Sandalwood Odour Research Articles

Identification of aroma‐active components from cultivated agarwood ‘Qi‐Nan’ based on GC‐O‐MS combined with aroma extract dilution analysis

AbstractAgarwood ‘Qi‐Nan’ is commonly regarded as the highest quality agarwood, and has been highly valued for its fragrance. With the increasing amount of cultivated agarwood ‘Qi‐Nan’ in recent years, evaluation of the aroma compounds was drawn attention. Therefore, the volatile compounds in three cultivated ‘Qi‐Nan’ agarwood samples were extracted by simultaneous distillation‐extraction (SDE) and analysed by GC‐O‐MS, combined with aroma extract dilution analysis (AEDA). A total of 70 volatile compounds were identified from three samples, in which sesquiterpenes and aromatics were characterized as key aroma‐active components. Nine compounds were considered as common aroma‐active volatiles in these three essential oils according to their flavour dilution (FD) activity and relative flavour activity (RFA) value, and among them, dihydro‐β‐agarofuran and 4‐methoxy‐benzaldehyde were the most important aroma‐active compounds. Additionally, three ‘Qi‐Nan’ agarwood samples showed different aroma specificity. TD agarwood was characterized by sweet sandalwood odour due to the dominant aroma‐active compound of β‐Santalol. WS agarwood was distinguished by its woody odour because α‐kessyl acetate was its primary aroma. HQ agarwood was featured by woody, spicy and balsamic odour on account of its main aroma compounds of agarospirol and β‐elemene.

Selective palladium nanoparticles-catalyzed hydrogenolysis of industrially targeted epoxides in water

Palladium nanoparticles, with core sizes of ca. 2.5 nm, were easily synthesized by chemical reduction of Na2PdCl4 in the presence of hydroxyethylammonium salts and proved to be efficient for the selective hydrogenolysis of various aromatic, alkylphenyl, aliphatic epoxides in water as green solvent. Capping agents of the metal species were screened to define the most suitable micellar nanoreactors on two target substrates of industrial interest, epoxystyrene and 7,8-epoxy-2-methoxy-2,6-dimethyloctane. In our conditions, the hydrogenolysis of epoxystyrene proved to be pH-dependent, producing either the diol under acidic conditions, or the sweet-smelling 2-phenylethanol in the presence of a base. Promisingly, 7,8-epoxy-2-methoxy-2,6-dimethyloctane was completely and selectively hydrogenated into Florsantol®, a sandalwood odorant at a multigram scale (40 g and up to 175g). A general mechanism for the palladium nanoparticles-catalyzed hydrogenolysis of terminal epoxides was proposed according to steric and electronic properties and finely corroborated with deuterium labelling experiments.

A novel photothermo-responsive nanocarrier for the controlled release of low-volatile fragrances.

We herein present a facile approach to create polydopamine (PDA) modified silica-based nanocarriers for use in the encapsulation and photothermally responsive release of the synthetic sandalwood odorant Sandalore (SA) as a low-volatile model fragrance. The method involves impregnating mesoporous silica nanoparticles with an ethanol solution of SA followed by surface functionalization via the in situ self-polymerization of dopamine under alkaline conditions. The resulted nanocomposites have high fragrance loading capacity with up to ∼85% by weight of SA relative to the silica matrix and are capable of effectively preserving the cargo in the dark or indoors. The aroma release was significantly accelerated upon illumination due to the photothermal heating effect of the PDA shell, which is proportional to the coating content and the irradiation intensity. Additionally, the emulated laundry tests showed that the composites exhibited a higher deposition efficiency on the fabric surface and better washing-resistance as compared to the control particles without PDA coating.

