The skin contact allergy of essential oils or their constituents is a concern in fragrance compounding, and PEO is not an exception.309,372,373Neat or as the main constituent of PEO, patchoulol is a fragrance ingredient used in decorative cosmetics, fine fragrances, shampoos, toilet soaps and other toiletries as well as in non‐cosmetic products such as house- hold cleaners and detergents. In neat form, its use annual worldwide use is 0.5‐1 metric tonne, whereas the consumption of the essential oil is much bigger at ~1300 tonnes. Belsito et al. have made an assessment of the general toxicological and dermatological risk of many terpene alcohols including patchoulol‐containing products.374Their conclusion was that patchoulol has a low order of acute toxicity with dermal and oral NOAELs (no observed adverse effect levels) of 50 mg/kg body weight/day or greater and is negative in mutagenicity and genotoxicity tests. At current use levels, patchoulol is non‐irritating and sensitisation potential is generally low. In a separate note the results specific to patchoulol were summarised by Bhatia et al.375In a rat study, PEO orally administered for 90 days at a level in excess of at least 100 times the maximum estimated daily dietary intake in man evoked no adverse effect on growth, food consumption, haematology, blood chemistry, liver and kidney weights or on gross and microscopic appearance of major organs at autopsy.376
Over time, various groups have investigated PEO in more detail with respect to the risk of triggering allergic reactions on the skin.
Nakayama et al. found 3“strongly positive”and 8“weakly positive” reactions to“Patchouli oil”(unknown test concentration) in patch tests with 183 patients.377 The number of patients, mostly Japanese women, with pigmented cosmetic dermatitis thought to be caused in part by PEO, decreased significantly after 1978 when major cosmetic manufacturers began to eliminate strong contacts sensitizers (e.g., cinnamaldehyde) from their products.378 Clinical data published in 2002 reported that 0.8% positive reactions to PEO (10% in petrolatum) in 1606 consecutive patients were observed.379A more recent study on patch results with PEO identified 0.6% positive reactions in 2446 consecutively tested patients and 1.4% positive reactions in 828 patients tested in the context of a special series.380For assessing skin contact allergy of cosmetics, two "fragrances mixes" (14 components in total), the 26 allergens,381 which need to declared in cosmetics, and several essential oils were tested. When PEO was patch‐tested in this study (10% concentration in petrolatum), 53 patients out of 5539 (1%) gave a positive reaction.382It is regrettable that, no informa- tion was given in this report about the intensities of the reactions, and none of these reports gave any information about the quality of the tested essential oils (origin, genuineness, age, peroxide value, etc.).
Some of the above studies have been summarised by the Scientific Committee on Consumer Safety of the EU.383
Among the constituents ever reported in PEO, at least six are restricted in fragrance compounding: limonene, linalool, citronellol, farnesol,206eugenol,271and isophorone.252Whereas limonene, linal- ool, citronellol, farnesol and eugenol are suspected skin sensitisers with restricted use levels384 or purity requirements with regard to the level of oxidation, isophorone91is officially classified as a CMR (carcinogen, mutagen, reprotoxic) and should not be used at all as a fragrance ingredient.385However eugenol68occurs only at low ppm
levels in genuine PEO (see § 3.3) and the presence of isophorone and farnesol has not been confirmed to date. The other above cited compounds are trace elements in patchouli (<150 ppm) and can be detected and quantified accurately only by using a validated specific GC‐MS method.386 One should not rule out however that the presence of these compounds in PEO is the result of contamination during harvesting, distillation or manufacturing.
The European Chemicals Agency (ECHA) is the driving force among regulatory authorities in implementing the European Union's groundbreaking chemicals legislation for the benefit of human health and the environment as well as for innovation and competitiveness.
