Research Journal of Chemical Sciences ______________________________________________ ISSN 2231-606X Vol. 5(10), 7-12, October (2015) Res. J. Chem. Sci. International Science Congress Association 7 Compositional Analysis and Anti-Oxidant Assesment of Essential Oil of some Aromatic Plants Obtained from North-Eastern NigeriaRunde M., Kubmarawa D. and Maina H.M. Department of Chemistry, Modibbo Adama University of Technology Yola Adamawa State, NIGERIAAvailable online at: www.isca.in, www.isca.me Received 12th August 2015, revised 15th September 2015, accepted 17th October 2015 AbstractFresh leaves of Ocimum americanus, Vossia cuspidata,Eucalyptus camaldulensis and the bark of Bosweillia dalzielii were collected and pretreated for essential oil analysis. DPPH scavenging capacity of the respective essential oils was used to determine the potential anti-oxidant activities of the oils. The results obtained from the analysis shows that the major compounds in essential oil of Ocimum americanus are; Terpinen-4-ol (14.507 %), Copaene (7.438 %) and Terpinen (6.178 %). The essential oil of Vossia cuspidata are predominated by 4-acetyl-7-hydroxybenzo-2,1,3-thiadiazole (15.037 %), Caryophyllene (11.397) and -Pinene (10.285). The major compounds present in the essential oil of Eucalyptus camaldulensis being M-Cymene (19.74 %), -Phellandrene (19.280 %), and Eucalyptol (13.101 %) whereas the major componds of the oil of Bosweillia dalzielii are -Pinene (18.515 %), Isophthaldehyde (10.695 %) and -Pinene (5.641 %). The samples have exhibited some degree of antioxidant activities with values above 80%. However, the lowest scavenging capacity for each of the sample is observed in the corresponding lowest concentrations of vitamins E (80.39 %) a water insoluble antioxidant which presented with the least scavenging capacity, whereas vitamins C (98.87%) has the highest scavenging property followed by vosia cuspidata (97.44 %) at the most increased concentration of 50 µL/ml. Keywords: Antioxidant, essential oils, free radical. Introduction Free radicals are said to play a negative major role in the ageing process and in diseases progression. Antioxidants are the main defense agents against free radicals invasions, and are necessary for maintaining good health and wellbeing. The desire for antioxidant becomes even more important with increased risks for coming in contact with free radicals. Environmental pollutants such as cigarette smoke and other factors like drugs, illness, stress and even exercise can increase risk of free radical exposure. Humans utilize oxygen in order to metabolize fats and carbohydrates for energy; however this does not come without a cost. Oxygen is a highly reacting atom that is capable of becoming part of potentially damaging molecules commonly called free radicals. Free radicals can attack the healthy cells of the body, causing them to lose their morphology. Excessive production of oxygen-derive free radicals are involve in initiating many diseases such as cancer, rheumatoid arthritis, cirrhosis and arteriosclerosis. Although oxidation reactions are crucial to life, antioxidants are therefore essential for life sustenance. They are substances that shield cells from the damage caused by free radicals. Example of antioxidants includes: beta-carotene, lycopene, ascorbic acid, alpha-tocopherol, and other substances. The use of these antioxidants in supplement form in the body may help in reducing oxidative damage. Natural antioxidants are being thoroughly studied for their ability to protect human cells from damage due to oxidative stress. The use of essential oil as active ingredients in various industries such as foods, drinks, toiletries and cosmetics is becoming more common. Before now, essential oils have been studied mostly from view point of their flavor and fragrance chemistry for flavoring food, drinks and other goods. There is an increasing interest in antioxidants, particularly in those intended to prevent the presumed deleterious effects of free radicals in the human body, and