Hair Sciences: Sandalwood Demonstrated to Promote Human Hair Growth through Olfactory Receptors Present on the Hair Follicle

1. Vlad Ratushny, MD, PhD (vratushny{at}maderm.org) 1. Beverly, Massachusetts, USA ![][1] In their September 2018 publication in Nature Communications, Cheret and colleagues showed that a synthetic sandalwood odorant stimulated the olfactory receptor OR2AT4 located in the outer

Hydrogenation towards Synthetic Sandalwood Odorants in Fragrance Industry

AbstractThe use of metal hydrides as historical reagents for selective carbonyl group reduction is often still a really highly convenient solution for laboratory‐scale transformations due to the lack of requirement for specific equipment. Nevertheless, based on safety, environmental, but also economical industrial constraints, metal hydride reductions were replaced by hydrosilylation, hydrogen transfer, and mostly hydrogenation reactions. Among many other advantages, the use of hydrogen as a reducing agent indeed represents the most sustainable solution for implementation of such chemical transformation on industrial scale. Whereas heterogeneous catalysts have been initially sparsely employed, the most recent developments towards the synthesis of highly active and efficient homogeneous catalysts have become an indisputable solution for selective hydrogenation of both ketones and aldehydes in sandalwood odorant production according to green chemistry principles.

Odor-sensing protein spurs hair growth

If the cure to baldness has a scent, it may smell like sandalwood. Researchers have discovered a receptor in hair follicles that activates in response to a sandalwood-scented molecule, promoting hair growth (Nat. Commun. 2018, DOI: 10.1038/s41467-018-05973-0). Olfactory receptors capture odorant molecules, eventually producing the sense of smell. Originally identified in the nose, they were subsequently discovered in other parts of the body. In prior work, Ralf Paus of the University of Miami and colleagues studied an olfactory receptor, OR2AT4, found in skin cells. They observed an increase in skin-cell proliferation and wound healing after OR2AT4 bound to Sandalore (shown), a trademarked synthetic sandalwood odorant used in many products. Wound healing and hair growth are connected, Paus says, which gave him the idea to look for OR2AT4 in hair follicles. Now, the researchers have determined that hair follicles indeed express OR2AT4 during the part of their cycle associated with hair

Olfactory receptor OR2AT4 regulates human hair growth

Olfactory receptors are expressed by different cell types throughout the body and regulate physiological cell functions beyond olfaction. In particular, the olfactory receptor OR2AT4 has been shown to stimulate keratinocyte proliferation in the skin. Here, we show that the epithelium of human hair follicles, particularly the outer root sheath, expresses OR2AT4, and that specific stimulation of OR2AT4 by a synthetic sandalwood odorant (Sandalore®) prolongs human hair growth ex vivo by decreasing apoptosis and increasing production of the anagen-prolonging growth factor IGF-1. In contrast, co-administration of the specific OR2AT4 antagonist Phenirat® and silencing of OR2AT4 inhibit hair growth. Together, our study identifies that human hair follicles can engage in olfactory receptor-dependent chemosensation and require OR2AT4-mediated signaling to sustain their growth, suggesting that olfactory receptors may serve as a target in hair loss therapy.

A Novel Similarity-Based Algorithm for Supervised Binary Classification: Sandalwood Odor Application

Recent years have brought big advances in the field of Data mining; this is due to the immense advances in technologies which facilitate the analysis of data. In particular, binary classification techniques are a subdomain of Data Mining which is used to classify data into two classes according to desired criteria. Different algorithms have been developed and they can be categorized into statistical and machine learning. Each category has its own limits. In this paper, a set of molecules is chosen to illustrate the proposed approach of binary classification. The considered molecules are described by means of size, shape, functionality and other expert descriptors. This paper defines new measure functions to quantify the similarities between the molecules and then combines them in a new approach which differs from actual algorithms by its reliability computations. Results of the proposed approach exceeded most common classification techniques with a f-measure exceeding 70% on this molecules Dataset.

