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Agarwood (gaharu, gahuru) and derived commodities thereof are known by a confusing variety of other names: it is probably the original Lignum-aloes mentioned in the Bible (Proverbs 7:17, Psalms 45:8, Song of Solomon 4:14, John 19: 39), although this is disputed.
The most common forms are Agarwood & Aloeswood.
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Introduction.
Following on from the resolutions of the 13th CITES meeting in Bangkok in Oct 2004, the EU Commission has a new regulation (Commission Regulation (EC) No 1332/2005 of 9 August 2005) amending Council Regulation (EC) No 338/97 on the protection of species of wild fauna and flora, by regulating trade therein (this follows on from the resolutions of the 13th CITES meeting in Bangkok in Oct 2004).
For our purposes, and considering only the aromatic species affected, it is a reclassification whereby Aquilaria spp. (except for A. malaccensis, which was already listed in Appendix II), Gyrinops spp. and Gonystylus spp. (previously listed in Appendix III) were included in Appendix II* to the Convention.
The regulation affects all parts and derivatives of the above species, except: (a) seeds, spores and pollen (including pollinia); (b) seedling or tissue cultures obtained in vitro, in solid or liquid media, transported in sterile containers, and (c) cut flowers of artificially propagated plants.
[*Appendix II includes species not considered to be under the same threat as those in Appendix I, but which may become so if trade is not regulated. International trade in these species is monitored through a licensing system to ensure that trade can be sustained without detriment to wild populations. Appendix III contains species that are not necessarily threatened on a global level, but that are protected within individual states where that state has sought the help of other CITES Parties to control international trade in that species].
This outcome may give a little more muscle in the fight to combat the "eco-mafia" who make a trade out of smuggling protected species. However as is stated elsewhere in this data-base, licenses are easily fabricated at point of export by the “eco-mafia” and dispatched to the receiving customers of these illicit goods.
Agar is a scented product obtained from a pathological condition of the wood of standing trees of certain Aquilaria species (Fam. Thymelaeaceae), and exceptionally, perhaps, of Aquilaria trees buried underneath the ground for considerable periods. The condition is brought on by fungal infection, or by external wounding (or by both) – see Microbiology section below.
Agarwood is traded in the form of wood chips, powder/dust, oil or extracts for perfumery or incense use; It has been estimated that 2000 tons/annum of Agar is traded annually.
The trees have adapted to growing in various types of habitat from well drained rocky places, to calcareous soils and swampland, being found at 0-850m., and exceptionally to 1000m.
Not every Aquilaria tree contains agar – perhaps 10% in mature stands - and those expert enough to assertain from exernal characteristics whether or not a tree harbours the resin are few and far between, thus explaining why trees are being indiscriminately felled to the point of extinction in many areas.
Whilst the light coloured unscented wood has been used in Assam for papermaking and its’ wood fibre used for ropemaking, the scented wood is particularly used for incense, and also for clothing drawers. It is also used as a wine ingredient in Chu-yeh Ching and Vo Ka Py wine made in Taiwan.
Additionally, oud incense & perfumes are used as a skin daub, for enbalming, and to fragrance soaps and shampoos, and have been prized for thousands of years throughout the Arabian world, as well as being used for Islamic, Buddhist, Confucianist and Hindu ceremonial religious occasions.
Kyara wood is claimed as an ingredient in Shiseido’s Zen Scent (2000 Shiseido Co. Ltd), and M7 by Yves San Laurent claims agarwood as an ingredient. Incenses claiming to contain a supercritical CO2 extract from the oleoresin of cultivated trees are available from Eden Botanicals. |
Agarwood Odour descriptions and use in Incense ritual.
The Japanese art of appreciation of incense woods adopted the Chinese expression “wenxiang” (listening to incense) which becomes “mon-koh” in Japanese. Koh can be taken to refer to incense materials themselves, and koh-do to the incense ceremony.
Morita further describes five basic odour classifications of agarwood incense aromas in Japan, which take a lead from the five basic tastes:
(1) Sweet (resembling the smell of honey)
(2) Sour (resembling the smell of plums)
(3) Hot (resembling the smell of peppers on a fire). Other interpretations say spicy instead of hot.
