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 quantitative 1H 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.

RNA-Seq De Novo Assembly and Differential Transcriptome Analysis of Korean Medicinal Herb Cirsium japonicum var. spinossimum

“…Silymarin is reportedly produced via the oxidative coupling of two major precursors, namely, taxifolin and coniferyl alcohol [21]. Most major enzymes responsible to produce both taxifolin and coniferyl alcohol were present in our transcriptome data (Supplementary Table 2), which is consistent with other medicinal plants observed in the same family [6, 20]. In the C. japonicum transcriptome assembly, we identified silymarin biosynthesis-related unigenes (Fig.…”

“…Silymarins are the major flavolignans produced in C. japonicum . Taxifolin and coniferyl alcohol are the two major precursors responsible for the production of silymarin [20] and are produced by the flavonoid and phenylpropanoid pathways, respectively, as shown in Fig. 5 (the highlighted boxes represent the enzymes annotated in our data).…”

Single Laboratory Validation of a Quantitative Core Shell-Based LC Separation for the Evaluation of Silymarin Variability and Associated Antioxidant Activity of Pakistani Ecotypes of Milk Thistle (Silybum Marianum L.)

“…With such a mechanism, only equimolar mixtures silybin (A and B) and isosilybin (A and B) diasteroisomers are supposed to be produced. However, some authors have reported different molar ratios [ 31 , 51 , 58 , 59 ]. Recently, Martinelli et al [ 53 ] suggested the possible involvement of dirigent-like proteins that could explain such a discrepancy.…”

Natural compounds proposed for the management of non-alcoholic fatty liver disease

“…The methanolic extract of Milk Thistle ( Sylibum marianum L. Gaertner), called silymarin, is a mixture of at least 8 flavolignans [ 110 ], from which Silybins A and B are among the major compounds ( C8 ) [ 111 ]. The oral bioavailability of silymarin flavolignans is relatively low, mainly due to their poor intestinal resorption, low aqueous solubility, high hepatic first-pass effect and rapid excretion in bile and urine [ 112 ].…”