Identification of the novel odor active compounds "p-menthane lactones" responsible for the characteristic aroma of fresh peppermint leaf.

The comparative aroma extract dilution analysis (cAEDA) applied to the volatile fractions of two types of fresh mint leaves (Peppermint and Spearmint) revealed 20 odor-active peaks with high FD factors (≥64). Among the perceived odorants, five "sweet/milky" and "caramel-like/spicy" notes showing high FD factors were characteristic for the peppermint aroma, and were identified as p-menthane lactone derivatives. Especially, the three p-menthane lactone derivatives, "rel-(3S,3aS,6R,7aS)-dihydromintlactone, (3S,3aS,6R)-epoxymenthofurolactone, and 2E-ethylidene-5-methylcyclohexanone", were newly identified compounds in the peppermint. The biosynthetic routes of the p-menthane lactone derivatives have been suggested to be closely related to menthofuran. Therefore, these findings strongly suggest the possibility that the biosynthetic pathway leading to the p-menthane lactone derivatives via menthofuran plays a significantly important role in the formation of the characteristic aroma of peppermint.

A solvent-free squeezing method for extraction of collected mass from aerosols of electronic cigarettes and heated tobacco products.

Previous in vitro toxicological assessments have demonstrated that almost no mutagenic and genotoxic activities in electronic cigarette (e-cigarette) and heated tobacco product (HTP) aerosols were detected even at the maximum recommended concentration. To accurately compare the toxicity levels between cigarette smoke and e-cigarette or HTP aerosols, higher exposure concentrations increasing the possibility to detect toxicity in in vitro tests are necessary, while avoiding solvent-induced toxicity. This study aimed to develop a solvent-free extraction method to obtain concentrated aerosol extracts for improved toxicological evaluation. Our novel approach involved squeezing several Cambridge filter pads, which collected aerosol constituents, in closed containers to achieve solvent-free extraction with comparable efficiency to the conventional method using organic solvents. The optimized squeezing method yielded extracts with concentrations approximately 10 times higher than those obtained in conventional extraction methods. Yield comparison of various constituents, such as flavoring compounds, in e-cigarette aerosol extracts revealed similar extraction efficiencies between the squeezing and conventional methods. However, the extraction efficiency for constituents with high log Pow values, predominantly found in HTP aerosol extracts, was unacceptably low using the squeezing method. In addition, solvent-free centrifuging, another type of extraction method, exhibited unsatisfactory results for even e-cigarette aerosols compared with the conventional method. Our findings suggest that the solvent-free squeezing method is suitable for extracting aerosol collected mass from e-cigarette aerosol but not from HTP aerosol. We anticipate that the solvent-free squeezing method will contribute to a deeper understanding of toxicological differences between e-cigarettes and conventional combustible cigarettes.

Preparation of shape-persistent macrocycles with a single pyridine unit by double cross-coupling reactions of aryl bromides and alkynes.

A double Sonogashira-type coupling reaction between aryl bromides and alkynes using a catalytic Pd/XPhos (2-dicyclohexylphosphino-2',4',6'-triisopropylbiphenyl) system was introduced as an efficient method for the synthesis of shape-persistent macrocycles (SPMs). This approach is advantageous in the synthesis of SPMs with a single pyridine unit.