GC-MS Analysis on Volatiles of Iris lactea var. chinensis at Different Flowering Stages

  Objective   Floral fragrance and release of Iris at different stages were analyzed using GC-MS.

  Methods  Volatiles in the flowers of Iris lactea var. chinensis (Fisch.) Koidz at budding, blooming, and fading stages were determined by HS-SPME-GC-MS.

  Result   The analysis identified 69 distinct aromatics. The continuously released volatiles in the entire flowering period were mainly ketones, terpenes, and aldehydes. There were also alcohols, esters, as well as in smaller quantities of alkanes, benzenoids, and nitrogenous compounds. At different flowering stages, hexanal, cyclohexanone, 5-hepten-2-one, 6-methyl- and β−irone were detected in the buds, hexanal, (−)-β−pinene, and 5-hepten-2-one, 6-methyl- in the blooms, and (-)-β−pinene, 5-hepten-2-one, 6-methyl-, hexanal, phenylethyl alcohol, and cyclohexanone in the fading flowers. The OPLS-DA showed differentiations on heptane, 3-methyl-, 5-hepten-2-one, 6-methyl-, (−)-β−pinene, hexanoic acid, ethyl ester, α−pinene, 3-carene, linalool, phenethyl alcohol, decanoic acid, ethyl ester, and β−irone at these stages. The calculated odor activity values (OAVs) on pyrazine, 2-methoxy-3-(1-methylpropyl)-, hexanoic acid, ethyl ester, linalool, nonanal, hexanal, 2-nonenal, and (E)- indicated that these were the characteristic aromatic substances of I. lactea var. chinensis and that pyrazine and 2-methoxy-3-(1-methylpropyl)- significantly greater in quantity (P＜0.01).

  Conclusion   For the first time, the chemical composition of the fragrance of I. lactea var. chinensis flowers was analyzed, and compounds identified in detail. The released volatiles differed significantly during the floral development. It was at the fading stage when the fragrance peaked with the major aromatic contributors including hexanal, 5-hepten-2-one, 6-methyl-, cyclohexanone, and phenethyl alcohol.