97-53-0 Usage
Uses
Used in Flavor and Fragrance Industry:
Eugenol is used as a flavoring agent obtained from clove oil and is also found in carnation and cinnamon leaves. It is a stable, light yellow-green liquid with a clove odor, slightly soluble in water, and miscible in alcohol. It should be stored in glass or tin, avoiding iron containers. Eugenol is used in spice oils for application in condiments and meats at 100-200 ppm and in baked goods and candy at approximately 30 ppm. Esterification and etherification of the hydroxy group of Eugenol yield valuable fragrance and flavor materials, such as Eugenol acetate and Eugenol methyl ether.
Used in Dental Compounds:
Eugenol is used as a dental compound that exhibits cytotoxicity to human oral squamous cell carcinoma and oral cells. When glucosylated, this compound shows anti-inflammatory activity. It has a strong bactericidal and local anti-corrosive effect, making it useful for dental caries as a local analgesic drug.
Used in Cosmetic Formulations:
In cosmetic formulations, Eugenol can be used to mask odor or provide fragrance due to its strong aromatic odor of clove.
Used in Pharmaceutical Applications:
Eugenol is used as an analgesic (topical), antiseptic, and antifungal agent. It is also used to prepare isonicotin, a specific drug for the treatment of tuberculosis, and has the potential to lower blood pressure.
Used in Food Industry:
Eugenol is a botanical fraction that is anti-bacterial, anti-inflammatory, and pain-relieving. It can also be used as a local, topical anesthetic and antiseptic. In the food industry, it is used as a flavoring agent and preservative.
Used in Aromatherapy:
Eugenol has an aroma threshold value of 6 to 100 ppb, making it suitable for use in aromatherapy for its relaxing and pain-relieving properties.
Used in Chemical Synthesis:
Eugenol can be used as an intermediate in the synthesis of other spices and derivatives, such as methyl eugenol, methyl isobutyl eugenol, acetylbutanoic eugenol, acetyl tauereugenol, and benzyl isobornylphenol. When heated in potassium hydroxide, the double bond of propenyl is rearranged to form α-propenyl conjugated to the benzene ring, leading to the production of isobutanol. Further acetylation, mild oxidation, and α-propenyl cleavage result in the production of vanillin, a key ingredient in artificial flavoring.
Flavor
Eugenol exists naturally in eugenia oil, basil oil and cinnamon oil and other essential oils. It is a thick oily liquid, colorless to pale yellow, with a strong aroma of clove and a pungent aroma.
At present, most of the industries deal with essential oils rich in eugenol with alkali to produce eugenol. The sodium hydroxide solution is usually added to the separated oil, and then the mixture is heated and stirred. The oil of the non-phenol part floating on the liquid surface is extracted with a solvent, and it could be steamed off also. Add acid to acidify sodium salt to obtain crude eugenol, and then wash with water to neutral state, and finally distill in vacuum to get pure eugenol.
Physical and chemical properties
The scientific name for eugenol is 4-allyl-2-methoxyphenol. Some data about it are as follows: molecular formula C10H12O2; molecular weight 164.21; boiling point 253 ℃; melting point-9.2 ~-9.1℃; relative density d2525 1.053~1.064; refractive index nD20 1.538~1.542. It is miscible with alcohol, ether, chloroform and volatile oil. What’s more, it is slightly soluble in water, and soluble in acetic acid and caustic solution. It gradually darkens and thickens in the air. Iron, zinc and other metal ions could catalyze its oxidation. So we should store it below 25 ℃, and protect it from light. Eugenol could make the red litmus and ferric chloride ethanol solution blue. It is present in the clove oil (90%), clove basil oil (about 60%), violet flower oil (about 20%), cinnamon leaf oil, lauric oil, camphor oil, acacia oil and citronella oil. It can be used as fixative and modifier for woody and oriental essence in the spice. It is the main essence for preparation of clove and carnation flavor. It is also often used in the mint, nut and spicy food flavor and tobacco flavor. It can also be used to synthesize vanillin. It is applied for medical and health products and dental hygiene. Eugenol is available in the United States FEMA2467, and it is approved for food by US FDA.
Preparation
Guaiacol is used as raw material. Allyl chloride and allyl alcohol have a direct effect of allylation on guaiacol (patent in the former Soviet Union 352872; US patent 3929904).
There are some disadvantages of synthetic method in making eugenol. These shortcomings need to be improved in the future. Disadvantages are as follows: Many side effects result in difficult separation and purification, and they also affect the quality of product.
