Medicinal & Aromatic Plants

Medicinal & Aromatic Plants
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Research Article - (2012) Volume 1, Issue 7

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Analysis of the Hydrosol Aroma of Indian Oregano

Ram S. Verma*, Rajendra C. Padalia and Amit Chauhan
CSIR-Central Institute of Medicinal and Aromatic Plants, Research Centre, Pantnagar, P.O.- Nagla, Dairy farm, Udham Singh Nagar, Uttarakhand-263149, India
*Corresponding Author: Ram S. Verma, CSIR-Central Institute of Medicinal and Aromatic Plants, Research Centre, Pantnagar, P. O. Nagla, Dairy Farm, Udham Singh Nagar, Uttarakhand-263149, India, Tel: 91-9756021222 Email: ,

Abstract

Background: Hydrosols or aqueous distillates are herbal medicinal water obtained as a side product during the process of hydro or steam distillation of aromatic plant materials for getting essential oils. Generally, hydrosols are fragrant due to presence of a fraction of hydrophilic components of essential oils. Typically, in commercial production, the essential oils are decanted after completion of distillation process, whereas the hydrosols are discarded as waste or in few cases cohobated back to the distillation still. Methods: In present study, Indian oregano (Origanum vulgare L.) populations (two chemotypes, viz. thymol, and carvacrol) were hydrodistilled and the compositions of resulted main essential oil (primary oil) and essential oil fraction dissolved in hydrosol (secondary oil) have compared using gas chromatography (GC/FID) and gas chromatography mass spectrometry (GC/MS) techniques. Results: The primary oils of both the investigated populations were dominated by hydrocarbons (monoterpene, sesquiterpene, benzene derivatives; 53.4-57.6%), followed by their oxygenated derivatives (38.1-44.9%). However,secondary oils were mainly dominated by oxygenated compounds (92.0-96.2%). Conclusion: Present study concluded that the hydrosols of O. vulgare populations, a byproduct of essential oil industry, can be used as a potential source of phenolic compounds, viz. thymol and carvacrol.

Keywords: Origanum vulgare L., Hydrodistillation, Essential oil, Hydrophilic fraction, Composition

Introduction

The essential oils or volatile oils are complex mixture of terpenoids (generally C10 and C15) and some other classes of components, isolated from aromatic plants by physical means, e.g. steam-distillation, hydro-distillation, hydro-cum-steam distillation, and hydro-diffusion processes. These oils find extensive application in flavour, perfumery, cosmetic, and pharmaceutical industries. The process of distillation of aromatic plant material yields essential oil as a main product (primary oil or prime oil) and distillate water, also known as hydrosol as a byproduct. Typically, in commercial production, the essential oils are skimmed off and the hydrosol is discarded as waste or cohobated back to the source solution. The slightly hydrophilic part of essential oil, passes in to the aqueous phase during process of distillation, gives pleasant aroma to the resulted hydrosol. Typically, the essential oil fraction present in hydrosol is highly aromatic and its composition is often different from the primary essential oil [1,2]. However, the major components are generally the same of those present in oxygenated fraction of corresponding essential oils [3]. Biological and organoleptic properties of the hydrosols make them useful for food and cosmetic industries [2,4-9]. In addition, hydrosols also find application in biological agriculture against mushrooms, mildew, insects, and for fertilization of soils [10].

In Indian subcontinent, Origanum vulgare L. is locally known as ‘Jungali Tulsi’ or ‘Oregano’ or ‘Himalayan marjoram’. The plant is widely used as a very popular spice. Oregano is of great economic value owing to its various traditional and modern applications. It is used as a traditional remedy to treat various ailments such as whooping and convulsive coughs, digestive disorders, and menstrual problems [11,12]. Dried Origanum leaves and essential oils are used by the flavouring industry in various liqueur formulations, tomato sauces, condiments, in baked goods such as pizzas and salad dressings [13]. The genus, Origanum is known for its huge morphological and chemical diversity [14]. The chemotypic and ontogenic variations occurring in the essential oil composition of Indian oregano (Origanum vulgare L.) have been explored [15-18].

