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Seven new cassane-type diterpenoids, echinalides A-G (1-7), were isolated from the stem of Caesalpinia echinata LAM. (Leguminosae). The structures were established on the basis of their chemical properties and spectroscopic evidence, including two dimensional (2D)-NMR analysis. These compounds were assessed for inhibitory activity against nuclear factor κB (NF-κB). Echinalides C and D, in particular, significantly inhibited NF-κB-responsive reporter gene expression at 5.0 µM, an effect almost equivalent to that of parthenolide, a known potent inhibitor of NF-κB.

Six new cassane diterpenoids, named caesalls H-M (1-6), were isolated from the seed kernels of Caesalpinia bonduc. Their structures were elucidated on the basis of spectroscopic analysis, mainly NMR and MS. The absolute configurations of compounds 1 and 3 were determined by a single-crystal X-ray study using a mirror CuKα radiation and circular dichroism (CD) spectra, respectively. None of the compounds were cytotoxic against HepG-2, MCF-7 and MG-63 cells.

Four new cassane-type diterpenes, Neocaesalpin S (1), Neocaesalpin T (2), Neocaesalpin U (3), and Neocaesalpin V (4) were isolated from Caesalpinia minax HANCE together with seven known compounds Neocaesalpin A (5), Neocaesalpin K (6), Neocaesalpin L (7), Neocaesalpin M (8), Neocaesalpin O (9), Neocaesalpin MP (10), and Magnicaesalpin (11). Their structures were elucidated on the basis of 1D- and 2D-NMR, MS, and circular dichroism (CD) analysis. Compounds 1-4 were tested against liver cancer (HepG-2) and breast cancer (MCF-7), and showed mild antiproliferative activity.

One new homoisoflavonoid, (3E)-2,3-dihydro-6,7-dimethoxy-3[(3-hydroxy-4-methoxyphenyl)methylene]-4H-1-benzopyran-4-one and four naturally new analogues, (3E)-3-(1,3-benzodioxol-5-ylmethylene)-2,3-dihydro-7-hydroxy-4H-1-benzopyran-4-one, (3E)-3-(1,3-benzodioxol-5-ylmethylene)-2,3-dihydro-7-methoxy-4H-1-benzopyran-4-one, (3E)-2,3-dihydro-7-hydroxy-3-[(3-hydroxy-4-methoxyphenyl)methylene]-4H-1-benzopyran-4-one and (3E)-2,3-dihydro-3-[(3,4-dimethoxyphenyl)methylene]-7-methoxy-4H-1-benzopyran-4-one, along with four known homoisoflavonoids, bonducellin, sappanone A, 2'-methoxybonducellin and 7-O-methylbonducellin were isolated from aerial parts of Caesalpinia pulcherrima. The structures of the new compounds were elucidated by interpretation of their 1D and 2D NMR spectra. Syntheses of the naturally new compounds and the known compounds have also been accomplished. The antibacterial and antifungal activities of the isolated homoisoflavonoids were studied.

Chemical examination of the stems of Caesalpinia millettii HOOK. et ARN. led to the isolation of new flavonol glycoside caffeiate ester (1) and homoisoflavone (2), along with four known homoisoflavones: eucomin (3), bonducellin (4), 8-methoxybonducellin (5) and intricatinol (6). The structures of 1 and 2 were established to be tamarixetin 3-O-(6''-O-E-caffeoyl)-beta-D-galactopyranoside (1) and (Z)-7-hydroxy-8-methoxy-3-(4-methoxybenzyl) chroman-4-one (2) on the basis of detailed analyses of physical, chemical, and spectral data. Compounds 3-6 were isolated from this plant for the first time.

Glutathione S-transferase inhibition assay-guided fractionations on the ethanolic extract of the bark of Caesalpinia bonduc resulted in the isolation of a new sterol, 17-hydroxy-campesta-4,6-dien-3-one (1) along with four known compounds, 13,14-seco-stigmasta-5,14-dien-3alpha-ol (2), 13,14-seco-stigmasta-9(11),14-dien-3alpha-ol (3), caesaldekarin J (4) and pipataline (5) as active constituents. Structures of compounds 1-5 were established on the basis of extensive NMR spectroscopic studies. The compounds (1-5) were isolated on the basis of their inhibitory activity against glutathione S-transferase, an enzyme that has been implicated in resistances during treatment of cancer and parasitic infections. Efforts to study structure-activity relationships of compounds 2 and 3 were also made by modifying their structures. The IC50 values of these compounds and their derivatives ranged from 57-380 microM and were compared to the inhibitory effects due to sodium taurocholate, an isoprene-derived GST inhibitor (IC50=398 microM). A plausible biosynthesis of 13,14-seco-steroids has also been proposed.

