Cassane-type diterpenoids from the seed kernels of Caesalpinia bonduc

Botany, traditional usages, phytochemistry, pharmacology, and toxicology of Guilandina bonduc L.: a systematic review

Guilandina bonduc L. is popularly known as a fever nut that grows widely in evergreen forests and moist deciduous forests with a pantropical distribution. The plant is highly therapeutic in various systems of medicine, including Ayurveda, Siddha, and homeopathy. The purpose of this review is to analyze the published data on G. bonduc, including traditional uses, taxonomic position, botanical description, phytochemistry, pharmacological properties, and toxicological assessment of its various parts. Phytochemical and pharmacological studies were the main focus of this review. The previously published research on G. bonduc was tracked from scientific databases such as Online Library, Google, Taylor and Francis, PubMed, Research Gate, Scopus, Springer, Wiley, Web of Sciences. Numerous phytochemical, pharmaceutical, and pharmacological studies have been carried out on the various parts of G. bonduc. To date, more than 97 phytochemicals have been isolated from the leaves, roots, stems, stem bark, flowers, twigs, and seeds of this plant. The phytochemicals isolated from the plants are flavonoids, homoisoflavonoids, terpenoids, diterpenoids, steroids, fatty acids, alkanes, acids, phenols, ketones, esters, amides, azides, silanes, and ether groups. This plant has been extensively studied in in vitro and in vivo pharmacological experiments, where it showed analgesic, anti-inflammatory, antioxidant, antiviral, antidiabetic, abortive, anticataleptic, immunomodulatory, and antiestrogenic effects. This comprehensive review revealed that phytochemicals isolated from various parts of G. bonduc have significant therapeutic efficacy, with promising anticancer, antidiabetic, hepatoprotective, antioxidant, and antimicrobial activities. This review provides a good source of information for the development of a drug using modern scientific tools, in view of its underexplored traditional uses. Further studies on preclinical and clinical trials and toxicological studies on the bioactive molecules of G. bonduc to validate its traditional uses are warranted.

New cassane-type alkaloids and diterpenoids from the pericarps of Caesalpinia bonduc

The phytochemical investigation of the pericarps of Caesalpinia bonduc led to the isolation and identification of five new cassane-type alkaloids: caesalminines C - G (1-5) and six new diterpenoids: caesalbonducin K - P (6-11), along with seven known compounds (12-18). Compounds 1-5 were identified as a group of rare alkaloids possessing a tetracyclic cassane-type diterpenoid skeleton with a lactam D-ring instead of a typical furan or lactone moiety. The structures of 1-11 were elucidated on the basis of 1D and 2D NMR including HSQC, HMBC, COSY and NOESY, and other spectroscopic analyses. The cytotoxic activities of the isolated compounds were evaluated in the A431, A549 and U87MG cancer cell lines.

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.

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.

Administration of Caesalpinia bonduc Seed Extracts Ameliorates Testosterone-Induced Benign Prostatic Hyperplasia (BPH) in Male Wistar Rats

Introduction

Benign prostatic hyperplasia (BPH) is a major chronic disease affecting men, and the therapeutic agents currently used to manage it have significant side effects. As a result, an alternative medicine with improved therapeutic properties with no side effects is desperately needed. The current investigation aims to study whether the Caesalpinia bonduc seed extracts (ethanolic-A, hydroalcoholic-B, and aqueous-C) have inhibitory potential on testosterone propionate (TP)-induced BPH in Wistar rats.

Methods

Wistar rats (male) were randomly allocated to one of five groups: control, BPH (TP-3 mg/kg, subcutaneously daily), low dose (TP + C. bonduc seed extracts – 200 mg/kg body weight), high dose (TP + C. bonduc seed extracts – 400 mg/kg body weight), and standard drug (TP + finasteride – 10 mg/kg body weight). At the end of drug treatment, the rats were sacrificed and their serum and prostates were taken for biochemical and histological studies.

Results

C. bonduc seed extracts treatment significantly decreased prostate weight and prostatic index in rats with TP-induced BPH. The seed extracts exhibited a potent inhibitory effect on dihydrotestosterone (DHT) in serum and prostate. In addition, the PSA level in the serum showed a noteworthy decrease in comparison with the BPH group. Histopathological examination also indicated that extracts improved the tissue morphology of the prostate significantly. Out of three extracts tested, ethanolic and hydroalcoholic extract recorded significant effect. Finally, liquid chromatography quadrupole time-of-flight mass spectrometry (LC/MS-QTOF) analysis showed that the major compounds present in the extracts were tocopherols, fucosterol, linoleic acid, β-amyrin, β-sitosterol, campesterol, cassane furanoditerpene, norcassane furanoditerpene and other diterpenes.