Eugenol is used in the formula of perfume essence, a variety of cosmetic essence and soap essence, with the amount of less than 20%. It can also be used in food flavors. There is no restriction in IFRA.
Preparation
Since sufficient eugenol can be isolated from cheap essential oils,
synthesis is not industrially important. Eugenol is still preferentially isolated from
clove leaf and cinnamon leaf oil (e.g., by extraction with sodium hydroxide solution).
Nonphenolic materials are then removed by steam distillation. After the
alkaline solution is acidified at low temperature, pure eugenol is obtained by distillation.
Lilac
Clove tree is a variant name for lilac. It is bud of Syzygium Myrtaceous plant. There are more than 500 kinds of Syzygium in the world, about 72 species in China.
Clove is a tropical and humid forest plant. The growth environment should be warm and humid, and should not be cold. Uniform and abundant rain is needed. In addition, deep, fertile and well-drained soil is better. It can be harvested when the buds turn from green to red in September to March of the following year. After it is harvested, we should remove the pedicel and dry it.
The bud is nail-shaped, and the length is 1~2cm. Calyx tube is cylindrical and slightly quadrangular, with the length of 6~14mm, diameter of about 5mm. The base gradually becomes narrow. And rough surface engraved seepage oil. The upper part has 4triangular sepals that are reddish brown or dark brown and the length is about 3mm. The top corolla is round, with diameter of 4 to 6 mm. 4 tan petals wrap around in tiles. Cut open buds, we could see the situation: a lot of stamens; filaments bent to the center; the central has a straight sturdy which is easy to sink in the water. The section is oily. It has a strong aroma and spicy taste, with a sense of hemp. Lilac is better with these characteristics: large, stout, fresh purple brown, strong aroma, more oil. There are volatile oil 16~19% in buds. The main oil contained in volatile oil are eugenol 80~87%, β-clove 9%, aceto-eugenol7%. In addition, some trace components are present, for example, heptanone-2, methyl salicylate, α-clove Benzene, Benzaldehyde, Benzyl Alcohol, Benzyl Acetate, Methoxybenzaldehyde, Yulanene, and Piperin.
Clove has an antibacterial effect. Ether extract of clove with 1% concentration, water immersion or decoction of Saboura's medium of clove with 8% concentration could inhibit the trichophyton schoenleinii, candida albicans and other pathogenic fungi. Clove oil and eugenol have a strong inhibition on the brucellosis, mycobacterium tuberculosis in the test tube. Clove oil and eugenol also have significant inhibitory effects on common pathogenic fungi. Clove oil and eugenol have antibacterial effect on the staphylococcus aureus, pneumonia, dysentery, large intestine, deformation and other bacteriat with the concentration 1: 2000~1: 8000.
Picture of lilac
Eugenin
Eugenin is naturally present in essential oils such as ylang ylang oil, Tuberose, jonquil oil and calamus oil. Eugenin is heavy with scent of flowers and clove. It has two isomers. The trans-isomer has a melting point of 33~ 34 ° C, and a boiling point of 140 ° C/1.6 Kpa, 118 ° C/670 Pa. The cis-isomer is a liquid having a boiling point of 115 ° C/670 Pa and 98 ° C/130 Pa. The product is a mixture of cis-isomer and trans-isomer, of with the majority is trans-isomers. The ratio of trans-isomer and cis-isomer is about 85:15, and the freezing point is about 12 ℃. According to the information provided by RIFM, the acute toxicity data of eugenol: Oral LD501.56 g/kg (rat), 1.41 g/kg (guinea pig). Cis-isomer has a LD50 of 0.365 g/kg and a trans-form of 0.54 g/kg. The highest doses of cis-isomer and trans-form which did not cause death are 0.10 g/kg and 0.20 g/kg respectively, and the lowest doses which cause death of all animals are 0.60 g/kg and 0.80 g/kg respectively.
Eugenin can be widely used in cosmetics and soaps and flavors. However, allergy is present if the concentration of Eugenin is too high, so IFRA prescribes a maximum concentration with 1% in the essence formula, no more than 0.2% in consumer products, and no more than 0.5% in consumer products that are not in contact with the skin.
Content analysis
Method 1: gas chromatography (GT-10-4) with non-polar column. The content is determined by area percentage.
Method 2: According to determination of phenol (OT-37). It was placed in the water bath for 30 minutes with heating, and cooled at room temperature.
