Reversed-phase liquid chromatographic analysis of hydrophobic interaction between proanthocyanidins and a C8-alkyl compound in aqueous solution

Three new flavonoid glycosides isolated from Pteridium aquilinum

Three new flavonoid glycosides, (S)-4',6,8-trihydroxyflavanone-7-C-glucoside (1), (R)-4',6,8- trihydroxyflavanone-7-C-glucoside (2) and distenin-7-O-β-D-glucoside (3), along with nine known flavonoids (4-12) were isolated from the aerial of Pteridium acquilinum. Their structures were elucidated by the analysis of spectroscopy data and their comparison with the reported values. The two C-glycosyl flavanones (1 and 2), were isolated from this specie, which might be chemotaxonomic markers of this specie. In addition, three new flavonoids were preliminarily examined for their anti-inflammatory activity. Compounds 1-3 inhibited the NF-κB induction by 46.3%, 59.6% and 29.2%, respectively.

Metabolic Fate of Orally Ingested Proanthocyanidins through the Digestive Tract

Proanthocyanidins (PACs), which are oligomers or polymers of flavan-3ols with potent antioxidative activity, are well known to exert a variety of beneficial health effects. Nonetheless, their bioaccessibility and bioavailability have been poorly assessed. In this review, we focused on the metabolic fate of PACs through the digestive tract. When oligomeric and polymeric PACs are orally ingested, a large portion of the PACs reach the colon, where a small portion is subjected to microbial degradation to phenolic acids and valerolactones, despite the possibility that slight depolymerization of PACs occurs in the stomach and small intestine. Valerolactones, as microbiota-generated catabolites of PACs, may contribute to some of the health benefits of orally ingested PACs. The remaining portion interacts with gut microbiota, resulting in improved microbial diversity and, thereby, contributing to improved health. For instance, an increased amount of beneficial gut bacteria (e.g., Akkermansia muciniphila and butyrate-producing bacteria) could ameliorate host metabolic functions, and a lowered ratio of Firmicutes/Bacteroidetes at the phylum level could mitigate obesity-related metabolic disorders.

Flavonoids isolated from the fresh sweet fruit of Averrhoa carambola, commonly known as star fruit

Thirteen flavonoids were isolated from the fresh sweet fruit of Averrhoa carambola L. (Oxalidaceae), commonly known as star fruit, and their structures were determined by spectroscopic and chemical methods. 8-Carboxymethyl-(+)-epicatechin methyl ester, pinobanksin 3-O-β-d-glucoside, and carambolasides M-Q were undescribed structures. (+)-Epicatechin, aromadendrin 3-O-β-d-glucoside, helicioside A, taxifolin 3'-O-β-d-glucoside, galangin 3-O-rutinoside, and isorhamnetin 3-O-rutinoside were reported from this species for the first time. Pinobanksin 3-O-β-d-glucoside and carambolasides M-Q showed more potent 2,2'-azinobis-(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) radical cation scavenging activity (IC₅₀ = 5.3-2.3 μM) than l-ascorbic acid (10.5 μM). Further, (+)-epicatechin, pinobanksin 3-O-β-d-glucoside, isorhamnetin 3-O-rutinoside, and carambolasides O-Q exhibited weak porcine pancreatic lipase inhibitory activity.