inflammatory, antitumor, and anti-infective activities have been discovered. Structurally, two-thirds of LSs exist as oligomers with interesting skeletons through diverse polymeric patterns, especially Diels-Alder [4 + 2] cycloaddition. Fascinated by their diverse bioactivities and intriguing polycyclic architectures, synthetic chemists have engaged in the total synthesis of natural LSs in recent decades. In this review, the research achievements related to LSs from 1925 to July of 2023 are systematically and comprehensively summarized, focusing on the classification of their structures, chemical synthesis, and bioactivities, which will be helpful for further research on LSs and their oligomers.

Lindenane sesquiterpenoid dimers from Chloranthus japonicus improve LDL uptake by regulating PCSK9 and LDLR

UPLC-TOF-MS/MDF directed phytochemical research of Chloranthus japonicus led to the isolation of 46 lindenane sesquiterpenoid dimers, which included 13 new analogs. Their structures with absolute configurations were elucidated by analysis of spectroscopic data. Fourteen compounds with ester chains significantly decreased PCSK9 protein level in medium of HepG2 cells, especially for compounds 14 and 29 (5 µM) with inhibition rates of 69.0% and 72.8%, respectively. Compound 14 in HepG2 cells was evaluated via DiI-LDL uptake assays and found to increase LDL uptake by upregulating LDLR mRNA and protein level. Meanwhile, 14 decreased the secretion of PCSK9 protein in medium and downregulated intracellular PCSK9 protein and mRNA level. The discovery of these natural small molecule compounds provides a novel structure basis for design PCSK9 regulators, making them a promising lead for development of new lipid-lowering agents.

Lindenane sesquiterpenoid monomers and oligomers: Chemistry and pharmacological activities

Lindenane sesquiterpenoid monomers and oligomers, characterized by a sterically congested cyclopentane and an unusual trans-5/6 ring junction, are mainly found in Chloranthaceae species and the genus Lindera Thunb (Lauraceae). Numerous studies have shown that lindenane sesquiterpenoid monomers and oligomers exhibit a broad range of biological activities, such as cytotoxicity, anti-inflammation, neuroprotection, antifungal, and anti-malarial activities. This review covers publications from the first identification of lindeneol in 1925-2023 and classifies the lindenane sesquiterpenoid derivatives into sesquiterpenoid monomers, sesquiterpenoid-monoterpene conjugates, sesquiterpenoid homodimers, sesquiterpenoid heterodimers, and trimeric sesquiterpenoids. In addition, their biological activities are summarized. This review will establish a scientific basis and provide guidance for utilizing this unique class of natural products as potential lead compounds to develop their application in treating diseases corresponding to inflammation, cancer, and plasmodium.

Chlorahololide D, a Lindenane-Type Sesquiterpenoid Dimer from Chloranthus holostegius Suppressing Breast Cancer Progression

Aimed at discovering small molecules as anticancer drugs or lead compounds from plants, a lindenane-type sesquiterpene dimer, chlorahololide D, was isolated from Chloranthus holostegius. The literature review showed that there were few reports on the antitumor effects and mechanisms of chlorahololide D. Our biological assay suggested that chlorahololide D blocked the growth and triggered apoptosis of MCF-7 cells by stimulating the reactive oxygen species (ROS) levels and arresting the cell cycle at the G2 stage. Further mechanism exploration suggested that chlorahololide D regulated apoptosis-related proteins Bcl-2 and Bax. Moreover, chlorahololide D inhibited cell migration by regulating the FAK signaling pathway. In the zebrafish xenograft model, chlorahololide D was observed to suppress tumor proliferation and migration significantly. Considering the crucial function of angiogenesis in tumor development, the anti-angiogenesis of chlorahololide D was also investigated. All of the research preliminarily revealed that chlorahololide D could become an anti-breast cancer drug.

Targeting proteases involved in the viral replication of SARS-CoV-2 by sesquiterpene lactones from chicory (Cichorium intybus L.)

SARS-CoV-2 is a highly transmissible and pathogenic coronavirus causing a respiratory disease that emerged in 2019, leading to a public health emergency situation which continues to date. The treatment options are still very limited and vaccines available are less effective against new variants. SARS-CoV-2 enzymes, namely main protease (Mpro) and papain-like protease (PLpro), play a pivotal role in the viral life cycle, making them a putative drug target. Here, we described for the first time the potential inhibitory activity of chicory extract against both proteases. Besides, we have identified that the four most abundant sesquiterpene lactones in chicory inhibited these proteases, showing an effective binding in the active sites of Mpro and PLpro. This paper provides new insight for further drug development or food-based strategies for the prevention of SARS-CoV-2 by targeting viral proteases.

