The miracles of Australian sandalwood

If the Bard of Avon were to have written his famous sonnet 18 to the sandalwood, it would probably have included these lines-

 “But thy eternal fragrance shall not fade

Nor lose possession of that air thou ow’st”…

The sandalwood is one rare tree that seems to have a stock of fragrance that never gets depleted. Besides smelling good, it also packs a number of skin improving benefits within its grains. No wonder then, griffin+row has included the oil of Australian sandalwood in their centess+complex™ making it an ingredient in their Cleanse, Hydrate, Nourish and Enrich formulations.

Introducing Santalum spicatum

Australian sandalwood has been classified as Santalum spicatum, based on the characteristics it shares with the earlier known sandalwood Santalum album. It was known as Uilarac, Wollgat, Wolgol and Waang by the Noongar community of aboriginal people in Australia’s south western coast 1

The genus Santalum derives its name from the Sanskrit word ‘chandanam’ used for Indian sandalwood. The species ‘spicatum ’ refers to the inflorescence which emerges on spikes.

Santalum spicatum is a native of the Western Australian semi-arid lands. A hemi-parasite, it grows best on Acacia spp. especially Acacia acuminata which is used as the host in plantations. It is also found in pockets in some parts of the Northern territory 2.

Other species of Santalum that are indigenous to Australia are S. acuminatum (quandong) S. obtusifolium, S. lanceolatum and S. murrayanam3. However, only S. spicatum is of commercial importance and is cultivated in plantations in South-Western Australia.

Today, Australia is the only producer and exporter of sandalwood oil distilled from S.spicatum. Although Santalum grows in southern India, China and parts of Malaysia, the local consumption far exceeds production. Sandalwood trees grow slowly and need to be 30 to 50 years old for the extraction of good quality oil. In Australia, since there is negligible consumption, the country has become the sole exporter of sandalwood/sandalwood oil in the world.

Traditional uses of Australian sandalwood oil 

The aboriginals of Australia have been well aware of the special properties of the sandalwood tree for many centuries. The wood of the tree is used for carvings and as the preferred wood for use in ceremonies.

The kernel of the sandalwood seed has been used as medicine. The seed oil was applied to afflicted joints and the powdered kernel on skin afflictions, sores and burns to provide relief. The kernel was also taken internally for digestive problems. Even in healthy individuals, the use of the crushed kernel over the body was recommended for protection against the Outback conditions 4.

The advent of colonisation allowed for the commercial exploitation of sandalwood from the island continent. Well-traversed sea routes and better intercontinental communication opened new avenues of trade between the southern land and other countries in the northern hemisphere. The mid-1800s saw a decline in the availability of Mysore sandalwood (Santalum album) from southern India. Since sandalwood is used extensively in Buddhist and Hindu rituals, Ayurveda and Chinese traditional medicine, the potential of exporting the same seemed like a viable option. 

Commercial export of sandalwood from Australia began in 1840. Ironically, this was the species of Indian sandalwood (Santalum album) obtained from the Fiji islands and sold to India and China 5. Actual Australian sandalwood was considered to be inferior because the colour of its heartwood (from which the oil is distilled) differs from Indian sandalwood. When the oil was first distilled in 1875, it was found to retain the same woody fragrance and properties as that from S.album [6]. The export of Australian sandalwood then grew tremendously until it was regulated by the government in the 1920 to 1930s.

The importers of Australian sandalwood were long time users of both the wood and the oil derived from it. India, China as well as other South-East Asian countries were (and are) the world’s largest consumers of sandalwood and sandalwood oil. Called ‘chandan’ in India and ‘Tan Xiang’ in China the limited and precious sandalwood indigenous to these countries are used with reverence.

Blocks of wood rubbed against stone with a little bit of water generates sandalwood paste. This is used as a cooling agent, for worship and is incorporated into incense sticks. In Ayurveda, sandalwood paste is described to have antipyretic and astringent properties. Chinese traditional medicine recommends the use of the paste for skin inflammation, cystitis and biliary problems.

Wood shavings and powder are mixed with binders to make incense cones that burn slowly and release the long-lasting fragrance. This was (and is still) used extensively in worship to create an atmosphere to release tension and nervous anxiety 7.

Sandalwood was used to carve chests which had natural moth-repellent action and lent a fragrance to the clothes stored in them 8.

Trade had earlier introduced the wonder of Indian sandalwood to the Middle East. In that region, sandalwood gained an important place in the production of perfumed oils (called ‘attar’). Pharmacies of 8th century Baghdad were even referred to as ‘as-saydanani’ or ‘as-saydalani’ which translates to ‘he who sells sandalwood’ 9 Surprisingly, the 11th century philosopher and medical practitioner, Ibn Sina (Avicenna) who translated Chinese treatises on medicine did not include sandalwood in his Canon of Medicine. It was the Damascus-born Ibn al-Nafis who included sandalwood in two prescriptions in his treatise of medicine 10. In the West, sandalwood was used to treat venereal disease before the discovery of antibiotics 8.

