Polar secondary metabolites from Ocimum sanctum L.

The aim of this study was to investigate the polar constituents of Ocimum sanctum L. (Lamiaceae), which is used in ayurvedic medicine under the common name tulsi. In continuation to our previous studies [1 – 3], we now investigated the methanol: water (7:3) extract of its aerial parts. The extract was fractionated using RP₁₈-MPLC, CC on Sephadex LH 20 (MeOH) and semi-prep RP₁₈-HPLC and afforded trans-p-coumaric acid 4-O-β-D-glucopyranoside; 3-(3,4-dihydroxyphenyl)lactic acid; protocatechuic acid; (-)-rhabdosin, a caffeic acid tetramer with a lignan skeleton; the neolignan shimobashiric acid C, recently isolated from Keiskea japonica-Lamiaceae [4]; apigenin 7-O-β-D-glucuronide and luteolin 7-O-β-D-glucuronide. The structures of the isolated compounds were confirmed by spectroscopic methods, including 1D- & 2D-NMR, UV-Vis. Our results corroborate with literature concerning the flavonoid pattern. The genus Ocimum L. is divided in three subgenera: subgenus Ocimum (sections Ocimum, Gratissima and Hiantia), subgenus Nautochilus and subgenus Gymnocimum. O. sanctum L. belongs to the subgenus Gymnocimum, which is characterized by the presence of flavonoid glucuronides, totally absent in the taxa of the other two subgenera [5].

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