We studied the chemotypes of S₁ plants derived from the self-pollination of Mentha japonica Makino, which contains menthone and pulegone as major components. Sixty-three plants were harvested when blooming and treated by steam distillation to yield essential oil. The components in the oil were detected by GC-MS and the amount of each component was expressed as a percentage of the total, in terms of the areas of the peak. Calculation was by a Chromatoprocessor combined with GC. These S₁ plants could be grouped into three chemotypes on the basis of the parent chemotype. Eighteen of the S₁ plants were similar to the parent; 38.2_??_61.1% of the oil was menthone, and 20.3_??_40.7% was pulegone. Another chemotype was shown by 26 of the St plants; 60.1_??_68.4% of the oil was menthone, and 10.5_??_20.0% was pulegone. The third chemotype was that of the remaining 19 S₁ plants, with 70.3_??_78.2% of the oil being menthone and 2.5_??_9.2% being pulegone. Oil of the parent and all S₁ plants contained 1.6_??_2.8% borneol plus bornyl acetate. There were two kinds of plants, including the parent: those with 0.8_??_2.1% menthol pulus menthyl acetate, and those with 0.1% or less.

View full abstract