Just as for any other chemical entering the EU or used in the EU, ECHA provides information on PEO and addresses toxicological concerns.387
7
|C O N C L U S I O N
Among the sesquiterpene‐rich essential oils in the category "natural woody commodities", patchouli is of major importance for the fragrance industry. Similar to other important raw materials of this type such as vetiver and sandalwood oils (and to a lesser extent agarwood), sesquiterpenes represent more than 95% of PEO, including at least six nor‐and two seco‐sesquiterpenes, but its composition has not yet been investigated in‐depth to the same level. Hence, whereas more than 150 volatile constituents have been identified in vetiver,5sandalwood,3and agarwood,4including many minor or even trace elements of high olfac- tory relevance, the number of such compounds identified so far in PEO is unfortunately smaller. Considering that the main vectors of the earthy‐mouldy note, namely the trio patchoulol33, norpatchoulenol 34and nortetracyclopatchoulol35, alone cannot account for the rich- ness and high complexity of PEO odour, there is an on‐going need to identify more high impact odour‐donating components of PEO, includ- ing carbonyl‐containing sesquiterpenes such as rotundone40.
It is noteworthy that only six important odour contributors have been conclusively identified during a 30‐year period (1962‐92) represented by
~25% of the references cited in the present review, and no such compo- nents–with exception of rotundone–have been identified during the last 25‐year period representing ~65% of the references! Notwithstanding the very recent findings concerning ultra‐trace constituents,165this is a para- dox, when one considers the availability of efficient GC‐olfactometry devices to pinpoint key odorants, and improved separation techniques as well as more sensitive and powerful spectroscopic tools for the identifica- tion of complex chemical structures. The launching in the late 1980s of low cost GC‐MS systems, leading to a proliferation of lower quality publica- tions in the domain of essential oil analysis, partially accounts for this regrettable situation. More GC‐MS analyses will by themselves not provide the structures of the many still unknown PEO constituents, even if occur- ring at the 1‐2% level.
Furthermore, what happens in fresh patchouli leaves during the
"drying‐fermentation" step and subsequent storage prior to steam distillation in relation to PEO odour is still enigmatic and remains to be clarified, despite recent reports.388-390This holds also true for the ill‐understood increase in olfactory quality of PEO after years of storage. Finally, the fate of some genuine leaf constituents–already identified or pending identification–during the distillation process also needs to be better understood. The present review is therefore a
strong invitation for skilled phytochemists to reopen, in collaboration with other scientists, the patchouli case.
8
|S U M M A R Y O F S U P P L E M E N T A R Y I N F O R M A T I O N
The Supplementary Information belonging to this paper consists of:
Table S1. List of non‐cited patchouli‐related papers of which the focus is outside the scope of this review or contain possibly erroneous analytical chemical data. Papers are presented in chronological order.
Figure S1. Complete chromatogram of PEO B (see also Figure 7b), i.e., including monoterpenes.
Figure S2. Chromatogram of oil B (Figure 7b) on a dimethyl polysiloxane phase (DB1).
Figure S3. Chromatogram of oil B (Figure 7b) on a polyethylene glycol phase (Wax).
Figure S4. Complete gas chromatogram of a commercial steam distilled PEO on a 30 m DB5 stationary phase with a different temper- ature programme.
Figure S5. Chromatogram of heavily adulterated commercial PEO on a DB5 phase.
A C K N O W L E D G E M E N T S
We gratefully acknowledge Bo Chen, Xiao Wei, Bruno Maurer, Charles Cornwell, Arnaldo Bandoni, Philip Kraft, Robin Clery, Shashikumar Paknikar, Brian Lawrence, Toshio Hasegawa, Anil Pant, Arjen Schots, David Leach, Suaib Luqman, Andre Krause, Annette Bierman, Pat Sandra, Luigi Mondello, Lydia Ziegler, Sascha Beutel, Laura McGregor, Eranki Prakasa Rao, Louis Peyron, Sabrina Boutefnouchet, Keita Tanaka and Liang Xiong for providing information, literature or translations.
Without their generous help this review would not be the same. We are greatly indebted to Maarten Posthumus who kindly provided us with the results of many of his unpublished but very high‐quality analyses of patchouli oils and the corresponding chromatograms some of which made it into this review (Figure 7a‐c). Last but not least we wish to thank the late Hans Siwon who set up his own patchouli distillation facility in Indonesia and carried through several innovations leading to oils with dif- ferent olfactory properties. Over a period of ten years, he gave both authors many high‐quality genuine patchouli oils and proverbially speak- ing he planted the small seed that eventually led to this review.
