Analysis and Chemistry of Distilled Lime Oil (Citrus aurantifoliaSwingle)

Experimental Paper. The effect of different development stages on the quantity and quality of the essential oil of Citrus aurantifolia (Christm.) Swingle in Iran

Introduction: The Mexican lime tree with the scientific name of Citrus aurantifolia (Christm.) Swingle have great economic value because of its essential oil with a unique flavour. Objective: The essential oils from the peel of C. aurantifolia were collected during three development periods. Methods: The essential oil was analyzed by capillary GC and GC-MS. Results: The essential oil yields (v/w%) were 1.54%, 0.88% and 1.23%, respectively. The highest oil yield was obtained at stage I (1.54% v/w). The analysis of the essential oil indicated that limonene, β-pinene, geranial, neral and γ-terpinene were the main compounds of all samples. At the first stage, the highest percentages belonged to limonene (39.38%), geranial (14.32%) and neral (11.01%). On the other hand, the highest percentages of β-pinene and γ-terpinene (24.25% and 8.92%, respectively) were found at the final stage. Conclusion: Therefore, it is concluded that the harvest time has a considerable effect on the content and amount of lime fruit essential oil.

Chemical composition of hexane extract of Citrus aurantifolia and anti-Mycobacterium tuberculosis activity of some of its constituents

The main aim of this study was to isolate and characterize the active compounds from the hexane extract of the fruit peels of Citrus aurantiifolia, which showed activity against one sensitive and three monoresistant (isoniazid, streptomycin or ethambutol) strains of Mycobacterium tuberculosis H37Rv. The active extract was fractionated by column chromatography, yielding the following major compounds: 5-geranyloxypsoralen (1); 5-geranyloxy-7-methoxycoumarin (2); 5,7-dimethoxycoumarin (3); 5-methoxypsoralen (4); and 5,8-dimethoxypsoralen (5). The structures of these compounds were elucidated by 1D and 2D NMR spectroscopy. In addition, GC-MS analysis of the hexane extract allowed the identification of 44 volatile compounds, being 5,7-dimethoxycoumarin (15.79%), 3-methyl-1,2-cyclopentanedione (8.27%), 1-methoxy-ciclohexene (8.0%), corylone (6.93%), palmitic acid (6.89%), 5,8-dimethoxypsoralen (6.08%), a-terpineol (5.97%), and umbelliferone (4.36%), the major constituents. Four isolated coumarins and 16 commercial compounds identified by GC-MS were tested against M. tuberculosis H37Rv and three multidrug-resistant M. tuberculosis strains using the Microplate Alamar Blue Assay. The constituents that showed activity against all strains were 5 (MICs = 25-50 mg/mL), 1 (MICs = 50-100 mg/mL), palmitic acid (MICs = 25-50 mg/mL), linoleic acid (MICs = 50-100 mg/mL), oleic acid (MICs = 100 mg/mL), 4-hexen-3-one (MICs = 50-100 mg/mL), and citral (MICs = 50-100 mg/mL). Compound 5 and palmitic acid were the most active ones. The antimycobacterial activity of the hexane extract of C. aurantifolia could be attributed to these compounds.

Multidimensional enantio gas chromtography/mass spectrometry and gas chromatography-combustion-isotopic ratio mass spectrometry for the authenticity assessment of lime essential oils (C. aurantifolia Swingle and C. latifolia Tanaka)

This article focuses on the genuineness assessment of Lime oils (Citrus aurantifolia Swingle and C. latifolia Tanaka), by Multi Dimensional Gas Chromatography (MDGC) to determine the enantiomeric distribution of α-thujene, camphene, β-pinene, sabinene, α-phellandrene, β-phellandrene, limonene, linalool, terpinen-4-ol, α-terpineol and by gas chromatography-combustion isotope ratio mass spectrometry (GC-C-IRMS) to determine the isotopic ratios of α-pinene, β-pinene, limonene, α-terpineol, neral, geranial, β-caryophyllene, trans-α-bergamotene, germacrene B. To the author's knowledge this is the first attempt to assess the authenticity and differentiate Persian Lime from Key lime oils by GC-C-IRMS. The results of the two analytical approaches were compared. The simultaneous use of the two techniques provides more reliable capability to detect adulteration in Citrus essential oils. In fact, in some circumstance only one of the two techniques allows to discriminate adulterated or contaminated oils. In cases where only small anomalies are detected by the two techniques due to subtle adulterations, their synergic use allows to express judgments. The advantage of both techniques is the low number of components the analyst must evaluate, reducing the complexity of the data necessary to deal with. Moreover, the conventional analytical approach based on the evaluation of the whole volatile fraction can fail to reveal the quality of the oils, if the adulteration is extremely subtle.

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.