Essential Oils of Four Virginia Mountain Mint (Pycnanthemum virginianum) Varieties Grown in North Alabama

Abstract

Virginia mountain mint (Pycnanthemum virginianum) is a peppermint-flavored aromatic herb of the Lamiaceae and is mainly used for culinary, medicinal, aromatic, and ornamental purposes. North Alabama’s climate is conducive to growing mint for essential oils used in culinary, confectionery, and medicinal purposes. There is, however, a need for varieties of P. virginianum that can be adapted and easily grown for production in North Alabama. Towards this end, four field-grown varieties with three harvesting times (M1H1, M1H2, M1H3; M2H1, M2H2, M2H3; M3H1, M3H2, M3H3, M4H1, M4H2, M4H3) were evaluated for relative differences in essential oil yield and composition. Thirty-day-old greenhouse-grown plants of the four varieties were transplanted on raised beds in the field at the Alabama A & M University Research Station in North Alabama. The plots were arranged in a randomized complete block with three replications. The study’s objective was to compare the four varieties for essential oil yield and their composition at three harvest times, 135, 155, and 170 days after planting (DAP). Essential oils were obtained by hydrodistillation with continuous extraction with dichloromethane using a Likens–Nickerson apparatus and analyzed by gas chromatographic techniques. At the first harvest, the essential oil yield of the four varieties showed that M1H1 had a yield of 1.15%, higher than M2H1, M3H1, and M4H1 with 0.91, 0.76, and 1.03%, respectively. The isomenthone concentrations increased dramatically through the season in M1 (M1H1, M1H2, M1H3) by 19.93, 54.7, and 69.31%, and M3 (M3H1, M3H2, M3H3) by 1.81, 48.02, and 65.83%, respectively. However, it increased only slightly in M2 and M4. The thymol concentration decreased slightly but not significantly in all four varieties; the thymol in M2 and M4 was very high compared with M1 and M3. The study showed that mountain mint offers potential for production in North Alabama. Two varieties, M1 and M3, merit further studies to determine yield stability, essential oil yield, composition, and cultivation development practices.

Characterization of Odorants in White Leaf Mountain Mint, Pycnanthemum albescens

“…pycnanthemoides, and P. virginianum . Alternatively, linalool and borneol were determined to be present in nearly racemic mixtures with the ratio of enantiomers being 58% ( R )-(−)-linalool to 42% ( S )-(+)-linalool and 57% (1 S ,2 R ,4 S )-(−)-borneol to 43% (1 R ,2 S ,4 R )-(+)-borneol.…”

“…These findings are consistent with previous reports in other species of Pycnanthemum, including P. incanum, 5,7 P. pycnanthemoides, 8 and P. virginianum. 6 Alternatively, linalool and borneol were determined to be present in nearly racemic mixtures with the ratio of enantiomers being 58% (R)-(−)-linalool to 42% (S)-(+)-linalool and 57% (1S,2R,4S)-(−)-borneol to 43% (1R,2S,4R)-(+)-borneol. The enantiomeric composition of these compounds have been found to vary in other species of Pycnanthemum 7 and related plants such as Salvia officinalis.…”

“…incanum and P. virginianum have also been characterized. , The major volatiles in P. incanum essential oil were identified as 1,8-cineole and α-terpineol .…”

“…4 More recently, the volatile compounds of P. incanum and P. virginianum have also been characterized. 5,6 The major volatiles in P. incanum essential oil were identified as 1,8-cineole and α-terpineol. 5 Whereas the composition of P. virginianum essential oil was found to vary based on harvest time, the major components included pulegone, menthone, isomenthone, and thymol.…”

“…5 Whereas the composition of P. virginianum essential oil was found to vary based on harvest time, the major components included pulegone, menthone, isomenthone, and thymol. 6 Although volatiles have been reported in several Pycnanthemum species, less research has been conducted on the odor-active compounds responsible for the odor profile of Pycnanthemum species. The exception to this trend is the recent work conducted by our group on P. incanum and P. pycnanthemoides.…”