Analytical Investigation of the Sesquiterpene Hydrocarbons of Distilled Lime Oil (Citrus aurantifoliaSwingle)

Germacrene B - a central intermediate in sesquiterpene biosynthesis

Germacranes are important intermediates in the biosynthesis of eudesmane and guaiane sesquiterpenes. After their initial formation from farnesyl diphosphate, these neutral intermediates can become reprotonated for a second cyclisation to reach the bicyclic eudesmane and guaiane skeletons. This review summarises the accumulated knowledge on eudesmane and guaiane sesquiterpene hydrocarbons and alcohols that potentially arise from the achiral sesquiterpene hydrocarbon germacrene B. Not only compounds isolated from natural sources, but also synthetic compounds are dicussed, with the aim to give a rationale for the structural assignment for each compound. A total number of 64 compounds is presented, with 131 cited references.

Comparative Study of the Chemical Profiles of the Essential Oils of Ripe and Rotten Fruits of Citrus Aurantifolia Swingle

Most often during the processing of lime fruits for essential oil extraction, rotten fruits are used along with ripe ones. In this study, we examine the volatile constituents of the essential oils from both ripe and rotten lime fruits (Citrus aurantifolia Swingle) from Nigeria. The oils were isolated by hydrodistillation and analyzed using GC-MS. The ripe and rotten lime oils contained 55 and 49 components, respectively. Both oils were rich in limonene (21.0%, ripe lime; 21.3% rotten lime), α-terpineol (11.7%, ripe; 14.1%, rotten), terpinene (8.3%, ripe; 8.9% rotten lime), α–terpinolene (2.5%, ripe; 8.5%, rotten) and ( E)-α-farnesene (6.3% ripe lime; 4.8% rotten lime). The other major components, α-pinene (11.1%), and linalool (5.5%) were identified in ripe lime oil only. Limonene and citral, which are believed to be the two major citrus odour contributors, were present in both ripe and rotten lime oils. Aldehydes like decanal and the farnesenes, which are also important in citrus flavor, were represented in both lime oils. Some notable components of ripe lime fruit oil, like trans-β-ocimene, linalool, myrcenol, dodecanal, trans-β–bergamotene and trans-γ–bisabolene, were absent in the rotten fruit oil. It could be suggested that some compounds like cis-ocimene, trans-linalool oxide, p-mentha-3-en-1-ol, mentha-1,4,8-triene, citronellal, trans- β–bergamotene and α–copaene, which were not identified in the ripe fruit oil, were introduced into the lime oil by the incorporation of rotten fruits in the distilled samples.