No abstract

The flower scent of the damask rose (Rosa damascena) was studied. Two ultratrace components exhibiting high flavor dilution factors were detected as odor-active compounds via aroma extract dilution analysis (AEDA). One of these had a woody note and was identified as rotundone using multidimensional gas chromatography-mass spectrometry-olfactometry (MD-GC-MS-O), while the other had a citrus note and was identified as 4-(4-methylpent-3-en-1-yl)-2(5H)-furanone (MPF) by fractionation of a commercial rose absolute from R. damascena. To the best of our knowledge, this is the first study addressing the organoleptic importance of these two compounds in the rose scent. Sensory analysis was conducted to evaluate the effects of rotundone and MPF. Adding 50 μg/kg rotundone and 5 μg/kg MPF to the aroma reconstitute of R. damascena provided it with blooming and natural characteristics. Additionally, the existence of rotundone and MPF in five types of fragrant roses was investigated.

Isolation and Stomatal Opening Activity of Two Oxylipins from Ipomoea tricolor. -Known cis-12-oxophytodienoic acid (I) and a novel oxylipin (II) are isolated from a methanol extract of Ipomoea tricolor using bioassay-guided fractionation. Both compounds induce significant stomatal opening of Commelina communis in darkness. -(OHASHI, T.; ITO, Y.; OKADA, M.; SAKAGAMI*, Y.; Bioorg. Med. Chem. Lett. 15 (2005) 2, 263-265; Grad. Sch. Bioagric. Sci., Nagoya Univ., Chikusa, Nagoya 464, Japan; Eng.) -R. Staver 21-216

Our group recently isolated 4‐(4‐methylpent‐3‐en‐1‐yl)‐2(5H)‐furanone (DAMASCENOLIDE or MPF), which has a citrus‐like odour, from damask rose (Rosa damascena). DAMASCENOLIDE has two double bonds, and we were interested in how the position and the geometric isomerism of these double bonds change the odour. Therefore, we synthesized eleven novel double‐bond isomers of DAMASCENOLIDE and evaluated their odours. Some of them have similar odours to DAMASCENOLIDE, while many others have different odours such as metallic, tropical and fishy. Especially, a Z‐form double‐bond moiety changed the odour significantly. Regarding the odour intensity, compounds with 2(3H)‐furanone skeleton tend to be stronger than compounds with 2(5H)‐furanone skeleton. From these results, it was found that the position and the geometric isomerism of the double bond greatly affected the odour.