Miliutine C methyl ester, a new drimane sesquiterpene and bioactive alkaloids from the stems of Miliusa velutina.

Previous results from the our research group have isolated numerous compounds, including novel ones, but the anticancer activity of Miliusa velutina has not been demonstrated. In this study, from the most active ethyl acetate extract of the stems of Miliusa velutina, seven compounds were isolated and determined structures, including a new drimane sesquiterpenoid compound named miliutine C methyl ester (1) and three bioactive alkaloids (5-7). These three alkaloids (5-7) exhibited strong anticancer activities against various cancer cell lines such as MCF-7, HepG2, HeLa, NCI H460 and normal fibroblasts. Especially, on MCF-7 and normal fibroblasts with values of IC50 (µM) in order for compounds 5 (3.38, 31.15), 6 (21.96, 102.00), 7 (7.90, greater than 300), to compare with positive control camptothecin (0.020, 4.51); which is highly noteworthy. These results contribute to elucidating and confirming the value of Miliusa velutina, similar to other published and folkloric findings.

Miliutine A acid, a new cyclofarnesane sesquiterpene from the stems of Miliusa velutina.

Six compounds were isolated from the ethyl acetate extract of the stems of Miliusa velutina, including miliutine A acid (1), a new cyclofarnesane sesquiterpenoid; miliutine B methyl ester (2), a cyclofarnesane sesquiterpenoid which was determined the absolute configuration for the first time and four known phenol derivatives (3-6). NMR spectroscopic and mass spectrometry were used for identifying relative configurations. The assignments of the absolute configurations were determined based on Electronic Circular Dichroism (ECD) and NOESY spectra analysis. All six compounds were screened for their in vitro cytotoxic activities against HepG2 cell line using the SRB assay and they showed weak or none activities.

A new sesquiterpene lactone from the leaves of Panax vietnamensis Ha et Grushv. (Vietnamese ginseng).

Panax vietnamensis (Vietnamese ginseng, Ngoc Linh ginseng) is an endemic Panax species of Vietnam. From the methanol extract of the leaves of Panax vietnamensis, five compounds (1-5) were isolated, including one new sesquiterpene lactone such as panaxolide (1) and four known compounds. The structures of the compounds (1-5) were elucidated by spectral techniques such as 1 D NMR (1H NMR, 13C NMR), 2 D NMR (COSY, HSQC, HMBC, NOESY) and mass spectrometry. The absolute configuration of 1 was determined based on the Cotton effects in the CD spectrum. All of the five compounds were screened for their in vitro growth inhibitory activities against cancerous cells (HepG2) and normal cells (fibroblast) using the SRB assay. Panaxolide (1) showed the highest potential for the growth inhibition of cancerous cells HepG2 with the IC50 values of 63.8 µM.

Wedelolides A and B: novel sesquiterpene delta-lactones, (9R)-eudesman-9,12-olides, from Wedelia trilobata.

Two new sesquiterpene lactones, wedelolides A (1) and B (2), were isolated by bioassay-guided fractionation from the leaves of Wedelia trilobata, together with known trilobolides 6-O-isobutyrate (3) and 6-O-methacrylate (4). The compounds 1 and 2 were the first examples of an unprecedented framework: a novel sesquiterpene delta-lactone, (9R)-eudesman-9,12-olide. The structures of the antimalarial wedelolides A (1) and B (2) were determined on the basis of MS and 2D NMR spectral analysis. The absolute configuration of eight carbon stereocenters of compounds 1 and 2 was determined to be 1S,4S,5S,6R,7S,8S,9R,10S by mean of auxiliary chiral MTPA derivatives.

Schiff bases of gossypol: an NMR and DFT study.

Schiff bases of gossypol with benzylamine, methylamine, 4-aminoacetophenone and 4-fluoroaniline have been synthesized and characterized by NMR spectroscopy. All the Schiff bases of gossypol are in the enamine form according to (3)J(HC,NH) and (1)J(N,H) coupling constants. The spectra are basically unchanged by change of solvent (CD(2)Cl(2), THF-d(8) and CD(3)OD) and by variation of temperature. For the derivative of benzylamine, deuterium isotope effects on (13)C chemical shifts are determined. They support strongly the enamine form and serve as a reference for other tautomeric Schiff bases. Structures and NMR nuclear shieldings of model compounds (the second monomer is replaced by a 2-hydroxybenzene ring) have been calculated by density functional theory (DFT) methods. A good correlation is observed between calculated (13)C nuclear shieldings of the enamine form and observed (13)C chemical shifts.