Aquilaria malaccensis (Agarwood): Wood, Oils and CITES

Which Aquilaria malaccensis Lam. material do the two studies describe?

In the dataset article of Abdul Kadir et al. (2020), the trees containing agarwood resins were Aquilaria malaccensis Lam. trees in which the resin had been induced through natural conditions or by a synthetic method, and samples from a healthy, undamaged A. malaccensis tree served as the control.

How were the agarwood samples of Abdul Kadir et al. (2020) obtained?

According to Abdul Kadir et al. (2020), the naturally formed agarwood was obtained from a tree trunk broken and damaged by natural phenomena such as lightning, strong wind and insects gnawing on the trunk, which had eventually become rotten. In the same study, the synthetically induced agarwood was produced by boring holes in the trunk with nails and filling them with an inoculation mixture that contained honey; the resin formed after five years was used as the induced agarwood sample. The trunks of the healthy tree and of the trees with naturally formed and synthetically induced agarwood came from Hulu Langat (3° 7′ 0″ N, 101° 51′ 0″ E), in Selangor, Malaysia, at 28 °C in the field; the samples were cleaned, dried, cut into small slices and ground mechanically.

How were the oils of the three trunk samples extracted and analysed?

Abdul Kadir et al. (2020) extracted the oils of the non-resinous sample (healthy tree) and of the resinous samples (naturally formed and synthetically induced agarwood) by hydrodistillation: 200 g of ground wood were soaked overnight in 1 L of distilled water, placed in a 2 L round-bottomed flask with the water volume adjusted to 1.5 L, connected to a Clevenger-type apparatus and distilled for 5 h. The oil was separated with n-hexane, dried in a vacuum rotary evaporator at 45 °C and kept in amber bottles at −20 °C. Each oil was analysed in nine replicates by GC-MS (total run time 38.5 min, helium at 1 mL/min, injector at 200 °C and detector at 300 °C, oven from 60 °C to 285 °C) on a capillary column, in full scan from m/z 30 to 300; retention indices were calculated with a series of n-alkanes (C8–C40). The GC-MS data were deconvoluted with AMDIS, compounds were identified against the NIST Mass Spectral 2008 library, putative metabolites were assigned to peaks with a similarity index above 70 %, and peak areas were normalised to the internal standard (“nanodecanoic acid”), log-transformed and auto-scaled. The authors describe their dataset as an MS Excel table (xlsx format) giving the compound name, retention time, retention index, molecular formula, molecular weight, fragment ions (m/z), significance value and normalised peak area.

How was the A. malaccensis wood of Samadi et al. (2020) prepared?

According to Samadi et al. (2020), the A. malaccensis wood studied was collected in the garden of the Forest Research Institute Malaysia (FRIM). It was air-dried in a dark room away from sunlight, then stored in a bag at a cool room temperature (4 °C). The wood was cut into smaller pieces with a saw, each piece was shredded with a small knife, and the shredded wood was crushed in a grinder.

How was the wood hydrodistilled in Samadi et al. (2020)?

The hydrodistillation used a Clevenger-type apparatus “described by European pharmacopeia”; the wood was first soaked in water for seven days, then 100 g of air-dried, size-reduced wood and an “appropriate” amount of distilled water were placed in a heating mantle attached to the Clevenger and boiled at 100 °C and 1 atm. The hydrodistilled oil analysed by GC/MS was extracted at the conditions the authors call optimum for this process: HD (100 °C, 0.1 g/mL, 16 h). According to the authors, scanning electron microscopy “provided evidence” that, despite the long duration of the process (one week of soaking followed by 16 h of extraction), hydrodistillation failed to completely extract the oil from the cells of the wood.

How did the subcritical water extraction of Samadi et al. (2020) work?

