Isolation of major alkaloids from the leaves of Malaysian uncaria cordata, merr. / Siti Najihah Abu Bakar

The alkaloids of Malaysian Uncaria cordata (Rubiaceae) leaves were isolated and their structures were elucidated. The methanolic extract of the Uncaria cordata leaves was fractionated using the solid phase extraction technique (SPE) before being introduced to various chromatographic techniques namely column chromatography, thin layer chromatography and centrifugal chromatography to isolate the alkaloids. 1H NMR spectroscopy and hyphenated GC-MS technique were used in determining the structures of the alkaloids isolated. Two heteroyohimbine-type alkaloids from Uncaria cordata were successfully isolated and they are specifically from the allo-type. These alkaloids have never been reported to be isolated from the Uncaria cordata leaves in any literature review. Compound X was found to be Uncarine E whereas the structure of compound Y could not be identified due to a poorly resolved 1H NMR spectrum obtained. However, its structure was narrowed down to two allo-type oxindole alkaloids namely Uncarine E and rauniticineallo- oxindole A.