O R C I D
Teris A. van Beek http://orcid.org/0000-0002-9843-7096 Daniel Joulain http://orcid.org/0000-0001-9662-9732
R E F E R E N C E S
1. Joulain D, Tabacchi R. Lichen extracts as raw materials in perfumery.
Part 1: oakmoss.Flavour Frag J. 2009;24:49‐61.
2. Joulain D, Tabacchi R. Lichen extracts as raw materials in perfumery.
Part 2: treemoss.Flavour Frag J. 2009;24:105‐116.
3. Baldovini N, Delasalle C, Joulain D. Phytochemistry of the heartwood from fragrantSantalumspecies: a review.Flavour Frag J. 2011;26:7‐26.
4. Naef R. The volatile and semi‐volatile constituents of agarwood, the infected heartwood ofAquilariaspecies: A review. Flavour Frag J.
2011;26:73‐89.
5. Belhassen E, Filippi J‐J, Brévard H, Joulain D, Baldovini N. Volatile constituents of vetiver: a review.Flavour Frag J. 2015;30:26‐82.
6. Anonis DP. Woody notes in perfumery: patchouli in fragrances, part II.
Perfum Flavor. 2007;32:30‐35.
7. Haarmann & Reimer.Guide to Fragrance Ingredients. Vol. 4. Hamburg:
Gloess Publishing; 1985;113.
8. Lawrence BM. A preliminary report on the world production of some selected essential oils and countries.Perfum Flavor. 2009;34:38‐44.
9. Anonymous. Socio‐economic committed report on patchouli ‐ Pogostemon cablin(Blanco) Benth. IFEAT World‐International Feder- ation of Essential Oils & Aroma Trades, May edition. 2014;4‐5.
10. Howarth J. Natural product supply bulletin: patchouli, Mexican lime and the Crimean conflict.Perfum Flavor. 2015;40‐January:32‐37.
11. Lawrence BM.Personal Communication2016.
12. Swamy MK, Mohanty SK, Sinniah UR, Maniyam A. Evaluation of patchouli (Pogostemon cablinBenth.) cultivars for growth, yield and quality parameters.J Essent Oil‐Bear Plants. 2015;18:826‐832.
13. Frister T, Beutel S. Moschusduft und Patchouliöl‐Zwei Duftbausteine fur Parfümerie und Kosmetik.Chem unserer Zeit. 2015;49:2‐9.
14. Verlet N. Commercialization of essential oils and aroma chemicals. In A Manual on the Essential Oil Industry, Tuley de Silva K (ed.). United Nations Industrial Development Organization: Vienna, 1995;203‐232.
15. Rochleder F.Phytochemie. Leipzig: Verlag von Wilhelm Engelmann;
1854;155.
16. Hunt R, Rudler FW.Ure's Dictionary of Arts, Manufactures, and Mines.
III. 7th edition. London: Longmans, Green, and Co.; 1875;516.
17. Anonymous. Patchouli (Pogostemon Patchouli, var.suavis).Bull Misc Inf (Royal Bot Gardens, Kew). 1889;135‐139.
18. Gildemeister E, Hoffmann F.Die Aetherischen Oele. Berlin: Verlag Julius Springer; 1899;855‐859.
19. Beilstein F. Handbuch der Organischen Chemie.Dritte Auflage, dritter Band. Hamburg und Leipzig: Verlag von Leopold Voss; 1897;514 & 538.
20. Anonymous. U.S. Food and Drug Administration, Code of Federal Regulations, Title 21, Vol. 3, Part 172‐Food additives permitted for direct addition to food for human consumption. Sec. 172.510 Natural flavoring substances and natural substances used in conjunction with flavors (21CFR172.510). 2016.
21. Hall RL, Oser BL. Recent progress in the consideration of flavoring ingredients under the food additives amendment. III. GRAS sub- stances.Food Technol. 1965;19:151‐197.
