Characterization of the chemical constituents of Croton crassifolius Geisel extract and plasma pharmacokinetics of 6 terpenoids after oral administration by UPLC-Q/TOF-MS

INTRODUCTION

Croton crassifolius Geisel. (CCG) is a traditional Chinese medicine widely used in South China. It has various pharmacological effects and is often used in treating rheumatoid arthritis and gastric and duodenal ulcers. However, the chemical characteristics and its effective constituents are still scarcely studied.

OBJECTIVE

To determine the phytochemical profile of the CCG extract and to investigate the chemical characteristics of terpenoids extracted from rat plasma following oral administration of CCG extract based on UPLC-Q/TOF-MS. Moreover, six terpenoids in CCG were quantified, and in vivo pharmacokinetic behavior after oral CCG extract was further explored.

RESULTS

In total, 56 terpenoids were tentatively identified in the CCG extract and 16 terpenoids were detected in rat plasma after oral CCG extract. In addition, the contents of six terpenoids in CCG were clarified. The plasma quantification method of six terpenoids was further established, validated, and confirmed to have good sensitivity and specificity. The six analytes exhibited excellent linearity in respective concentration ranges (r ≥ 0.998). The intra-day and inter-day precisions relative standard deviation (RSD, %) were less than 11.27%, and the accuracies ranged from -7.06% to 9.91%. Stability, extraction recovery, and matrix effect in plasma were within the required limits (RSD < 15%).

CONCLUSION

A total of 56 terpenoids were identified in CCG and 16 prototype components in plasma after oral CCG. The validated quantitative method was successfully applied to the simultaneous determination of six major terpenoids in plasma. The pharmacokinetic parameters are clarified, which can guide the clinical application of CCG.

A Comprehensive Review of the Classification, Sources, Phytochemistry, and Pharmacology of Norditerpenes

Norditerpenes are considered to be a common and widely studied class of bioactive compounds in plants, exhibiting a wide array of complex and diverse structural types and originating from various sources. Based on the number of carbons, norditerpenes can be categorized into C19, C18, C17, and C16 compounds. Up to now, 557 norditerpenes and their derivatives have been found in studies published between 2010 and 2023, distributed in 51 families and 132 species, with the largest number in Lamiaceae, Euphorbiaceae, and Cephalotaxaceae. These norditerpenes display versatile biological activities, including anti-tumor, anti-inflammatory, antimicrobial, and antioxidant properties, as well as inhibitory effects against HIV and α-glucosidase, and can be considered as an important source of treatment for a variety of diseases that had a high commercial value. This review provides a comprehensive summary of the plant sources, chemical structures, and biological activities of norditerpenes derived from natural sources, serving as a valuable reference for further research development and application in this field.

Biogenetic and biomimetic synthesis of natural bisditerpenoids: hypothesis and practices

Covering: up to March 2022Bisditerpenoids, or diterpenoid dimers, are a group of natural products with high structural variance, deriving from homo- or hetero-dimeric coupling of two diterpenoid units. They usually possess complex architectures resulting from the diversity of monomeric diterpenoids as building blocks and the dimerization processes. These compounds have attracted the attention of synthetic and biological scientists owing to the rarity of their natural origin and their significant biological activities. Herein, we provide a review highlighting some of the interesting bisditerpenoids reported since 1961 and showcase the chemical diversity in both their structures and biosynthesis, as well as their biological functions. This review focuses on the biosynthetic dimerization pathways of interesting molecules and their biomimetic synthesis, which may act as useful inspiration for the discovery and synthesis of more bisditerpenoids and further pharmacological investigations.

Caesalpinbondin A, a Novel Diterpenoid Lactone With an Unprecedented Carbon Skeleton from the Seeds of Caesalpinia bonduc

One novel diterpenoid lactone named caesalpinbondin A (1) that possesses an unprecedented tetracyclic ring system in which a 6/6/5-fused tricyclic ring and a 4,5-dimethyldihydrofuran-2(3H)-one were connected by a C-C single bond comprising a 5-(naphtho [2,3-b]furan-7-yl)dihydrofuran-2(3H)-one moiety was isolated from the seeds of Caesalpinia bonduc. Its chemical structure was established by extensive spectroscopic methods, and its absolute configuration was further determined by single-crystal X-ray diffraction analysis and electronic circular dichroism calculation. The biological evaluation suggested that compound 1 demonstrated potent anti-Alzheimer’s disease (AD) bioactivity, which could delay paralysis of transgenic AD Caenorhabditis elegans. A possible biogenetic pathway of 1 was also proposed.