(4) Salty (resembling the smell of ocean water when seaweed is dried on a fire )
(5) Bitter (resembling the smell of bitter herbal medicines when mixed or boiled).
The oil possesses an animalic/leathery character with notes reminiscent of castoreum & labdanum. It is extremely long-lasting. In perfumery the oil can be used to introduce novel effects in men’s fragrances, where a rich leathery character is required. It is particularly interesting in masculine-chypre type accords enhancing the ambery warmth of cistus notes. |
Medicinal and Traditional Uses
Medicinal Uses
Medicinal uses of the heartwood, bark, resinous stem, resinous wood and aloeresin, prepared from Aquilariaspp., have been recorded in traditional medical systems including Chinese (TCM), Tibetan, Ayurvedic (Indian) and Unani (Greek derived Islamic). External and Internal preparations have been used citing a variety of Aquilaria species.
These traditional medical systems have been used for indigenous health-care for thousands of years and can stand up on their own merits, because of the general non-scientific ‘universal truths’ on which all these systems are based, there are inevitably similarities in some major classifications. We can therefore also see similarities in uses:
TCM (Traditional Chinese Medicine) herbs are classified by the way that they reorganise the body constituents to a state of balance (Qi, moisture and blood) and classified into five tastes (closely linked to smell) not dissimilar from the five basic odour classifications of agarwood incense listed in the previous section, of sour, bitter, sweet, spicy and salty. TCM recognises primal forces which govern the body of which fire is the force that has an eliminative action which discharges qi downwards.
Likewise, Tibetan medicine recognises similar primal forces that govern the body but has six tastes sour, bitter, sweet, salty, hot and astringent. Selections of herbs are made based on their taste and potency with regard to the primal forces for re-balancing and restoring health – fire being the force that transforms.
In Ayurveda, there are five primary categories of matter (which combine to create 3 doshas or forces), five attributes and five elements. Fire is the element that transforms. Ayurveda recognises six tastes - sour, bitter, sweet, salty, pungent and astringent.
Unani medicine recognises the four humors which have elements, body substances ~ blood, phlegm, yellow bile and black bile and qualities ascribed to each humor. These classifications are based on temperament both of people and the humors themselves. Temperaments of humors and person need to be diagnosed so that humors of plants can be prescribed to bring the body back to a state of balance. |
TCM
Aquilaria-derived formulations in general seem to relieve spasms and other forms of stagnant or stuck energy particularly in the digestive (stomach, kidneys, liver, bowel) and respiratory systems. The warming properties of Aquilaria derived medications has been noted. In TCM it warms the kidneys (Subhuti Dharmananda), In Ayurveda it is similarly recognised for It’s warming properties, In Tibetan medicine and in the Unani system It is balancing.
Shizen Li notes that agarwood [Aquilaria sinensis (Lour.) Gilg.] is mentioned in ancient Chinese Herbals in 1596 (Li, 1596), being sought after for it’s physical therapeutic and energetic applications. Hsu (1996) notes that Aquilariae Lignum (aloeswood) in his Chinese Materia Medica consists of the heartwood containing the dark-brown resin which is derived from:
1. Aquilaria sinensis (Lour.) Gilg. in Kuanung Province and Hainan Island
2. Aquilaria agollocha (Roxburgh) in Vietnam & Malaysia
3. Excoecaria agollocha L. in India. (N.B. – this Indian mangrove tree although susceptible to soft rot, is not usually associated with gaharu formation).
Its use was first recorded in Ming i pieh lu, Agarwood being the heartwood that emits fragrance and sinks in water, from which the drug gets its name. The Revolutionary Health Committee of Hunan Province (1995) considered a decoction of A. agallocha to have slight warming properties, to lower energy (activity), reinforce the kidneys, to regulate the central organs and to alleviate pain. The authors recommend use in abdominal pain, tightness of the chest, vomiting and regurgitation, diarrhoea and asthma. [Authors note – the statement ‘lower energy’ above is a poor translation, rather: ‘to move energy down towards the kidneys where it can continue to be utilised efficiently by the body’]. |
Ayurveda
Similarly, in the Indian Ayurvedic healing system, the burning of agarwoods has a warming and centering effect on the chakras and promotes a deep meditational state.