22. Anonymous. Patchouli oil, https://echa.europa.eu/fr/substance‐infor- mation/‐/substanceinfo/100.109.383, accessed on April 29, 2017.
23. Anonymous. Inventory of Existing Cosmetic Ingredients in China (CFDA, Decree No. 105, 2015) ‐ 02634 Pogostemon cablin oil, http://www.cirs‐reach.com/news‐and‐articles/new‐inventory‐of‐ existing‐cosmetic‐ingredients‐in‐china‐launched‐(iecic‐2015,‐final‐ver- sion).html, accessed on May 9, 2017.
24. Zörnig H. Arzneidrogen. Vol. II. Leipzig: Werner Klinkhardt;
1911;203‐206.
25. Parry EJ.The Chemistry of Essential Oils and Artificial Perfumes. Vol. I.
Fourth Edition. London: Scott, Greenwood and Son; 1921;250‐255.
26. Gildemeister E, Hoffmann F. Die Ätherischen Öle. Dritter Band.
Dritte Auflage. Miltitz bei Leipzig: Verlag der Schimmel & Co.
Aktiengesellschaft; 1931;893‐908.
27. Guenther E.The Essential Oils. Vol. III. Princeton: Van Nostrand Co.
Inc.; 1949;552‐575.
28. Soepadyo R, Tan HT. Patchouli, a profitable catch crop.World Crops.
1968;3:48‐54.
29. Kumar A, Gauniyal AK, Virmani OP. Cultivation ofPogostemon cablin for its oil.Curr Res Med Aromat Plants. 1986;8:79‐86.
30. Husain A, Virmani OP, Sharma A, Kumar A, Misra LN.Major Essential Oil‐bearing Plants of India. Lucknow: Central Institute of Medicinal and Aromatic Plants; 1988, Chapter 35‐Patchouli Oil, 187‐191.
31. Husain A.Essential Oil Plants and their Cultivation. Lucknow: Central Institute of Medicinal and Aromatic Plants; 1994;136‐140.
32. Maiti S, Raju S, Greta KA, Mandal K.Good Agricultural Practices for Patchouli, Geranium and Lemongrass. Boriavi, Anand‐387310, Gujarat, India. 2006;1‐7.
33. Robbins SRJ. Selected markets for the essential oils of patchouli and vetiver. Report of the Tropical Products Institute, G167, London, 1982.
34. Manheimer S. Long live Patchouli!Cosmet World News. 1983;33.
35. Akhila A, Tewari R. Chemistry of patchouli oil: a review.Curr Res Med Aromat Plants. 1984;6:38‐54.
36. Boelens MH. Chemical and sensory evaluation of trace compounds in naturals, InProceedings of 13th International Congress of Flavours, Fra- grances and Essential Oils, Istanbul, Turkey, Boelens Aroma Chemical Information Service (BACIS), 1995;177‐185.
37. Lawrence BM. Progress in essential oils‐patchouli oil.Perfum Flavor.
1976;1:20.
38. Lawrence BM. Recent progress in essential oils. Perfum Flavor.
1978;2:44‐50.
39. Lawrence BM. Progress in essential oils. Perfum Flavor.
1981;6:73‐74,76.
40. Lawrence BM. Progress in essential oils. Perfum Flavor. 1990;15:
(March/April) 75‐77.
41. Lawrence BM. Progress in essential oils. Perfum Flavor.
1995;20(3):67‐68,70,72.
42. Lawrence BM. Progress in essential oils. Perfum Flavor.
2002;27(3):48,50‐54,56‐60,62,64‐66,68‐69.
43. Lawrence BM. Progress in essential oils‐Patchouli oil and extracts.
Perfum Flavor. 2014;39:46,48,50‐52.
44. Bhat KKS. Agrotechnology of aromatic plants. InA Manual on the Essential Oil Industry, Tuley de Silva K (ed.). UNIDO: Vienna, 1995;31‐32.
45. Leung AY, Foster S. Encyclopedia of Common Natural Ingredients Used in Food, Drugs, and Cosmetics. New York: Wiley & Sons;
1996;411‐413.