Toxicity
ADI 0~2.5 (FAO/WHO, 1994)
LD50 1930~2680mg/kg (rat, oral)
GRAS (FDA $ 184.1257, 2000
Use limit
FEMA (mg/kg): soft drink 1.4; cold drink 3.1 0 candy 32; baked goods 33, pudding 0.60; chewing gum 500.
Production
Eugenol can be isolated from natural essential oils, also be synthesized by chemical method in industry. However, chemical synthesis method produces isomers. Boiling point of two isomers is very close, resulting in difficult separation. So isolation method is the main method at present.
Isolation method from natural essential oil:
Take perennial sub-shrub clove basil as raw material, we get the mixture of essential oil and water through steam distillation. Add 20% of sodium hydroxide into the mixture, and then distill with steam to remove non-acidic substances. The resulting solution of sodium eugenol is added to 30% sulfuric acid at 50 ° C and stirred to pH = 2~3 (water layer). After standing, separate the lower layer of lilac oil, and then we get eugenol product through reduced pressure distillation.
Chemical synthesis
Allyl bromide, o-methoxyphenol, anhydrous acetone and anhydrous potassium carbonate are added to the kettle and heated to reflux for several hours. After cooling, dilute with water and then extract with ether. The extract is washed with 10% sodium hydroxide and dried over anhydrous potassium carbonate. Recover diethyl ether and acetone after distillation at atmospheric pressure, and then distill under reduced pressure and collect fraction at 110~113 ℃ (1600Pa), finally we get o-methoxyphenyl allyl ether. The mixture is boiled and refluxed for 1 hour and then cooled. The resulting grease is dissolved in ether and extracted with 10% sodium hydroxide solution. The extract is acidified with hydrochloric acid and extracted with ether. Dry the extract over anhydrous sodium sulfate and recover the ether through air distillation, and finally we get product. We could also get product through one step reaction between o-methoxyphenol and allyl chloride with copper as catalyst at 100 ℃.
Take essential oils containing large amounts of eugenol, such as clove oil, as raw materials, and add 30% sodium hydroxide solution, and then add inorganic acid or carbon dioxide to precipitate. In addition, addition reaction between clove oil and sodium acetate is also available.
Eugenol could be prepared by synthetic methods, but it is generally isolated from plants or aromatic oils in industry. We could take clove basil which originating from Seychelles, Comoros as raw material. In 1965, it was introduced into China from the former Soviet Union. It is cultivated in the south of the Yangtze River. The clove basil content is the highest in spike, followed by leaves, and stems are the last. The main ingredient in the oil is eugenol, accounting for 60-70%. There are linalool, parachute, ocimene and so on. We could prepare eugenol by synthetic method, in which o-methoxyphenol reacts with bromopropene. And then rearrangement is carried out with heating.
Toxic grading
Moderate toxicity
Acute toxicity
Oral-LD50: 1930 mg/kg; Oral-Mouse LD50: 3000 mg/kg
Stimulate data
Skin-Rabbit 100 mg/24 h???? severe
Storage characteristics
Ventilated warehouse, low temperature, dry; separated from food materials
Extinguishing agent
Dry powder, foam, sand.
Air & Water Reactions
Darkens and thickens on exposure to air. Also darkens with age. Eugenol may decompose on exposure to light. Insoluble in water.
Reactivity Profile
Eugenol is incompatible with strong oxidizers. This includes ferric chloride and potassium permanganate. Eugenol reacts with strong alkalis. Eugenol is incompatible with iron and zinc.
Hazard
Questionable carcinogen.
Fire Hazard
Eugenol is combustible.
Contact allergens
Eugenol is a fragrance allergen obtained from many
natural sources. Occupational sensitization to eugenol
may occur in dental profession workers. Eugenol is
contained in “fragrance mix” and has to be listed by
name in cosmetics within the EU.
Anticancer Research
This compound was tested on a model of skin tumor induced by DMBA croton oilin Swiss mice. The eugenol affects the cellular proliferation by increasing apoptosiscellular death. There is evidence for a downregulation of c-myc, H-ras, and Bcl-2expression and an upregulation of p53, Bax, and active caspase-3 (Grondona et al.2014).
Clinical Use
4-Allyl-2-methoxyphenol is obtained primarily from cloveoil. It is a pale-yellow liquid with a strong aroma of clovesand a pungent taste. Eugenol is only slightly soluble in waterbut is miscible with alcohol and other organic solvents.Eugenol possesses both local anesthetic and antiseptic activityand can be directly applied on a piece of cotton to relievetoothaches. Eugenol is also used in mouthwashes because ofits antiseptic property and pleasant taste. The phenol coefficientof eugenol is 14.4.
