alexa Essential Oil Chemotypes of Three Ocimum Species Found in Sierra Leone and Nigeria | Open Access Journals
ISSN: 2167-0412
Medicinal & Aromatic Plants
Make the best use of Scientific Research and information from our 700+ peer reviewed, Open Access Journals that operates with the help of 50,000+ Editorial Board Members and esteemed reviewers and 1000+ Scientific associations in Medical, Clinical, Pharmaceutical, Engineering, Technology and Management Fields.
Meet Inspiring Speakers and Experts at our 3000+ Global Conferenceseries Events with over 600+ Conferences, 1200+ Symposiums and 1200+ Workshops on
Medical, Pharma, Engineering, Science, Technology and Business

Essential Oil Chemotypes of Three Ocimum Species Found in Sierra Leone and Nigeria

Olugbade TA*

Department of Pharmaceutical Chemistry, Obafemi Awolowo University, Osun State, Nigeria

*Corresponding Author:
Olugbade TA
Department of Pharmaceutical Chemistry
Faculty of Pharmacy
Obafemi Awolowo University
Ile-Ife, Osun State 220005, Nigeria
Tel: +2347038324641
E-mail: tiwaolugbade@yahoo.com

Received Date: February 26, 2017 Accepted Date: February 26, 2017 Published Date: March 04, 2017

Citation: Olugbade TA (2017) Essential Oil Chemotypes of Three Ocimum Species Found in Sierra Leone and Nigeria. Med Aromat Plants 6:284. doi: 10.4172/2167-0412.1000284

Copyright: ©2017 Olugbade TA. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Visit for more related articles at Medicinal & Aromatic Plants

Abstract

Chemical composition of the essential oil of Ocimum basilicum L., O. gratissimum L. and O. americanum L. varieties found in Sierra Leone and Nigeria were determined by GC-FID and GC-MS. The antimicrobial test was evaluated by agar diffusion. The Sierra Leone and Nigeria O. americanum L. varieties were identified as the linalool chemotype and similarly, varieties of O. gratissimum L. from both countries are thymol chemotype. The high thymol content is consistent with the relative high antimicrobial activity of the O. gratissimum L oils. The Sierra Leone O. basilicum L. sample was established as the methyl eugenol chemotype while the Nigerian collection is predominantly methyl chavicol in composition. The high methyl eugenol content of the Sierra Leone collection is consistent with the observation of attraction of fruit flies to the distillate. To the best of our knowledge, there has been no report on essential oils of Ocimum species in Sierra Leone, hitherto.

Keywords

Chemotypes; Ocimum species; O. basilicum L; Lamiaceae

Introduction

The family Lamiaceae of which the genus Ocimum belongs is composed of diverse and rich source of essential oil containing plants. Ocimum contains between fifty to one hundred and fifty species of herbs and shrubs from the tropical regions of Asia, Africa, and Central and South America [1]. O. gratissimum L. is referred to as holy basil. In Sierra Leone, it is known as “Tea bush” (Krio) and “orgbethor” (Themne) while it is known as “efirin nla” in the Yoruba speaking culture of Nigeria. O. basilicum L. is also referred to as sweet basil. It is known as “Patmenji” (Krio) and “Sorow” (Themne) of Sierra Leone and “efinrin wewe” by the Yorubas. O. americanum L. (synonym of O. canum Sims) [2,3] is known as American basil or hoary basil. In Sierra Leone both the available varieties of O. americanum L and O. basilicum L. are used in culinary as “Patmengy” indiscriminately. The different varieties of O. gratissimum L. [implying different chemotypes] have been used extensively in the traditional system of medicine in many countries as had been reviewed [4-10]. The main issues of concern with the use of herbal drugs remain safety, validation of claims and standardisation of product. There exist the problems of significant variation in the content of Ocimum plants across and within species, with implication of varied biological activities. In spite of the popular use of the genus Ocimum in food and confectionery as spices and application in the treatment of gastrointestinal infections and conjunctivitis in Sierra Leone, the varieties of the plant growing in Sierra Leone have not been, hitherto, investigated. The present study therefore determined the essential oil constituents of the Ocimum species collected in Freetown, Sierra Leone compared with varieties growing in Ile-Ife, Nigeria in order to establish the specific chemotypes in the specific regions.