The subcritical water extraction was performed in static mode, in batches, in a laboratory-size system with a 20 L heating bath whose heating medium was either silicone oil or a potassium nitrate/sodium nitrate salt. The ground, dried sample was loaded into a stainless-steel reactor (30 mL, 65 mm long, 16 mm internal diameter), filled with water according to the set solvent-to-sample ratio and purged with argon to remove trapped air; at the end of the extraction, the reactor was pulled out and immediately dipped into cool water. In the recovery step to which the subcritical water extraction section refers, the oil was separated from the aqueous phase by liquid–liquid extraction with 5 mL of n-hexane, repeated twice; the hexane was removed with a rotary evaporator, the residual water with anhydrous sodium sulphate, and the oils were stored in a dark sealed vial at 4 °C. The authors write that, because subcritical water extraction takes place at high temperatures and pressures in the presence of water, unwanted reactions such as hydrolysis, degradation and charring “are inevitable”.

How did Samadi et al. (2020) model the oil yield?

In this study, the oil yield is expressed in % v/w, from the volume of oil collected (mL) and the mass of plant material (g); the experiments were carried out in triplicate, with relative standard deviations between replicates below 5 %. Response surface methodology (RSM) with a two-level central composite design (CCD) was used to look for the optimum oil yield of the subcritical water extraction; twenty-eight experiments were performed and analysed by ANOVA. The quadratic model “is deemed” the model recommended through the ANOVA (the cubic model being “aliased”), and the regression analysis of the quadratic model “could explain” 98.6 % of the yield variation. The authors write that the response surface and regression analyses “verified” that, for the subcritical water extraction of the oil of A. malaccensis wood, temperature is “the most influential factor”, followed by time and then the sample-to-water ratio, and that the interaction between temperature and reaction time “greatly influences” the oil yield. The time–temperature interaction and the squares of time, ratio and temperature have negative coefficients, which, in the authors’ words, “may be explained” by a possible degradation of the oil at very high temperatures and prolonged extraction times. According to the authors, the FTIR and SEM results “verify” the inability of hydrodistillation to effectively break down the cell walls of A. malaccensis wood and extract its oil, which in their reading explains the lower oil yield of hydrodistillation compared with subcritical water extraction.

How were the two oils of Samadi et al. (2020) analysed?

The oils obtained by hydrodistillation and by subcritical water extraction were analysed by GC/MS with an auto-injector and an FID detector; 20 µL of oil were diluted in 500 µL of n-hexane, the carrier gas was helium, the run time 90 min, and temperature and pressure were raised from 50 to 250 °C and from 37.1 to 100 kPa. Retention indices were determined from the retention times of n-alkanes (C5–C30) run on the same instrument under the same conditions, compounds were identified with the NIST and WILEY libraries, and the relative amount of each component was calculated as a percentage of the oil by a computerised integrator on the total ion chromatograms.

What did GC/MS identify in the two oils of Samadi et al. (2020)?

Forty-three chemical components were identified in the hydrodistilled oil of A. malaccensis wood, described as “dark greenish”, and 50 in the oil obtained by subcritical water extraction, described as “light orange/brownish”. According to the text of the article, GC/MS identified “n-hexadecenoic acid” (17.238 %), 2-butanone, 4-phenyl (10.732 %) and agarospirol (7.618 %) as the major compounds of the hydrodistilled oil. In Table 4, the row that carries 17.238 in the HD column is named “Hexadecanoic acid”: the text and the table name this value in two ways, and this page does not choose between them. According to the text, the major compounds of the oil obtained by subcritical water extraction are furfural (14.36 %), guaiacol (13.504 %) and 2-butanone, 4-phenyl (12.042 %). The authors write that this oil also contained some low molecular weight compounds (C5 series, for example furfural and acetylfuran), “non-existent” in the hydrodistilled oil.

What does Table 4 give for each oil?

Table 4 of Samadi et al. (2020), titled “Chemical composition of essential oil from Aquilaria malaccensis’ wood”, gives under “%Presence” one column for the hydrodistilled oil (HD) and one for the subcritical water oil (SCWE). Each value is a relative amount in that oil, not a composition of the species.

Which rows have a value in both columns?

