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AUSTRALIAN SANDALWOOD Santalum spicatum

Key Properties

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🪵 West Australian sandalwood 🪵 Where the trees were sampled 🪵 Extraction and analysis 🪵 Extract yield 🪵 Ethanol heartwood extract 🪵 ISO standards 🪵 References
Introduction
Australian sandalwood (Santalum spicatum).

Species

BinomialSantalum spicatum
Accepted nameSantalum spicatum (R.Br.) A.DC.
POWO statusaccepted
FamilySantalaceae
GenusSantalum
IPNI identifierurn:lsid:ipni.org:names:780643-1

Source: Govaerts R. (ed.), World Checklist of Vascular Plants (WCVP), Royal Botanic Gardens, Kew, accessed on 21/09/2026.

What is West Australian sandalwood?

According to the introduction of Moniodis et al. (2017), West Australian sandalwood (Santalum spicatum (R.Br.) A.DC.) belongs to the genus Santalum L. (Santalaceae), hemi-parasitic trees widely exploited for their fragrant heartwood. The same introduction states that Indian sandalwood (Santalum album L.) has historically provided the bulk of sandalwood products, and that S. spicatum is frequently used as a supplement to incense feedstock and, to a lesser extent, as “extracted fragrance oil”. According to the same introduction, S. spicatum is traditionally harvested from natural stands of non-domesticated tree populations throughout south-western Australia, and plantations have been established on former grazing and marginal agricultural land to reduce pressure on wild stands.

Where and when were the trees sampled?

Moniodis et al. (2017) collected S. spicatum plant material in spring 2009 from trees growing throughout the southern half of Western Australia: the south-west Wheatbelt (n = 152), the south-east Goldfields (n = 19) and “the Northwest” (n = 23). The xylem was collected by drilling into the stems at 30 cm above ground with a 25 mm drill bit and a cordless drill; only trees with a stem diameter greater than 7 cm were sampled, and the wood shavings were air-dried in paper bags for two weeks before extraction.

How were the heartwood samples extracted and analysed?

The study extracted the ground wood (3–5 g) with ethanol in 25 mL volumetric flasks for 7–14 days; the product, which the article calls “sesquiterpene rich oil”, is an ethanol extract of the heartwood, not a distilled essential oil. Isobutylbenzene (IBB) at 10 mM was added as an internal standard for quantification, chosen because it elutes earlier than the sandalwood components on a DB-Wax column. The extracts were separated by gas chromatography (GC) and quantified by flame ionisation detection (GC-FID); components were identified by mass spectrometry (MS), by comparing their mass spectra with the NIST libraries and their retention indices with literature values. An external calibration curve, built from a dilution series of an authentic S. spicatum standard, was used to determine total yield from the extracts, and relative response factors were determined for α-bisabolol and farnesol standards; the authors state that, to their knowledge, pure standards of the other components are not commercially available. The GC used a DB-Wax column of 30 m × 0.25 mm ID × 0.25 µM film thickness (unit as written in the article), helium as carrier gas at 1 mL/min, a 1 µL injection with a split ratio of 10:1, an injector at 200 °C and a detector at 250 °C. The oven was held at 40 °C for 1 min, then raised by 3 °C per minute to 220 °C, where it was held for a further 25 min. GC-MS column conditions were similar to those of GC-FID, except that the detector was opened 5 min after injection, and scan mode covered 41 to 250 m/z.

How were the results analysed statistically?

A hierarchical cluster analysis (Primer 6, standardised data, Bray-Curtis similarity for the dendrogram) explored co-occurrence patterns of the main sesquiterpene constituents across the 194 individuals. A principal component analysis (PCA) was run in R on the percentage composition data, among other aims to identify “possible” S. spicatum chemotypes.

How much extract did the heartwood yield?

According to Moniodis et al. (2017), the total yield of sesquiterpene extracts — ethanol extracts of heartwood sampled at 30 cm above ground in spring 2009 — did not differ significantly between the three regions. In the text, the ethanol heartwood extracts of Wheatbelt trees (3.22 ± 1.08%, n = 152) and Goldfields trees (2.40 ± 0.94%, n = 19) had similar total sesquiterpene contents, with individuals ranging from 0.01% to 6.41% by dry weight.

What is in the ethanol heartwood extract?

How much E,E-farnesol do the extracts contain?

In the ethanol heartwood extracts measured by Moniodis et al. (2017), mean E,E-farnesol content was 19.4 ± 5.6% in Goldfields trees (n = 19), 14.4 ± 8.5% in Wheatbelt trees (n = 152) and 9.1 ± 5.4% in northern trees (n = 23). Across all regions, E,E-farnesol in these extracts ranged from 2.0% to 46.2% of the total sesquiterpene profile. In the same extracts, ten percent of the sampled trees had farnesol levels above 35%, and trees below 5% farnesol were similarly infrequent. The authors write that some chemotypes “appear” to exist with high or low E,E-farnesol levels, but that more than half of the trees analysed had extracts containing 10% to 35% E,E-farnesol, “suggesting a continuous distribution”.

How much α-santalol and β-santalol do the extracts contain?