to prevent the deterioration of fats and other constituents of foodstuffs. In both cases, there is a preference for antioxidants from natural rather than from synthetic sources7,8. There is therefore a parallel increase in the use of methods for estimating the efficiency of such substances as antioxidants9,10. One such method that is currently popular is based upon the use of the stable free radical 2,2-Diphenylpicryl-1-hydrazyl (DPPH). The purpose of this paper is to examine, analyze the composition of various essential oils and to establish the possibility for their use as antioxidant. Material and Methods Essential oil extraction: The leaves of Ocimum americanus, Vosia cuspidata, Eucalyptus camaldulensis and the stem bark of Bosweilia dalzielii (each weighing 1 kg) obtained in the month of January 2015 from Girei Local Government of Adamawa state, North-eastern Nigeria and immediately subjected to extraction to avoid loss of some essential oils as a result of Research Journal of Chemical Sciences ___________________________________________________________ ISSN 2231-606XVol. 5(10), 7-12, October (2015) Res. J. Chem. Sci. International Science Congress Association 8 drying process, and using a modified type of steam distillation apparatus (in which the receiver end of the distiller has been pass through another vessel containing ice) for 2.5 h essential oils of the plants were collected over water and later kept at 4 C until further required. Gas chromatography Mass spectroscopy (GC-MS): GC-MS analysis was performed on a J and W Scientific gas chromatography directly coupled to the mass spectrometer system (model GC Agilent technologies 7890A, Agilent technologies MSD 5975C), 5 % phenyl methyl silox: 469.56 509 packed capillary column (30M x 250µm) was used under the following conditions: ovum temperature 500 C for 1 min, then raised within intervals of 10C/min to 200C for 1min, and 200 C/min to 300 C for 2 min.Injector temperature was 230C while the carrier gas was Helium flowing at the rate of 1ml/min, the volume of the injected sample was 0.2µL of diluted oil in hexane, splitless injection techniques was used and the ionization energy was 70ev in the electron ionization (EI) mode. Ion source temperature was 230C while the scan mass range of M/Z 60-335 was used. The constituents of the essential oils were identified based on comparison of the retention indices and mass spectra of most of the compounds with data generated under identical experimental conditions by applying a two dimensional search algorithm considering the retention index as well as mass spectral similar with those of authentic compounds available in NBS75K and NIST08 Libraries.The retention indices (RI) are in relation to a homologous series of n-alkanes on the GC column under the same chromatographic condition. Relative concentration will be obtained by peak area normalization as describe by Brand-Williams W et. al.11 DPPH free radical scavenging assay: The 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assay was carried out for the evaluation of the antioxidant activity of the various essential oils. This assay measures the free radical scavenging strength of the tested essential oil. DPPH is a molecule containing a stable free radical however, in the presence of an antioxidant which can donate an electron to DPPH, the purple color, typical for free DPPH radical fades, and the change in absorbency at = 517 nm is measured spectrophotometrically. This test provides information on the ability of a compound to serve as antioxidant. The method will be carried out as described previously by Wei C.L. et. al.12 and Kubmarawa D. et.al.13. The essential oil will be dissolved in methanol, and various concentrations (2, 6, 12, 24, and 50 L/mL) will be used. The assay mixture contained in a total volume of 1 mL, 500 L of the oil, 125 L prepared DPPH (1 mM in methanol), and 375 L solvent (methanol). After 30 min incubation at 25°C, the decrease in absorbance will be measured at = 517 nm. The radical scavenging activity