Diversified cassane family diterpenoids from the leaves of Caesalpinia minax exerting anti-neuroinflammatory activity through suppressing MAPK and NF-κB pathways in BV-2 microglia.

ETHNOPHARMACOLOGICAL RELEVANCE: Caesalpinia minax Hance, whose seeds are known as "Ku-shi-lian" in China, have been used in Chinese folk medicine for treatment of rheumatism, dysentery, and skin itching. However, the anti-neuroinflammatory constituents of its leaves and their mechanism are rarely reported. AIM OF THE STUDY: To search for new anti-neuro-inflammatory compounds from the leaves of C. minax and elucidate their mechanism on anti-neuroinflammatory effect. MATERIALS AND METHODS: The main metabolites of the ethyl acetate fraction from C. minax were analyzed and purified via HPLC and various column chromatography techniques. Their structures were elucidated on the basis of 1D and 2D NMR, HR-ESI-MS, and single crystal X-ray diffraction analysis. Anti-neuroinflammatory activity was evaluated in BV-2 microglia cells induced by LPS. The expression levels of molecules in NF-κB and MAPK signaling pathways were analyzed through western blotting. Meanwhile, the time- and dose-dependent expression of associated proteins such as iNOS and COX-2 were detected by western blotting. Furthermore, Compounds 1 and 3 were performed on the NF-κB p65 active site using molecular docking simulation to elucidate the molecular level inhibition mechanism. RESULTS: 20 cassane diterpenoids, including two novel ones (caeminaxins A and B) were isolated from the leaves of C. minax Hance. Caeminaxins A and B possessed a rare unsaturated carbonyl moiety in their structures. Most of the metabolites exhibited potent inhibition effects with IC50 values ranging from 10.86 ± 0.82 to 32.55 ± 0.47 µM. Among them, caeminaxin A inhibited seriously the expression of iNOS and COX-2 proteins and restrained the phosphorylation of MAPK and the activation of NF-κB signaling pathways in BV-2 cells. The anti-neuro-inflammatory mechanism of caeminaxin A has been studied systematically for the first time. Furthermore, biosynthesis pathways for compounds 1-20 were discussed. CONCLUSIONS: The new cassane diterpenoid, caeminaxin A, alleviated the expression of iNOS and COX-2 protein and down-regulated of intracellular MAPK and NF-κB signaling pathways. The results implied that cassane diterpenoids had potential to be developed into therapeutic agents for neurodegenerative disorders such as Alzheimer's disease.

Antibacterial Activity of Two New Cassane Diterpenoids from Caesaplinia pulcherrima against Bacillus cereus by Damage to Cell Membrane.

Bacillus cereus, a Gram-positive bacterium, is a food contaminant that threatens the health of thousands of people around the world. Because of the continuous emergence of drug-resistant strains, the development of new classes of bactericides from natural products is of high priority. In this study, two novel cassane diterpenoids (pulchins A and B) and three known ones (3-5) were elucidated from the medicinal plant Caesaplinia pulcherrima (L.) Sw. Pulchin A, with a rare "6/6/6/3" carbon skeleton, showed significant antibacterial activity against B. cereus and Staphylococcus aureus, with MIC values of 3.13 and 6.25 µM, respectively. Further investigation of its mechanism of antibacterial activity against B. cereus is also discussed in detail. The results revealed that the antibacterial activity of pulchin A against B. cereus may be caused by pulchin A interfering with bacterial cell membrane proteins, affecting membrane permeability and causing cell damage or death. Thus, pulchin A may have a potential application as an antibacterial agent in the food and agricultural industries.

Discovery of diversified cassane diterpenoids as potent antibacterial agents from Caesaplinia pulcherrima and their mechanisms.

BACKGROUND: Natural products play a significant role in the development of novel bactericide candidates. Caesalpinia pulcherrima, a traditional medicine, had anti-inflammatory, antimicrobial, and antifeedant activities, therefore the previous bioassay results of C. pulcherrima implied that its main active ingredients may have potential to be used as botanical bactericides. RESULTS: Bio-guided isolation of C. pulcherrima was conducted to obtain 11 novel cassane diterpenoids (capulchemins A-K) and 10 known sesquiterpenes. Their structures were established by extensive spectroscopic methods and single-crystal X-ray diffraction analyses. Capulchemins A-F possess a rare aromatic C ring, while capulchemin K with a 15,16-degradative carbon skeleton represents a rare group of cassane diterpenes. Capulchemin A exhibited remarkable antibacterial activity against four phytopathogenic bacteria, particularly against Pseudomonas syringae pv. actinidae and Bacillus cereus, with minimal inhibitory concentration values of 3.13 µM. Meanwhile, capulchemin A showed significant control effect on kiwifruit canker in vivo. Further investigation of its mechanism of antibacterial activity revealed that compound 1 was closely related to destroy cell membrane to cause cell death. Additionally, some of those cassane diterpenoids showed potential antifeedant against Mythimna separate walker and Plutella xylostella. Consequently, capulchemin A could have the potential to be used as a template for the development for new eco-friendly NP-based bactericides. CONCLUSION: These data contribute to a better understanding of the antibacterial activity of cassane diterpenes. Cassane diterpenes have been discovered to be leading to broad application prospects in the development as novel botanical bactericides. © 2023 Society of Chemical Industry.

