title: Role of substituents in cyclodextrin derivatives for enantioselective gas chromatographic separation of chiral terpenoids in the essential oils of Mentha spicata.
abstract: Enantioselective GC-FID and enantioselective GC-MS have been utilized under temperature gradient mode with differently substituted heptakis- and octakis-cyclodextrins to achieve the resolution of chiral terpenoids in the essential oil of indigenously grown cultivars of Mentha spicata. Modified cyclodextrins were derivatized in GC column for the separation of chiral terpenoids. A 2,3-diethyl-6-tert-butyldimethylsilyl-β-cyclodextrin doped into 14% cyanopropylphenyl/86%dimethylpolysiloxane (TBDE-β-CD) showed good enantioselectivity for all the studied chiral compounds excluding carvone. Carvone enantiomers were well resolved in 2,3-diacetoxy-6-tert-butyldimethylsilyl-β-cyclodextrin column (TBDA-β-CD) with enantioseparation (Es) of 1.006. A TBDE-β-CD provides maximum enantiomeric separation for β-pinene (Es 1.038), sabinene (Es 1.051), limonene (Es 1.045), isomenthone (Es 1.029) and α-terpineol (Es 1.014). Furthermore, enantiomer elution order reversal was observed for sabinene, menthone, terpinen-4-ol and menthol while changing from β- to γ-cyclodextrin phase. Carvone exhibits enantiomer elution order reversal by changing substituents i.e., methyl to acetyl at 2- & 3- position of the cyclodextrin derivative. Chiral constituents such as (+)-isomenthone, (-)-menthone, (1R,2S,5R)-(-)-menthol and (4S)-(+)-piperitone exist as a single enantiomer with >99% excess. Existence of (R)-(+)-limonene and (S)-(+)-carvone enantiomers has been proven first time in M. spicata essential oils and can be used as the marker for Indian origin.
authors: Laboratory of Aromatic Plants and Chiral Separation, CSIR-Central Institute of Medicinal and Aromatic Plants, Lucknow 226015, India; Academy of Scientific and Innovative Research, CSIR-Central Institute of Medicinal and Aromatic Plants, Lucknow 226015, India.
authors: V S
authors: VS
authors: Pragadheesh
authors: Laboratory of Aromatic Plants and Chiral Separation, CSIR-Central Institute of Medicinal and Aromatic Plants, Lucknow 226015, India.
authors: Anju
authors: A
authors: Yadav
authors: Laboratory of Aromatic Plants and Chiral Separation, CSIR-Central Institute of Medicinal and Aromatic Plants, Lucknow 226015, India; Academy of Scientific and Innovative Research, CSIR-Central Institute of Medicinal and Aromatic Plants, Lucknow 226015, India. Electronic address: cs.chanotiya@cimap.res.in.
authors: Chandan Singh
authors: CS
authors: Chanotiya
mesh_terms: D002849:Chromatography, Gas / Q000379:methods*; D003505:Cyclodextrins / Q000737:chemistry*; D027541:Mentha / Q000737:chemistry*; D009822:Oils, Volatile / Q000737:chemistry*; D013237:Stereoisomerism; D013729:Terpenes / Q000302:isolation & purification*
chemical_list: D003505:Cyclodextrins; D009822:Oils, Volatile; D013729:Terpenes
keywords: (R)-(−)-carvone; (S)-(−)-limonene; Cyclodextrin derivatives; Enantioselective GC–FID; Mentha spicata