A Novel Similarity-Based Algorithm for Supervised Binary Classification: Sandalwood Odor Application

A Novel Similarity-Based Algorithm for Supervised Binary Classification: Sandalwood Odor Application

Simple synthesis of sandalwood odorant rac‐Osyrol® and its ethoxy homologue

Abstractrac‐Osyrol® (3,7‐dimethyl‐7‐methoxyoctane‐2‐ol), a commercially important sandalwood odorant has been prepared from dihydromyrcene in three steps. The key steps in the synthesis are the epoxidation of terminal double bond using urea hydrogen peroxide (UHP) and regioselective reduction of epoxide using Vitride®. The same strategy has been applied to the synthesis of its ethoxy homologue. Copyright © 2015 John Wiley & Sons, Ltd.

Structure-odor relationships of semisynthetic β-santalol analogs.

A series of eleven β-santalol analogs, including nine new derivatives, was prepared by semisynthesis from natural (-)-(Z)-β-santalol and studied by gas chromatography-olfactometry (GC-O) to characterize their olfactory properties and potencies. These compounds and 45 others selected in the literature were used to build three olfactophores by molecular modelling. Three models were obtained that gather structural and physicochemical constraints that will be useful for further design of new sandalwood odorants.

A Synthetic Sandalwood Odorant Induces Wound-Healing Processes in Human Keratinocytes via the Olfactory Receptor OR2AT4

As the outermost barrier of the body, the skin is exposed to multiple environmental factors, including temperature, humidity, mechanical stress, and chemical stimuli such as odorants that are often used in cosmetic articles. Keratinocytes, the major cell type of the epidermal layer, express a variety of different sensory receptors that enable them to react to various environmental stimuli and process information in the skin. Here we report the identification of a novel type of chemoreceptors in human keratinocytes, the olfactory receptors (ORs). We cloned and functionally expressed the cutaneous OR, OR2AT4, and identified Sandalore, a synthetic sandalwood odorant, as an agonist of this receptor. Sandalore induces strong Ca(2+) signals in cultured human keratinocytes, which are mediated by OR2AT4, as demonstrated by receptor knockdown experiments using RNA interference. The activation of OR2AT4 induces a cAMP-dependent pathway and phosphorylation of extracellular signal-regulated kinases (Erk1/2) and p38 mitogen-activated protein kinases (p38 MAPK). Moreover, the long-term stimulation of keratinocytes with Sandalore positively affected cell proliferation and migration, and regeneration of keratinocyte monolayers in an in vitro wound scratch assay. These findings combined with our studies on human skin organ cultures strongly indicate that the OR 2AT4 is involved in human keratinocyte re-epithelialization during wound-healing processes.

Structural Factors in the Odor of α-Santalol Derivatives

Alpha-Santalol is a sesquiterpene that is a major constituent of sandalwood (Santalum album L.), and is responsible for its distinctive woody odor. We replaced the polycyclic moiety and hydroxyl group of alpha-santalol with other moieties, and we compared the odors of the E/Z-isomers and their saturated analogues. Our previous study of the structure-odor relationships of alpha-santalols bearing hydroxyl, formyl, formyloxy, and acetoxy functional groups showed there was a similarity in odor between the Z-isomer and its saturated analogue. We synthesized alpha-santalols with a benzyl group in place of the hydroxyl group, because many benzyl compounds have strong characteristic odors. We found similar odors for the E-isomer and its saturated analogue. In contrast, the odors of the alpha-santalol derivatives with a hydroxyl, formyl, formyloxy, or acetoxy group were different. We also replaced the bulky polycyclic moiety with a linear alkyl chain. The polycyclic moiety was the most important structural factor in the characteristic sandalwood odor. The synthesis of derivatives and the evaluation of their odor allowed us to identify the key structural factors in the odor of alpha-santalol.