will be calculated from the equation below: % or radical scavenging = [(Abs control – Abs Sample) Abs control] x 100 Results and Discussion Chemical composition of essential oils of various plants: The GC-MS analysis of the essential oil obtained from the stem bark of Bosweilia dalzielii, leaves of Ocimum americanus, Vossia cuspidata and Eucalyptus camaldulensis (table-1) reveals that Pinene (18.515 %), Isophthaladehyde (10.695 %) and -Pinene (5.641 %) were the major component of the essential oil of Boweillia dalzielii stem bark whereas, the oil of Ocimum americanus was dominated by Terpinene-4-ol (14.507 %), Copaene (7.438 %), and Terpinene (6.178 %). Similar analysis carried on the essential oil of Vossia cuspidata shows that 4-Acetyl-7-hydroxybenzo-2,1,3-thiadiazole (15.037 %) was the most abundant compound, followed by -Caryophyllen (11.397 %), -Pinene (10.285 %). On the other hand the major compounds of the essential oil of Eucalyptos camaldulensiswere M-Cymene (19.74%) -Phellandrene (19.280 %) and Eucalyptol (13.101 %). The result also pointed at -Pinene as the most common compound with appreciable concentration among the essential oils of all the plants subjected under this test. Similar work on composition of Bosweillia dalzielii in Nigeria reveals that -Pinene (45.7 %) and Terpinene (11.5 %) were the major compounds14. In Iran, the analysis of essential oil of Eucalyptus camaldulensis obtained from two locations (Ghalegardan and seashore) indicate that the dominant compounds were Eucalyptol (29.2 %), -phellandrene (17.43 %) and -pinene (7.1 %) for Ghalegardan and for the seashore were Eucalyptol (46.74 %), Arommadenderene (12.1 %) and Terpinen-4-ol (7.6 %)14. These works by different authors from different locations have confirmed the result found in our work as being the composition of essential oils of various plants.DPPH scavenging activity of essential oils of various plants: The antioxidant activities of the essential oils of 4 plants were investigated using 2, 2-Diphenyl-1-picryl hydrazyl (DPPH). The DPPH percentage Scavenging capacity for each essential oil and that of the two standards (vitamin C and vitamin E) were measured at varying concentrations and recorded for further discussion.From the result all the samples have exhibited antioxidant activities with values above 80%. However, the lowest scavenging capacity for each of the sample is observed in the corresponding lowest concentrations vitamins E (80.39 %) a water insoluble antioxidant which is presented with the least scavenging capacity whereas vitamin C (98.87%) has the highest scavenging property followed by vosia cuspidata (97.44 %) at the most increased concentration of 50 µL/ml. Research Journal of Chemical Sciences ___________________________________________________________ ISSN 2231-606XVol. 5(10), 7-12, October (2015) Res. J. Chem. Sci. International Science Congress Association 9 Table-1 Composition of essential oils of various plantsCompounds Bosweilia dalzielii Ocimum americanus Vossia cuspidata Eucalyptus camaldulensis -Pinene 18.515 2.664 10.285 8.073 3-Carene 1.317 00 00 3.729 -pinen 5.641 2.277 00 00 Limonene 1.485 00 00 00 -Cubebene 1.137 00 00 00 Furanacetic acid, 4-hexyl-2,5-dihydro-2,5-dioxo 1.226 00 00 00 Bicycle[5.2.0] nonane, 2-methylene-4,8,8-trimethyl-4-vinyl 2.169 00 00 00 Imidazo [4,5-e][1,4] diazepine-5,8-dione, 2-chloro-1,4,6,7-tetrahydro-1,4-dimethyl- 1.430 00 00 00 Isophthaldehyde 10.695 00 00 00 Acetonitril (3,5,5-trimethyl-2-cyclohexen-1-ylidene)-(z)- 3.051 00 00 00 3-penimidic acid, 3-methyl-N-phenyl, methyl ester 4.598 00 00 00 1,3,8-Menthatriene 2.108 00 00 00 1,2-Naphthalenediol,1,2,3,4-tetrahydro-1-methyl-cis 1.017 00 00 00 1,3-cyclopentadiene, 1,2,3,4-tetramethyl-5-methylene 4.439 00 00 00 Cinnamyl carbanilate 2.298 00 00 00 5-Isopropylidene-4,6-dimethylnona-3,6,8-triene-2-ol 2.554 00 00 00 Humulene 3.412 00 00 00 10,12-Tricoadiyoic acid, methyl ester 3.048 00 00 00 Cyclohexanone, 5-ethenyl-5-methyl-4-(1-methylethenyl)-2-(1-methylethylidene)-, cis 2.794 00 00 00 -elemenone 1.009 00 00 00 -Thujene 00 1.483 00 00 Phenol, 3-(1-methylethyl)- 00 2.467 00 00 P-Cymene 00 1.278 00 00 D-Limonene 00 3.149 1.332 00 Research Journal of Chemical Sciences ___________________________________________________________ ISSN 2231-606XVol. 5(10), 7-12, October (2015) Res. 