Identification of the constituent flavanoid units in sainfoin proanthocyanidins by reversed-phase high-performance liquid chromatography

Analysis of proanthocyanidins

“…The first involves the degradation of procyanidins in the presence of benzyl mercaptan, and was introduced by Rigaud et al [104] and enhanced by Guyot et al [105]. Koupai-Abyazani et al [95] developed a similar method using the acid degradation of procyanidins in the presence of the nucleophilic agent phloroglucinol and subsequent RP-HPLC separation. More recently, Karonen et al [84] reported a limitation of the thiolysis method as some polymeric PAC are resistant to degradation with thiols (notably when PAC originate from aged tissues, e.g., outer bark).…”

“…Low molecular mass PAC, which can be subjected to chromatography as individual peaks on C18 material, are eluted -in contrast to NP chromatography -not according to their degree of polymerization. The main factor influencing the retention time is the stereochemistry and the overall polarity [95]. For example, epicatechin and its oligomers were more strongly retarded than the monomer and procyanidins consisting of catechin [95,96], and procyanidins with 4 6 linkage as well as doubly linked procyanidins were eluted later than 4 8-linked ones [34].…”

“…The main factor influencing the retention time is the stereochemistry and the overall polarity [95]. For example, epicatechin and its oligomers were more strongly retarded than the monomer and procyanidins consisting of catechin [95,96], and procyanidins with 4 6 linkage as well as doubly linked procyanidins were eluted later than 4 8-linked ones [34]. In general, the elution order of the dimeric and the trimeric procyanidins C1 and C2 remained nearly constant and was more or less unchanged by the type of eluent, acid and stationary phase, whereas the retention times of procyanidin B1 and B4 were slightly affected by changes of the chromatographic conditions [97].…”

Forage Yield and Quality of Chicory, Birdsfoot Trefoil, and Alfalfa During the Establishment Year

“…Neutral detergent fibre (NDF) was determined using the ANKOM filter bag technique [11], and subsequently used to derive neutral detergent soluble (NDS) levels (i.e., 100 -NDF % = NDS %) as well as calculate neutral detergent soluble yield (NDSY) (NDSY = DM yield X proportional NDS concentration). Condensed tannin levels in forages were determined using reversed-phase high-performance liquid chromatography [12].…”

Phytochemical Bioactives in Berries

“…Figure 8.5 shows the structure of procyanidin dimers identi ed in grapes and wines. Determination of proanthocyanidins is generally based on acid-catalyzed depolymerization in the presence of strong nucleophilic reagent (Thompson et al 1972;Foo et al 1983) followed with formation of adducts, which are analyzed by reversed phase high-performance liquid chromatography (Shen et al 1986;Rigaud et al 1991;Koupai-Abyazani et al 1992). In acidic media, proanthocyanidins are depolymerized, releasing terminal subunits, as flavan-3-ols and extensional subunits, as electrophilic flavan-3-ol intermediates (Figure 8.6).…”