Experimental Materials

Plant materials

Aerial parts of cultivated O. basilicum (OBS), O. gratissimum (OGS) and (OAS) at full flowering stage were collected from Krootown Road, Central Freetown, Sierra Leone while the Nigerian varieties O. basilicum (OBN), O. gratissimum (OGN) and O. americanum (OAN) were collected in Ile-Ife, Osun- State, Nigeria. The plants were identified at the Department of Botany, Faculty of Sciences, OAU, Ile-Ife, Nigeria where Voucher specimens were deposited.

Extraction of essential oils

Fresh or air-dried leaves of the plants were subjected to hydrodistillation using a Clevenger-type apparatus for 4 hours. The volatile oils were dried over anhydrous magnesium sulphate and stored in amber sealed vials at 4°C until analysis.

Analysis of the essential oils

The GC-MS analyses of the essential oils were carried out on Agilent 6890N coupled to a quadrupole MSD 5973. Column: DB-5MS (5% phenyl 95% dimethylarylene siloxane) 30 m × 0.25 mm × 1 mm film thickness (Agilent). Temperature program: from 50˚C (5 min) to 200˚C (10 min) at 2˚C/min. Injection temperature: 25˚C. Injection volume: 1.0 μL. Inlet pressure: 10.3 kPa PSI. Carrier gas: He, Linear velocity: 40 cm/sec. Injection mode: split (10:1). MS interface temp.: 230˚C; MS mode: EI at 70 eV; mass range: 30-400. The oil sample was dissolved in dichloromethane before injection.

The relative compositions of the essential oils were determined on Agilent 7890B coupled to FID and an autoinjector (Agilent G45138). Column: 19091J-413 HP-5 (5% phenyl methyl siloxane) 30 m × 0.32 mm × 0.25 mm film thickness (Agilent). Temperature program: from 50˚C (5 min) to 200˚C (10 min) at 2˚C/min. Injection temperature: 250˚C. Injection volume: 1.0 μL. Inlet pressure: 66.7 kPa. Carrier gas:He, Linear velocity: 40 cm/sec. Injection mode: split (50:1). FID temp.: 230˚C; H2 flow: 40 mL/min; air flow: 400 mL/min. The oil sample was dissolved in dichloromethane before injection.

Identification of the compounds

Compounds were identified by their retention indices determined using C8-C40 alkane standards and compared with literature data [11].

The identities were confirmed by the mass spectral data observed (Table 1) supported with library (National Institute of Standards and Technology).

NO.

m/z (abundance)

Compound
1 m/z 134 (35), M+. ; 119 (100); 91 (20) p-Cymene
2 m/z 154 (100), M+. ; 139 (70); 43 (75) 1,8-Cineole (Eucalyptol)
3 m/z 136 (50), M+. ; 121 (48); 93 (100); 91 (60) γ-Terpinene
4 m/z 152 (10), M+. ; 137 (2); 81 (100), 69 (46) L-Fenchone
5. m/z 154 (1), M+. ; 139 (3); 136 ( 20). ; 121(40); 93 (100); 71 (95) Linalool
6. m/z 152 (50), M+. ; 108 (40); 95 (100) Camphor
7 m/z 154 ( 40), M+. ; 136 (20); 111 (90); 93 (75), 71 (100) Terpinen-4-ol
8. m/z 148 (100), M+.; 133 (20); 117 (30)  Methyl chavicol (Estragole)
9. m/z 150( 35), M+. ; 135 (100); 115 (12.5) Thymol
10. (m/z 164 (100), M+. ; 149 (30) Eugenol
11 m/z 178 (100), M+. ; 163 (28); 147 (28) Methyl eugenol
12 m/z 204 (12), M+. ; 189 (24); 161 (45); 133 (100) β-Caryophylene (E)
13 m/z 204 (3), M+. ; 189 (5); 119 (100); 93 (82) α-Bergamotene (trans)
14 m/z 204 (45), M+. ; 189 (45); 161 (49); 93 (47); 28 (100)  β-Selinene (β-Eudesmene)
15 m/z 204 (60), M+. ; 189 (100); 161 (37); 133 (45) α-Selinene
16 m/z 220 (3), M+. ; 205 (10); 177 (23); 93 (90), 79 (100), 43 (70). Caryophyllene oxide
17 m/z 222 (2), M+. ; 204 (36); 189 (10); 179 (10); 161 (70); 95 (100) α-Muurolol
18. m/z 204 (48); 189 (20); 161 (100); 119 (75) α-Cadinol

Table 1: Observed Mass spectral features of the prominent components of the essential oils of Ocimum plants from Sierra Leone and Nigeria.