Aqueous distillate volatiles of some Indian aromatic plants have been subjected to phytochemical and antimicrobial studies [1,2,19-24]. However, literature survey revealed that there were no such reports available on emerging aromatic crop, Indian oregano; hence a comparison of the composition of primary (main essential oil) and secondary (dissolved fraction of essential oil) volatile oils of two chemotypes of O. vulgare have been conducted in this research.

Materials and Methods

Plant materials

The fresh samples of O. vulgare chemotypes (I & II) were collected from experimental field of Central Institute of Medicinal and Aromatic Plants, Research Centre, Purara, Uttarakhand on 29th June, 2009 when the plants were in flowering stage. Climatologically, the site falls in temperate region (1250 m) of western Himalaya where the monsoon usually breaking in June and continuing up to September.

Isolation of essential oil

Freshly harvested plant materials were hydro-distilled for 3 hrs in a slightly modified all glass Clevenger’s apparatus in which the recycling of distillate was stopped and diverted to a collection flask so that essential oil and hydrosol can be collected simultaneously (like field distillation without cohobation) [2]. The oil collected directly in extraction burette was separated and dehydrated by anhydrous sodium sulphate and designated as ‘primary oil’. The hydrosol collected simultaneously in a separate flask was used for isolation of ‘dissolved’ or ‘secondary oil’.

Isolation of dissolved essential oil

The hydrosol collected in a separate flask was shaken vigorously with hexane (10:1×2) using separatory funnel for 30 minutes to recover the dissolved oil. The mixture was then allowed to settle and the organic layer was separated. The organic layer was then dried over anhydrous sodium sulphate, filtered and the solvent evaporated (35°C) under reduced pressure to get the ‘secondary oil’. The primary and secondary oils were kept in a cool and dark place prior to analysis.

Gas chromatography (GC)

The GC analysis of the oil sample was carried out on a Nucon gas chromatograph model 5765 equipped with FID and DB-5 (30 m×0.32 mm; 0.25 μm film coating) fused silica capillary column. Oven temperature programming was done from 60-230°C at 3°C/min. Hydrogen was the carrier gas at 1.0 ml/min. The injector and detector temperatures were 220°C and 230°C, respectively. The injection volume was 0.02 μl neat (syringe: Hamilton 1.0 μl capacity, Alltech USA) and the split ratio was 1:30.

Gas chromatography-mass spectrometry (GC/MS)

GC/MS analysis of the essential oil sample was carried out on a PerkinElmer AutoSystem XL GC interfaced with a Turbomass Quadrupole Mass Spectrometer fitted with an Equity-5 fused silica capillary column (60 m × 0.32 mm i.d., film thickness 0.25 μm). The oven temperature was programmed from 60-210°C at 3°C/min using helium as the carrier gas at 1.0 mL/min. The injector temperature was 210°C, injection volume 0.1 μl prepared in n-hexane (dilution 10%), split ratio 1:40. MS were taken at 70 eV with a mass scan range of 40- 450 amu and scan rate 1 sec with interscan delay 0.5 sec.

Identification of components

Constituents were identified on the basis of a Retention Index (RI, determined with reference to homologous series of n-alkanes, C8-C30, under identical experimental conditions), co-injection with standards (Aldrich and Fluka) or known essential oil constituents, MS Library search (NIST/EPA/NIH version 2.1 and WILEY registry of MS data 7th edition), by comparing with the MS literature data [25]. The relative amounts of individual components were calculated based on the GC peak area (FID response) without using a correction factor.

Results and discussion

Primary and secondary volatile oils obtained from the hydrodistillation of fresh herbs of O. vulgare chemotypes (I & II) were analysed by GC/FID and GC/MS. Altogether, 55 constituents representing 95.2-98.3% of the total oil compositions were identified (Table 1). Chemotypes ‘I’ was rich in thymol, p-cymene, and γ-terpinene. While the chemotype II contained carvacrol, p-cymene, and γ-terpinene as major constituents. The amount of thymol and carvacrol was found to be very low in primary oil (30.8% and 1.0%, respectively) as compared to secondary oil (83.4% and 5.9%, respectively) of chemotype ‘I’. On the other hand, primary oil possessed higher amounts of γ-terpinene (21.4%), p-cymene (19.0%), myrcene (3.2%), carvacrol methyl ether (3.2%), α-terpinene (2.4%), (E)-caryophyllene (2.1%), (E)-β-ocimene (2.0%), and (Z)-β-ocimene (1.3%) as compared to secondary oil of this chemotype. Furthermore, the primary oil of chemotype ‘II’ contained lesser amount of carvacrol (42.3%) in comparison to secondary oil (94.7%). However, the amounts of γ-terpinene (23.4%), p-cymene (20.9%), myrcene (2.0%), and α-terpinene (2.0%) were noticed to be higher in primary oil than secondary oil of chemotype II.

