Isolation of the major chiral compounds from Bubonium graveolens essential oil by HPLC and absolute configuration determination by VCD. Issue 2 (26th December 2016)

• Record Type: Journal Article
• Authors: Said, Mohammed El‐Amin; Bombarda, Isabelle; Naubron, Jean‐Valère; Vanloot, Pierre; Jean, Marion; Cheriti, Abdelkrim; Dupuy, Nathalie; Roussel, Christian
• Is Part Of: Chirality. Volume 29:Issue 2(2017)
• Page Start: 70
• Page End: 79
• Publication Date: 2016-12-26
• Subjects: Bubonium graveolens -- chiroptical HPLC signature -- enantiomers -- essential oil -- vibrational circular dichroism; Chirality -- Periodicals; Pharmaceutical chemistry -- Periodicals; 541.22
• DOI: 10.1002/chir.22672
• Languages: English
• ISSNs: 0899-0042

Abstract

Abstract: The chirality issues in the essential oils (EOs) of leaves and flowers from Bubonium graveolens were addressed by chiral high‐performance liquid chromatography (HPLC) with polarimetric detection and vibrational circular dichroism (VCD). The chemical compositions of the crude oils of three samples were established by gas chromatography / mass spectrometry (GC/MS). The well‐known cis ‐chrysanthenyl acetate (1 ), oxocyclonerolidol (2 ), and the recently disclosed cis ‐acetyloxychrysanthenyl acetate (3 ), the three major chiral compounds, were isolated by preparative HPLC. The naturally occurring oxocycloneroledol (2 ), mostly found in the leaf oil (49.4–55.6%), presents a (+) sign in the mobile phase during HPLC on a chiral stationary phase (CSP) with a Jasco polarimetric detection. The naturally occurring cis ‐chrysanthenyl acetate (1 ) and cis ‐acetyloxychrysanthenyl acetate (3 ), mostly found in the flower EO (35.9–74.9% and 10.0–34.3%, respectively), both present a (−) sign. HPLC on a CSP with polarimetric detection is an unprecedented approach to readily differentiate the flower and leaf EOs according to their chiral signature. The comparison of the experimental and calculated VCD spectra of pure isolated1, 2, and3 provided their absolute configuration as being (1 S, 5 R, 6 S )‐(−)‐2, 7, 7‐trimethylbicyclo[3.1.1]hept‐2‐en‐6‐yl acetate1, (2 R, 6 R )‐(+)‐6‐ethenyl‐2, 6‐dimethyl‐2‐(4‐methylpent‐3‐en‐1‐yl)dihydro‐2H‐pyran‐3(4H)‐one)2 and (1 S, 5 R, 6 R, 7 S )‐(−)‐7‐(acetyloxy)‐2, 6‐dimethylbicyclo[3.1.1]hept‐2‐en‐6‐yl]methyl acetate3 . Compounds1, 2, and3 were already known in B. graveolens but this is the first report of the absolute configuration of (+)‐2 and (−)‐3 . The VCD chiral signatures of the crude oils were also recorded. Abstract : VCD spectra provide two chiral signatures of the crude leaf and flower EOs. Chiral HPLC with polarimetric detection revealed the sign of the optical rotation of the major compounds and can be employed to isolate optically pure samples.