Guaianolide Sesquiterpene Lactones from Centaurothamnus maximus

• Published in: Molecules (Basel, Switzerland) Switzerland), 2021-04, Vol.26 (7), p.2055
• Main Authors: Hussien, Taha A, Mohamed, Tarik A, Elshamy, Abdelsamed I, Moustafa, Mahmoud F, El-Seedi, Hesham R, Pare, Paul W, Hegazy, Mohamed-Elamir F
• Format: Article
• Language: English
• Subjects: Acids; Asteraceae; Asteraceae - chemistry; Biosynthesis; Biosynthetic Pathways; Carbon-13 Magnetic Resonance Spectroscopy; Centaurothamnus maximus; chemotaxonomy; Cytochrome; Dimethyl ether; Enzymes; Flavones - chemistry; Flavones - isolation & purification; Flavonoids; guaianolides; Hydrocarbons; Lactones; Lactones - chemistry; Lactones - isolation & purification; Mass spectrometry; Mass spectroscopy; Metabolites; Molecular Conformation; NMR; Nuclear magnetic resonance; Proton Magnetic Resonance Spectroscopy; Sesquiterpene lactones; Sesquiterpenes, Guaiane - chemistry; Sesquiterpenes, Guaiane - isolation & purification; Sesquiterpenoids; Two dimensional analysis
• ISSN: 1420-3049; 1431-5157; 1420-3049
• DOI: 10.3390/molecules26072055

(family Asteraceae), is a leafy shrub indigenous to the southwestern Arabian Peninsula. With a paucity of phytochemical data on this species, we set out to chemically characterize the plant. From the aerial parts, two newly identified guaianolides were isolated: 3β-hydroxy-4α(acetoxy)-4β(hydroxymethyl)-8α-(4-hydroxy methacrylate)-1α ,5α , 6α -gual-10(14),11(13)-dien-6,12-olide ( ) and 15-descarboxy picrolide A ( ). Seven previously reported compounds were also isolated: 3β, 4α, 8α-trihydroxy-4-(hydroxymethyl)-lα , 5α , 6β , 7α -guai-10(14),11(13)-dien-6,12-olide ( ), chlorohyssopifolin B ( ), cynaropikrin ( ), hydroxyjanerin ( ), chlorojanerin ( ), isorhamnetin ( ), and quercetagetin-3,6-dimethyl ether-4'- -β-d-pyranoglucoside ( ). Chemical structures were elucidated using spectroscopic techniques, including High Resolution Fast Atom Bombardment Mass Spectrometry (HR-FAB-MS), 1D NMR; H, C NMR, Distortionless Enhancement by Polarization Transfer (DEPT), and 2D NMR ( H- H COSY, HMQC, HMBC) analyses. In addition, a biosynthetic pathway for compounds - is proposed. The chemotaxonomic significance of the reported sesquiterpenoids and flavonoids considering reports from other species is examined.