Zhong-Hao Sun

Antimalarial and Antiproliferative Cassane Diterpenes of Caesalpinia sappan.

Bioassay-guided fractionation of a methanol extract of the seeds of Caesalpinia sappan led to the isolation of 12 new cassane-type diterpenes, caesalsappanins A-L (1-12). Their structures were elucidated on the basis of NMR and HRESIMS analysis, and the absolute configuration of compound 1 was determined by single-crystal X-ray crystallography. All isolated compounds were tested against a chloroquine-resistant Plasmodium falciparum strain for antiplasmodial activities and against a small panel of human cancer cell lines for antiproliferative activities. Compounds 7 and 8 displayed antimalarial activity against the chloroquine-resistant K1 strain of P. falciparum with IC50 values of 0.78 and 0.52 μM and selectivity indices of 17.6 and 16.4, respectively. Compound 10 showed antiproliferative activity against the KB cancer cell line with an IC50 value of 7.4 μM.

Antimalarial diterpene alkaloids from the seeds of Caesalpinia minax

Two new diterpene alkaloids, caesalminines A (1) and B (2), possessing a tetracyclic cassane-type furanoditerpenoid skeleton with γ-lactam ring, were isolated from the seeds of Caesalpinia minax. Their structures were determined by different spectroscopic methods and ECD calculation. The plausible biosynthetic pathway of caesalminines A and B was proposed. The anti-malarial activity of compounds 1 and 2 is presented with IC50 values of 0.42 and 0.79 μM, respectively.

Norcassane- and cassane-type furanoditerpenoids from the seeds of Caesalpinia sappan

Three novel furanoditerpenoids, norcaesalpinin J (1) featuring an unusual 20-norcassane hydroperoxide and phangininoxys B (2) and C (3) possessing cassane hemiketal skeletons, were isolated from the seeds of Caesalpinia sappan. Their structures were elucidated by extensive spectroscopic methods. All isolates were evaluated for the cytotoxic activities on three human cancer cell lines.

Cassane diterpenes with oxygen bridge from the seeds of Caesalpinia sappan.

The seeds of the medicinal plant Caesalpinia sappan yielded fourteen cassane-type diterpenes, including six new rearranged ones named as caesalppans A-F (1-6). Their structures were elucidated by spectroscopic analysis and comparison with literature data. The isolated new compounds 1-6 possess lactone-type cassane diterpenoid skeleton with an oxygen bridge between C-19 and C-20, and were tested cytotoxic activity against four cancer cell lines using the MTT method.

Four new phenolic acid with unusual bicycle [2.2.2] octane moiety from Clerodendranthus spicatus and their anti-inflammatory activity

Four new phenolic acids, clerodens A-D (1-4) possessing an unusual bicycle [2.2.2] octane moiety were isolated from the whole plants of Clerodendranthus spicatus. Their structures were elucidated by extensive spectroscopic methods, including NMR, MS, and ECD data. All isolates were evaluated for their anti-inflammatory activities on lipopolysaccharide (LPS)-induced nitric oxide (NO) production in RAW 264.7, and compound 4 showed significant inhibitory activities with IC50 value of 6.8 μM.

Novel dinorcassane- and cassane-type diterpenes from the seeds of Caesalpinia minax.

Two novel diterpenes, norcaesalpinin I (1) featuring an unusual ring C-contracted dinorcassane and caesalpinin U (2) possessing a highly oxygenated furanocassane skeleton were isolated from the seeds of Caesalpinia minax. Their structures were determined by different spectroscopic methods. A plausible biosynthetic pathway of 1 was proposed. The cytotoxic activity of compounds 1 and 2 against HepG2 and HeLa human tumor cell lines was evaluated.

New cucurbitane triterpenoids with cytotoxic activities from Hemsleya penxianensis

Seven new cucurbitane triterpenoids, Pengxianencins A-G (1-7) including one alkaloid, were isolated from the ethanol extract of the tubers of Hemsleya penxianensis. Their structures were elucidated on the basis of extensive spectroscopic data, including 1D and 2D NMR spectra as well as HR-ESI-MS. The evaluation of inhibition activity against human Hela, MCF-7, and A-549 cell lines showed that compounds 1, 4, 6, 7 have different levels of cytotoxic activities, with IC50 values ranging from 1.67 to 45.28μM.

Calenduloside E Analogues Protecting H9c2 Cardiomyocytes Against H2O2-Induced Apoptosis: Design, Synthesis and Biological Evaluation

Modulation of apoptosis is therapeutically effective in cardiomyocytes damage. Calenduloside E (CE), a naturally occurring triterpenoid saponin, is a potent anti-apoptotic agent. However, little is known about its synthetic analogues on the protective effects in apoptosis of cardiomyocytes. The present research was performed to investigate the potential protective effect of CE analogues against H2O2-induced apoptosis in H9c2 cardiomyocytes and the underlying mechanisms. Sixteen novel CE anologues have been designed, synthesized and biological evaluation. Among the 16 CE anologues, as well as the positive control CE tested, compound 5d was the most effective in improving cardiomyocytes viability. Pretreatment with anologue 5d inhibited ROS generation, maintained the mitochondrial membrane potential and reduced apoptotic cardiomyocytes. Moreover, exposure to H2O2 significantly increased the levels of Bax, cleaved caspase-3, and cleaved PARP, and decreased the level of Bcl-2, resulting in cell apoptosis. Pretreatment with anologue 5d (0.02–0.5 μg/mL) dose-dependently upregulated antiapoptotic proteins and downregulated proapoptotic proteins mentioned above during H2O2-induced apoptosis. These results suggested that CE analogues provide protection to H9c2 cardiomyocytes against H2O2-induced oxidative stress and apoptosis, most likely via anti-apoptotic mechanism, and provided the basis for the further optimization of the CE analogues.

Two new degradative cassane-type diterpenes isolated from Caesalpinia minax.

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.

New stigmastane type of steroidal glycosides from the roots of Vernonia cumingiana

GRAPHICAL ABSTRACT ABSTRACT Two new stigmastane type of steroidal glycosides, vernoniacums A and B (1 and 2), with a △7,9(11) steroidal core were isolated from the roots of Vernonia cumingiana. Their structures were elucidated based on various spectroscopic techniques, including IR, HR-FAB-MS, and 1D and 2D NMR. Both compounds were evaluated for their cytotoxicity against HeLa and HCT-8 cells, and compound 1 showed mild activity against the tested cell lines with IC50 values of 15.8 and 35.7 pounds were evaluated for their cytotoxicity against HeLa and HCT-8 cells, and compound 1 showed mild activity against the tested cell lines with IC50 values of 15.8 and 35.7 μM, respectively.