Agarwood heartwood is used in various Ayurvedic formulas including Chyavanprasha, Arimedadi Taila and Mahanarin Taila (Anon 1978: The Ayurvedic Formulary of India Vol 1). Its uses [“A. malaccensis Lam. syn. A. agollocha Rox.”] have been described as a cardiac tonic, carminative & refrigerant (Natarajan & Purushothaman 1991). In the Unani herbal medicine it is used as a stimulant, stomachic, laxative (purgative in large doses) and as an aphrodisiac. It is also used in the Ayurvedic system against skin diseases (Anon 1985: The Wealth of India - Raw Materials Vol 1), and powdered heartwood is given for treatment of diahorrea, dysentery, vomiting and anorexia (Anon 1969: Bhava Prakash Nighantu Nighantu, pub Chaukhamba Vidya Bhawan, Varanasai pp195-6). Agarwood oil, mixed with essential oil from Piper betel is used against bronchial asthma (ibid) [ - through Indian Medicinal & Aromatic Plants Facing Genetic Errosion – CIMAP, Lucknow 1978]. It is also reported as being used by the traditional vaidyas as a contraceptive (Nagarjun 1979-80 23,9), and the leaves boiled in oil used to remove fish bones stuck in the throat (Bull. Bot. Surv, India 1980 22,161). |
Tibetan Medicine & Ethinic Psychiatry.
Oleoresin, wood and oil are used in Tibetan medicine and incense, especially prized is “black aloeswood”, (Aquilaria agallocha) which Clifford (1984) describes as being relied on by contemporary Tibetan doctors for treatment of a whole range of nervous and emotional disorders. Clifford further describes black aloeswood as the most commonly used minor tranquilliser. |
Aromatherapy, Incense.
Although there are fewer documented folk-uses of agarwood essential oil in Western medicine, Franchomme & Peneol (1990) in their treatise on aromatherapy consider the oil of “Aquilaria agallocha Roxb. agospirolifera” to be a decongestant for the lymphatic and venous systems, and to be indicated for venous insufficiency & malaria. Miller and Miller (1995) in their book Ayerveda Aromatherapy the energetic warming, balancing effects of oud (:oil of A. agallocha), and its’ energy purifying and balancing, relaxant, rejeuvinative, transformative, clairvoyant and transcending actions.
The use of agarwood as an incense ingredient is recognised in written works from Japan, China and elsewhere but in the main, it is through the means of oral tradition that the secrets that accompany use of materials such as agarwoods lie. From welcoming ancestors long departed, to stilling the mind, through to stopping the spread of infection where large groups of people are gathered, Incense is burned for energetic, cleansing, mental, physical & spiritual effect. As is the case with certain grades of musk and ambergris, the high prices that can be achieved internationally for certain grades of gaharu is often based on availability rather than quality. Krishnan (1997) describes traditional ood attar made from wood from Assam fetching Rs 15,000 to RS 20,000 per tola (11.62g). |
Agarwood Trading
Most gaharu finds its way to the Middle East (especially Saudi Arabia) where it known as oud), with smaller amounts going to Japan, China etc. Agarwood oil is distilled from the lowest grades of gaharu (Dhum), and used in high-end perfumes for the Arabian and related markets.
An 80 year-old tree can yield 6-9 Kg of agarwood oil (Sadgopal 1960), although Mahindru (1992) puts the figure at 2.7 to 3.6 Kg/tree for 50 year old trees in India, and Gianno (1986) puts it even lower at 1kg per tree with a girth of above 20cm dbh.
Unfortunately the oil rarely reaches end-users in the West in an unadulterated condition; poor oils (where obtainable) currently sell at around £12,000 per Kg, with better oils selling for £30,000 per Kg upwards (prices & quality vary from dealer to dealer). One of the authors (TB) has known particular batches to sell for £100,000 a Kg or more to specific customers in Saudi Arabia.
