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

A new cassane diterpenoid from the seed of Caesalpinia sappan

In this study, a previously undescribed cassane diterpenoid, named caesalpinin JF (1), along with two known cassane diterpenoids caesanine C (2) and tomocinol B (3), was isolated from 95% EtOH extract of the seeds of Caesalpinia sappan Linn. Additionally, three known compounds including pulcherrin R (4), syringaresinol-4'-O-β-D-glucopyranoside (5) and kaempferol (6) were also identified. The structures of the isolated compounds were elucidated by comprehensive 1D and 2D NMR spectroscopic analyses. Additionally, electronic circular dichroism (ECD) calculation was used to identify the absolute structure of compound 1. Among the isolated compounds, compound 1 displayed a potent anti-neuroinflammation with an IC50 value of 9.87 ± 1.71 μM.

Two new cassane diterpenoids from the seed kernels of Caesalpinia sinensis

Two new cassane diterpenoids, sucupiranin MN (1) and sucupiranin ML (2), together with two known compounds sucutinirane C (3) and deacetylsucutinirane C (4) were isolated from the seed kernels of Caesalpinia sinensis. Their structures were elucidated by means of analysis of comprehensive spectroscopic data, especially HRESIMS and 1D/2D NMR spectroscopy. Compounds 1-4 are typical furan-type cassane derivatives with an aromatized C ring. Biological evaluation revealed that compounds 1-4 at the concentration of 10 μM could inhibit the overproduction of NO in LPS-stimulated RAW 264.7 macrophages.

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.

Two new norcassane-type diterpenoids from Mezonevron sinense Hemsl

Two new norcassane-type diterpenoids, named 6β-hydroxy-bisnorcass-13-en-12-one (1) and 6β-hydroxy-bisnorcassan-12-one (2), were isolated from the seeds of Mezonevron sinense Hemsl. The structures of compounds 1-2 were determined by extensive spectroscopic analysis. Two compounds exhibited immunosuppressive activity with the IC₅₀ values of 19.35 ± 0.87 μM and 18.69 ± 0.88 μM in the ConA induced T cell model and 65.04 ± 0.83 μM and 48.06 ± 0.76 μM in LPS induced B cell model, respectively.

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 ± 0.47μM. 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.

Three new cassane-type diterpenoids from Caesalpinia sinensis

Three new cassane-type diterpenoids, namely, (4S)-6β,12α,19-trihydroxy-cass-13(15)-en-16,12-olide (1), cass-13(15)-en-​16,12-olide (2), and 12α-hydroxy-cass-13(15)-en-16,12-olide (3), were isolated from the seeds of Caesalpinia sinensis. The structures of 1-3 were established by extensive spectroscopic analysis, and their absolute configurations were assigned by electronic circular dichroism (ECD) calculations. The inhibitory activities against PTP1B of the isolated compounds were evaluated. The results showed that compound 2 possessed PTP1B inhibitory activity with an IC₅₀ value of 217.45 ± 36.4 μM.

3-Deoxysappanchalcone isolated from Caesalpinia sinensis shows anticancer effects on HeLa and PC3 cell lines: invasion, migration, cell cycle arrest, and signaling pathway

To study the antitumor activity of compound 3-desoxysulforaphane (3-DSC) isolated from Caesalpinia sinensis, SRB assay, clone formation assay, flow cytometric cell cycle assay, scratch assay, transwell assay, and molecular docking were used to investigate the inhibitory effect of 3-DSC on HeLa and PC3 cells. The results showed that 3-DSC inhibited the cell migration and invasion by down-regulating expression of N-cadherin, Vimentin, MMP-2, and MMP-9 in HeLa and PC3 cells; It also inhibits cell proliferation by promoting the expression of CDK1 (cyclin-dependent kinases 1) and CDK2 (cyclin-dependent kinases 2), which arrests the tumor cell cycle at G2 phase. 3-DSC inhibits phosphorylation of AKT and ERK and upregulates the expression of the tumor suppressor gene p53. Molecular docking results confirmed that 3-DSC could bind firmly to AKT. In conclusion, 3-DSC inhibited the proliferation, migration and invasion of HeLa and PC3 cells.

Isolation and structure elucidation of two new cassane derivatives from the seed kernels of Caesalpinia sinensis

Two new cassane-type derivatives (1-2), together with three known compounds (3-5), were isolated from the seed kernels of Caesalpinia sinensis. Their structures were elucidated on the basis of interpretation of comprehensive spectroscopic data, including HRESIMS and 1D/2D NMR spectroscopy, and the absolute configuration were established by means of ECD calculation. Compound 2, possessing a 16-degradative cassane skeleton, was rarely encountered in cassane diterpenoids isolated from the genus Caesalpinia. All compounds were evaluated for their anti-inflammatory activities against the overproduction of NO in LPS-stimulated RAW 264.7 macrophages, and compounds 1-5 could inhibit production of NO at the concentration of 50 μM.

Study on the chemical composition of Caesalpinia sinensis

Five compounds were isolated from the methanolic extract of Caesalpinia sinensis stems and leaves including a new cassane-type butenolide norditerpenoid compound (1) and a new type of biphenyl compound (2); the compounds were identified as Norcaesalpin-one (1), 4'-hexyl 3-methyl 6-methoxy-[1,1'-biphenyl]-3,4'-dicarboxylate (2), rhapontigenin (3), 3-deoxysappanchalcone (4), isoliquiritigenin (5). Compounds 1-5 were first isolated from C. sinensis. Their structures were elucidaded on the basis of MS, IR, NMR spectroscopic, X-ray diffraction data analyses. The NGF-induced PC12 differentiation assay was performed on compound 1, and the results showed that compound 1 had a promotive effect on PC12 cell differentiation, with a differentiation rate of 12.32%. In addition, compounds 1-5 were evaluated for their cytotoxic activities against four human cancer cell lines (including A-549, BGC-823, MDA-MB-231, HepG2), and the results showed that compounds 3-5 showed inhibitory activity against these cancer cell lines with IC₅₀ values ranging from 22.96 to 74.92 μmol/L, compound 4 showing the best activity against human malignant melanoma cells A375 with an IC₅₀ value of 22.96 μmol/L.

Cassane diterpenoids from Caesalpinia pulcherrima and their anti-inflammatory and α-glycosidase inhibitory activities

Three undescribed cassane-type diterpenoids (CAs), caesalpulcherrins K-M (1-3), together with three known ones (4-6) were isolated from the aerial parts of Caesalpinia pulcherrima (L.) Sw (Fabaceae). Their structures were elucidated via analysis of NMR (1 D and 2 D) and HRESIMS data. The character for caesalpulcherrin K possessing the olefin bond at C-11 and C-12 in its cassane skeleton was observed, which belonged to a small group among more than 450 CAs. That is, only fifteen derivatives have been reported up to now, to our knowledge. Biological evaluation revealed that compounds 1-6 exhibited moderate anti-inflammatory activity, with an IC₅₀ value from 6.04 ± 0.34 to 8.92 ± 0.65 μM. Furthermore, compounds 5 and 6 exhibited significant α-glucosidase inhibitory activity at 10 μM.