Dihydrochalcone-derived polyphenols from tea crab apple (Malus hupehensis) and their inhibitory effects on α-glucosidase in vitro.

Three dihydrochalcone-derived polyphenols, huperolides A-C (1-3), along with thirteen known compounds (4-16) were isolated from the leaves of Malus hupehensis, the well-known tea crab apple in China. Their chemical structures were elucidated by extensive spectroscopic analysis including NMR (HSQC, HMBC, 1H-1H COSY and ROESY), HRMS and CD spectra. Huperolide A is a polyphenol with a new type of carbon skeleton, while huperolides B and C are a couple of atropisomers, which were isolated from natural sources for the first time. The antihyperglycemic effects of the isolated compounds were evaluated based on assaying their inhibitory activities against α-glucosidase. As a result, phlorizin (4), 3-hydroxyphloridzin (5), 3-O-coumaroylquinic acid (12) and ß-hydroxypropiovanillone (15) showed significant concentration-dependent inhibitory effects on α-glucosidase. Therefore, those compounds might be responsible for the antihyperglycemic effect of this herb, and are the most promising compounds to lead discovery of drugs against diabetes.

Comparative Evaluation of Chemical Profiles of Pyrrosiae Folium Originating from Three Pyrrosia Species by HPLC-DAD Combined with Multivariate Statistical Analysis.

Pyrrosiae Folium (PF) is a commonly used Chinese herb medicine originating from three Pyrrosia species for the treatment of urinary infection and urolithiasis. According to Chinese medicine practice, different specie origins led to some variations in the therapeutic effects of PF. To ensure the safety and efficacy of PF in clinical practice, it is necessary to establish a reliable and integrative method to distinguish PF occurring from the three species. In the present paper, a HPLC-DAD method was developed and applied to simultaneously analyze five major compounds in PF. Afterwards, multivariate statistical analyses including principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) were applied for specie discrimination and integrative quality evaluation based on quantitative data. The chemical determination and pattern recognition results of 35 batches of PF samples indicated that PF samples from three species showed different chemical profiles and could be discriminated clearly. In conclusion, the present method is rapid and reliable for the quality assessment and species discrimination of PF.

Enhanced Intestinal Permeability of Bufalin by a Novel Bufalin-Peptide-Dendrimer Inclusion through Caco-2 Cell Monolayer.

Bufalin (BFL) has excellent physiological activities such as defending tumors, improving cardiac function, and so on. However, due to its poor water-solubility and bioavailability, the clinical application of BFL remains limited. In order to improve bioavailability of BFL, in our previous research, a novel peptide-dendrimer (PD) was synthesized and applied to encapsulate BFL. In the present study, we investigate the absorption property and mechanism of BFL in free form and BFL-peptide-dendrimer inclusion (BPDI) delivery system by using the Caco-2 cell monolayer model in vitro. The apparent permeability coefficient (Papp) values of BFL in free or BPDI form were over 1.0 × 10-6 cm/s. Meanwhile, their almost equal bi-directional transport and linear transport percentage with time and concentration course indicated that BFL in both forms was absorbed mainly through passive diffusion. The most important result is that the Papp values of BFL increased about three-fold more BPDI than those of its free form, which indicated the intestinal permeability of BFL could be improved while BFL was encapsulated in BPDI form. Therefore, PD encapsulation may be a potential delivery system to increase the bioavailability of BFL.