Chemical constituents of the solvent extracted and hydrodistilled essential oils of African nutmeg ( Monodora myristica ) and turmeric ( Curcuma domestica ) from South West Nigeria

Investigations were conducted on the effect of solvents of extraction ( n–hexane, chloroform and toluene ) on the chemical constituents of the essential oils of two popular spices in Nigeria, namely; African nutmeg ( Monodora myristica ) and Turmeric ( Curcuma domestica ). Comparisons were made on the chemical constituents of these solvent extracts with the constituents from the popular hydrodistillation method. The analyses were made using a high-resolution gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). The hydrodistilled essential oil of M. myristica contained a total of 61 chemical constituents with the major ones as alpha-phellandrene expoxide (3.20%), carvacrol (2.09%) and delta-cadinene (2.21%). The n-hexane extract contained 39 chemical constituents with the major constituents as hexadecanoic acid (3.96%), (Z, Z) 9, 12–octadecadienoic acid (3.77%), propyl oleate (3.45%), thiosulfuric acid (2.98%) and 2-hydroxycyclopentanedecanone (2.2%). The chloroform extract contained 38 components with p-cymene (6.0%), alphaphellendrene epoxide (3.23%), ethyllinoleate (3.79%), linoleic acid (4.36%), oleic acid (14.66%), (Z, Z) 9, 12-octadecadienoic acid (7.89%) and 3-hydroxypropyl oleate (4.09%) as the major constituents, while the toluene extract contained 30 chemical constituents with the major ones as p-cymene (4.6%), alpha–phellandrene epoxide (2.41%), linoleic acid (23.31%) and (Z, Z) 9, 12–octadecadienoic acid (7.02%). The hydrodistillated oil of C. domestica contained 31 constituents, with alpha-phellandrene (4.6%), 1, 8–Cineole (3.0%), p-cymene (3.7%), Ar-curcumene (5.1%), tumerol (15.2%), 1-(1,2-dimethyl propylidene, 4-methenylcyclohex- 2-ene) (2.5%) and ar-tumerone (8.4%) as the major constituents. The n-hexane extract contained 17 constituents with the major ones as neral (2.79%), geranial (3.59%), artumerone (26.53%) and alpha-tumerone (11.99%). The chloroform extract of C. domestica contained 17 constituents with the major ones as ar-tumerone (21.17%), beta-tumerone (14.99%) and alpha-tumerone (11.99%); while the toluene extract contained 17 constituents with alpha-tumerone (12.01%), ar-tumerone (20.06%) and beta-tumerone (14.9%). The results show that the type of extracting solvent affects both the chemical constituents extracted and their concentration. Keywords: turmeric, Curcuma, C. domestica , solvent extraction, essential oil, African nutmeg, Monodora, M. myristica Nigerian Food Journal Vol. 23 2005: 21-32