Conclusion

Thus, C. bonduc seed extracts could be a potential source for the formulation of new drug for managing BPH. To the best of our knowledge, this is the first scientific animal investigation into the use of C. bonduc seed extract for the management of BPH.

Cassane-Type Diterpenoids from the Seeds of Caesalpinia bonduc (L.) Roxb

Ten new cassane-type diterpenoids were isolated from the seeds of Caesalpinia bonduc (L.) Roxb., including 6α-hydroxycaesalpinin P (1), 14-epi-caesalpinin E1 (2), 6-deacetylcaesalmin Z (3), 14-epi-caesalmin Z (4), caesalpinolides I (5), K (6), L (7), M (9) and N (10), and 14-epi-neocaesalpin L (8). Their planar structures and absolute configurations were fully determined by comprehensive spectroscopic methods, including 2D NMR and electronic circular dichroism spectra. Compounds 1-4 are tetracyclic cassane diterpenoids possessing a furan ring, and compounds 5-10 are tetracyclic cassane diterpenoids possessing a fused butenolide moiety. The anti-inflammatory and cytotoxic activities of the isolates were evaluated, while none of them showed obvious effects. The current study identified ten new cassane-type diterpenoids from the seeds of C. bonduc (L.) Roxb., which enriched the chemical diversity of the titled herbal medicine.

Acid-catalyzed transformation of cassane diterpenoids from Caesalpinia bonduc to aromatic derivatives

Transformations of cassane diterpenoids from Caesalpinia bonduc into aromatic derivatives, either in CDCl3 or in CHCl3 irradiated with UV light or catalyzed by AlCl3, were described. Caesalmin C (2) was hydrolyzed with Na2CO3 upon refluxing in MeOH to yield compound 1. Dissolving compound 1 with CDCl3 resulted in an unexpected aromatization process of a C ring to obtain 1a, and aromatic derivatives 6-acetoxy-3-deacetoxycaesaldekarin e (2a), caesall A (3a), caesaldekarin e (5a), caesalpinin MC (5b), 2-acetoxycaesaldekarin e (6a) and new compound 6b could be obtained from corresponding cassane diterpenoids (2-8) under the same conditions. Furthermore, the photochemical reactions of cassane diterpenoids 1-8 occurring in CHCl3 also yielded aromatic derivatives 1a, 2a, 3a, 5a, 6a, new compounds 2b and 3b, and 17-norcassane diterpenoids norcaesalpinin MC (2c) and caesalmin J (3c). In addition, cassane diterpenoids 1-8, treated with AlCl3 in CHCl3 or CH2Cl2, gave the same results in CDCl3 and with even shorter reaction time. The role of AlCl3 in the aromatization of 1 has been explained by DFT calculations.

Four new cassane-type diterpenoids from the seed kernels of Caesalpinia cucullata Roxb

The first investigation of chemical composition in seed kernels of Caesalpinia cucullata Roxb. resulted in the separation of four new cassane diterpenes, including three furanoditerpenes (1, 2 and 4) and one tricyclic type (3). It was the first found cassane diterpenoids from this plant. Their gross structures were elucidated by means of comprehensive spectroscopic analysis (UV, IR, NMR, HRESIMS) as well as electronic circular dichroism (ECD) calculation. The compound 1 possess a rare isomerized dihydrofuran ring in structure framework. In bioassay, compounds 1-4 exhibited moderate anti-inflammatory activity by inhibiting production of NO in LPS-induced RAW 264.7 cells.

Two new cassane-type diterpenoids from the seed kernels of Caesalpinia bonduc (Linn.) Roxb. and their anti-inflammatory activity

In this study, phytochemical investigation on the chloroform soluble fraction of seed kernels of Caesalpinia bonduc led to the isolation of two new cassane-type diterpenoids, norcaesalpinin Q (1) and caesalpinin MR (2), together with seven known compounds (3-9). The structures of the new compounds were elucidated on the basis of extensive NMR spectroscopic and mass spectrometric analyses, and their absolute configurations were determined by electronic circular dichroism (ECD) calculations. All compounds were evaluated for inhibitory effects against NO production of RAW264.7 cells induced by LPS, and compounds 5, 7 and 8 could inhibited the production of NO at the concentration of 50 µM.

