Delta-Nonalactone

Sweet scent lactones activate hot capsaicin receptor, TRPV1.[Pubmed:33239169]

Biochem Biophys Res Commun. 2020 Nov 22. pii: S0006-291X(20)32090-8.

In this study, we investigated the activation of Transient receptor potential vanilloid subtype 1, TRPV1, by lactones, a representative flavor ingredient currently used for foods and beverages. As a result, we found that some lactones having C4 acyl chain length, gamma-octalactone, Delta-Nonalactone and beta-methyl-gamma-octalactone, gamma-undecalactone with C7 acyl chain length and delta-undecalactone with C6 acyl chain length activated TRPV1. TRPV1 is known as a non-selective cation channels that respond to a wide range of physical and chemical stimuli such as high temperature, protons, capsaicin and so on. Furthermore, it has been also demonstrated that activation of TRPV1 induced energy expenditure enhancement and thermogenesis, suppressed accumulation of visceral fat in mice and prevented non-alcoholic fatty acid liver. Thus, lactones that function as TRPV1 agonists are thought to be important candidates for decreasing the risks of developing a metabolic syndrome.

Blending studies with selected waterbuck odor constituents or analogues in the development of a potent repellent blend against savannah tsetse.[Pubmed:32592683]

Acta Trop. 2020 Nov;211:105597.

Previous comparison of the body odors of tsetse-refractory waterbuck and those of tsetse-attractive ox and buffalo showed that a blend of 15 EAG-active compounds specific to waterbuck, including C5-C10 straight chain carboxylic acid homologues, methyl ketones (C8-C12 straight chain homologues and geranyl acetone), phenols (guaiacol and carvacrol) and delta-octalactone, was repellent to tsetse. A blend of four components selected from each class of compounds (delta-octalactone, pentanoic acid, guaiacol, and geranylacetone) showed repellence that is comparable to that of the 15 components blend and can provide substantial protection to cattle (more than 80%) from tsetse bites and trypanosome infections. Structure-activity studies with the lactone and phenol analogues showed that Delta-Nonalactone and 4-methylguaiacol are significantly more repellent than delta-octalactone and guaiacol, respectively. In the present study, we compared the responses of Glossina pallidipes and Glossina morsitans to i) blends comprising of various combinations of the most active analogues from each class of compounds, and ii) a four-component blend of Delta-Nonalactone, heptanoic acid, 4-methylguaiacol and geranyl acetone in different ratios in a two-choice wind-tunnel, followed by a field study with G. pallidipes population in a completely randomized Latin Square Design set ups. In the wind tunnel experiments, the blend of the four compounds in 6:4:2:1 ratio was found to be significantly more repellent (94.53%) than that in 1:1:1:1 proportion and those in other ratios. G. m. morsitans also showed a similar pattern of results. In field experiments with G. pallidipes population, the 6:4:2:1 blend of the four compounds also gave similar results. The results lay down useful groundwork in the large-scale development of more effective 'push' and 'push-pull' control tactics of the tsetse flies.

Resolving the smell of wood - identification of odour-active compounds in Scots pine (Pinus sylvestris L.).[Pubmed:29844440]

Sci Rep. 2018 May 29;8(1):8294.

Being one of the most common trees in forests, Pinus sylvestris L. is a frequently used raw material for wood products. Its specific odour is, however, mostly unresolved to date. Accordingly, we investigated Scots pine wood samples grown in Germany for their main odorant composition. We employed dedicated odorant analysis techniques such as gas chromatography-olfactometry (GC-O) and aroma extract dilution analysis (AEDA) and successfully detected 44 odour-active compounds; of these, 39 substances were successfully identified by gas chromatography-mass spectrometry/olfactometry (GC-MS/O) and two-dimensional gas chromatography-mass spectrometry/olfactometry (2D-GC-MS/O). Among the main odorants found were (E,E)-nona-2,4-dienal, vanillin, phenylacetic acid, 3-phenylpropanoic acid, delta-octalactone and alpha-pinene, all of them having been detected with high flavour dilution factors during GC-O analyses. The majority of the identified odorants were fatty acid degradation products, plus some terpenoic substances and odorous substances resulting from the degradation of lignin. Although some of the detected substances have previously been reported as constituents of wood, 11 substances are reported here for the first time as odour-active compounds in wood, amongst them heptanoic acid, gamma-octalactone, Delta-Nonalactone and (E,Z,Z)-trideca-2,4,7-trienal.