Neuroprotective Effects of Oligosaccharides in Rehmanniae Radix on Transgenic Caenorhabditis elegans Models for Alzheimer’s Disease

Rehmanniae Radix (RR, the dried tuberous roots of Rehmannia glutinosa (Gaertn.) DC.) is an important traditional Chinese medicine distributed in Henan, Hebei, Inner Mongolia, and Northeast in China. RR is frequently used to treat diabetes mellitus, cardiovascular disease, osteoporosis and aging-related diseases in a class of prescriptions. The oligosaccharides and catalpol in RR have been confirmed to have neuroprotective effects. However, there are few studies on the anti-Alzheimer’s disease (AD) effect of oligosaccharides in Rehmanniae Radix (ORR). The chemical components and pharmacological effects of dried Rehmannia Radix (DRR) and prepared Rehmannia Radix (PRR) are different because of the different processing methods. ORR has neuroprotective potential, such as improving learning and memory in rats. Therefore, this study aimed to prove the importance of oligosaccharides in DRR (ODRR) and PRR (OPRR) for AD based on the Caenorhabditis elegans (C. elegans) model and the different roles of ODRR and OPRR in the treatment of AD. In this study, we used paralysis assays, lifespan and stress resistance assays, bacterial growth curve, developmental and behavioral parameters, and ability of learning and memory to explore the effects of ODRR and OPRR on anti-AD and anti-aging. Furthermore, the accumulation of reactive oxygen species (ROS); deposition of Aβ; and expression of amy-1, sir-2.1, daf-16, sod-3, skn-1, and hsp-16.2 were analyzed to confirm the efficacy of ODRR and OPRR. OPRR was more effective than ODRR in delaying the paralysis, improving learning ability, and prolonging the lifespan of C. elegans. Further mechanism studies showed that the accumulation of ROS, aggregation, and toxicity of Aβ were reduced, suggesting that ORR alleviated Aβ-induced toxicity, in part, through antioxidant activity and Aβ aggregation inhibiting. The expression of amy-1 was downregulated, and sir-2.1, daf-16, sod-3, and hsp-16.2 were upregulated. Thus, ORR could have a possible therapeutic effect on AD by modulating the expression of amy-1, sir-2.1, daf-16, sod-3, and hsp-16.2. Furthermore, ORR promoted the nuclear localization of daf-16 and further increased the expression of sod-3 and hsp-16.2, which significantly contributed to inhibiting the Aβ toxicity and enhancing oxidative stress resistance. In summary, the study provided a new idea for the development of ORR.

In Vitro Cytotoxicity and Anti-HIV Activity of Crude Extracts of Croton macrostachyus, Croton megalocarpus and Croton dichogamus

INTRODUCTION

Human immunodeficiency virus (HIV) affects the body's defense mechanisms and leads to a number of opportunistic infections which later cause fatality as a result of an acquired immunodeficiency syndrome (AIDS). More than half a million individuals have lost their life in 2020 due to this disease. Antiretroviral drugs have played a great role in improving the quality of life of HIV infected individuals. The side effects of these drugs coupled with resistance of the virus to the various regimens, necessitates the search for potentially new and effective antiretroviral medication. The objective of this study is to evaluate anti-HIV activity of crude extracts of three Croton plants.

METHODS

As part of our effort in screening anti-HIV medications, we evaluated the cytotoxicity and anti-HIV activity of three Croton species used as herbal medicine in Africa. Crude extracts of Croton macrostachyus, Croton megalocarpus and Croton dichogamus were tested for their replication inhibition activity against laboratory adapted strains HIV-1IIIB in Human T-lymphocytic MT-4 cell line.