Bioassay-guided Isolation of Flavonoids from Caesalpinia bonduc (L.) Roxb. and Evaluation of Their Cytotoxicity

Cancer is one of the most important causes of death all around the world. Screening plants and their secondary metabolites as cytotoxic agents is one of the common methods for identifying new compounds used in chemotherapy and inhibition cancer process. Caesalpinia bonduc (L.) Roxb. from the Fabaceae family was used for improving wound, fever, tumor, hydrocele, hernia, smallpox, toothache, inflammation, and as astringent, anthelmintic, antidiabetic, and antimalarial agent in traditional medicine. A bioassay-guided study of this species led to the isolation of three flavonoids. At first, the cytotoxicity of methanol extract of aerial parts (leaves and stems), seeds, and legumes of this plant was tested against MCF-7 and PC-3 by MTT assay. The methanol extract of legumes showed better inhibitory activities (IC50 < 500 µg/mL). As a result, this extract was selected for fractionation. In the next step, the ethyl acetate (EtOAc) fraction was selected for phytochemical analysis based on the inhibitory activity (IC50 = 170 ± 0.9 µg/mL). In this way, total phenol content (625 ± 7.2 GAE/g extract) and antioxidant activity (IC50 = 6.1 ± 0.3 µg/mL) was compared by BHT (IC50 = 13.5 ± 0.7 µg/mL). Finally, three compounds including, quercetin-3-methyl ether (1), kaempferol (2), and kaempferol-3-O-α-L-rhamnopyranosyl-1→2)-β-D-xylopyranoside (3) were isolated from EtOAc fraction, and all isolated compounds were tested for their cytotoxicity and compound 1 showed better inhibitory activity than other two compounds. This study suggests that Caesalpinia bonduc could be considered for further investigations as a natural source of biological compounds.

Anti-proliferative cassane-type diterpenoids from the seeds of Caesalpinia minax

The seeds of Caesalpinia minax Hance have shown anti-tumor potential, while the chemical principle is still unknown. In a search for anti-tumor compounds, six new cassane-type diterpenoids, 12-demethylcaesalpin G (1), caesalpinolide H (2), 12-demethylcaesalpin H (3), caesalpinolide J (4), 12-O-ethyl neocaesalpin B (5), and 3-deacetyldecapetpene B (6), were isolated from the seeds of C. minax Hance, along with fifteen known analogues. The structures of the new compounds were established by means of spectroscopic techniques (NMR, HRESIMS and IR). The absolute configurations of the new compounds were determined by their ECD spectra. All of the new compounds were tested for their anti-proliferative activity against human lung cancer A549 cells, breast cancer MCF-7 cells, and ovarian cancer HEY cells. The results indicated that only compound 6 displayed moderate cytotoxicity against three cancer cell lines. Thus, the opening of furan ring in cassane-type diterpenoids might enhance the cytotoxic activity.

Potential Anti-Cancer Flavonoids Isolated From Caesalpinia bonduc Young Twigs and Leaves: Molecular Docking and In Silico Studies

Tyrosine kinase (TK), vascular endothelial growth factor (VEGF), and matrix metalloproteinases (MMP) are important cancer therapeutic target proteins. Based on reported anti-cancer and cytotoxic activities of Caesalpinia bonduc, this study isolated phytochemicals from young twigs and leaves of C bonduc and identified the interaction between them and cancer target proteins (TK, VEGF, and MMP) in silico. AutoDock Vina, iGEMDOCK, and analysis of pharmacokinetic and pharmacodynamic properties of the isolated bioactives as therapeutic molecules were performed. Seven phytochemicals (7-hydroxy-4′-methoxy-3,11-dehydrohomoisoflavanone, 4,4′-dihydroxy-2’-methoxy-chalcone, 7,4′-dihydroxy-3,11-dehydrohomoisoflavanone, luteolin, quercetin-3-methyl, kaempferol-3-O-β-d-xylopyranoside and kaempferol-3-O-α-l-rhamnopyranosyl-(1 → 2)-β-D-xylopyranoside) were isolated. Molecular docking analysis showed that the phytochemicals displayed strong interactions with the proteins compared with their respective drug inhibitors. Pharmacokinetic and pharmacodynamic properties of the compounds were promising suggesting that they can be developed as putative lead compounds for developing new anti-cancer drugs.

Cassane Diterpenoids from the Pericarps of Caesalpinia bonduc

Ten new cassane-type diterpenoids, caesalbonducins D-F (1-3), 6-deacetoxybonducellpin B (4), 3-acetoxy-α-caesalpin (5), 2(3)-en-α-caesalpin (6), 1α-hydroxycaesalpinin J (7), 1α-hydroxy-6-decaetoxysalpinin J (8), 6α-hydroxycaesall M (9), and 6α-hydroxy-14(17)-dehydrocaesalpin F (10), along with eight known compounds (11-18), were isolated from the pericarps of Caesalpinia bonduc. Compounds 1-3 and 11 are methyl-migrated cassane-type diterpenoids with a 19(4→3)-cassane skeleton. The structures of 1-10 were elucidated on the basis of 1D and 2D NMR methods and other spectroscopic analysis. The neuroprotective effects of the isolated compounds were evaluated.

Diterpenoids of terrestrial origin

This review covers the isolation and chemistry of diterpenoids from terrestrial as opposed to marine sources and includes, labdanes, clerodanes, pimaranes, abietanes, kauranes, gibberellins, cembranes and their cyclization products. The literature from January to December, 2014 is reviewed.