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International Science Congress Association 10 Compounds Bosweilia dalzielii Ocimum americanus Vossia cuspidata Eucalyptus camaldulensis Terpinene 00 6.178 00 00 Cis--Terpineol 00 3.914 00 00 Terpinolene 00 2.006 00 00 5-caranol, (1s,3R,5s,6R)- 00 2.123 00 00 Octan-1-ol.acetate 00 1.662 00 00 Terpinene-4-ol 00 14.507 00 00 Cyclone 00 1.377 00 00 Bornyl acetate 00 1.025 00 00 Myrtenyl acetate 00 1.139 00 00 Bicyclo [7.2.0] undec-4-ene,4,11,11-trimethyl-8-methylene- 00 4.285 00 00 Copaene 00 7.438 00 00 -Caryophyllene 00 1.147 11.397 00 1H-Cyclopenta [1,3], cyclopropa [1,2]benzene, octahydro-7-methyl-3-methylene-4-(1-methylethyl)- 00 1.144 00 00 Isocaryophyllene 00 1.041 00 00 -bergomotene 00 2.598 00 00 Cadinene 00 2.062 00 00 -Gurjunene 00 1.698 00 00 1H-Indole-2-carboxylic acid, 3-amino-5-methoxy-ethyl ester 00 4.059 00 00 2,2,5,6-Tetramethyl-1,3-oxathiane 00 1.344 00 00 4-Piperidinecarboxamide,1-(2-hydroxybenzoyl)- 00 2.641 00 00 -Myrcene 00 00 4.179 00 Benzene, 1,3,5-trimethyl- 00 00 1.459 00 -Linalool 00 00 1.153 00 3-Cyclohexen-1-carboxylic acid, 4-methyl- ester 00 00 3.753 00 Benzyl cyclobutane 00 00 6.565 00 Thiophene 00 00 3.477 00 Aziridine, 1-phenyl- 00 00 3.487 00 Research Journal of Chemical Sciences ___________________________________________________________ ISSN 2231-606XVol. 5(10), 7-12, October (2015) Res. 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International Science Congress Association 11 Compounds Bosweilia dalzielii Ocimum americanus Vossia cuspidata Eucalyptus camaldulensis 1,5-Cyclooctadiene,1,5-dimethyl- 00 00 1.989 00 4-acetyl-7-hydroxybenzo-2,13-thiadiazole 00 00 15.037 00 Caryophyllene 00 00 6.079 00 Ylangene 00 00 4.390 00 Camphene 00 00 2.770 00 Octahydropyrolo [1,2-a]pyrazine perdeutero benzene 00 00 5.829 00 Sabinene 00 00 00 1.022 -Phellandrene 00 00 00 19.740 (+)-2-carene 00 00 00 5.437 M-Cymene 00 00 00 14.981 Benzene, 1-methyl-3-(1-methylethyl)- 00 00 00 4.736 Eucalyptol 00 00 00 13.101 1,4-Cyclohexadiene, 1-methyl-4-(1-methylethyl)- 00 00 00 5.031 Isovaleric acid, butyl ester 00 00 00 2.114 3-Cyclohexan-1-ol, 4-methyl-1-(1-methyl)- 00 00 00 4.085 Piperitone 00 00 00 1.830 2-Hydroxy-4,5-dimethylacetophenone 00 00 3.862 00 TOTAL 22 24 18 10 Table-2 Evaluation of % scavenging activity of essential oils of various plants Conc.(µL/ml) Bosweillia dalzielii Ocimum americanus Vossia cuspidata Eucalyptus camaldulensis Ascorbic acid (µg/ml) -tocopherol (µg/ml) 2 90.67 94.47 89.66 88.74 98.77 80.39 6 90.79 94.49 90.17 88.86 98.77 81.20 12 90.89 94.89 90.77 90.37 98.85 86.16 24 91.19 95.35 92.73 94.88 98.87 87.17 50 91.79 95.49 97.44 95.15 98.87 88.53 Research Journal of Chemical Sciences ___________________________________________________________ ISSN 2231-606XVol. 5(10), 7-12, October (2015) Res. J. Chem. Sci. International Science Congress Association 12 ConclusionThe major components of Bosweillia dalzielii Hutch essential oil, included -Pinene (18.515%) Isophthaldehyde (10.695 %) and -pinen (5.641 %). Ocimum bassilicum essential oil mainly contained Terpinen-4-ol (14.507 %), Copaene (7.438 %) and Terpinene (6.178). The essential oil from Vossia cuspidata is characterized by a high content of 4-Acetyl-7-hydroxhbenzo-2,1,3-thiadiazole (15.037 %), -caryophyllene (11.397 %) and -pinene (10.285%). The predominant compounds in Eucalyptus camaldulensis essential oil M-cymene (19.74%), phellandrene (19.280) and -Pinene (8.073 %). There is then, great variability and similarities in the chemical composition of essential oils obtained from these plants. The essential oil of these plants also exhibit great antioxidant activity as revealed by their DPPH scavenging activity. 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