RESULTS

Based on our findings, the crude aerial part extract of C. dichogamus displayed the highest anti-HIV activity by inhibiting 73.74% of viral induced cytopathic effect (CPE) at IC50 value of 0.001 + 0.00 μg/mL giving a selectivity index (SI) of 3116.0. In addition, the crude leaf extract of C. megalocarpus showed higher anti-HIV activity by inhibiting 74.65% of CPE at IC50 value of 0.05 + 0.03 μg/mL giving an SI of 571.3.

CONCLUSION

Out of five extracts from three Croton species screened for anti-HIV activity using human T-lymphocytic MT-4 cells, the leaf extract of Croton megalocarpus and aerial part extract of Croton dichogamus could be considered as promising extracts as they display high antiviral activity with low toxicity and high selectivity index values. To investigate the active constituents responsible for the anti-HIV activity, chemical identification of the active constituents is now in progress in our laboratory. Since there is no previously reported anti-HIV activity for these plants, there is a great need to isolate the compounds responsible for the noted activity.

New C9 -Monoterpenoid Alkaloids Featuring a Rare Skeleton with Anti-Inflammatory and Antiviral Activities from Forsythia suspensa

Forsyqinlingines C (1) and D (2), two C₉ -monoterpenoid alkaloids bearing a rare skeleton, were isolated from the ripe fruits of Forsythia suspensa. Their structures, including absolute configurations, were fully elucidated by extensive spectroscopic data and ECD experiments. The plausible biogenetic pathway for compounds 1 and 2 was also proposed. In vitro, two C₉ -monoterpenoid alkaloids showed anti-inflammatory activity performed by the inhibitory effect on the release of β-glucuronidase in rat polymorphonuclear leukocytes (PMNs), as well as antiviral activity against influenza A (H1N1) virus and respiratory syncytial virus (RSV).

Trinorlabdane diterpenoid alkaloids featuring an unprecedented skeleton with anti-inflammatory and anti-viral activities from Forsythia suspensa

Two unique trinorlabdane diterpenoid alkaloids, forsyqinlingines A (1) and B (2), were isolated from the ripe fruits of Forsythia suspensa. Their structures, including absolute stereochemical configurations, were fully elucidated from extensive spectroscopy experiments, single-crystal X-ray diffraction, and electronic circular dichroism (ECD). In addition, a plausible biosynthetic pathway for the formation of compounds 1 and 2 in Forsythia suspensa was also proposed. In vitro, the two C₁₇-labdane diterpenoid alkaloids exhibited anti-inflammatory activities by inhibiting the release of β-glucuronidase in rat polymorphonuclear leukocytes (PMNs), and antiviral activities against influenza A (H1N1) virus and respiratory syncytial virus (RSV).

Two unique trinorlabdane diterpenoid alkaloids, forsyqinlingines A (1) and B (2), were isolated from the ripe fruits of Forsythia suspensa, and found to show significant anti-inflammatory activities and anti-viral activities.

Polyoxygenated sesquiterpenoids from Salvia castanea and their potential anti-Alzheime's disease bioactivities

Salvia castanea (Family Labiatae), a perennial fragrant herb with castaneous flowers, is mainly distributed in areas with an altitude of 2500-3750 m. The roots of this plant were used as a tea drink by local residents to strengthen physical health. The aim of present study was to acquire secondary metabolites of the ethanol extract obtained from the whole plant of S. castanea and to evaluate their potential anti-Alzheimer's disease. Six new sesquiterpene lactones, salcastanins A-F (1-6), together with three known guaiane-type sesquiterpenoids nubiol (7), nubdienolide (8), and nubenolide (9), were separated from the whole plant of S. castanea. The structures of these compounds were determined by HRESIMS and NMR experiments. The absolute configurations of 1-6 were ascertained by electronic circular dichroism (ECD) experiments. The humanized Caenorhabditis elegans AD pathological model was used to evaluate anti-Alzheimer's disease (AD) activities of 1-9. The results showed the compounds 1-3 and 7 significantly delayed AD-like symptoms of worm paralysis phenotype, which could be used as novel anti-AD candidates.

