Biotransformation of Carvone by <i>Hylocereus undatus</i> Shoots

The aim of the study was to assess the potential of in vitro cultures of Hylocereus undatus (pitaya; dragon fruit) to biotransform carvone and determine the products. Pitaya plants were used for their rich enzymatic system capable of complex biochemical reactions. Carvone enantiomers were chosen as model compounds. The biotransformation was conducted in liquid phosphate buffer under controlled laboratory conditions for two days. Samples were taken at 24 and 48 h and analyzed using gas chromatography. The reaction yield in both cases was approximately 17%. The reaction pathway for both isomers differed from previous reports. In both cases, the carbonyl group was first reduced, followed by the reduction of the double bond. The main transformation products of (R)-(-)-carvone included n-dihydrocarveol (13.47%), with minor amounts of trans-carveol (2.09%) and iso-dihydrocarveol (0.71%). Additionally, for the (S)-isomer, trans-dihydrocarvone formation was observed, indicating complex metabolic pathways. Biotransformation of the (S)-enantiomer resulted in a mixture of trans-carveol (0.64%), cis-carveol (6.43%), dihydrocarveol (5.74%), and trans-dihydrocarvone (4.43%). This study is the first to use pitaya for organic compound transformation, bridging research on tropical and temperate plants.