Traders reliably distinguish eight agarwood grades (CITES 2004) on quality, but complications arise concerning botanical origins when one considers that a particular agarwood species can only be identified by morphological characters (by those expert at botanical systematics), preferably at the flowering stage. Batch tracking of commodities from botanically identified sources is not in place. In some instances, only one or two species may predominates from a particular location, so only the origin needs to be known. The chemical analysis of agarwood commodities (wood, chips, dust, oil) from various geographic origins is becoming more advanced, but is a practical impossibility at most points of trade – expensive equipment and highly trained operators being required. End-user analysis (for fragrance companies) is also possible, but is extremely unusual – most estimates of quality being carried out organoleptically.
A decision was taken by the Eleventh meeting of the Parties to CITES directed the Plants Committee to resolve issues in distinguishing Aquilaria species from each other when traded, particularly when traded as agarwood. A system of identification might help prevent the large amount of illegally logged and traded Aquilaria wood, chips and dust (but not oil).
The need to distinguish Aquilaria timbers and their origins is discussed by Koopman & Diemont in an article on molecular markers for CITES-protected timber species where the authors argue the merits of DNA sequence markers and DNA fragment markers for this purpose. The authors refer to unpublished work carried out by Eurlings and Gravendeel who examined nine Aquilaria spp. and five Gyrinops spp., being able to identify four Aquilaria spp. and three Gyrinops spp., the remaining seven species being mutually indistringuishable.
Yance et al. (2001) compared the anatomical characters of five ‘agar wood species, Aquilaria malaccensis, Aetoxylon sympetalum, Gonystylus bancanus, Gonystylus macrophyllus, and Gyrinops versteegii. The authors found that Aquilaria malaccensis and Gyrinops versteegii have included phloem, whilst the other three gaharu wood species did not. Aquilaria malaccensis could be differentiated from Gyrinops versteegii on vessel characteristics. The authors also stated that the presence of very thick-walled fibres and 1-3 seriate rays could be used to differentiate Aetoxylon sympetalum from Gonystylus spp. The presence of very thick-walled fibres and 1-3 seriate rays could be used to differentiate Aetoxylon sympetalum sympetalum from Gonystylus spp. - the latter has fibres of medium wall thickness and its rays are commonly uniserate. |
Distillation of Agarwood.
Accounts of agarwood distillation vary from source to source as we will see. Baruah et al. (1982) distinguished four grades of infected fragrant wood: the poorest grade being buff-coloured (Dhum) and being exclusively used for distillation, better grades being used to make incense agar-battis. Chaudhari (1993) named these as:
Grade 1 Black/True Agar: mainly exported to Arabia as incense
Grade 2 Bantang: mainly exported to Arabia as incense
Grade 3 Bhuta or Phuta: sometimes extracted for a superior oil
Grade 4 Dhum: used for oil
Chaudhari also estimated the amount of wood available in India as 31 metric tons, which would yield 77.5Kg agarwood oil on a 0.25% yield basis, naming the stills in the Naga Hills as being at Manipar Road (3 stills), Barapathar (27 stills) and Dhansari (now shut down).
Distillation of dhum yields 0.75% to 2.5% agarwood oil according to Mahindru (1992), but Sadgopal (1980) had earlier maintain that dhum yielded a smaller amount of oil (0.1%) compared with infected brown wood (0.4%), with infected dark brown wood giving 0.9% and the best grade of black wood giving 1.2% plus. Chakrabarty et al. (1994) give the yield of agarwood oil from black agar as 0.09-2.5%.
An 80 year-old tree can yield 6-9 Kg of agarwood oil (Sadgopal 1960), although Mahindru (1992) puts the figure at 2.7 to 3.6 Kg/tree for 50-year-old trees in India, and Gianno (1986) puts it even lower at 1kg per tree with a girth of above 20cm dbh.