46. Das K. Patchouli (Pogostemon CablinBenth) Oils. InEssential Oils in Food Preservation, Flavor and Safety, Preedy V (ed.). Academic Press:
Amsterdam, 2016;633‐639.
47. Weiss EA.Essential Oil Crops. Wallingford: CAB International; 1997, 138‐154.
48. Oyen LPA. Pogostemon Desf. InEssential‐Oil Plants, Oyen LPA, Dung NX (ed.). Backhuys Publishers: Leiden, 1999;151‐157.
49. Panda H. Patchouli. New Delhi: Asia Pacific Business Press Inc.;
2005;85‐93.
50. Wu Y‐g, Guo Q‐s, Zheng H‐q. Textual research on history of introduc- tion and herbal medicine ofPogostemon cablin.China J Chin Materia Med. 2007;32:2114‐2117.
51. Murugan R, Livingstone C. Origin of the name‘patchouli’and its his- tory.Curr Sci. 2010;99:1274‐1276.
52. Ohloff G, Pickenhagen W, Kraft P.Scent and Chemistry‐The Molecular World of Odors. Weinheim: Wiley‐VCH; 2012;251‐258.
53. Chakrapani P, Venkatesh K, Chandra SSB, et al. Phytochemical, pharma- cological importance of Patchouli (Pogostemon cablin(Blanco) Benth) an aromatic medicinal plant.Int J Pharm Sci Rev Res. 2013;21:7‐15.
54. Swamy MK, Sinniah UR. A comprehensive review on the phytochem- ical constituents and pharmacological activities ofPogostemon cablin Benth.: an aromatic medicinal plant of industrial importance.
Molecules. 2015;20:8521‐8547.
55. Ramya HG, Lpalanimuthu V, Singla R. An introduction to patchouli (Pogostemon cablinBenth.)‐a medicinal and aromatic plant: it's impor- tance to mankind.Agric Eng Int. 2013;15:243‐250.
56. Anonymous. Patchouli (Pogostemon cablinBenth.) Family‐Lamiaceae, Assam Small Farmers' Agri Business Consortium, http://
assamagribusiness.nic.in/NEDFi/map6.pdf, accessed on September 28, 2016.
57. Swamy MK, Sinniah UR. Patchouli (Pogostemon cablin Benth.):
botany, agrotechnology and biotechnological aspects.Ind Crops Prod.
2016;87:161‐176.
58. Chen Y, Wu Y‐G, Xu Y, et al. Dynamic accumulation of sesquiterpenes in essential oil of Pogostemon cablin. Rev Bras Farmacogn.
2014;24:626‐634.
59. Tripathi YC, Hazarika P. Impact of harvesting cycle, maturity stage, drying and storage on essential oil content of patchouli leaves grown in Northeast region of India. J Essent Oil‐Bear Plants.
2014;17:1389‐1396.
60. Hussin N, Mondello L, Costa R, Dugo P, Yusoff NIN, Yarmo MA, Wahab AA, Said M. Quantitative and physical evaluation of patchouli essential oils obtained from different sources ofPogostemon cablin.
Nat Prod Commun. 2012;7:927‐930.
61. (a) Blank AF, Sant'ana TCP, Santos PS, et al. Chemical characterization of the essential oil from patchouli accessions harvested over four seasons.Ind Crops Prod. 2011;34:831‐837; (b) de Sant'ana TCP, Blank AF, Vieira SD, Arrigoni‐Blank MF, de Jesus HCR, Alves PB. Influência do armazenamento de folhas secas no óleo essencial de patchouli.
Quim Nova. 2010;33:1263‐1265.
62. Zhang L‐G, Zhang C, Ni L‐J, Yang Y‐J, Wang C‐M. Rectification extrac- tion of Chinese herbs' volatile oils and comparison with conventional steam distillation.Sep Purif Technol. 2011;77:261‐268.
63. Santos AV, Arrigoni‐Blank MF, Blank AF, et al. Mass multiplication of Pogostemon cablin(Blanco) Benth genotypes and increase of essential oil and patchoulol yield.Ind Crops Prod. 2010;32:445‐449.