Sarcanolides C-E: three new lindenane sesquiterpenoid dimers with anti-inflammatory activities from Sarcandra glabra

Three new lindenane-type sesquiterpenoid dimers, sarcanolides C-E (1-3), were isolated from the roots of Sarcandra glabra. Sarcanolide C (1) possesses a unique decacyclic scaffold with an unusual orthoformate unit. The structures of 1-3 were determined through extensive spectroscopic analysis, while their absolute configurations were determined by comparison of calculated and experimental electronic circular dichroism (ECD) spectra. Compounds 1-3 were evaluated for their inhibitory activity against LPS-induced nitric oxide (NO) production in RAW264.7 macrophages. All the isolates displayed a moderate inhibitory effect against NO production with IC50 values in the range of 13.4-17.2 μM, comparable to that of the positive control L-NMMA.

Plant-Based Natural Products and Extracts: Potential Source to Develop New Antiviral Drug Candidates

Viral infections are among the most complex medical problems and have been a major threat to the economy and global health. Several epidemics and pandemics have occurred due to viruses, which has led to a significant increase in mortality and morbidity rates. Natural products have always been an inspiration and source for new drug development because of their various uses. Among all-natural sources, plant sources are the most dominant for the discovery of new therapeutic agents due to their chemical and structural diversity. Despite the traditional use and potential source for drug development, natural products have gained little attention from large pharmaceutical industries. Several plant extracts and isolated compounds have been extensively studied and explored for antiviral properties against different strains of viruses. In this review, we have compiled antiviral plant extracts and natural products isolated from plants reported since 2015.

Discovery of eudesmane-type sesquiterpenoids with neuroprotective effects from the roots of Chloranthus serratus

Seven eudesmane-type sesquiterpenoids, including three pairs of racemic compounds (1a-3a and 1b-3b) and a sesquiterpenoid lactone (4), were obtained from the roots of Chloranthus serratus. The structures of these sesquiterpenoids were characterized based on spectroscopic analyses, ECD calculations, and X-ray diffraction experiment. Neuroprotection assays of the isolated eudesmane-type sesquiterpenoids were conducted on H₂O₂ damaged PC12 cells. At the concentration of 10 μM, compounds 1b and 4 increased cell viability from 54.8 ± 3.3% to 76.8 ± 2.3 and 72.7 ± 8.2%, respectively.

Three pairs of sesquiterpene enantiomers from Chloranthus multistachys pei

Phytochemical investigation on the whole plant of Chloranthus multistachys pei (Chloranthaceae) afforded three pairs of new sesquiterpene enantiomers (+)/(-)-chlorantene M [(+)/(-)-1], (+)/(-)-chlorantene M1 [(+)/(-)-2] and (+)/(-)-chlorantene N [(+)/(-)-3]. The structures of new compounds were determined through spectroscopic techniques (HR-ESI-MS, 1 D and 2 D NMR), besides, their absolute and relative configurations were established by using Single-crystal X-ray diffraction analysis and CD spectrum. The anti-inflammatory potential of all compounds was evaluated by applying LPS induced RAW 264.7 macrophage inflammatory model, and the results were that none of these compounds showed activity (IC₅₀ > 100 μM).

Biomimetic Approaches to the Synthesis of Natural Disesquiterpenoids: An Update

Natural disesquiterpenoids represent a small group of secondary metabolites characterized by complex molecular scaffolds and interesting pharmacological profiles. In the last decade, more than 400 new disesquiterpenoids have been discovered and fully characterized, pointing out once more the "magic touch" of nature in the design of new compounds. The perfect blend of complex and unique architectures and biological activity has made sesquiterpene dimers an attractive and challenging synthetic target, inspiring organic chemists to find new and biomimetic approaches to replicate the efficiency and the selectivity of natural processes under laboratory conditions. In this work, we present a review covering the literature from 2010 to 2020 reporting all the efforts made in the total synthesis of complex natural disesquiterpenoids.

Sesquiterpenoids with neuroprotective activities from the Chloranthaceae plant Chloranthus henryi

A rare sesquiterpenoid possessing a 6/6 bicyclic system fused with two clustered furan units and a pair of guaiane-type sesquiterpenoids were acquired from the roots of Chloranthus henryi. Their structures with absolute configurations were characterized with spectroscopic data, ECD, and X-ray diffraction analysis. All three sesquiterpenoids showed moderate neuroprotective activities on PC12 cells damaged with hydrogen peroxide.