Antimicrobial Tests

Overnight broth cultures of the test organisms were diluted to give cell suspensions of 10/6 -10/7 CFU which were used to surfaceinoculate nutrient agar (Oxoid, London) (bacteria) and Sabouraud dextrose agar (Oxoid, London) (C. albicans). The antimicrobial activity tests of the oils were performed using paper disc method with Whatman No. 1 paper of size 6 mm which were each saturated with the test neat essential oil and subsequently placed on the surface of the inoculated plates [12]. The plates were kept at 4˚C for 1 h to allow for diffusion before subsequent incubation at 37˚C for 24 h for bacteria and 25˚C for 48 h for C. albicans. The reference antibacterial agents were Streptomycin (1 mg/ml) or acriflavine (1%). The tests were carried out in duplicate and the average zones of inhibition were determined.

Results and Discussion

The yields of the essential oils from the six plants are 0.34% (OAS), 0.98% (OAN), 0.71% (OBS), 0.96% (OBN), 0.93% (OGS) and 0.84% (OGN). The results of the antimicrobial test of the oils are presented below. The compounds identified in the different oil samples are presented in Table 2.

S/n % composition  of Sierra Leone collections % composition  of Nigeria  collections Compounds Retention index
  O. ame* O. basil* O. grat* O. ame O. basil O. grat    
1. - - - Trace - 0.5 3-Hexen-1-ol 855.8
2. Trace - - Trace Trace 2.5 α-Thujene 924.1
3. Trace - Trace 0.2 Trace 0.7 α-Pinene 928.7
4. - - - - - 0.2 Camphene 940.9
5. - - - - - 0.5 Sabinene 967.1
6. Trace - - Trace 0.3 1.9 β-Pinene 969.5
7. Trace - Trace Trace - 1.8 β-Myrcene 993.5
8. - - - - - 0.2 α-Phellandrene 1001.4
9. - - - - - 0.2 (+)-3-Carene 1006.7
10. Trace - Trace 0.2 0.5 1.9 α-Terpinene 1014.5
11. 2.5 - 1.5 0.5 - 4.1 p-Cymene 1022.2
12. - - - - - 0.6 D-Limonene 1030.7
13. 0.7 0.6 - 2.4 4.3 - 1,8-Cineole (Eucalyptol) 1033.3
14. - - -   - 0.5 β-Ocimene (Z) 1039.2
15       1.5   0.2 β-Ocimene (E) 1049.1
16. 1.2 - 0.8 0.5 - 10.8 γ-Terpinene 1058.3
17. 0.6 - 0.8 - - - Cis-Sabinene hydrate 1065.1
18. - - - 2.3 - - L-Fenchone 1084.8
19. - - - - - 0.2 Terpinolene 1085.7
20. - - - - - 1.2 P-Cymenene 1089.9
21. 49.1 0.6 10.3 39.6 - 0.4 Linalool 1102.7
22. - 0.6 - - - - Fenchol (endo) 1120.1
23. 10.4 - 5.7 0.2 - - Camphor 1144.7
24. 6.3 0.8 3.2 7.5 0.1 1.3 Terpinen-4-ol 1175.1
25. 0.7 - - 0.5 - - α- Terpineol 1184.4
26. - 0.4 - - 89.8 - Estragole (Methyl chavicol) 1197.4
27. 0.5 - 0.9 - Trace 1.0 Methyl thymol 1235.0
28. - - - 0.8 - - Geraniol 1260.1
29. - - - - - 0.7 Unidentified 1270.8
30. - - - 0.2 - - Bornyl acetate 1283.3
31. 5.6 - 60.5 - - 42.2 Thymol 1294.4
32. - - 1.7 - - 0.6 Carvacrol 1300.5
33. 1.0 - - - - - Terpinen-4-ol acetate 1301.1
34. - - - 0.2 - - Unidentified 1329.7
35. 3.4 - - 18.0 - 0.5 Eugenol 1354.8
36. - - - 1.9 0.2 - β-Elemene 1391.0
37. 1.1 89.7 0.9 0.4 - - Methyl eugenol 1402.1
38. 1.7 - 3.1 - 1.2 1.5 β-Caryophyllene (E) 1419.9
39. 2.4 - - 6.6 - 0.3 α-Bergamotene (trans) 1436.6
40. 0.7 - - - - 0.5 Humulene (α-Caryophyllene) 1453.4
41. - - - 0.5 - - (E) - β-Farnesene 1457.4
42. - - - 1.0 - - γ-Muurolene 1475.5
43. - - - 0.7 - - Germacrene D 1480.3
44. - - - 0.44 - - Bicyclogermacrene 1489.5
45. 0.7 - 3.6 - - 7.1 β-Selinene 1491.0
46. - - 1.3 - - 2.5 α -Selinene 1496.0
47. - - 1.4 - - 0.9 Unidentified 1499.5
48. - - - 0.3 - - α-Bulnesene 1507.8
49. 1.3 0.9 - 0.9 - 1.7 γ-Cadinene 1509.6
50. - - - - - 1.2 α-selinene-7-epi 1515.4
51. - - - 0.2 - 0.2 δ-Cadinene 1519.1
52. - - - 0.4 - - β-Sesquiphellandrene 1521.4
53. - 0.9 - 0.3 - - Spathulenol 1578.5
54. 0.6 0.9 3.8 - - 3.2 Caryophyllene oxide 1583.1
55. - - - - - 0.6 Humulene epoxide II 1604.7
56. - - - 0.6 - - Unidentified 1609.4
57. 1.2 0.7 - - - - Cubenol 1635.2
58. - - - 3.57 - - α-Muurolol 1641.1
59. 7.7 3.3 - 2.3 - - α-Cadinol 1651.9
  99.4 % 99.4 % 99.5% 95.7 % 96.4 % 94.3 % TOTAL COMPOSITION  