64. Paul A, Thapa G, Basu A, Mazumdar P, Kalita MC, Sahoo L. Rapid plant regeneration, analysis of genetic fidelity and essential aromatic oil content of micropropagated plants of Patchouli,Pogostemon cablin (Blanco) Benth.‐An industrially important aromatic plant.Ind Crops Prod. 2010;32:366‐374.
65. Kumar A, Srivastava NK, Kalra A, Mishra BN, Luqman S, Khanuja SPS.
Allocation of14CO2into primary metabolites and leaf terpenoid in relation with storage duration in patchouli (Pogostemon cablin).J Plant Biol (New Delhi, India). 2009;36:33‐40.
66. Kumar A. Effect of soaking time of Patchouli leaves on oil yield and chemical composition.Indian Perfum. 2009;53:27‐28.
67. Rana VS, Blazquez MA. Volatile leaf essential oil of commercial Pogostemon cablin Benth. cultivated in Manipur. Indian Perfum.
2009;53:30‐32.
68. Kongkathip N, Sam‐ang P, Kongkathip B, Pankaew Y, Tanasombat M, Udomkusonsri P. Development of patchouli extraction with quality control and isolation of active compounds with antibacterial activity.
Kasetsart J (Nat Sci). 2009;43:519‐525.
69. Rekha K, Bhan MK, Dhar AK. Development of erect plant mutant with improved patchouli alcohol in patchouli [Pogostemon cablin(Blanco) Benth].J Essent Oil Res. 2009;21:135‐137.
70. Donelian A, Carlson LHC, Lopes TJ, Machado RAF. Comparison of extraction of patchouli (Pogostemon cablin) essential oil with supercrit- ical CO2and by steam distillation.J Supercrit Fluids. 2009;48:15‐20.
71. Ramachandra KM, Farooqi AA, Srinivasappa KN. Effect of gamma rays on growth, yield and oil composition in patchouli (Pogostemon patch- ouliPellet.).Indian Perfum. 2008;52:58‐60.
72. Prakash O, Joshi S, Shukla AK, Pant AK. Sesquiterpenoid rich essential oil from the leaves ofPogostemon patchoulipellet grown organically under tarai conditions.J Essent Oil‐Bear Plants. 2007;10:157‐161.
73. Bhaskar S, Kumar TV. Agronomic bottlenecks, genetic barriers and marketing impediments in patchouliPogostemon patchouliproduction.
J Med Aromat Plant Sci. 2000;22:396‐403.
74. Sugimura Y, Ichikawa Y, Otsuji K, et al. Cultivarietal comparison of patchouli plants in relation to essential oil production and quality.
Flavour Frag J. 1990;5:109‐114.
75. Bruns K. Contribution to the study and quality evaluation of patchouli oil.Parfüm Kosmet. 1978;59:109‐115.
76. Singh R, Singh M, Srinivas A, Rao EVSP, Puttanna K. Assessment of organic and inorganic fertilizers for growth, yield and essential oil quality of industrially important plant patchouli (Pogostemon cablin) (Blanco) Benth.J Essent Oil‐Bear Plants. 2015;18:1‐10.
77. von Rechenberg C. Theorie der Gewinnung und Trennung der Ätherischen Öle durch Destillation. Miltitz bei Leipzig: Selbstverlag von Schimmel & Co.; 1910;441.
78. Ambrose DCP, Annamalai SJK, Naik R. Effect of drying on the volatile oil yield of patchouli.Indian J Sci Technol. 2013;6:5559‐5562.
79. Rulianah S, Meilany D, Maryanty Y, Purwanto RE, Nanda D, Silvia W.
Production of pachouli oil by fermentation methode using Phanerochaete chrysosporiumwith kieserite as sustitution MgSO4.Int J Eng Res Developm. 2015;11:14‐19.
80. Reliance Life Sciences PVT LTD, Process for increased patchulol con- tent in essential oil ofPogostemon cablin, World Patent 2007/080606, January 16, 2006.
81. Ravindra NS, Ramesh SI, Gupta MK, et al. Evaluation of somaclonal variation for genetic improvement of patchouli (Pogostemon patchouli), an exclusively vegetatively propagated aromatic plant. J Crop Sci Biotech. 2012;15:33‐39.
