Antimalarial and cytotoxic activities of pregnene-type steroidal alkaloids from Holarrhena pubescens roots

The phytochemical investigation of an alkaloidal extract of Holarrhena pubescens roots led to the isolation and identification of a new pregnene-type alkaloid, mokluangin D (1), together with nine known steroidal alkaloids (2–10). The structure of the new metabolite was determined on the basis of spectroscopic analyses including 1D- and 2D-NMR spectroscopy and mass spectrometry. Compounds 3 and 4 showed potent antimalarial activity against Plasmodium falciparum K1 stain with IC₅₀ values of 1.2 and 2.0 μM, respectively, and showed weak cytotoxic activity against the NCI-H187 cell line with IC₅₀ values of 27.7 and 30.6 μM, respectively. The substituent groups at C-3 and the carbonyl group at C-18 are important for the activity against the P. falciparum K1 stain.     

New cytotoxic cardenolide glycoside from the seeds of Cerbera manghas

A new cytotoxic cardenolide glycoside, 3beta-O-(2'-O-acetyl-alpha-L-thevetosyl)-14beta-hydroxy-7-en-5beta-card-20(22)-enolide, (7,8-dehydrocerberin), together with five known cardenolides, 17beta-neriifolin, deacetyltanghinin, tanghinin, cerberin and 2'-O-acetyl-cerleaside A were isolated from the seeds of Cerbera manghas L. Their structures were elucidated by 1D- and 2D-NMR techniques as well as UV, IR and mass spectral data. 7,8-Dehydrocerberin, deacetyltanghinin and tanghinin exhibited cytotoxic activities against oral human epidermoid carcinoma (KB), human breast cancer cell (BC) and human small cells lung cancer (NCI-H187).     

Cassane‐Type Diterpenes from the Seeds of Caesalpinia crista

A new dimer 1 and two new cassane‐type diterpenes 2 and 3 , designated taepeenin J–L, were isolated from the seeds of Caesalpinia crista L. Compound 1 possesses a dimeric vouacapane skeleton. Their structures were elucidated on the basis of spectroscopic analysis.     

Clausenawallines A and B, two new dimeric carbazole alkaloids from the roots of Clausena wallichii

Two new dimeric carbazole alkaloids, clausenawallines A and B, were isolated from the roots of Clausena wallichii. Their structures were elucidated by spectroscopic methods. Clausenawalline A was evaluated for its biological activities [anti-malaria (IC₅₀ 2.46 μg/mL), anti-TB (MIC 12.50 μg/mL)] and cytotoxicity against three human cancer cell lines [KB (IC₅₀ 7.87 μg/mL), MCF7 (IC₅₀ 25.43 μg/mL), and NCI-H187 (IC₅₀ 10.97 μg/mL)].     

New diterpenoids from stems and roots of Caesalpinia crista

Nine new cassane-type diterpenes, named taepeenin A-I, and two new norcassane-type diterpenes, named nortaepeenin A-B, were isolated from the stems and roots of Caesalpinia crista along with three known diterpenes: vinhaticoic acid, methyl vinhaticoate and ent-11β-hydroxy-rosa-5,15-diene. Their structures were elucidated on the basis of spectroscopic analysis. In addition, the structure of taepeenin A was confirmed by X-ray diffraction analysis.