S. No. Compound RIa RIb Content (%)
        I II
        PO SO PO SO
1. a-Thujene 930 924 1.5 t 1.3 t
2. a-Pinene 936 932 0.8 0.8 1.0 t
3. Camphene 944 946 0.1 0.3 0.2 -
4. β-Pinene 979 974 1.7 0.5 0.2 t
5. 3-Octanone 986 979 0.7 - - -
6. Myrcene 991 988 3.2 t 2.0 0.1
7. δ-2-Carene 1000 1001 - - 0.2 -
8. a-Phellandrene 1006 1002 0.2 t - -
9. a-Terpinene 1018 1014 2.4 0.1 2.0 t
10. p-Cymene 1024 1020 19.0 0.8 20.9 0.7
11. (Z)-b-Ocimene 1038 1032 1.3 - - -
12. (E)-b-Ocimene 1046 1044 2.0 t 0.1 -
13. g-Terpinene 1058 1054 21.4 0.4 23.4 0.4
14. Terpinolene 1089 1086 0.2 0.1 0.1 0.1
15. Linalool 1099 1095 0.1 0.4 0.1 t
16. trans-p-Menth-2 en-1-ol 1142 1136 t 0.1 t -
17. Camphor 1144 1141 - - t -
18. Borneol 1162 1165 0.4 0.8 0.5 0.1
19. Terpinen-4-ol 1175 1174 0.6 0.2 0.3 0.2
20. p-Cymen-8-ol 1183 1179 t t t 0.1
21. a-Terpineol 1185 1186 0.1 0.2 0.1 0.1
22. Thymol methyl ether 1232 1232 0.3 - t -
23. Carvacrol methyl ether 1246 1241 3.2 0.1 0.1 t
24. Bornyl acetate 1282 1284 0.1 0.3 t 0.2
25. Thymol 1292 1289 30.8 83.4 0.6 0.3
26. Carvacrol 1302 1298 1.0 5.9 42.3 94.7
27. Thymyl acetate 1350 1349 t 0.1 t t
28. Eugenol 1352 1356 - - t t
29. Carvacryl acetate 1372 1370 t - 0.1 -
30. a-Copaene 1375 1374 t - t -
31. Geranyl acetate 1378 1379 - - t t
32. b-Elemene 1395 1389 t - - -
33. (E)-Caryophyllene 1418 1417 2.1 0.1 1.2 0.1
34. b-Copaene 1427 1430 t t t t
35. Aromadendrene 1441 1439 0.1 - 0.1 -
36. (Z)-β-Farnesene 1445 1440 t t 0.1 -
37. a-Humulene 1451 1452 0.1 t 0.1 -
38. g-Gurjunene 1472 1475 - - t -
39. Germacrene D 1481 1484 0.7 t 0.1 -
40. a-Muurolene 1498 1500 t t 0.1 t
41. (E,E)-α-Farnesene 1502 1505 0.1 t 0.1 -
42. Germacrene A 1506 1508 - - 0.2 -
43. g-Cadinene 1516 1513 0.5 0.1 - -
44. d-Cadinene 1524 1522 0.2 t t -
45. a-Cadinene 1538 1537 - - t -
46. Germacrene-D-4-ol 1575 1574 t t 0.2 t
47. Caryophyllene oxide 1583 1582 0.3 t 0.3 t
48. Viridiflorol 1595 1592 t t t -
49. epi-α-Cadinol 1640 1638 t t - -
50. epi-α-Muurolol 1644 1640 t - - -
51. α-Muurolol 1646 1644 t t t -
52. β-Eudesmol 1651 1649 0.4 0.5 0.1 -
53. α-Cadinol 1652 1652 - - 0.1 0.4
54. β-Bisabolol 1671 1674 t - 0.1 0.1
55. α-Bisabolol 1689 1685 0.1 t - -
  CLASS COMPOSITION            
  (1) Hydrocarbons            
  Monoterpene hydrocarbon     34.8 2.2 30.5 0.6
  Sesquiterpene hydrocarbon     3.8 0.2 2.0 0.1
  Benzenoid hydrocarbon     19.0 0.8 20.9 0.7
        57.6 3.2 53.4 1.4
  (2) Oxygenated compounds            
  Oxygenated monoterpene     1.3 2.0 1.0 0.6
  Oxygenated sesquiterpene     0.8 0.5 0.8 0.5
  Oxygenated benzenoid     35.3 89.5 43.1 95.1
  Aliphatic compound     0.7 - - -
        38.1 92.0 44.9 96.2
  Total identified (%)     95.7 95.2 98.3 97.6
RIa: experimental retention index on DB-5 column (relative to n-Alkane, C8-C30); RIb: retention index from literature (Adams, 2007); I: thymol rich population: II: carvacrol rich population; PO: primary oil; SO: secondary oil (recovered from hydrosol); t: trace (<0.05%).