Structure-Activity Relationships of Sandalwood Odorants: Synthesis of a New Campholene Derivative

Structural modifications of natural (-)-(Z)-beta-santalol have shown that the sandalwood odor impression is highly sensitive, even to small structural changes. Particularly, the substitution of the quaternary carbon is of great influence on the scent. Epi-compounds with side chains in the endo-position possess sandalwood odor in only a few derivatives, whereas modifications at this side chain, as well as modification at the bicyclic ring systems mostly lead to a complete loss of sandalwood fragrance.

Isolation of new constituents with a formyl group from the heartwood of Santalum album L.

AbstractSandalwood (Santalum album L.) is a traditional incense, and its essential oil is used in fragrances. The hexane extract from Indian sandalwood chips had a sandalwood odour similar to sandalwood chips, but it clearly differed from that of commercial essential oil. By fractional distillation of the extract under reduced pressure, a fraction was obtained that had a sandalwood‐like odour and contained several unknown formyl compounds as the main constituents. Santalyl formates were isolated as new components from this fraction by chromatography and characterized by 1H‐ and 13C‐NMR spectroscopy. These constituents were less abundant in the commercial essential oil than in the hexane extract. Santalyl formates were synthesized from the corresponding alcohols.

QSAR of α-campholenic derivatives with sandalwood odor, and molecular design

Quantitative structure–activity relationship (QSAR) studies have been carried out in a series of α-campholenic derivatives with sandalwood odor based on quantum-chemical data derived by use of the Hartree–Fock (HF) method. To build QSAR models, a multiple linear regression method was used. The models obtained have good predictive ability and are of high statistical significance, with good correlation coefficients, and p values less than 0.05. The models contribute also to identification of important quantum-chemical aspects of the sandalwood odor. On the basis of the QSAR models built, several new sandalwood compounds were designed and the best candidate for experimental synthesis was suggested.

Study of the structural and electronic origin of the sandalwood odor of some terpenylcyclohexanols

The correlation between structural and electronic features and the sandalwood odor of some terpenylcyclohexanols is established on the basis of quantum chemical calculation methods. A definite structural fragment with electronic properties determining the origin of the odor is revealed. The effects of HOMO–LUMO energy gaps and total energies of some terpenylcyclohexanols on their odor intensity are investigated.

Enantioselective Synthesis of (−)‐β‐Santalol by a Copper‐Catalyzed Enynol Cyclization–Fragmentation Reaction

We report herein the first enantioselective, direct synthesis of the highly prized natural sandalwood odorant ( )-b-santalol (( )-1). The key step in the synthesis is an efficient copper-catalyzed rearrangement of an enynol. The increasing scarcity of East Indian sandalwood oil has motivated research chemists over the last 40 years to develop a synthesis of the most valuable component, ( )-b-santalol ( )-1, which makes up 20–25% of the composition of the oil, or its racemate. Despite extensive efforts, this excellent fragrance ingredient is still not commercially available. Recently, we reported the cost-efficient copper-catalyzed cycloisomerization of 5-en-1-yn-3-ols (cyclopropanation/1,2alkyl shift; Scheme 1, A!E) and related enynol esters.

Synthesis and Olfactory Evaluation of Bulky Moiety-Modified Analogues to the Sandalwood Odorant Polysantol®

Five new bulky moiety-modified analogues of the sandalwood odorant Polysantol® have been synthesized by aldol condensation of appropriate aldehydes with butanone, deconjugative α-methylation of the resulting α,β-unsaturated ketones, and reduction of the corresponding β,γ-unsaturated ketones. The final compounds were evaluated organoleptically and one of them seemed to be of special interest for its natural sandalwood scent.

Recent Developments in the Chemistry of Sandalwood Odorants

Natural sandalwood oil, a unique and valuable ingredient in fine perfumery, has been the focus of scientific interest for many years. Due to its scarcity and its high price, the search for novel synthetic raw materials imitating the characteristic odor profile of sandalwood oil is as challenging as ever. In this context, the preparation of the novel sandalwood odorants 26, 33, and 39 will be discussed, including their sensory properties and structure-odor relationship.