82. Misra M. Regeneration of patchouli (Pogostemon cablinBenth.) plants from leaf and node callus, and evaluation after growth in the field.
Plant Cell Reports. 1996;15:991‐994.
83. Sarma A, Sarma TC. Patchouli oil recovery and effect of leaf ageing.
Indian Perfum. 2003;47:151‐154.
84. Misra M. Growth, photosynthetic pigment content and oil yield of Pogostemon cablingrown under sun and shade conditions. Biologia Plantarum. 1995;37:219‐223.
85. Misra M. Application of gibberellin to Pogostemon cablin plants:
growth, photosynthetic pigment content and oil yield. Biologia Plantarum. 1995;37:635‐639.
86. Hussain AI, Anwar F, Nigam PS, et al. Antibacterial activity of some Lamiaceae essential oils using resazurin as an indicator of cell growth.
LWT‐Food Sci Technol. 2011;44:1199‐1206.
87. Manjunatha R, Farooqi AA, Vasundhara M, Srinivasappa KN. Effect of biofertilizers on growth, yield and essential oil content in patchouli (Pogostemon cablinPellet.).Indian Perfum. 2002;46:97‐104.
88. Singh M, Ganesha Rao RS. Influence of sources and doses of N and K on herbage, oil yield and nutrient uptake of patchouli [Pogostemon cablin (Blanco) Benth.] in semi‐arid tropics. Ind Crops Prod.
2009;29:229‐234.
89. Yang Y, Kong W, Feng H, et al. Quantitative and fingerprinting analy- sis of Pogostemon cablin based on GC‐FID combined with chemometrics.J Pharm Biomed Anal. 2016;121:84‐90.
90. Benveniste B. Indonesian oil of patchouli.Perfum Flavor. 1980;5:43‐45.
91. Muyassaroh, Daryono ED, Hudha MI. Determinating patchouli alcohol of patchouli oil using distillation technique. Int J ChemTech Res.
2016;9:108‐116.
92. Singh M. Effect of potassium on growth and yield of patchouli [Pogostemon cablin (Blanco) Benth.]. J Spices Aromatic Crops.
2014;23:76‐79.
93. Saha P, Chaudhuri A, Yadav GS, Babu S. Effect of nitrogen levels and planting geometry on growth, herbage and oil yields of patchouli (Pogostemon cablinBenth.) under humid sub‐tropical climate of North Eastern Himalayas.Ann Agric Res New Series. 2014;35:274‐279.
94. Asangi H, Vasundhara M. Effect of pinching and growth regulators on growth, herbage yield, essential oil content and oil yield of patchouli (Pogostemon patchouliPellet.).J Hortl Sci. 2013;8:214‐216.
95. Bhaskar S. Growth, herbage and oil yield of patchouli (Pogostemon patchouli) as influenced by cultivars and nitrogen fertilization.Indian Perfum. 1995;39:35‐38.
96. Saha BN, Dutta SC, Bordoloi DN, Mathur RK. Introduction of patch- ouli in Itanagar.Indian Perfum. 1989;33:14‐19.
97. Saha BN, Dutta SC, Bordoloi DN, Mathur RK. Prospect of growing patchouli (Pogostemon patchouli) in Arunachal Pradesh ‐ Effect of nitrogen on its yield.Indian Perfum. 1992;36:57‐60.
98. Hamidi N. Extraction of essential oils from patchouli plant using advanced techniques of microwave‐assisted hydrodistillation.J Engin Appl Sci. 2016;11:796‐799.
99. (a) Singh M, Rao RSG, Ramesh S. Influence of nitrogen and nitrogen carrier on herbage, oil yield and nitrogen uptake of patchouli [Pogostemon cablin (Blanco) Benth.] in semi‐arid tropical condition.
J Spices Aromatic Crops. 2007;16:106‐110. (b) Rao EVSP, Rao RSG, Narayana MR, Ramesh S. Influence of shade on yield and quality of patchouli (Pogostemon cablin) oil.Indian Perfum. 1997;41:164‐166.
