Alkaloids constituents from the stem bark of Polyalthia cauliflora var. cauliflora (Annonaceae)
Polyalthia cauliflora Hook. f. & Thomson var. cauliflora from the Annonaceae family is known as 'Semukau' among 'Kelabit' community in Bario Sarawak, Malaysia. It is a small tree with 14m tall and 13cm diameter and has purplish fruits at the trunk of the plant and is widely distributed in Peninsular Malaysia, Borneo, Sumatra and Thailand . This plant has been used traditionally for birth control . Alkaloidal crude extract (4.94g) was subjected to vacuum liquid chromatography (VLC) on silica gel using Hex/DCM/MeOH mixtures of increasing polarity to obtained 52 fractions. The same patterned of spots were pooled together into 10 fractions. Fraction 3 was subjected to radial chromatography to yield compounds 1 (1.3mg) and 2 (1.2mg). Fraction 5 and 6 were subjected to preparative thin layer chromatography to afford compounds 4 (4.1mg) and 3 (3.6mg). The spectral data analysis (1D and 2D NMR spectroscopy, MS) of compounds 1–4 revealed that 1 and 2 are oxoaporphine, 3 is isoquinoline and 4 is aporphine alkaloids. Comparison with literature determined compounds 1–4 as liriodenine , lanuginosine , 6-hydroxy-7-methoxy-2-methyl-3,4-dihydroisoquinolinone  and dehydrodomesticine , respectively. The synthesis of 3 and 4 have been reported previously but this is their first occurence naturally.
Acknowledgement: This study was supported by the grant from FRGS (No.: 600-RMI/ST/FRGS/5/3/Fst (32/2009)) and scholarship of one of the authors was financed by National Science Fellowship (NSF) from Ministry of Science, Technology and Innovation, Malaysia (MOSTI).
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