Search

Two new indole alkaloids with the methyl chanofruticosinate skeletal system viz., methyl 3-oxo-12-methoxy-N1-decarbomethoxy-14,15-didehydrochanofruticosinate (1) and methyl 3-oxo-11,12-methylenedioxy-N-decarbomethoxy-14,15-didehydrochanofruticosinate (2), together with four known compounds, methyl 12-methoxy-N1-decarbomethoxychanofruticosinate, methyl 12-methoxychanofruticosinate, methyl 11,12-dimethoxychanofruticosinate and methyl 11,12-methylenedioxy-N1-decarbomethoxychanofruticosinate, were isolated in continuing studies on the leaves of Kopsia flavida Blume. The structures of the new indole alkaloids were assigned by NMR spectral data using various 2D-techniques.

A new Corynanthe-type indole alkaloid, (−)-9-methoxymitralactonine ( 1 ), having a highly conjugated system was isolated from the young leaves of Mitragyna speciosa in Malaysia, and its structure was first deduced by spectroscopic analysis and then confirmed by chiral-total synthesis starting from optically pure epoxy-ketone and 5-methoxy-3,4-dihydro-β-carboline. The chiral HPLC analysis demonstrated that the natural 9-methoxymitralactonine contained predominantly the (−)-enantiomer over the (+)-enantiomer in the ratio of 62:38.

Three new monoterpenoid indole alkaloids, i.e., 3,4,5,6-tetradehydromitragynine, mitralactonal, and mitrasulgynine carrying a sulfonate function, were isolated, together with seven known compounds, from the leaves of Mitragyna speciosa native to Malaysia.

Equimolecular amounts of amino acids (l-leucine and l-valine) and d-glucose were refluxed at 140 °C for 2 h in propylene glycol. The volatiles were isolated by simultaneous steam distillation and extraction. The extracts were separated in advance by column chromatography on silica gel with a benzene−ether gradient. The resulting fractions were analyzed by GC and GC-MS. Twenty-seven compounds, including 13 pyrazines, 6 dioxolanes, 2 aldehydes, 2 acids, and 2 pyridines, were identified. Dioxolanes, aldehydes, and pyrazines are the major volatiles, and the percentages of their total gas chromatographic peak areas are 41.13, 23.67, and 17.69 respectively. Formation pathways and sensory properties are described. Keywords: Volatile compounds; Maillard reaction; model reaction system

The structure of mitragynaline, an indole alkaloid isolated from Malaysian Mitragyna speciosa, was revised as formula 3 by analysis of the NMR spectra measured at low temperature and by chemical transformation with DDQ oxidation from the known alkaloid mitragynine ( 5 ).

A new 2-arylbenzofuran derivative (diptoindonesin G) (1), along with nine known oligostilbenes, have been isolated and identified from the acetone extract of the tree bark of Hopea mengarawan. The structures of these compounds were determined based on spectroscopic data, including 2D NMR and HREIMS spectra. On cytotoxic evaluation of the isolated compounds against murin leukemia P-388 cells, compound 1 was the strongest in inhibiting the growth of the cells.

A new alkaloid, 4'-hydroxy-3', 5'-dimethoxybenzoylvincamajine [1], was isolated with nine known alkaloids from the roots of Alstonia angustifolia (Apocynaceae)