Safety Profile
Moderately toxic by
ingestion, intraperitoneal, and subcutaneous
routes. Human mutation data reported. A
human skin irritant. Questionable
carcinogen with experimental carcinogenic
and tumorigenic data. Combustible liquid.
When heated to decomposition it emits
acrid smoke and irritating fumes. See also
ALLYL COMPOUNDS.
Synthesis
The oil containing eugenol is treated with a 3% aqueous solution of NaOH; the nonacid components are extracted with
ether; the alkaline solution is acidified to isolate the phenols and subsequently is fractionally distilled under reduced pressure; to
avoid the formation of emulsions, a pretreatment of the oil with tartaric acid is preferred; eugenol is the starting material in one of the
syntheses for the preparation of vanillin.
Metabolism
No absorption of eugenol occurred within 2hr of application to the intact shaved skin of mice (Meyer & Meyer, 1959). Following ip injec tion of [14C]eugenol into rats, radioactivity was dis tributed in various organs and the presence of 14CO2 in the expired air indicated the demethylation of eugenol (Weinberg, Rabinowitz, Zanger & Gennaro, 1972). Over 70% of an oral dose of eugenol was excreted in the urine of rabbits (Schr?der & Vollmer, 1932).
Purification Methods
Fractional distillation of eugenol gives a pale yellow liquid which darkens and thickens on exposure to air. It should be stored under N2 at -20o. [Waterman & Priedster Recl Trav Chim Pays-Bas 48 1272 1929, Beilstein 6 H 961, 6 IV 6337.]
Check Digit Verification of cas no
The CAS Registry Mumber 97-53-0 includes 5 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 2 digits, 9 and 7 respectively; the second part has 2 digits, 5 and 3 respectively.
Calculate Digit Verification of CAS Registry Number 97-53:
(4*9)+(3*7)+(2*5)+(1*3)=70
70 % 10 = 0
So 97-53-0 is a valid CAS Registry Number.
97-53-0Relevant articles and documents
Me3SI-promoted chemoselective deacetylation: a general and mild protocol
Gurawa, Aakanksha,Kashyap, Sudhir,Kumar, Manoj
, p. 19310 - 19315 (2021/06/03)
A Me3SI-mediated simple and efficient protocol for the chemoselective deprotection of acetyl groups has been developedviaemploying KMnO4as an additive. This chemoselective deacetylation is amenable to a wide range of substrates, tolerating diverse and sensitive functional groups in carbohydrates, amino acids, natural products, heterocycles, and general scaffolds. The protocol is attractive because it uses an environmentally benign reagent system to perform quantitative and clean transformations under ambient conditions.
Continuous flow study of isoeugenol to vanillin: A bio-based iron oxide catalyst
Filiciotto, Layla,Márquez-Medina, María Dolores,Pineda, Antonio,Balu, Alina M.,Romero, Antonio A.,Angelici, Carlo,de Jong, Ed,van der Waal, Jan C.,Luque, Rafael
, p. 281 - 290 (2019/12/25)
The use of a biorefinery co-product, such as humins, in combination with an iron precursor in a solvent-free method yields a catalytic material with potential use in selective oxidative cleavage reactions. In particular, this catalyst was found active in the hydrogen-peroxide assisted oxidation of a naturally extracted molecule, isoeugenol, to high added-value flavouring agent, vanillin. By carrying out the reaction in continuous flow, not only a better understanding of the reaction mechanism and of the catalyst deactivation can be achieved, but also important insights for optimised conditions can be developed. The findings of this paper could pave the way to a more sustainable process for the production of a valuable food and perfume additive, vanillin.
Molybdate Stabilized Magnesium‐Iron Hydrotalcite Materials: Potential Catalysts for Isoeugenol to Vanillin and Olefin Epoxidation
Neethu, P. P.,Sakthivel, A.,Sreenavya, A.
