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Homoisoflavone contains 16 carbon atoms in the skeleton. The homoisoflavonoid skeleton from natural products can be roughly divided into 13 kinds, among which 5 kinds of common skeletons contain a large amount of compounds and 8 kinds of abnormal skeletons comprise a small amount of compounds. In this article, the structure identification experience of homoisoflavonoids found in Caesalpinia mimosoides was used as references and an efficient 1 H NMR spectroscopic method for identifying homoisoflavonoid structure has been established. Using the chemical shift differences of H-2, 3, 4 and 9, the common natural homoisoflavonoids can be quickly and conveniently determined.

Three new cassane-type diterpenoids, namely, (4 S )-6 β ,12 α ,19-trihydroxy-cass-13(15)-en-16,12-olide ( 1 ), cass-13(15)-en-​16,12-olide ( 2 ), and 12 α -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 IC 50 value of 217.45 ± 36.4 μM.

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.

Plant-derived natural products have been the highly significant sources of novel antitumor agents. The cassane-type diterpenes of genus Caesalpinia have been reported to bear antiproliferative activities toward different types of cancer cells. In this study, we evaluated the antineoplasmic activities of 16 natural origin cassane-type diterpenes isolated from the CHCl 3 extract of the seeds of C. minax in pituitary adenomas cells and identified caesalpin G (CAG) showed the strongest cytotoxicity. Moreover, we further investigated the structure-activity relationship and molecular mechanism of these derivatives systematically. The results confirmed the unsaturated lactone-type ring, hydroxyl at C-7, and alkenyl at C-11 or C-14 functionality as critical for anticancer activity in this family of natural products. In addition, the mechanism experiments also demonstrated unfolded protein response and ER stress and Wnt/β-catenin pathway were involved in the CAG-induced apoptosis.

Phytochemical investigation on the seeds of Caesalpinia decapetala led to the isolation of a new cassane diterpenoid with an unusual O bridge between C-19 and C-20, named phanginin Q (1), together with three known cassane diterpenoids, caesaljapin (2), caesaldekarin A (3), and caesaldekarin B (4). The structure of the new compound was elucidated by spectroscopic methods, including (1)H NMR, (13)C NMR, HSQC, (1)H - (1)H COSY, HMBC, NOESY, and HR-ESI-MS.

Two new homoisoflavans, 4'-hydroxy-7-methoxy-3-benzyl-2H-chromene (1) and 3,4-cis-di-O-3-hydroxy-7-methoxy-3-(4-hydroxybenzyl)-4-ethoxychroman (2), one new coumarin, 7-methoxy-3-(4-hydroxybenzyl)coumarin (4), together with seven known phenolic compounds, bonducellin (3), anemarcoumarin A (5), (+)-syringaresinol (6), curuilignan D (7), scopoletin (8), and p-hydroxybenzaldehyde (9), were isolated from Tara (Caesalpinia spinosa Kuntze). The structures of the new compounds were characterized from their 1D and 2D NMR spectral data. All the compounds were isolated from this plant for the first time.

Molecules with diterpene skeletons often possess valuable medicinal properties. Two new diterpenes 1α,6α,7β-triacetoxy-5α-hydroxy-14β-ethyl-O-vouacapane (1) and 2α-acetoxy-14,15-cyclopimara-7β,16-diol (2) were isolated from the seeds of Caesalpinia minax Hance. Their structures were established on the basis of extensive spectroscopic analyses, including HR-ESI-MS, UV, IR, 1D, and 2D NMR (HSQC, HMBC, NOESY) methods. The stereochemical structure of 1 was confirmed via the circular dichroism spectrum and calculated ECD experiment. The inhibitory activity of nitric oxide production of RAW264.7 macrophages stimulated by lipopolysaccharide of compounds 1 and 2 was evaluated, and compound 1 was found to show significant inhibitory effect.

Two new cassane-type diterpenes, phangininoxys D and E (1 and 2), together with five known compounds were isolated from the seeds of Caesalpinia crista Linn. The structures of these compounds were elucidated by means of various spectroscopic analyses. All the isolated compounds were evaluated for cytotoxicity activities against HeLa, HT-29 and KB cell lines, and compound 7 showed moderate selective activities against KB cell line with an IC50 value of 17.1 μM.

Cassane-type diterpenes are main bioactive constituents of Caesalpinia minax HANCE. As a part of our ongoing chemical investigation of C. minax, two new degradative cassane-type diterpenes, named caesalpins I (1) and J (2), were isolated from the EtOAc extract of the seeds of C. minax. The structures were elucidated by means of spectroscopic analysis.

Two new cassane-type diterpenes, neocaesalpin MR and minaxin C, were isolated from Caesalpinia minax HANCE. The structures of these compounds were elucidated by means of spectroscopic analysis. Among these isolated compounds, neocaesalpin MR showed mild activities toward HeLa and colon cancer (HCT-8) human cancer cell lines.

Three new cassane-diterpene-lactones, methyl 1α,7β-diacetoxy-5α,12α-dihydroxy-cass-13(15)-en-16,12-olide-17β-carboxylate (1), methyl 7β-acetoxy-1α,5α,12α-trihydroxy-cass-13(15)-en-16,12-olide-17β-carboxylate (2), and 12α-ethoxyl-1α,6α,7β-triacetoxy-5α,14β-dihydroxy-cass-13(15)-en-16,12-olide (3), were isolated from the seeds of Caesalpinia minax Hance. Their structures were established on the basis of HR-ESI-MS, 1D and 2D NMR spectral analysis.