In the ethanol heartwood extracts measured by Moniodis et al. (2017), α- and β-santalol were highest in trees from the north (n = 23), at 33.0 ± 11.6% santalols. About one quarter of all trees surveyed had less than 5% combined α- and β-santalol; more than half of the trees had extracts with less than “10%–15%” combined santalol content. The authors write that all individuals from the north contained at least twice as much “α- and α- santalol” as farnesol in the extract; as written in the article, the phrase can be read either as α- and β-santalol or as α-santalol alone, and this page does not decide between the two readings.

What other constituents were measured?

In the ethanol heartwood extracts, the authors write that α-bisabolol, dendrolasin and nerolidol “were more variable across sampling locations”. Mean α-bisabolol content in these extracts was 1.50 ± 1.7% in the north (n = 23) and 1.80 ± 3.3% in the Wheatbelt (n = 152), which the authors call markedly lower than in Goldfields trees (9.70 ± 4.9%, n = 19), “suggesting” that an α-bisabolol chemotype “might” be present in that region. Table 1 of the article, which covers ethanol extracts of heartwood (its legend says “heartwood oil extracts”) and does not state the basis of its percentages, gives for the row “Z-nuciferol, Z-ϒ-curcumen-12-ol” (R.I. 2520 and 2525) an average of 11.2% (min 3.1, max 23.3, SD 4.6) in the south-west (Wheatbelt, n = 152), 8.9% (3.6 to 15.4, SD 3.0) in the south-east (Goldfields, n = 19) and 5.9% (0.7 to 19.0, SD 4.7) in the north (Carnarvon/Shark Bay, n = 23). In the same table of ethanol heartwood extracts, Z-β-curcumen-12-ol (R.I. 2470) averages 6.9% (0.3 to 17.1, SD 3.5) in the Wheatbelt, 6.8% (0.6 to 14.0, SD 4.2) in the Goldfields and 6.9% (0.3 to 19.8, SD 5.2) in the north. In the same table of ethanol heartwood extracts, Z-α-trans-bergamotol (R.I. 2358) averages 2.8% (0.0 to 14.0, SD 2.2) in the Wheatbelt (n = 152), 2.7% (0.2 to 6.3, SD 1.6) in the Goldfields (n = 19) and 4.2% (1.2 to 7.3, SD 1.9) in the north (n = 23). In the same table of ethanol heartwood extracts, Z-lanceol (R.I. 2496) averages 1.4% (0.3 to 8.7, SD 1.4) in the Wheatbelt, 5.0% (1.5 to 9.6, SD 2.4) in the Goldfields and 2.3% (0.9 to 6.9, SD 1.4) in the north. In the same table of ethanol heartwood extracts, dendrolasin (R.I. 1927) averages 1.3% (0.2 to 5.3, SD 0.9) in the Wheatbelt (n = 152), 2.3% (0.7 to 5.4, SD 1.2) in the Goldfields (n = 19) and 0.7% (0.2 to 1.5, SD 0.4) in the north (n = 23). In the same table of ethanol heartwood extracts, trans-nerolidol (R.I. 2033) averages 0.4% (0.0 to 1.7, SD 0.3) in the Wheatbelt, 0.6% (0.2 to 1.5, SD 0.4) in the Goldfields and 0.7% (0.1 to 2.2, SD 0.6) in the north.

Which chemotypes did the authors describe?

In the PCA of the extract composition, the first two principal components explained 83% of the variance and indicated that trees within a region tended to share a more similar heartwood chemistry than geographically distant populations, with similarities among regions as well, particularly between north and Wheatbelt trees. The first three components accounted for 95% of the variance; the analysis indicated that E,E-farnesol and α-santalol were two largely independent drivers of variability, mainly responsible for the ordination in the S. spicatum extract. The α-santalol chemotypes with low E,E-farnesol were mostly represented by northern trees, and the same sentence of the article adds that several individuals from the south-west (Wheatbelt) “displayed some remarkable similarities in total sesquiterpene profiles despite their geographic separation”. The PCA also “suggested” that the sampled Goldfields trees included no individual with a high α-santalol content, E,E-farnesol and α-bisabolol contributing more to the total sesquiterpene profile of these trees. E,E-farnesol and dendrolasin showed a strong positive correlation, “suggesting some level of shared biogenesis”; the authors describe dendrolasin as a furan sesquiterpenoid structurally similar to farnesol and consider it “possible” that the two compounds share a common origin.

In their conclusions, the authors write that the study highlighted variations in “sandalwood quality” — assessed, in their words, by α- and β-santalol content and E,E-farnesol — of S. spicatum across the semi-arid and arid regions of Western Australia, and showed different chemotypes in three regions: the semi-arid south-west Wheatbelt, the arid south-east Goldfields and the north Carnarvon region. They write that the northern trees showed, on average, sesquiterpene profiles “of higher quality” than trees from the south, while yields varied within regions rather than across them, and that the PCA indicated that α-santalol and E,E-farnesol chemotypes existed.

Which ISO standards name Australian sandalwood?

In the ISO catalogue for ICS 71.100.60, ISO 22769:2022, titled “Essential oil of Australian sandalwood [Santalum spicatum (R.Br.) A.DC.]”, is listed without the mention “[Withdrawn]”. In the same copy of the catalogue, ISO 22769:2009, titled “Oil of Australian sandalwood [Santalum spicatum (R.Br.) A.DC.]”, is marked “[Withdrawn]”.

References