, (2021/08/03)
A series of molybdate-intercalated and stabilized magnesium‐iron hydrotalcite (HMFeMo) materials with different molybdate loadings were successfully prepared by an in-situ hydrothermal method. The prepared HMFeMo materials were systematically characterized using Fourier-transform infrared spectroscopy (FT-IR), powder X-ray diffraction (XRD), Ultraviolet-visible spectroscopy, scanning electron microscopy, thermo-gravimetric analysis, nitrogen adsorption-desorption and X-ray photoelectron spectroscopy (XPS) experiments. The XRD results demonstrated the successful intercalation of molybdate ions in the interlayer space of magnesium-iron hydrotalcite and the stabilization of the layered structure. In addition, the XPS spectra of the HMFeMo materials revealed the presence of molybdenum in a higher-valent oxidation state. The calcination of HMFeMo materials led to the formation of solid solution of mixed metal oxides. Both the as-prepared and calcined HMFeMo catalysts showed promising activity for the epoxidation of cyclooctene, as a model reaction. Furthermore, the performance of the as-prepared and calcined HMFeMo catalysts for the oxidation of a biomass model compound, namely isoeugenol to vanillin, was evaluated. The isoeugenol conversion over the as-prepared HMFeMo catalysts under solvent-free conditions and using tertiary-butyl hydroperoxide in decane as the oxidant was good. Moreover, the isoeugenol conversion and selectivity toward vanillin of HMFeMo0.1, with a molybdate loading of 0.1 mol %, were the highest (86.2% and 83.1%, respectively) of all HMFeMo catalysts in this study at 80 °C for 5 hr. HMFeMo0.1 presented the best catalytic activity for both the epoxidation of cyclooctene and oxidation of isoeugenol to vanillin, and its activity remained unchanged after several runs.
Controlled lignosulfonate depolymerization: Via solvothermal fragmentation coupled with catalytic hydrogenolysis/hydrogenation in a continuous flow reactor
Al-Naji, Majd,Antonietti, Markus,Brandi, Francesco
supporting information, p. 9894 - 9905 (2021/12/24)
Sodium lignosulfonate (LS) was valorized to low molecular weight (Mw) fractions by combining solvothermal (SF) and catalytic hydrogenolysis/hydrogenation fragmentation (SHF) in a continuous flow system. This was achieved in either alcohol/H2O (EtOH/H2O or MeOH/H2O) or H2O as a solvent and Ni on nitrogen-doped carbon as a catalyst. The tunability according to the temperature of both SF and catalytic SHF of LS has been separately investigated at 150 °C, 200 °C, and 250 °C. In SF, the minimal Mw was 2994 g mol-1 at 250 °C with a dispersity (?) of 5.3 using MeOH/H2O. In catalytic SHF using MeOH/H2O, extremely low Mw was found (433 mg gLS-1) with a ? of 1.2 combined with 34 mg gLS-1. The monomer yield was improved to 42 mg gLS-1 using dual catalytic beds. These results provide direct evidence that lignin is an unstable polymer at elevated temperatures and could be efficiently deconstructed under hydrothermal conditions with and without a catalyst. This journal is
3'-KETOGLYCOSIDE COMPOUND FOR THE SLOW RELEASE OF A VOLATILE ALCOHOL
-
, (2021/08/20)
The present invention relates to a 3'-ketoglycoside compound defined by formula (I) and its use for controlled release of alcohols, in particular alcohols showing an insect repellent effect. It relates also to a process for preparing the 3'-ketoglycoside compound of formula (I). It further relates to a composition comprising a 3'- ketoglycoside compound of formula (I). It relates also to the use of a 3'-ketoglycoside compound of formula (I) for the controlled release of alcohols. It related also to a method of use of such composition.
Nickel-catalyzed reductive deoxygenation of diverse C-O bond-bearing functional groups
Cook, Adam,MacLean, Haydn,St. Onge, Piers,Newman, Stephen G.
, p. 13337 - 13347 (2021/11/20)
We report a catalytic method for the direct deoxygenation of various C-O bond-containing functional groups. Using a Ni(II) pre-catalyst and silane reducing agent, alcohols, epoxides, and ethers are reduced to the corresponding alkane. Unsaturated species including aldehydes and ketones are also deoxygenated via initial formation of an intermediate silylated alcohol. The reaction is chemoselective for C(sp3)-O bonds, leaving amines, anilines, aryl ethers, alkenes, and nitrogen-containing heterocycles untouched. Applications toward catalytic deuteration, benzyl ether deprotection, and the valorization of biomass-derived feedstocks demonstrate some of the practical aspects of this methodology.