Table 1: Chemical composition of primary and hydrosol recovered volatile oils of Indian oregano (Origanum vulgare L.)

Further, the class compositions of the primary and secondary volatile oils of O. vulgare chemotypes also showed clear and considerable differences in their nature. The primary oils of O. vulgare chemotypes were dominated by hydrocarbons (chemotype I: 57.6%; chemotype II: 53.4%), followed by oxygenated compounds (chemotype I: 38.1%; chemotype II: 44.9%). However, secondary oils were dominated only by oxygenated compounds (chemotype I: 92.0%; chemotype II: 96.2%). These variations are observed due to relatively higher solubility of oxygenated compounds in water over the solubility of hydrocarbons.

Thus, on the basis of present study, it can be said that the hydrosol of O. vulgare populations should not be discarded as usually done with commercial distillation of aromatic crops. It could be redistilled by introducing cohobation system in field distillation unit to improve the organoleptic property of the primary oil or reused for distillation of fresh herb to minimize the loss of valuable components of the essential oil. Alternatively, hydrosols could also be used for isolation of pure compounds (thymol, and carvacrol) or it can be used as such for disinfection and cosmetic applications.

Acknowledgements

We are thankful to Director, CSIR-Central Institute of Medicinal and Aromatic Plants, Lucknow, India for continuous support.