100. Singh M. Effect of organic and inorganic fertilizers on growth, yield and nutrient uptake of patchouli [Pogostemon cablin(Blanco) Benth.]
in a semi‐arid tropical climate.J Spices Aromatic Crops. 2011;20:48‐51.
101. Singh M, Guleria N. Effect of cultivars and fertilizer levels on growth, yield and quality of patchouli [Pogostemon cablin (Blanco) Benth.]
under shaded condition.J Spices Aromatic Crops. 2012;21:174‐177.
102. Singh M. Effects of the amount of water applied, method of irrigation, and rate of N‐application, on herbage and oil yields, N‐uptake, and water‐use efficiency in patchouli [Pogostemon cablin(Blanco) Benth.]
grown under semi‐arid tropical conditions. J Hortl Sci Technol.
2012;87:441‐444.
103. Bhaskar S, Vasantha Kumar T, Srivastava HC. Effect of growth regula- tors on production of herbage and oil in patchouli (Pogostemon patchouli).Indian Perfum. 1997;41:98‐101.
104. Arpana J, Bagyaraj J, Prakasa Rao EVS, Parameswaran TN, Abdul Rahiman B. Symbiotic response of patchouli (Pogostemon cablin (Blanco) Benth.) to different arbuscular mycorrhizal fungi. Adv Environm Biol. 2008;2:20‐24.
105. Ramachandra KM, Vasundhara M, Farooqi AA, Srinivasappa KN. Eval- uation of patchouli (Pogostemon patchouliBenth.) varieties in relation to different plant densities.Indian Perfum. 2002;46:7‐14.
106. Arpana J, Bagyaraj DJ, Prakasa Rao EVS, Parameswaran TN, Abdul Rahiman B. Response of patchouli to inoculation with an arbuscular mycorrhizal fungus and plant growth promoting rhizomicroorganisms.
J Soil Biol Ecol. 2014;34:70‐83.
107. Schrader T, Murasira P, Jouitteau F. Rwanda Agribusiness case: Patch- ouli‐Biolandes. Production d'huile essentielle de patchouli dans le nord du Rwanda. 2012, 23 pages, http://library.wur.nl/WebQuery/
wurpubs/fulltext/264607.
108. Costa GA, Carvalho Filho JLS, Deschamps C. Rendimento e composição do óleo essencial de patchouli (Pogostemon cablin) conforme o tempo de extração.Rev Bras Pl Med, Campinas. 2013;15:319‐324.
109. Chacko M. Characterization, evaluation and micropropagation of Patchuli (Pogostemon patchouliBenth.): An important aromatic plant in South India. Ph.D. Thesis, Mahatma Gandhi University, Kottayam, Kerala, India, 2009.
110. Singh M. Influence of spacing and intercropping on biomass and essential oil yield of patchouli [Pogostemon cablin(Blanco) Benth.].
J Spices Aromatic Crops. 2008;17:235‐239.
111. Magalhaes MT, Mendes PH, Wilberg VC. O óleo essencial de patchuli da Amazônia.Acta Amazonica. 1976;6:467‐469.
112. Masetto MAM, Deschamps C, Castro LWP, Monteiro R, Guerios IT, Sheer AdP, Côcco LC, Yamaemoto C. Rendimento e qualidade do óleo essencial de Pogostemon cablin Benth em diferentes períodos de secagem, InProceedings of IV Simpósio Brasileiro de Óleos Essenciais, Fortaleza, 2007.
113. (a) Nuryani Y. Characteristic of four accessions of patchouli (Pogostemon cablin).Indon Agric Res Abstr. 2010;27:11‐12. (b) Rahman M, Shoeb M, Nandi NC, Alamgir M, Husain M. Introduction of patch- ouli,Pogostemon cablin(Blanco) Benth : an essential oil bearing plant in Bangladesh.Bangladesh J Sci Ind Res. 2001;36:14‐18.
114. Wu Y, Li M. Induction of tetraploid plants of Pogostemon cablin (Blanco) and its quality evaluation.Phcog J. 2013;5:281‐285.