KMnO4-catalyzed chemoselective deprotection of acetate and controllable deacetylation-oxidation in one pot
Gurawa, Aakanksha,Kumar, Manoj,Rao, Dodla S.,Kashyap, Sudhir
supporting information, p. 16702 - 16707 (2020/10/27)
A novel and efficient protocol for chemoselective deacetylation under ambient conditions was developed using catalytic KMnO4. The stoichiometric use of KMnO4 highlighted the dual role of a heterogeneous oxidant enabling direct access to aromatic aldehydes in one-pot sequential deacetylation-oxidation. The reaction employed an alternative solvent system and allowed the clean transformation of benzyl acetate to sensitive aldehyde in a single step while preventing over-oxidation to acids. Use of inexpensive and readily accessible KMnO4 as an environmentally benign reagent and the ease of the reaction operation were particularly attractive, and enabled the controlled oxidation and facile cleavage of acetate in a preceding step. This journal is
METHOD OF FORMING MONOMERS AND FURFURAL FROM LIGNOCELLULOSE
-
, (2020/06/05)
The present disclosure relates to a method of producing monophenolicmonomers and furfural from lignocellulosic biomass beating the biomass in a solvent together with a zeolite based catalyst.
Structural features and antioxidant activities of Chinese quince (Chaenomeles sinensis) fruits lignin during auto-catalyzed ethanol organosolv pretreatment
Cheng, Xi-Chuang,Guo, Xin-Ran,Liu, Hua-Min,Liu, Yu-Lan,Qin, Zhao,Wang, Xue-De
, p. 4348 - 4358 (2020/09/22)
Chinese quince fruits (Chaenomeles sinensis) have an abundance of lignins with antioxidant activities. To facilitate the utilization of Chinese quince fruits, lignin was isolated from it by auto-catalyzed ethanol organosolv pretreatment. The effects of three processing conditions (temperature, time, and ethanol concentration) on yield, structural features and antioxidant activities of the auto-catalyzed ethanol organosolv lignin samples were assessed individually. Results showed the pretreatment temperature was the most significant factor; it affected the molecular weight, S/G ratio, number of β-O-4′ linkages, thermal stability, and antioxidant activities of lignin samples. According to the GPC analyses, the molecular weight of lignin samples had a negative correlation with pretreatment temperature. 2D-HSQC NMR and Py-GC/MS results revealed that the S/G ratios of lignin samples increased with temperature, while total phenolic hydroxyl content of lignin samples decreased. The structural characterization clearly indicated that the various pretreatment conditions affected the structures of organosolv lignin, which further resulted in differences in the antioxidant activities of the lignin samples. These results can be helpful for controlling and optimizing delignification during auto-catalyzed ethanol organosolv pretreatment, and they provide theoretical support for the potential applications of Chinese quince fruits lignin as a natural antioxidant in the food industry.
Photoactivatable Odorants for Chemosensory Research
Gore, Sangram,Ukhanov, Kirill,Herbivo, Cyril,Asad, Naeem,Bobkov, Yuriy V.,Martens, Jeffrey R.,Dore, Timothy M.
, p. 2516 - 2528 (2020/10/02)
The chemosensory system of any animal relies on a vast array of detectors tuned to distinct chemical cues. Odorant receptors and the ion channels of the TRP family are all uniquely expressed in olfactory tissues in a species-specific manner. Great effort has been made to characterize the molecular and pharmacological properties of these proteins. Nevertheless, most of the natural ligands are highly hydrophobic molecules that are not amenable to controlled delivery. We sought to develop photoreleasable, biologically inactive odorants that could be delivered to the target receptor or ion channel and effectively activated by a short light pulse. Chemically distinct ligands eugenol, benzaldehyde, 2-phenethylamine, ethanethiol, butane-1-thiol, and 2,2-dimethylethane-1-thiol were modified by covalently attaching the photoremovable protecting group (8-cyano-7-hydroxyquinolin-2-yl)methyl (CyHQ). The CyHQ derivatives were shown to release the active odorant upon illumination with 365 and 405 nm light. We characterized their bioactivity by measuring activation of recombinant TRPV1 and TRPA1 ion channels expressed in HEK 293 cells and the electroolfactogram (EOG) response from intact mouse olfactory epithelium (OE). Illumination with 405 nm light was sufficient to robustly activate TRP channels within milliseconds of the light pulse. Photoactivation of channels was superior to activation by conventional bath application of the ligands. Photolysis of the CyHQ-protected odorants efficiently activated an EOG response in a dose-dependent manner with kinetics similar to that evoked by the vaporized odorant amyl acetate (AAc). We conclude that CyHQ-based, photoreleasable odorants can be successfully implemented in chemosensory research.