Responses of Glossina pallidipes and Glossina morsitans morsitans tsetse flies to analogues of delta-octalactone and selected blends.[Pubmed:27143219]

Acta Trop. 2016 Aug;160:53-7.

Previous studies have shown that delta-octalactone is an important component of the tsetse-refractory waterbuck (Kobus defassa) repellent odour blend. In the present study, structure-activity comparison was undertaken to determine the effects of the length of the side chain and ring size of the lactone on adult Glossina pallidipes and Glossina morsitans morsitans. The responses of the flies to each compound were studied in a two-choice wind tunnel. Increasing the chain length from C3 (delta-octalactone) to C4 (Delta-Nonalactone) enhanced repellency to both species (G. pallidipes from 60.0 to 72.0%, and G. m. morsitans from 61.3 to 72.6%), while increasing the ring size from six (delta-octalactone) to seven members (epsilon-nonalactone) changed the activity from repellency to attraction that was comparable to that of the phenolic blend associated with fermented cow urine (p>0.05). Blending Delta-Nonalactone with 4-methylguaiacol (known tsetse repellent) significantly (p<0.05) raised repellency to 86.7 and 91.7% against G. pallidipes and G. m. morsitans respectively. Follow-up Latin Square Designed field studies (Shimba hills in coastal areas in Kenya) with G. pallidipes populations confirmed the higher repellence of Delta-Nonalactone (with/without 4-methylguaiacol) compared to delta-octalactone (also, with/without 4-methylguaiacol). The results show that subtle structural changes of olfactory signals can significantly change their interactions with olfactory receptor neurons, and either shift their potency, or change their activity from repellence to attraction. Our results also lay down useful groundwork in the development of more effective control of tsetse by 'push', 'pull' and 'push-pull' tsetse control tactics.

Characterization of the most odor-active compounds in an American Bourbon whisky by application of the aroma extract dilution analysis.[Pubmed:18570373]

J Agric Food Chem. 2008 Jul 23;56(14):5813-9.

Application of the aroma extract dilution analysis (AEDA) on the volatile fraction carefully isolated from an American Bourbon whisky revealed 45 odor-active areas in the flavor dilution (FD) factor range of 32-4096 among which (E)-beta-damascenone and Delta-Nonalactone showed the highest FD factors of 4096 and 2048, respectively. With FD factors of 1024, (3S,4S)-cis-whiskylactone, gamma-decalactone, 4-allyl-2-methoxyphenol (eugenol), and 4-hydroxy-3-methoxy-benzaldehyde (vanillin) additionally contributed to the overall vanilla-like, fruity, and smoky aroma note of the spirit. Application of GC-Olfactometry on the headspace above the whisky revealed 23 aroma-active odorants among which 3-methylbutanal, ethanol, and 2-methylbutanal were identified as additional important aroma compounds. Compared to published data on volatile constituents in whisky, besides ranking the whisky odorants on the basis of their odor potency, 13 aroma compounds were newly identified in this study: ethyl (S)-2-methylbutanoate, (E)-2-heptenal, (E,E)-2,4-nonadienal, (E)-2-decenal, (E,E)-2,4-decadienal, 2-isopropyl-3-methoxypyrazine, ethyl phenylacetate, 4-methyl acetophenone, alpha-damascone, 2-phenylethyl propanoate, 3-hydroxy-4,5-dimethyl-2(5H)-furanone, trans-ethyl cinnamate, and (Z)-6-dodeceno-gamma-lactone.