Trichloranoids A–D, antimalarial sesquiterpenoid trimers from Chloranthus spicatus

Four new anti-malarial sesquiterpenoid trimers including two rearranged skeletons were isolated from Chloranthus spicatus. The structurally different but biogenetically related compounds 1, 2 and 5 rationalized the biradical pathway, and vice versa.

Atypical Lindenane-Type Sesquiterpenes from Lindera myrrha

Two new lindenane sesquiterpenes were obtained from the roots of Lindera myrrha. These compounds were structurally elucidated by HRMS data, extensive NMR analyses, and comparison between experimental and theoretical ¹³C-NMR data. Myrrhalindenane A is the first monomeric seco-d lindenane displaying a non-rearranged, cyclohexanic C-ring. Myrrhalindenane B is the second occurrence of an angular lindenane-sesquiterpene related to a C₆-C₇ lactonization.

Neuroprotective racemic germacranolides from the roots of Chloranthus henryi

Three pairs of new germacranolides, (+)/(-)-chlogermacrones A-C, along with two known analogues were obtained from the roots of Chloranthus henryi. Spectroscopic techniques and single-crystal X-ray crystallographic analyses were used for the structure elucidation of the compounds. All of the isolated compounds were tested for their neuroprotective effects on H₂O₂ damaged PC12 cells, compounds 3 and 5 increased cell viability from 43.4 ± 1.3% to 99.6 ± 8.7 and 68.1 ± 4.8% at 10 μM, respectively.

Naturally occurring [4 + 2] type terpenoid dimers: sources, bioactivities and total syntheses

This review article highlights recent progress on their sources, bioactivities, biosynthetic hypotheses and total chemical syntheses of naturally occurring [4 + 2] type terpenoid dimers.

Natural disesquiterpenoids: an update

This review highlights the progress on the isolation, bioactivity, biogenesis and total synthesis of dimeric sesquiterpenoids since 2010.

A new lindenane-type sesquiterpenoid lactone from Chloranthus japonicus

Chromatographic fractionation of the EtOH extracts of the Traditional Chinese Medicine (TCM) Chloranthus japonicus, has led to the isolation of a new lindenane-type sesquiterpenoid lactone derivative (1). Rosmarylchloranthalactone E (1), which consists of lindenane sesquiterpenoid lactone and rosmarinic acid moieties linked via an ester bridge, was structurally elucidated by 1D and 2D NMR and HRMS data. Compound 1 was a potent phosphodiesterase-4 (PDE4) inhibitor with an IC₅₀ value of 0.96 ± 0.04 μM.

Total syntheses of shizukaols A and E

Shizukaols possess a common heptacyclic framework containing more than ten contiguous stereocenters and potential biological activities. Here we report that the total syntheses of shizukaols A (1) and E (2), two lindenane-type dimers from the Chloranthaceae family, are achieved via a modified biomimetic Diels–Alder reaction. The common crucial biomimetic diene 23 and ethylene species (6, 17) are obtained through either a highly Z-selective olefination of α-siloxy ketone with ynolate anions or an intramolecular Horner–Wadsworth–Emmons olefination from commercially available Wieland–Miescher ketone (7). This synthetic approach here opens up practical avenues for the total syntheses of the intriguing Chloranthaceae family members, as well as the understanding of their relevant biological action in nature.

Shizukaols, bioactive dimers naturally occurring in the Chloranthaceae family, possess a complex polycyclic framework with more than ten contiguous stereocenters. Here the authors report the total syntheses of shizukaols A and E achieved via a modified Diels–Alder reaction mimicking the biosynthetic pathway.

Medicinal Plants Used in the Treatment of Human Immunodeficiency Virus

Since the beginning of the epidemic, human immunodeficiency virus (HIV) has infected around 70 million people worldwide, most of whom reside is sub-Saharan Africa. There have been very promising developments in the treatment of HIV with anti-retroviral drug cocktails. However, drug resistance to anti-HIV drugs is emerging, and many people infected with HIV have adverse reactions or do not have ready access to currently available HIV chemotherapies. Thus, there is a need to discover new anti-HIV agents to supplement our current arsenal of anti-HIV drugs and to provide therapeutic options for populations with limited resources or access to currently efficacious chemotherapies. Plant-derived natural products continue to serve as a reservoir for the discovery of new medicines, including anti-HIV agents. This review presents a survey of plants that have shown anti-HIV activity, both in vitro and in vivo.