References

  1. Verma RS (2010) Chemical investigation of decanted and hydrophilic fractions of Salvia sclarea essential oil. Asian J Trad Med 5:102-108.
  2. Verma RS, Pandey V, Padalia RC, Saikia D, Krishna B (2011) Chemical composition and antimicrobial potential of aqueous distillate volatiles of Indian peppermint (Mentha piperita) and spearmint (Mentha spicata). J Herbs Spices Med Plants 17: 258-267.
  3. Price L, Price S (2004) Understanding hydrolats: the specific hydrosols for aromatherapy, a guide for health professionals. Churchill Livingstone, Elsevier, Amsterdam, pp. 1-8.
  4. Lis-Balchin M, Steyrl H, Krenn E (2003) The comparative effect of novel Pelargonium essential oils and their corresponding hydrosols as antimicrobial agents in a model food system. Phytother Res 17: 60-65.
  5. Sagdiç O, Ozcan M (2003) Antibacterial activity of Turkish spice hydrosols. Food Control 14: 141-143.
  6. Boyraz N, Özcan M (2005) Antifungal effect of some spice hydrosols. Fitoterapia 76: 661-665.
  7. Ozcan MM, Arslan D, Aydar AO (2008) The use of the oregano (Origanum vulgare L.) essential oil and hydrosol in green olive fermentation. Braz Arch Biol Technol 51: 601-605.
  8. Aazza S, Lyoussi B, Miguel MG (2011) Antioxidant activity of some Moroccan hydrosols. J Med Plant Res 5: 6688-6696.
  9. Verma RS (2012) Distillate water: overlooked golden drops. MAP 1: 3. doi:10.4172/map.1000e112.
  10. Paolini J, Leandri C, Desjobert JM, Barboni T, Costa J (2008) Comparison of liquid-liquid extraction with headspace methods for the characterization of volatile fractions of commercial hydrolats from typically Mediterranean species. J Chromatogr A 1193: 37-49.
  11. Sharma PK, Lal B (2005) Ethnobotanical notes on some medicinal and aromatic plants of Himachal Pradesh. Indian J Trad Know 4: 424-428.
  12. Ozbek T, Gulluce M, Sahin F, Ozkan H, Sevsay S, Baris O (2008) Investigation of the antimutagenic potentials of the methanol extract of Origanum vulgare L. subsp. vulgare in the Eastern Anatolia region of Turkey. Turk J Biol 32: 271-276.
  13. Ozel MZ, Kaymaz H (2004) Superheated water extraction, steam distillation and soxhlet extraction of essential oils of Origanum onites. Anal Bioanal Chem 379: 1127-1133.
  14. Kokkini S (1997) Taxonomy, diversity and distribution of Origanum species, In: Padulosi S, ed. Oregano.Proceedings of the IPGRI international workshop on Oregano, 8-12 May 1996, CIHEAM, Valenzano (Bari), Italy, 2-12.
  15. Verma RS, Padalia RC, Chauhan A, Verma RK, Yadav AK, et al. (2010) Chemical diversity in Indian Oregano (Origanum vulgare L.).J Chem Biodivers7: 2054-64.
  16. Verma RS, Rahman L, Verma RK, Chanotiya CS, Chauhan A, et al. (2010) Changes in the essential oil content and composition of Origanum vulgare L. during annual growth from Kumaon Himalaya. CurrSci98: 1010-1012.
  17. Verma RS, Verma RK, Chauhan A, Yadav AK (2010) Volatile terpenoid composition of Origanum vulgare derived from top, middle and lower portions of the plant cultivated in Uttarakhand. J Essent Oil-Bear Pl 13: 692-698.
  18. Verma RS, Padalia RC, Chauhan A (2012) Volatile constituents of Origanum vulgare L., ‘thymol’ chemotype: variability in North India during plant ontogeny. Nat Prod Res 26: 1358-62.
  19. Kishore WM, Keshavan N, Pangarkar VG (1997) Recovery of dissolved essential oils from condensate waters of basil and Mentha arvensis distillation. J Chem Tech Biotechnol 69: 362-366.
  20. Rao BRR, Kaul PN, Syamasundar KV, Ramesh S (2002) Water soluble fractions of rose scented geranium (Pelargonium species) essential oil. Bioresource Technol 84: 243-246.
  21. Rao BRR, Kaul PN, Syamasundar KV, Ramesh S (2003) Comparative composition of decanted and recovered essential oils of Eucayptus citriodora Hook. Flavour Frag J 18: 133-135.
  22. Rao BRR, Kaul PN, Syamasundar KV, Ramesh S (2005) Chemical profiles of primary and secondary essential oils of palmarosa (Cymbopogon martini Roxb.) Wats var. motia Burk.). Ind Crops Prod 21: 121-127.
  23. Rao BRR, Kaul PN, Bhattacharya AK, Rajput DK, Syamasundar KV (2006) Comparative chemical composition of steam-distilled and water-soluble essential oils of south American marigold (Tagetes minuta L.). J Essent Oil Res 18: 622-626.
  24. Babu, Singh GD, B (2007) Comparative chemical composition of direct, recovered and combined essential oils of Lavandula angustifolia Mill. Indian Perfumer 51: 50-54.
  25. Adams RP (2007) Identification of essential oil components by gas chromatography/mass spectrometry. Allured Publishing Corp, Carol Stream, Illinois, USA.
Citation: Verma RS, Padalia RC, Chauhan A (2012) Analysis of the Hydrosol Aroma of Indian Oregano. Med Aromat Plants 1:112.

Copyright: © 2012 Verma RS, et al. 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.
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