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The chemical composition of the ginger oils (obtained by hydrodistillation) of fresh and dried rhizomes of Nigerian origin were investigated by means of a combination of column chromatography, high resolution gas chromatography (GC) and GC-MS. The essential oils contained mainly mono-and sesqui-terpenoids of which geranial, neral, 1 ,&cineole, zingiberene, f3-bisabolene and f3-sesquiphellandrene were the major components. Among the 54 constituents identified, (E)(E)-a-farnesene, viridiflorol and (E)(E)-farnesal have not been found previously in ginger.

The chemical inhibition of acetyl-cholinesterase (AChE) is a potent strategy for addressing signal related neuropathology and natural products are potential sources of compounds with such properties. Essential oil extracts from leaf, seed, stem and rhizome of four medicinal plants [Aframomum melegueta K. Schum, Crassocephalum crepidioides (Benth S. More), Monodora myristica (Gaertn.), and Ocimum gratissimum (Linn)] were tested for acetyl-cholinesterase inhibitory activity (AChEI) using Ellman's colorimentric method and compared to a reference acetyl-cholinesterase inhibitor (galantamine). The seed (IC50 = 6.71 mg/l) and leaf (IC50 = 6.54 mg/l) extracts from O. gratissimum showed values that matched the capacity of the reference inhibitor (IC50 = 6.62 mg/l). The least potent extract was rhizome extracts of A. melegueta (IC50 = 28.97 mg/l) about four times that of the reference inhibitor. Principal component analysis (PCA) showed that the intrinsic properties (bioactive ingredient factor) of each extract (PC1 = 29.50%) was the most important factor defining the difference or similarity in potency to the reference acetyl-cholinesterase inhibitor while ‘dose response’ (PC2 = 11.38%) was the second most important factor. The outstanding AChEI property of O. gratissimum extracts could largely be attributed to the high monoterpene content while the weak potency of rhizome extracts of A. melegueta may be attributed to its predominant concentrations of sesquiterpenes. Since potency could be related to interaction between bioactive components, understanding the interaction between ratios of monoterpene and sesquiterpene in extracts could be important in determining their potency for AChEI.

The essential oils from the leaves and fruits of Murraya paniculata (L.) Jack. grown in Nigeria were analysed by means of gas chromatograph and gas chromatograph interfaced with mass spectrometry. Both oils were rich in sesquiterpenoids. The principal constituents of the leaf oil were β β β β β-cyclocitral (22.9%), methyl salicylate (22.4%), trans-nerolidol (11.7%), α α α α α-cubebene (7.9%), (− − − − −)-cubenol (6.8%), β β β β β-cubebene (5.8%) and isogermacrene (5.7%). The most abundant constituent of the fruit essential oil was β β β β β-caryophyllene (43.4%). Other major components were (− − − − −)-zingiberene (18.9%), germacrene D (8.3%), α α α α α-copaene (5.5%) and α α α α α-humulene (5.1%). The compositions of both oils varied qualitatively and quantitatively.

Sixty‐six oils from eleven offshore and onshore fields in the NW Niger Delta, Nigeria were analyzed geochemically for their biomarker and isotopic compositions. Multivariate statistical analysis was employed to distinguish generic oil families from the large, complex data set. Biomarker and isotopic source parameter distributions were used to group the oils into three generic families. Family A oils, located in the onshore swamp to transitional area, received charges from predominantly Late Cretaceous or younger marine source rocks laid down in a sub‐oxic to oxic depositional environment. Family B oils occur in the near‐offshore area and are derived from Tertiary source facies that received an input of mixed terrigenous and marine organic matter. Family C oils, which dominate the offshore area, were derived from Tertiary source rocks typical of those deposited in oxic, nearshore or deltaic settings receiving significant terrestrial organic matter. Biomarker maturity parameters showed that the onshore (swamp) oils were generated at the peak of the oil generating window, while the transitional to offshore oils were expelled at an earlier stage of oil generation.

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