The fragrant oils that result from the individual field still distillations are classified as follows: ¬ primary grade oil, usually a darker colour originating from the more heavily stained¬ wood sections, which incidentally are often associated with the ¬pathogenic fungus Philophora parasita.
Secondary grade oil is ¬usually lighter in colour, often originating from pale to ¬gray-stained fungal infected sections. The spent wood after distillation is dried and often used for making agar-battis, although processes are reported for extracting oil from the spent wood.
The Chakrabarty K et al. (1994) describe the distillation of Agarwood oil in great detail in the towns of Hojai, Nilbagan and Islamnagar in the Naogaon district of Assam as a result of the Traffic investigations of 1993, speculating that 500-1000 tolas a month of oil (1 tola = 46.48g) are produced in Hojai, legally obtained wood being supplemented by that illegally obtained from India and Bhutan. The report also mentions distillation in Manipur in Thambu Bazar, and pinpoint Bombay as the production centre for agarwood attars. Finally the authors identify Myanmar and Tuensang in Nagaland as a major smuggling points.
Wood from felled trees is cut into pieces and thrown into water – those pieces containing more than 25% oleoresin, will sink. Infected areas of wood are carefully scraped out with a special tool (called a batali). After sorting pieces into grades, the selected pieces are ground and soaked in water (often in a drum container) for 48 hours, although other reports say 1-5 days.
The wood is the powdered manually with a dhenki. Distillation is carried out for 5-6 hours with cohabitation of the distillation waters, although 24-48 hours is reported elsewhere. Chakrabarty et al. (1994) suggest 8-12 Kg of wood in 80 litres of water are distilled for 3 days, describing a cohabitation arrangement, although it also describes an improved process developed at the Regional Research Laboratory, Jorhat in Assam which uses a stainless steel still and yields a clear oil free from metallic impurities. |
Agarwood Microbiology
Various fungi are associated with gaharu formation although it is still not absolutely clear which are important or even necessary. Infection and gaharu formation appears to be a slow process and Hooper (1904) had noted that trees that were at least 50 years old yielded the largest amounts of oleoresin. Bose (1934) isolated a member of the fungi imperfecti from the diseased wood of A. agallocha: Sadgopal (1959) comments that a Torula sp. isolated by Bose inoculated into A. agollocha trees successfully produced agar formation, but the experiments were abandoned in 1931 because of contamination of the inoculum stock. Further work by Bose involved the successful use of a Cladosporium sp. but the trees were subsequently destroyed. A later repeat of the work yielded no postive results.
Following this, Battcaharrya (1952) isolated Epicoccum granulatum from infected wood, and together with Sadopal (1960) and Varma (1977) further investigated the possibility that agaru formation was due to fungal activity, and the prospect of deliberately infecting trees with the causative agents became a popular goal, but the literature often showed conflicting results. One serious contender for the infectious agent was the pathogenic fungus
Philophora parasitica, identified by Gibson (1977) and earlier by Hawksworth et al. (1976), who ascribed spiral cavitation of the tracheid walls of the wood of A. agallocha to this organism. Gibson indicated that the most frequently isolated fungi from infected wood also include Pencillium citrinum, Aspergillus tamarii, and other Aspergillusspp., Fusarium solani, Botryodiplodia theobromae and others. But there were several reports that Phialophora parasitica was frequently associated with better quality portions of agaru. It emerged however (Gibson 1977; Rahman 1980) that gaharu formation rarely occurred in trees under 25 years old, and formation probably followed injury to the tree, for example following wind or storm damage. Yu Chenhung (1980) working independently in the S. China Institute of Botany in Guangzhou with A. sinensis, , note that no scented oleoresin or secretory tissues were found, but when traditional drug-gatherers cut notches in the trunk, oleoresin was formed after mycelia had been observed leading to infection of the cells containing starch cells.