Caenorhabditis elegans as a possible model to screen anti-Alzheimer's therapeutics

Alzheimer's disease (AD) is regarded as one of the significant health burdens, as the prevalence is raising worldwide and gradually reaching to epidemic proportions. Consequently, a number of scientific investigations have been initiated to derive therapeutics to combat AD with a concurrent advancement in pharmacological methods and experimental models. Whilst, the available experimental pharmacological approaches both in vivo and in vitro led to the development of AD therapeutics, the precise manner by which experimental models mimic either one or more biomarkers of human pathology of AD is gaining scientific attentions. Caenorhabditis elegans (C. elegans) has been regarded as an emerging model for various reasons, including its high similarities with the biomarkers of human AD. Our review supports the versatile nature of C. elegans and collates that it is a well-suited model to elucidate various molecular mechanisms by which AD therapeutics elicit their pharmacological effects. It is apparent that C. elegans is capable of establishing the pathological processes that links the endoplasmic reticulum and mitochondria dysfunctions in AD, exploring novel molecular cascades of AD pathogenesis and underpinning causal and consequential changes in the associated proteins and genes. In summary, C. elegans is a unique and feasible model for the screening of anti-Alzheimer's therapeutics and has the potential for further scientific exploration.

Isolation, Characterization, and Possible Anti-Alzheimer's Disease Activities of Bisabolane-Type Sesquiterpenoid Derivatives and Phenolics from the Rhizomes of Curcuma longa

One new bisabolane-type sesquiterpenoid, together with four known bisabolane-type sesquiterpenoid derivatives and seven phenolics, was isolated from the rhizomes of Curcuma longa. Their structures were elucidated by extensive spectroscopic (IR, HR-ESI-MS, and NMR) data analysis. The possible anti-Alzheimer's disease (AD) activities of the isolated compounds were also evaluated using Caenorhabditis elegans AD pathological model, and 1β-hydroxybisabola-2,10-dien-4-one had the highest possible anti-AD activity.

Eupulcherol A, a triterpenoid with a new carbon skeleton from Euphorbia pulcherrima, and its anti-Alzheimer's disease bioactivity

Eupulcherol A (1), a novel triterpenoid with an unprecedented carbon skeleton, was isolated from Euphorbia pulcherrima.

Narjatamanins A and B, a pair of novel epimers possessing a 2,3-seco-iridoid skeleton with an unusual 1,10-oxygen bridge from Nardostachys jatamansi and evaluation of their effects on worm paralysis in AD C. elegans

Narjatamanins A (1) and B (2), a pair of epimers possessing a novel 2,3-seco-iridoid skeleton with an unusual 1,10-oxygen bridge, were isolated from the whole plants of Nardostachys jatamansi. Their structures were elucidated by a combination of various spectroscopic methods, including HRESIMS, IR and 1D and 2D NMR techniques. The absolute configurations of 1 and 2 were established by electronic circular dichroism (ECD) calculations. The pharmacological activities of 1 and 2 to alleviate AD-like symptoms were also evaluated using the Caenorhabditis elegans Alzheimer's disease (AD) pathological model, and narjatamanins A (1) and B (2) showed statistically significant delay in the worm paralysis phenotype of AD-like symptoms.

Narjatamanins A (1) and B (2), a pair of epimers possessing a novel 2,3-seco-iridoid skeleton with an unusual 1,10-oxygen bridge, were isolated from the whole plants of Nardostachys jatamansi.

Chemical Constituents from Croton Species and Their Biological Activities

The genus Croton belongs to the Euphorbiaceae family, which comprises approximately 1300 species. Many Croton species have been used as folk medicines. This review focuses on the chemical constituents from Croton species and their relevant biological activities, covering the period from 2006 to 2018. A total of 399 new compounds, including 339 diterpenoids, were reported. Diterpenoids are characteristic components of the Croton species. These isolated compounds exhibited a broad spectrum of bioactivities, including cytotoxic, anti-inflammatory, antifungal, acetylcholinesterase inhibitory, and neurite outgrowth-promoting properties. The present review provides a significant clue for further research of the chemical constituents from the Croton species as potential medicines.

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Four novel sesquiterpenoids with their anti-Alzheimer's disease activity from Nardostachys chinensis

Nardochinins A–D (1–4), four novel sesquiterpenoids, were isolated from Nardostachys chinensis. Nardochinin B (2) can significantly inhibit the Alzheimer's disease (AD) like symptom of worm paralysis.