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