The row “Benzaldehyde” carries 0.923 under HD and 2.019 under SCWE. The row “2-Butanone, 4-phenyl-” carries 10.732 under HD and 12.042 under SCWE. The row “4-Ethylphenyl acetate” carries 4.713 under HD and 1.11 under SCWE. The row “Guaiene Alpha” carries 0.925 under HD and 1.248 under SCWE. The row “beta-Selinene” carries 1.053 under HD and 0.308 under SCWE. The row “Isoeugenol” carries 0.204 under HD and 1.158 under SCWE. The row “Guaiene delta” carries 3.355 under HD and 1.427 under SCWE. The row “10-epi-gama-eudesmol” carries 3.298 under HD and 2.312 under SCWE. The row “viridiflorol” carries 1.015 under HD and 0.61 under SCWE. The row “beta-Eudesmol” carries 1.594 under HD and 0.421 under SCWE. The row “Agarospirol” carries 7.618 under HD and 3.52 under SCWE. The row “Bulnesol” carries 4.882 under HD and 2.103 under SCWE. The row “γ-costol” carries 2.635 under HD and 1.104 under SCWE. The row “Oxo-agarospirol” carries 1.542 under HD and 0.491 under SCWE. The row “valerenic acid” carries 1.606 under HD and 0.522 under SCWE. The row “9-Octadecenal, (Z)-” carries 1.356 under HD and 0.56 under SCWE. The row “Octadecanal” carries 1.249 under HD and 0.44 under SCWE. The row “Hexadecanoic acid” carries 17.238 under HD and 10.104 under SCWE.

Which rows carry “0” in the SCWE column?

The row “gamma.-Eudesmol” carries 1.974 under HD and “0” under SCWE. The row “α-Eudesmol” carries 1.887 under HD and “0” under SCWE. The row “Eudesmol” carries 3.067 under HD and “0” under SCWE.

Which rows have an empty SCWE cell?

The row “Lactic acid, 3-phenyl-, methyl ester” carries 1.281 under HD; its SCWE cell is empty. The row “beta agarofuran” carries 2.845 under HD; its SCWE cell is empty. The row “Rosifoliol” carries 2.287 under HD; its SCWE cell is empty. The row “Postogol” carries 1.405 under HD; its SCWE cell is empty.

Which rows have an empty HD cell?

The row “Valerolactone” has an empty HD cell and carries 2.041 under SCWE. The row “2-Acetylfuran” has an empty HD cell and carries 1.516 under SCWE. The row “2-furylacetone” has an empty HD cell and carries 1.066 under SCWE. The row “Furfural” has an empty HD cell and carries 14.36 under SCWE. The row “Furfural <5methyl->” has an empty HD cell and carries 4.011 under SCWE. The row “Cyclotene” has an empty HD cell and carries 1.423 under SCWE. The row “Guaiacol” has an empty HD cell and carries 13.504 under SCWE. The row “Syringol” has an empty HD cell and carries 4.02 under SCWE. The row “Vanillin” has an empty HD cell and carries 1.386 under SCWE.

Is Aquilaria malaccensis listed by CITES?

According to the Species+ record of taxon 24742 (Aquilaria malaccensis, consulted on 06/10/2026), the current CITES listing is in Appendix II, with an effective date of “23/02/2023”.

References

• Samadi M., Zainal Abidin Z., Yoshida H., Yunus R., Awang Biak D.R., « Towards Higher Oil Yield and Quality of Essential Oil Extracted from Aquilaria malaccensis Wood via the Subcritical Technique », Molecules 2020;25(17):3872, doi:10.3390/molecules25173872 — https://www.ebi.ac.uk/europepmc/webservices/rest/PMC7503260/fullTextXML
• Abdul Kadir F.A., Azizan K.A., Othman R., « Datasets of essential oils from naturally formed and synthetically induced Aquilaria malaccensis agarwoods », Data in Brief 2020;28:104987, doi:10.1016/j.dib.2019.104987 — https://www.ebi.ac.uk/europepmc/webservices/rest/PMC7093814/fullTextXML
• Species+, taxon record 24742 « Aquilaria malaccensis Lam. » (Thymelaeaceae), consulted 06/10/2026 — https://speciesplus.net/api/v1/taxon_concepts/24742?taxonomy=cites_eu
• Govaerts R. (ed.), World Checklist of Vascular Plants (WCVP), Royal Botanic Gardens, Kew — https://sftp.kew.org/pub/data-repositories/WCVP/wcvp.zip