title: Chemotaxonomic and biosynthetic relationships between flavonolignans produced by Silybum marianum populations.
abstract: Flavonolignans constitute an important class of plant secondary metabolites formed by oxidative coupling of one flavonoid and one phenylpropanoid moiety. The standardized flavonolignan-rich extract prepared from the fruits of Silybum marianum is known as silymarin and has long been used medicinally, prominently as an antihepatotoxic and as a chemopreventive agent. Principal component analysis of the variation in flavonolignan content in S. marianum samples collected from different locations in Egypt revealed biosynthetic relationships between the flavonolignans. Silybin A, silybin B, and silychristin are positively correlated as are silydianin, isosilychristin, and isosilybin B. The detection of silyamandin in the extracts of S. marianum correlates with isosilychristin and silydianin content. The positive correlation between silydianin, isosilychristin, and silyamandin was demonstrated using quantitative1H nuclear magnetic resonance spectroscopy (qHNMR). These correlations can be interpreted as evidence for the involvement of a flavonoid radical in the biosynthesis of the flavonolignans in S. marianum. The predominance of silybins A & B over isosilybin A & B in the silybin-rich samples is discussed in light of the relative stabilities of their respective radical flavonoid biosynthetic intermediates.
authors.affiliation: Department of Pharmacognosy, Faculty of Pharmacy, Beni-Suef University, Beni-Suef 62111, Egypt. Electronic address: sameh.zaid@pharm.bsu.edu.eg.
authors.forename: Sameh F
authors.initials: SF
authors.lastname: AbouZid
authors.affiliation: Department of Pharmacognosy, Faculty of Pharmacy, Beni-Suef University, Beni-Suef 62111, Egypt.
authors.forename: Hayam S
authors.initials: HS
authors.lastname: Ahmed
authors.affiliation: Department of Pharmacognosy, Faculty of Pharmacy, Beni-Suef University, Beni-Suef 62111, Egypt.
authors.forename: Abeer S
authors.initials: AS
authors.lastname: Moawad
authors.affiliation: Department of Pharmacognosy, Faculty of Pharmacy, Beni-Suef University, Beni-Suef 62111, Egypt.
authors.forename: Asmaa I
authors.initials: AI
authors.lastname: Owis
authors.affiliation: UIC/NIH Center for Botanical Dietary Supplements Research, College of Pharmacy, University of Illinois at Chicago, 833 S. Wood St., M/C 781, Chicago, IL 60612, United States; Department of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, University of Illinois at Chicago, 833 S. Wood St., M/C 781, Chicago, IL 60612, United States.
authors.forename: Shao-Nong
authors.initials: SN
authors.lastname: Chen
authors.affiliation: Department of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, University of Illinois at Chicago, 833 S. Wood St., M/C 781, Chicago, IL 60612, United States.
authors.forename: Amandine
authors.initials: A
authors.lastname: Nachtergael
authors.affiliation: Department of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, University of Illinois at Chicago, 833 S. Wood St., M/C 781, Chicago, IL 60612, United States.
authors.forename: James B
authors.initials: JB
authors.lastname: McAlpine
authors.affiliation: Department of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, University of Illinois at Chicago, 833 S. Wood St., M/C 781, Chicago, IL 60612, United States; Physical Sciences Department, Rosary College of Arts and Sciences, Dominican University, 7900 West Division Street, River Forest, IL 60305, United States.
authors.forename: J
authors.initials: J
authors.lastname: Brent Friesen
authors.affiliation: UIC/NIH Center for Botanical Dietary Supplements Research, College of Pharmacy, University of Illinois at Chicago, 833 S. Wood St., M/C 781, Chicago, IL 60612, United States; Department of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, University of Illinois at Chicago, 833 S. Wood St., M/C 781, Chicago, IL 60612, United States.
authors.forename: Guido F
authors.initials: GF
authors.lastname: Pauli
mesh_terms: D004534:Egypt; D044947:Flavonolignans / Q000096:biosynthesis* / Q000737:chemistry*; D005638:Fruit / Q000737:chemistry; D020944:Silybum marianum / Q000737:chemistry*; D015394:Molecular Structure; D064210:Secondary Metabolism; D000077385:Silybin; D012838:Silymarin / Q000031:analogs & derivatives / Q000737:chemistry*
chemical_list: D044947:Flavonolignans; D012838:Silymarin; C524554:silyamandin; D000077385:Silybin; C015505:silidianin; C523198:isosilybin A; C015504:silychristin
keywords: Biosynthesis; Flavonolignans; Principal component analysis; Silybum marianum; qHNMR