Much before the Arabs, it is possible that the ancient Egyptians also traded goods for sandalwood with India. Sandalwood oil was used extensively in embalming dead Pharaohs 11. Coincidentally, the association of sandalwood with death is also seen in Hindu communities that cremate their dead on a pyre with a small block of the wood added to it. For persons of eminence, the entire pyre is made of sandalwood. In 1948, the cremation of M.K Gandhi was performed with sandalwood. And since the large quantity could be sourced only from Australia, Santalum spicatum holds the honour of being part of the last rites of that icon of non-violence 8.

Today sandalwood powder is used in mosquito coils and the chips are included in potpourris. The oil of sandalwood is used in the bottom note of perfumes and lotions for its lingering, woody fragrance. 

Bioactivity associated with the plant

Sandalwood trees have distinct properties in the heartwood and their seeds.

The heartwood is the pith that runs longitudinally inside of the trunk of the tree. The oil distilled from the wood contains the following-

  • Terpenols– α-santalol, cis-β-santalol, trans-farnesol, epi- α -bisalobol, lanceolol, nuciferol, trans-α-bergamotol.
  • Terpenes – santalene, bergamotene, curcumene

The terpenol santalol is responsible for the release of tension and anxiety by slowing down the mind and breathing. Farnesol is an antimicrobial compound. Bisabolol and santalenes are anti-inflammatory molecules.

Although sandalwood oil is certified as non-irritating, non-toxic and non-sensitising, Australian sandalwood oil has a higher percentage of farnesol which is a suspected allergen and is used only in formulations and not applied directly on the skin 12.

Sandalwood seeds also contain oil that can be extracted. The main component in this oil is xymenenic acid (santalbic acid). This acetylenic fatty acid is a unique molecule of plant origin 13. Xymenenic acid has anti-inflammatory and anti-oxidative activities. It also improves the microcirculation of the skin, leading to a more youthful looking skin 14.

α- Santolol and farnesol: a spotlight on the main bioactive components

  • α-Santalol is a terpene alcohol.

Santolols are terpenols that are unique to the genus Santalum. These molecules are known to stimulate the pineal gland and release endorphins, giving a sense of well-being. The woody, pleasant fragrance of sandalwood oil is due to β-santolol while α-santolol has therapeutic and healing properties 15.

  • Farnesol is a sesquiterpene.

Farnesol is found in the essential oils of citronella, lemon grass, neroli and even rose and musk. It is formed as a plant defense mechanism against mites. It also acts as a pheromone to attract insects that help in pollination. Farnesol has anti-bacterial activity and may have anti-tumour activity 16.

General health benefits and uses of Australian sandalwood oil

The oil obtained from the steam distillation of the heartwood of Santalum spicatum is viscous and light yellow in colour. Australian sandalwood oil has a woody, earthy fragrance with a slight balsamic sweetness. Although it is considered to be inferior to Indian sandalwood oil, it has a distinct sweet fragrance of its own 15.
The oil is used in formulations and perfumes for the following

  • Antibacterial effects: The sesquiterpenes in sandalwood oil make it naturally antimicrobial. This is especially important in the context of reducing acne-causing bacteria in the skin such as Staphylococcus aureus2.
  • Anti-inflammatory effects: Although bisabolol is present at a lower percentage in Australian sandalwood oil, it confers a significant anti-inflammatory property on the oil 17.
  • Skin care: Sandalwood oil is an excellent emollient for dry, aging skin. It can also promote the regeneration of keratinocytes, leading to reduction in scar formation and in the repair of skin damage 18.
  • Use in aromatherapy:The incorporation of sandalwood oil into perfumes, diffusers and massage oils is recommended to relieve anxiety and mental stress.
  • Botany and grow it yourself

    Santalum trees are root parasites. The plants take root on the existing root system of the host plant and derive their soil nutrition from it. The most common host for Australian sandalwood (Santalum spicatum) is Acacia acuminata.

    Australian sandalwood grows in dry to semi-arid areas. Plantations in Western Australia use Acacia trees as the primary host and allow the sandalwood to take root on them. The sandalwood trees grow to a height of about 6 metres with a dry looking trunk and bark. The bark may even develop cracks as the tree ages. The leaves are greyish-green and the flowers appear on a spike. The fruit is spherical and orange-red in colour. The seed of the fruit germinates under moist conditions.

    For all its wonderful fragrance, the sandalwood tree is not very attractive. It is, however, surprisingly hardy under conditions of high salt or drought. The tree needs to age up to at least 20 years before the heartwood can be used for the distillation of essential oil. The older the tree, the stronger the oil obtained from the heartwood. The entire tree has to be cut down and the branches, bole and root are all used for oil extraction 12

    Glossary

    Terpene: A class of volatile aromatic compound characterised by the presence of two isoprene units (4-carbon units with alternating double bonds). Pinene (from pine), myrcene (from hops), limonene (from citrus fruits) and linalool (from lavender) are monoterpenes. Farnesol contains 3 isoprene units and is a sesquiterpene. Santalol is a cyclic sesquiterpene and contains an alcoholic (-OH) group.

    Hemi-parasite: A hemi-parasite is an organism that is partially dependent on its host for some nutrients or protection. In the case of the sandalwood tree, all the soil nutrients are derived from the host through its root system. The tree is still capable of photosynthesis to make its glucose for energy and growth.

    Pheromone: A pheromone is a volatile molecule that is carried through the air or water as a signalling molecule. Pheromones resemble hormone in that they bind to specific receptors and bring about select reactions.


    References:

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