Chemical composition of Nigella sativa L. seed extracts obtained by supercritical carbon dioxide

Chemical composition of black cumin (Nigella
sativa L.) seed extracts obtained by supercritical carbon
dioxide at two different conditions that result in total extract
(28 MPa/50°C, SFE 1) and major volatile part (12 MPa/
40°C, SFE 2) and essential oil obtained by hydrodistillation
of SFE-1 (HD SFE). SFE have been carried out to
characterize the compounds and the variation of quinones
and phenolics. The extracts were analysed by GC and GCMS
and the presence of phenolic compounds was further
confirmed by 2D HSQCT 1H and 13C NMR spectroscopy.
Forty-seven volatile compounds were detected where
sixteen compounds were reported for the first time in the
oil of this seed. Moreover, thymoquinone (TQ), dithymoquinone
(DTQ), thymohydroquinone (THQ) and thymol
(THY) were the major phenolic compounds. It can be
concluded that the chemical composition of extracts
obtained by SC CO2 extraction of the seeds showed better
recovery of phenolic compounds than HD SFE and proved
the occurrence of thermally labile or photosensitive
bioactive volatiles of four major quinonic phenol compounds.