New cassane- and norcassane-type diterpenoids from the seed kernels of Caesalpinia sinensis and their anti-inflammatory activity in vitro.

The first investigation of phytochemistry on the seed kernels of Caesalpinia sinensis led to the isolation and characterization of six new compounds including three tricyclic-type cassane diterpenoids (1--3) and three norcassane-type diterpenoids (4-6), together with three know compounds (7-9). Compounds 1-9 represented the first discovery of cassane-type diterpenoids from C. sinensis. Their structures were elucidated by a combination of spectroscopic analysis, single-crystal X-ray diffraction experiment and ECD calculation. The characters for compounds 4 and 5 possessing the 15,16-degradative cassane skeleton were observed, which was extremely rare structural type in the genus Caesalpinia. The anti-inflammatory activities of all isolates were evaluated via examining their inhibitory effects against NO production in LPS-simulated RAW 264.7 cells. The results demonstrated that compound 1 exhibited the most significantly inhibitory efficacy with inhibition rate 67.3% at 10 µM. The iNOS enzyme activity assay further revealed that compound 1 showed potent NO inhibitory effect by reducing the enzymatic activity of iNOS.

Cassane diterpenoid derivative induces apoptosis in IDH1 mutant glioma cells through the inhibition of glutaminase in vitro and in vivo.

BACKGROUND: Glioblastoma multiforme (GBM) is the most frequent, lethal and aggressive tumour of the central nervous system in adults. The discovery of novel anti-GBM agents based on the isocitrate dehydrogenase (IDH) mutant phenotypes and classifications have attracted comprehensive attention. PURPOSE: Diterpenoids are a class of naturally occurring 20-carbon isoprenoid compounds, and have previously been shown to possess high cytotoxicity for a variety of human tumours in many scientific reports. In the present study, 31 cassane diterpenoids of four types, namely, butanolide lactone cassane diterpenoids (I) (1-10), tricyclic cassane diterpenoids (II) (11-15), polyoxybutanolide lactone cassane diterpenoids (III) (16-23), and fused furan ring cassane diterpenoids (IV) (24-31), were tested for their anti-glioblastoma activity and mechanism underlying based on IDH1 mutant phenotypes of primary GBM cell cultures and human oligodendroglioma (HOG) cell lines. RESULTS: We confirmed that tricyclic-type (II) and compound 13 (Caesalpin A, CSA) showed the best anti-neoplastic potencies in IDH1 mutant glioma cells compared with the other types and compounds. Furthermore, the structure-relationship analysis indicated that the carbonyl group at C-12 and an α, ß-unsaturated ketone unit fundamentally contributed to enhancing the anti-glioma activity. Studies investigating the mechanism demonstrated that CSA induced oxidative stress via causing glutathione reduction and NOS activation by negatively regulating glutaminase (GLS), which proved to be highly dependent on IDH mutant type glioblastoma. Finally, GLS overexpression reversed the CSA-induced anti-glioma effects in vitro and in vivo, which indicated that the reduction of GLS contributed to the CSA-induced proliferation inhibition and apoptosis in HOG-IDH1-mu cells. CONCLUSION: Therefore, the present results demonstrated that compared with other diterpenoids, tricyclic-type diterpenoids could be a targeted drug candidate for the treatment of secondary IDH1 mutant type glioblastoma through negatively regulating GLS.

Pharmacokinetic and tissue distribution studies of cassane diterpenoids, in rats through an ultra-high-performance liquid chromatography-Q exactive hybrid quadrupole-Orbitrap high-resolution accurate mass spectrometry.