Jaluddin (1977) isolated the fungus Cytosphaera mangiferae Died. from the diseased wood of standing trees, indicating this to be the causative infective agent for standing trees. Tamuli et al. (1999) were able to identify four fungal species associated with A. agallocha seeds (Aspergillus sp., Fusarium sp., Penicillium sp. & Epicoccum sp.) the authors subsequently turning their attention to the A. agallocha rhizosphere (Tamuli et al. 2000a). More recently Tamuli et al. (2000) identified two fungal cultures from the diseased wood: Fusarium oxysporum Schlect. and Chaetum globosum Kunze, and succeeded in inoculating healthy wooden blocks so that colony growth occurred. In the same paper, Tamuli et al. report that they deposited these cultures with the MTCC, Institute of Microbial Technology (CSIR), Chandigarh.
Reports were made in 1991 (Indian Perfumer35(1), 10) that the skill of artificial infecting of agarwood had been solved in N.E. India (in Galaghat, Jorhat and Jtojoi in Assam) making the tree wood suitable for distillation in 5-6 years. Mahindru further notes that only copper stills produce an agarwood oil quality acceptable to the trade. The Tropical Rainforest Project (see elsewhere in this document) have embarked on a program of artificial infection of agarwood trees grown in plantations. No environmental or social impact studies have been seen by Cropwatch regarding these developments, and there are fears the demand for agarwood commodities could actually increase (see Cropwatch 7).
A recent article by Tabata et al. (2003) describes the artificial induction of five seven year old Gyrinops versteegii trees in Matram on Lombok Island and twelve Aquilaria spp. in Pekanbaru, Sumatra by drilling eight 10cm deep by 1cm wide holes and inoculating with five Fusarium spp. including Fusarium trifosfrium. Agarwood formation was observed around the drilled sites in inoculated trees but also in control trees. |
Agarwood Chemistry
Agarwood oil contains many unusual substances. The elucidation of the structures of many minor components of agarwood oil, especially of Far Eastern origin, have kept many structural organic chemists busy for years, and continue to do so [see Lawrence (1998) for a review of progress from 1973-1998].
Indian Agarwood
The presence of eight sesquiterpenes including agarol and agarospirol together with a- and b- agofuran, were characterised by Battacharrya et al. in 1959 & 1965 [Jain & Battacharrya (1959), Varma, Maheshwari & Battacharrya (1965)]. Maheshwari et al. (1963, 1963a) characterised alpha- and beta-agaofuran, dihydroagarofuran, nor-ketoaragofuran, 4-hydroxydihydroagarofuran and 3,4 dihydroxydihydroagarofuran by solvent extraction of infected agarwood of Indian origin. Subsequent total synthesis of nor-ketoagarofuran by Heathcock & Kelly (1968) showed the formula presented by Maheshwari et al. was incorrect. Pant & Ragosti (1980) used instrumental techniques to show that dihydroagarofuran was dihydro-beta-agarofuran and isodihydroagarofuran was isodihydro-alpha-agarofuran.
Pant & Rastogi (1980) also confirmed the presence of two sesquiterpenes: agarol & gmelofuran in the fragrant wood. Ishihara et al. (1991a) described seven newly identified compounds in agarwood oil from A. agallocha based on the guaiane skeleton, including guaia-1(10),11-dien-15-ol, guaia-1(10),11-dien-15-carboxylic acid, methylguaia-1(10)-11-dien-15-carboxylate, guaia-1(10),11-dien-9-one, 1,1`0-epoxyguaia-11-ene, guaia-1(10),11-dien-15,2-olide and guaia-1(5),11-dien-2-one. In a subsequent paper Ishihara (1991b) described a further 3 sesquiterpenes and ascribed odour descriptions to some characterised components.