Two new homoisoflavonoids, (E)-7-methoxy-3-(4'-methoxybenzylidene)chroman-4-one (1) and (E)-7-hydroxy-3-(3',4',5'-trimethoxybenzylidene)chroman-4-one (5), along with three known homoisoflavonoids (Z)-7-hydroxy-3-(4'-methoxybenzylidene)chroman-4-one (isobon ducellin) (2), (E)-7-hydroxy-3-(4'-methoxybenzylidene)chroman-4-one (bonducellin) (3) and (E)-7-hydroxy-3-(2',4'-dimethoxybenzylidene)chroman-4-one (4) were isolated from the whole plant of Caesalpinia pulcherrima. The structures of these new compounds were elucidated by electron impact mass spectrometry (EI-MS) and 1D and 2D-NMR spectral studies. Antimicrobial activity of the new compounds was evaluated.

Ten new furanocassane-type diterpenes named, caesalpinins H-P (1-9) and norcaesalpinin F (10), were isolated from the CH(2)Cl(2) extract of the seed kernels of Caesalpinia crista, together with 13 known diterpenes. Their structures were determined based on the spectroscopic analysis. Among the isolated compounds, caesalpinin N (7) represents the first example of furanocassane-type diterpene possessing an aldehyde group at C-14.

From the CH2Cl2 extract of seed kernels of Caesalpinia crista from Myanmar, two rare and biogenetically interesting methyl migrated cassane-type furanoditerpenes [caesalpinins MM (1) and MN (2)] and two normal cassane-type furanoditerpenes [caesalpinins MO (3) and MP (4)] have been isolated, together with eight known cassane-type diterpenes, 1-deacetoxy-1-oxocaesalmin C (5), 1-deacetylcaesalmin C (6), caesalmin C (7), bonducellpin C (8), caesaldekarin e (9), 2-acetoxycaesaldekarin e (10), 2-acetoxy-3-deacetoxycaesaldekarin e (11), and norcaesalpinin E (12). Among the known compounds, compounds 5 and 6 were for the first time isolated from a natural source. The structures of these compounds were elucidated by the use of spectroscopic techniques.

From the MeOH extract of Vietnamese Caesalpinia sappan, a novel biogenetically exclusive benzindenopyran, with a new carbon framework, neoprotosappanin (1), and a new compound, protosappanin A dimethyl acetal (3), were isolated together with protosappanin E-2 (2), neosappanone A (4), and 13 previously reported phenolic compounds (5-17). Their structures were elucidated on the basis of spectroscopic data. Compounds 1-4, 7, 13, and 15-17 showed significant xanthine oxidase inhibitory activity in a concentration-dependent manner, and sappanchalcone (17) showed the most potent activity with an IC50 value of 3.9 microM, comparable to that of positive control allopurinol (IC50, 2.5 microM). The kinetic study of these inhibitors indicated that they are competitive inhibitors, the same as allopurinol, except for 1 and 16 which are noncompetitive inhibitors.

A new cassane diterpenoid, caesaldecan, was isolated from Caesalpinia decapetala with eight known compounds, spathulenol, 4,5-epoxy-8(14)-caryophyllene, squalene, lupeol, trans-resveratrol, quercetin, astragalin, and stigmasterol. The (1)H- and (13)C-NMR spectra of the new compound were completely assigned by using a combination of 2D NMR techniques, namely, (1)H-(1)H COSY, HMQC, HMBC, and ROESY.

Seven new cassane-type diterpenes, caesalpinin MF-ML (1-7), and a new norcassane-type diterpene, norcaesalpinin MD (8), have been isolated from the CH2Cl2 extract of seed kernels of Caesalpinia crista from Myanmar, together with sixteen known cassane-type diterpenes, 7-acetoxybonducellpin C, caesaldekarin e, caesalmin C, caesalmin G, 2-acetoxycaesaldekarin e, zeta-caesalpin, caesalpinin D, caesalpinin E, caesalpinin F, caesalpinin H, caesalpinin I, caesalpinin J, caesalpinin K, caesalpinin M, caesalpinin N, and caesalpinin O. The structures of the isolated compounds were elucidated by the use of spectroscopic techniques.