The genus, Conradina (Lamiaceae family) consists of six understudied plant species that are endemic to the southeastern United States. Cumberland rosemary (Conradina verticillata Jennison), is a rare, federally listed threatened plant species present only in wild populations in Tennessee and Kentucky. It is a woody perennial shrub, with reclining branches and long narrow needle-like leaves that are arranged in whorls. Cumberland rosemary is highly fragrant, with an aroma reminiscent of culinary rosemary, Rosmarinus officinalis, but differing in subtle odor nuances such as piney, terpene, and camphor-like aroma characters. The objective of this present investigation has been: 1) identification of the key odorants in Cumberland rosemary by employing solvent-assisted flavor evaporation (SAFE) and aroma extract dilution analysis (AEDA), followed by gas chromatography-mass spectrometry (GCMS); 2) quantitation of high impact odorants by stable isotope dilution assay (SIDA); and 3) determination of the enantiomeric ratio of selected chiral odorants by chiral GCMS. Chiral GCMS was used to determine the enantiomeric ratios of several selected odorants present in volatile fractions of Cumberland rosemary, including the ratios for: (1S)-(−)-α-pinene : (1R)-(+)-α-pinene, (S)-(+)-1-octen-3-ol : (R)-(−)-1-octen-3-ol, and (1S)-(−)-camphor : (1R)-(+)-camphor. To aid in the determination of the enantiomeric ratios of the selected chiral odorants, solid phase extraction (SPE) was employed to simplify the complex mixture and reduce the number of co-eluting volatiles prior to chiral GCMS. This talk will discuss the unique biology and aroma of plants from the Conradina genus and identification of key odorants characteristic to Cumberland rosemary, as well as highlighting analytical challenges that need to be overcome to separate complex mixtures of plant volatile natural products required prior to enantiomeric analysis of chiral flavor compounds.

Chiral odorants from Cumberland rosemary (Conradina verticillata)

2019 Spring National Meeting

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