Näf et al. (1992, 1995) described components in fresh agarwood oil distilled from some freshly purchased Indian wood (identified as A. agallocha), The authors identified beta-agarofuran, vetispira-2(11),6(14)-dien-7-ol, dihydrokaranone and valerianol as major constituents of Indian agarwood oil. Eight new valencane-, eremophilane- and vetispirane- derivatives were described (see abstract in bibliography) including (3R, 7R, 9R, 10S)-9,10-dimethyl-6-methylene-4-oxatricyclo[7.4.0.0 3,7]1-tridecene, and compounds synonymous with 2,14-epoxyvetaspira-6-ene and 2,14-epoxyvetaspira-6(14),7-diene were also described (1995), odour descriptions being ascribed to three of the characterised compounds:
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Table 1. Odour Descriptions of Compounds from Indian Agarwood Compound | Odour | 8,12-epoxy-eremophila-9,11(13)-diene | Woody with vetiver subtonality | 2,14-epoxy-vetispir-6-ene | Woody with typically agarwood-like, sweet, woody, smoky, phenolic like oak-moss but weak. | 2,14-epoxy-vetaspira-6,(14),7-diene | Woody but nearly odourless |
,7-diene.jpg)
Amongst other components, an Indian patent reveals the presence of 1,7-oxoaporphine and liriodenine in the heartwood [Indian Patent (1979) 145857 through Chem Abstr. (1980) 93, 80049f]. Bhandari et al. (1982) confirmed the presence of a coumarinolignan, aquillochin, from A. agallocha.
Indonesian Agarwood (A. malaccensis/A. agallocha).
Jinkohol (2b-hydroxy-(+)-prezizane) was characterised by Nakanishi et al. (1980) following work on a benzene extract of Indonesian agarwood imported via Singapore.
In 1983, two new sesquiterpenes: jinkoh-eremol and jinkohol II were characterised by the same author from “Aquliaria sp; (not A. agallocha) probably A. malaccensis Benth.” from agarwood “collected in Indoneisa and imported via Singapore ”, which they called “type” B agarwood, reserving the description “type A” for agarwood from A. agallocha.
 
The authors reasoned that “type B” agarwood contained nootkatane (e.g. kusunol, jinkoh-eremol), spirovetivane (e.g. agarospirol) and tricyclic (+)-prezizane (e.g. jinkohol, jinkohol II) type sequiterpenes, and that these structural types also occur in vetiver oil, and may evolve from a common precursor. The authors also indicated that four compounds possessed intense odours (agarospirol, kusunol, jinkohol & jinkohol II) and “appear to be the source of the fragrance of agarwood”.
Subsequently Nakanishi et al. (1984) isolated alpha-agarofuran, (-)-10-epi-gamma-eudesmol and oxo-agarospirol as major constituents from “type B” agarwood.
Yoneda et al. (1984) were able to list the major sesquiterpenes of agarwood from type A and type B agarwoods imported from Indonesia and Vietnam through Singapore. A.agallocha (agawood type A) was found to contain b-agarofuran 0.6%, nor-ketoagarofuran 0.6%, agarspirol 4.7%, jinko-eremol 4.0%, kusunol 2.9%, dihydrokaranone 2.4%, and oxo-agarospirol 5.8%. In type B agarwood the following compounds were identified a-agarofuran, (-)-10-epi-g-eudesmol 6.2%, agarospirol 7.2%, jinkohol 5.2%, jinko-eremol 3.7%, kusunol 3.4%, jinkohol II 5.6%, and oxo-agarospirol 3.1%. From their findings the authors concluded that type A wood exclusively contains nor-ketoagarofuran and dihydrokaranone, but does not contain (-)-10-epi-gamma-eudesmol, jinkohol and jinkohol II, findings which might be used to distinguish the products. |
Cambodian Agarwood
Nagashima et al. (1983) found the following compounds in an oil distilled from agarwood collected in Cambodia: alpha-agarofuran, ar-curcumene, nerolidol, agarospirol, benzyl acetone, nor-ketoagarofuran, kusunol, & jinkoh-eremol, as well as characterising new components: dihydrokaranone, karanone, oxo-agoarospirol & iso-agarospirol.
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Chinese Agarwood (Aquilaria sinensis)
Yoshi et al. (1978) elicidated the structure of the highly oxygenated chromone, agarotetrol from Jinkoh (A. sinesis). In a series of published studies, Yang and Cheng (1983, 1986) Yang et al., 1989a, 1989b, 1990) identified the presence of benzylacetone, p-methoxybenzylacetone, anisic acid and beta-agarofuran as well as the sesquiterpenes baimuxinic acid, baimuxinal, baimuxinol, dehydrobaimuxinol &isobaimuxinol.