Table 2: The composition of essential oils of Ocimum species collected from Sierra Leone and Nigeria.

The chemotyping of Ocimum plants had been defined in terms of the combination of all major components constituting more than 20% rather than a dominant single component of the essential oil of the plant [13]. In this respect, both the Sierra Leone and Nigeria O. americanum L. leaf materials were thus identified as the linalool chemotype, constituting 49.1% and 39.6% respectively, in the present study. This chemotype of O. americanum L. is consistent with those previously reported in Benin [14], Rwanda [15], Cameroon [6] and Brazil [16]. The high content of linalool in some varieties of O. basilicum characterises the varieties as the best grade of commercial sweet basil for culinary use [17,18].

The Sierra Leone O. basilicum examined in the present study was clearly identified as the methyl eugenol chemotype (89.7%). This chemotype had been reported in Togo [19] and Turkey [20]. Methyl eugenol has been known in literature as a powerful insect attractant, [7,21-23], known to attract fruit flies from a distance as far as 0.8 km [7]. In the present study, attracted dead fruit insects (Drosophilia melanogaster) were found in the waste distillate (aqueous portion) drained into a bowl and left overnight. This observation underscores the potential use of methyl eugenol, or even this chemotype of O. basilicum co-formulated with an insecticide, as a powerful insecticidal product. On the other hand, the essential oil of the Nigerian O. basilicum variety was the methyl chavicol (89.8%) chemotype.

Both the Sierra Leone and Nigerian O. gratissimum L. varieties examined in this study are identified as the thymol chemotype having 60.5% and 42.2% thymol content respectively. This chemotype is widespread in West Africa (Nigeria [24], Cameroon [25], Togo [26] and Sao Tome [27]) although the presence of a Thymol-Cymene- Terpinene chemotype has been reported from the sub-region (Benin [14]). While O. gratissimum L. is the commercial source of eugenol in India [18,28], this component was not detected in the present material. The second most abundant constituent of Sierra Leone variety of L. is linalool (10.3%) which is a minor component in the Nigerian variety [0.4%] while the second most abundant constituent of the Nigerian variety is γ-terpinene (10.8%) which is only a minor component of the Sierra Leone variety (0.8%). Caryophyllene oxide constitutes a prominent sesquiterpene in both varieties of O. gratissimum L. The predominant thymol content probably explains the superior antibacterial activities of both O. gratissimum collections in the antimicrobial test (Table 3).

