Highly modified nor-clerodane diterpenoids from Croton yanhuii

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.

Asponchimides A-E: new enantiomeric N-acetyldopamine trimers from Aspongopus chinensis

Five new racemic N-acetyldopamine (NADA) trimers, asponchimides A-E (1-5), were isolated from Aspongopus chinensis, a prominent traditional Chinese medicinal insect employed for alleviating pain, treating indigestion, and addressing kidney ailments. Compounds 1-5 were successfully resolved by chiral high-performance liquid chromatography (HPLC), yielding five pairs of enantiomers: (+)- and (-)-asponchimides A-E (1a/1b-5a/5b). Their structural identities were discerned by extensive spectroscopic analyses, including high-resolution mass spectrometry (HRMS), ultraviolet-visible (UV-Vis) spectroscopy, infrared (IR) spectroscopy, and nuclear magnetic resonance (NMR), and their absolute configurations were determined by electronic circular dichroism (ECD) calculations. Compounds 1-5 are pioneering instances of NADA trimers featuring a Δ7 double bond. When subjected to a series of bioassays, a majority of the compounds exhibited weak inhibitory activity against nitric oxide (NO) production in LPS-induced RAW 264.7 cells.

New halimane and clerodane diterpenoids from Croton cnidophyllus

Three new halimane furanoditerpenoids (1-3) and three new clerodane furanoditerpenoids (4-6), along with seven known terpenoids including four pimarane diterpenoids (7-10) and three norisoprenoids (11-13) were isolated from the 95% EtOH extracts of the plants of Croton cnidophyllus. The 2D structures including absolute configuration of new furanoditerpenoids (1-6) were elucidated by analysis of their HRMS and NMR data as well as comparison of experimental and calculated ECD curves. Bioassay revealed that two compounds (8 and 9) possessed certain inhibitory effects against NO production stimulated by LPS, with IC₅₀ values of 19.00 ± 1.76 and 21.61 ± 1.11 μM, respectively.

Anti-Inflammatory and Cytotoxic Activities of Clerodane-Type Diterpenes

The secondary metabolites of clerodane diterpenoids have been found in several plant species from various families and in other organisms. In this review, we included articles on clerodanes and neo-clerodanes with cytotoxic or anti-inflammatory activity from 2015 to February 2023. A search was conducted in the following databases: PubMed, Google Scholar and Science Direct, using the keywords clerodanes or neo-clerodanes with cytotoxicity or anti-inflammatory activity. In this work, we present studies on these diterpenes with anti-inflammatory effects from 18 species belonging to 7 families and those with cytotoxic activity from 25 species belonging to 9 families. These plants are mostly from the Lamiaceae, Salicaceae, Menispermaceae and Euphorbiaceae families. In summary, clerodane diterpenes have activity against different cell cancer lines. Specific antiproliferative mechanisms related to the wide range of clerodanes known today have been described, since many of these compounds have been identified, some of which we barely know their properties. It is very possible that there are even more compounds than those described today, in such a way that makes it an open field to discover. Furthermore, some diterpenes presented in this review have already-known therapeutic targets, and therefore, their potential adverse effects can be predicted in some way.

New cembranoids from the leaves and twigs of Croton yanhuii Y. T. Chang

Crotonyanes A (1) and B (2), two new cembranoids were isolated from the leaves and twigs of Croton yanhuii Y. T. Chang. Their structures were elucidated by extensive spectroscopic analyses and quantum chemical calculations. Bioassays verified that compound 1 exhibited an inhibitory effect on nitric oxide (NO) production in RAW 264.7 cells, with an IC50 value of 30.6 ± 4.3 µM.

A review on natural products with cage-like structure

Natural products with diverse structures and significant biological activities are essential sources of drug lead compounds, and play an important role in the research and development of innovative drugs. Cage-like compounds have various structures and are widely distributed in nature, especially caged xanthones isolated from Garcinia genus, paeoniflorin and its derivatives isolated from Paeonia lactiflora Pall, tetrodotoxin (TTX) and its derivatives, and so on. In recent years, the development and utilization of cage-like compounds have been a research hotspot in chemistry, biology and other fields due to their special structures and remarkable biological activities. In this review, we mainly summarized the cage-like compounds with various structures found and isolated from natural drugs since 1956, summarized its broad biological activities, and introduced the progress in the biosynthesis of some compounds, so as to provide a reference for the discovery of more novel compounds, and the development and application of innovative drugs.

Diterpenoids and C13 Nor-Isoprenoid Identified From the Leaves and Twigs of Croton yanhuii Activating Apoptosis and Pyroptosis

Croton yanhuii (Family Euphorbiaceae) is an annual aromatic plant endemic to Yunnan Province, China, which yields an aromatic, spicy oil used as a flavoring and fragrance. The aim of the present study was to acquire secondary metabolites from the leaves and twigs of C. yanhuii and to evaluate their cytotoxic activity. Five new diterpenoids, croyanhuins A–E (1–5), and one new C₁₃ nor-isoprenoid, croyanhuin F (6), were isolated from the leaves and twigs of C. yanhuii. Their structures and absolute configurations were determined by extensive spectroscopic methods (1D and 2D NMR, IR, and HRESIMS) and confirmed by electronic circular dichroism (ECD) spectra or single-crystal X-ray diffraction analysis. Among the new terpenoids, compounds 1 and 3 inhibited cell proliferation and viability in a dose- and time-dependent manner, whereas both induced cleavage of either caspase-3 or PARP-1 in the SW480 cell line. Additionally, we observed that Z-YVAD-FMK and Z-VAD-FMK, two caspase inhibitors, inhibited the compound-dependent cell viability loss, suggesting that either of them can induce pyroptosis and caspase-dependent apoptosis. These biological assay results revealed that compounds 1 and 3 induce different kinds of programmed cell death in SW480 cells.