Characteristic odor components of essential oils from Eurya japonica.

The chemical compositions of essential oils from the flower and aerial parts (i.e., leaf and branch) of Eurya japonica were determined and quantified using gas chromatography-mass spectrometry (GC-MS). A total of 87 and 50 compounds were detected in the oils from the flower and aerial parts, respectively. The main compounds of the flower oil were linalool (14.0%), (9Z)-tricosene (12.0%), and nonanal (7.4%). In the oil from the aerial parts, linalool (37.7%), α-terpineol (13.5%), and geraniol (9.6%) were detected. In the oils from the flower and aerial parts, 13 and 8 aroma-active compounds were identified by GC-olfactometry (GC-O) analysis, respectively. The key aroma-active compounds of the flower oil were heptanal [fatty, green, flavor dilution (FD) = 128, odor activity value (OAV) = 346], nonanal (sweet, citrus, FD = 128, OAV = 491), and eugenol (sweet, spicy, FD = 64, OAV = 62): in the oil from the aerial parts, the key aroma-active compounds were linalool (sweet, citrus, FD = 64, OAV = 95), (E)-ß-damascenone (sweet, FD = 256, OAV = 4000), and (E)-ß-ionone (floral, violet, FD = 128, OAV = 120). This study revealed that nonanal and eugenol impart the sweet, citrus, and spicy odor of the flower oil, while (E)-ß-damascenone and (E)-ß-ionone contribute the floral and sweet odor of the oil from the aerial parts.

Novel compound, (2Z,6E)-1-hydroxy-3,7-dimethyl-2,6-octadien-8-oic acid produced from biotransformation of nerol by Spodoptera litura larvae.

Biotransformation of nerol by larvae of the common cutworm (Spodoptera litura) was investigated. The resulting major metabolites were (2Z,6E)-1-hydroxy-3,7-dimethyl-2,6-octadien-8-oic acid and 8-hydroxynerol, and the minor metabolites were 9-hydroxynerol and (2Z,6E)-1-hydroxy-3,7-dimethyl-2,6-octadien-8-al. (2Z,6E)-1-Hydroxy-3,7-dimethyl-2,6-octadien-8-oic acid is a novel compound. The results indicate that biotransformation of nerol by S. litura larvae involved 2 pathways; the main pathway involved oxidation at the methyl group of the geminal dimethyl at C-8 position followed by carboxylation, and the minor pathway involved oxidation at the methyl group of the geminal dimethyl at C-9 position.

Quantitative evaluation of (+)-Δ(3)-carene metabolites from living larvae of Spodoptera litura by headspace solid-phase microextraction.

In this study, a simple, rapid, and solvent-free method for quantitative determination of (+)-Δ(3)-carene metabolites released from larvae of Spodoptera litura was developed using headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS). Further, we calibrated and validated the HS-SPME method for the quantitation of the loss of substrates owing to their biotransformation by the larvae. (+)-Δ(3)-Carene metabolites were extracted at 25°C for 30 min using an SPME fiber over a period of 24 h; the SPME fiber used was made of divinylbenzene-carboxen-polydimethylsiloxane. This technique was used to analyze the time course of the larval headspace, and the results of this analysis were used to propose a metabolic pathway. An external calibration curve was used for the quantification of (+)-Δ(3)-carene metabolites from the larval headspace. The total release volume of the larvae was calculated at 24 % of the dosage. Moreover, the biotransformation by S. litura began 2 h after it was injected with (+)-Δ(3)-carene. The method was validated by calculating the limit of detection (LOD), limit of quantification (LOQ), accuracy, precision, and linearity. The LOD and LOQ corresponded to signal/noise ratios of 3 and 10, respectively. The LODs ranged from 0.002 to 0.003 nmol/mL, and the LOQs ranged from 0.007 to 0.009 nmol/mL. This method was sensitive enough to quantitate the (+)-Δ(3)-carene metabolites released from the Spodoptera larvae. The developed SPME method can have wide applications in various in vivo larval metabolite studies.