Microorganism OAN OBS OBN OGS OGN Streptomycin Acriflavine
S. aureus (NCTC 6571)
B. subtilis (NCTC 8236)
E. coli (ATCC 25922)
Ps. aeruginosa (ATCC 10145)
C. albicans
13 16 11.5 R 27 17 nt nt nt nt 8.5 R 8 R 10 44 nt 24 nt nt 48 42 27 10 44 23 26 15 R Nt Nt nt nt nt 8

Table 3: The zones of inhibition (mm) of essential oils from Ocimum species collected from Sierra Leone and Nigeria (average of duplicate) compared with reference standards. Note: R=completely resistant, nt=not tested; OAN=O. americanum (Nigeria); OBS=O. basilicum (Sierra Leone); OBN=O. basilicum (Nigeria); OGS=O. gratissimum (Sierra Leone) and OGN=O. gratissimum (Nigeria).

Conclusion

Both Sierra Leone and Nigeria O. americanum L. varieties were identified as linalool chemotype. The Sierra Leone O. basilicum L. variety is the methyl eugenol chemotype, while the Nigerian variety is predominantly methyl chavicol. Both varieties of O. gratissimum L collected from Sierra Leone and Nigeria are of thymol chemotype.

Acknowledgements

MIK is grateful to Obafemi Awolowo University Central Science Laboratory - Carnegie Corporation of New York Project for Visiting Fellowship. TAO is grateful to COMAHS - Ministry of Health and Sanitation World Bank Assisted Project RCHP for visiting appointment. The support of Nigeria TetFund for TETF/NRF/OAU grant is also acknowledged. The assistance of Mr. I. I. Ogunlowo of the Department of Pharmacognosy, OAU, for the collection of plants, is similarly acknowledged.

References

Select your language of interest to view the total content in your interested language
Post your comment

Share This Article

Relevant Topics

Recommended Conferences

Article Usage

  • Total views: 229
  • [From(publication date):
    April-2017 - Jun 29, 2017]
  • Breakdown by view type
  • HTML page views : 197
  • PDF downloads :32
 
 

Post your comment

captcha   Reload  Can't read the image? click here to refresh

Peer Reviewed Journals
 
Make the best use of Scientific Research and information from our 700 + peer reviewed, Open Access Journals
International Conferences 2017-18
 
Meet Inspiring Speakers and Experts at our 3000+ Global Annual Meetings

Contact Us

Agri, Food, Aqua and Veterinary Science Journals

Dr. Krish

agrifoodaquavet@omicsonline.com

1-702-714-7001 Extn: 9040

Clinical and Biochemistry Journals

Datta A

clinical_biochem@omicsonline.com

1-702-714-7001Extn: 9037

Business & Management Journals

Ronald

business@omicsonline.com

1-702-714-7001Extn: 9042

Chemical Engineering and Chemistry Journals

Gabriel Shaw

chemicaleng_chemistry@omicsonline.com

1-702-714-7001 Extn: 9040

Earth & Environmental Sciences

Katie Wilson

environmentalsci@omicsonline.com

1-702-714-7001Extn: 9042

Engineering Journals

James Franklin

engineering@omicsonline.com

1-702-714-7001Extn: 9042

General Science and Health care Journals

Andrea Jason

generalsci_healthcare@omicsonline.com

1-702-714-7001Extn: 9043

Genetics and Molecular Biology Journals

Anna Melissa

genetics_molbio@omicsonline.com

1-702-714-7001 Extn: 9006

Immunology & Microbiology Journals

David Gorantl

immuno_microbio@omicsonline.com

1-702-714-7001Extn: 9014

Informatics Journals

Stephanie Skinner

omics@omicsonline.com

1-702-714-7001Extn: 9039

Material Sciences Journals

Rachle Green

materialsci@omicsonline.com

1-702-714-7001Extn: 9039

Mathematics and Physics Journals

Jim Willison

mathematics_physics@omicsonline.com

1-702-714-7001 Extn: 9042

Medical Journals

Nimmi Anna

medical@omicsonline.com

1-702-714-7001 Extn: 9038

Neuroscience & Psychology Journals

Nathan T

neuro_psychology@omicsonline.com

1-702-714-7001Extn: 9041

Pharmaceutical Sciences Journals

John Behannon

pharma@omicsonline.com

1-702-714-7001Extn: 9007

Social & Political Science Journals

Steve Harry

social_politicalsci@omicsonline.com

1-702-714-7001 Extn: 9042

 
© 2008-2017 OMICS International - Open Access Publisher. Best viewed in Mozilla Firefox | Google Chrome | Above IE 7.0 version