Cassane diterpenoids (CA) are considered as the main active constituents of medicinal plants belonging to the Caesalpinia genus. Three cassane derivatives, bonducellpin G (BG), 7-O-acetyl-bonducellpin C (7-O-AC) and caesalmin E (CE), isolated from Caesalpinia minax Hance seeds, showed strong anti-inflammatory activity. In this paper, pharmacokinetics (BG, 7-O-AC, CE) and tissue distribution (7-O-AC, CE) properties were studied for the first time using a reliable, sensitive and rapid UHPLC-Q-Orbitrap HR-MS to develop new anti-inflammatory agents. A novel quantitative method with full scan in positive ion mode was used to determine the contents of compounds. They were separated using acetonitrile-water (0.1% formic acid) as gradient mobile phase. The calibration curve displayed good linearity and the lower limit of quantitation was 0.005-0.02 µg/mL for all analytes. Meanwhile, the absorption, distribution, metabolism, excretion (ADME) property was predicted using PreADMET web. The pharmacokinetic parameters indicated that they were absorbed quickly, eliminated rapidly together with high blood concentration. The results of tissue distribution demonstrated that CE was distributed rapidly and widely among tissues, and stomach was the main tissue site of CE and 7-O-AC, followed by small intestine/liver. This study indicates that the structures and dosages of active CA should be modified to help improve the absorption rate and residence time, and the findings are helpful for the pharmaceutical design of CA derivatives.

Naturally occurring cassane diterpenoids (CAs) of Caesalpinia: A systematic review of its biosynthesis, chemistry and pharmacology.

Natural products, especially diterpenoids, are enriched with numerous compounds with a broad spectrum of therapeutic indications, suggesting that functional moieties serve as a core pharmacophore. Cassane diterpenoids (CAs), as the main and characteristic constituents of medical plants in the Caesalpinia genus, have been widely studied due to their bioactivities, and >450 compounds have been reported since the 1960s, including 283 compounds that have been reported in the past decade. There are five main types of structures for these compounds: tricyclic cassane diterpenoids with a fused furan ring (I) or butanolide lactone (II), tricyclic cassane diterpenoids (III), norcassane diterpenoids (IV), and other types (V). CAs derivatives have a wide range of biological properties, including anti-inflammatory, antimalarial, antitumour, antiviral, antimicrobial, antinociceptive, and antioxidant effects. This review highlights the role of the biosynthetic pathway, including those with abnormal skeletons, as well as advances in structure, pharmacological activities and primarily mechanisms of CAs obtained from the Caesalpinia genus. The findings herein provide new insights into the development of this kind of natural diterpenoids.

Caesalminaxins O-T, cassane diterpenoids from the seeds of Caesalpinia minax and their anti-inflammation.

Six previously undescribed cassane diterpenoids, named caesalminaxins O-T (1-6), together with 28 known compounds (7-34), were isolated from the seeds of Caesalpinia minax Hance. Their structures, including their absolute configurations were elucidated by extensive spectroscopic analysis, X-ray diffraction, and quantum chemical calculations. Among the undescribed diterpenoids, compound 6 that possessed an unusual enol group at C-7 with a highly deshielded 1H NMR signal was the first example in cassane diterpenoids. All of the isolates were evaluated for their inhibitory activity against lipopolysaccharide-activated NO production in RAW264.7 cells. Compound 16 showed moderate inhibitory activity with an IC50 value of 17.3 µM, which was more potent than the positive control (indomethacin, IC50 = 29.7 µM).

Simultaneous identification and analysis of cassane diterpenoids in Caesalpinia minax Hance by high-performance liquid chromatography with quadrupole time-of-flight mass spectrometry.

Cassane diterpenoids were successfully and simultaneously identified in Caesalpinia minax Hance by high-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry. A total of 59 peaks were detected, and among them 51 compounds, including 41 furanocassane diterpenoids, 10 furanolactone cassane diterpenoids were simultaneously identified and characterized on the basis of the protonated molecule, retention behavior, and fragments in MS(2) . Ten compounds, including seven novel compounds, were identified or tentatively identified for the first time in C. minax. In a positive ion mode, the fragmentation pathways of cassane diterpenoids were also analyzed for the first time. The relative amounts of the five main diterpenoids (caesalpinin L, caesalpinin F2 , bondcellpin C, caesalpinin E, and ξ-caesalmin) were simultaneously quantified by high-performance liquid chromatography. Results showed that the newly discovered and known components of C. minax can be used to determine the material basis of bioactivity; this method can also be applied to analyze cassane diterpenoids in herbal medicines from the genus Caesalpinia belonging to the family Fabaceae.

Cassane-type diterpenoids from the seed kernels of Caesalpinia bonduc.

Seven new cassane diterpenoids (1-7), along with three known compounds (8-10), were isolated from the seed kernels of Caesalpinia bonduc. The structures were elucidated by extensive 1D and 2D NMR (HSQC, HMBC and ROESY) and mass (HRESIMS) spectroscopic data analyses. The structure and absolute configuration of compound 1 were confirmed by a single-crystal X-ray diffraction experiment. All isolates were tested for their cytotoxicity against HepG-2, MCF-7 and MG-63 cells, and 8-10 showed weak inhibitory activities.