Xu et al. (1988) characterised six compounds in Chinese agarwood (A. sinensis):
Yang et al. (1989) from an ether fraction of an alcohol soluble extract of A. sinensis distinguished a new chromone, 6-hydroxy-2-[2-(4'-methoxylphenyl)ethyl] chromone and the other five known chromones: 2-(2-phenylethyl)chromone, 6-methoxy-2-(2-phenylethyl)chromone , 6.7-dimethoxy-2-(2-phenylethyl)chromone , 6-methoxy-2[2-(3'-methoxyphenyl)ethyl]chromone and 6-hydroxy-2-(2-phenylethyl) chromone. Later Yang & Wang (1990) elucidated the structure of three 2-(2-phenylethyl) chromone derivatives isolated from the ethyl acetate soluble fraction of the alcoholic extract of Aquilaria sinensis (Lous.) Gilg. These were: 5,8-dihydroxy-2-(2-p-methoxyphenylethyl) chromone and 6,7-dimethoxy-2-(2-p-methoxyphenylethyl) chromone. This was followed by Yagura (2003) who identified 5-hydroxy-6-methoxy-2-(2-phenylethyl)chromone, 6-hydroxy-2-(2-hydroxy-2-phenylethyl)chromone, 8-chloro-2-(2-phenylethyl)-5,6,7-trihydroxy-5,6,7,8-tetrahydrochromone, 6,7-dihydroxy-2-(2-phenylethyl)-5,6,7,8-tetrahydrochromone were isolated from a methanol extract of withered wood of Aquilaria sinensis.
Hsu (1996) notes the presence of agarospirol, agarol, agarofuran, dihydroagarofuran, 4-hydroxyagarofuran, 3,4-hydroxydihydroagarofuran, and norketoagarofuran in infected extracted wood, and the presence of benzylacetone, p-methoxybenzylacetone, hydrocinnamic acid, p-methoxyhydrocinnamic acid, agarospirol, agarol, agarofurans and agarotetrol in the essential oil, the inference being this is from non-infected wood.
 
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Thai Agarwood.
The presence of the cytotoxic compounds 1,3-dibehenyl-2-ferulyl glyceride, which is novel, and 12-O-n-deca- 2, 4, 6-trienoylphorbol-13-acetate isolated from the stem bark of an A. malaccensis tree growing in Thailand was demonstrated by Gunasekera et al (1981) |
Vietnamese Agarwood: Aquilaria agallocha.
Ishara et al. (1993) found the following compounds, amongst others, in a Vietnamese agarwood extract, describing their odours as follows:
Compound | Odour | selina 3,11-dien-14-al | floral woody with smoky sandalwood nuance | selina-4,11-dien-14-oic acid | pennyroyal-minty | dehydrojinkoh-eremol | woody, slightly balsamic, bitter | (+)-dihydrokaranone | fumigating | neopetasane | fumigating |
Table 2. Odour Descriptions of Compounds from Vietnamese Agarwood extract (Ishara et al. 1993)
and in a further paper Ishara et al. (1993b) describe the volatiles from extracts of 4 different agarwoods, concluding that major sesquiterpene volatile in Kanankoh (Murrasaki from Vietnam) was oxo-agarospirol, and from two samples of Kanankoh (Ryoku-yu & Cha-yu – both from Vietnam) the major volatiles were the compounds below:
In a third study Ishara et al. (1993c) looked at the volatiles from ground agarwood from a heated flask, capturing the volatiles in a Tenax trap. Clear differences in trapped volatiles composition were seen between Kanankoh (Ryoku-ku) and Jinkoh (Bateikel) agarwoods, with the latter showing a higher propotion of lower molecular weight materials such as 3,4-dimethoxyphenol, benzylacetone and benzaldehyde, but with a more complex picture with higher molecular weight materials. Lower levels of jinkoh-eremol, kusunol and guaia-1(10),11-dienal were shown by the Jinkoh (Bateikel) agarwood, but it had higher levels of beta-agarofuran, neopetasane and dihydrokaranone
Agarwood
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