•Five fractions isolated from Choerospondias axillaris peels were studied.•The fractions were rich in proanthocyanidins.•Each fraction was characterized by HPLC to determine degree of polymerization.•Antioxidant activity was analyzed by chemical and biological assays.•Considerable differences were found between different antioxidant assays.An extract isolated from Choerospondias axillaris peels was separated into five fractions using size-exclusion chromatography. The structural composition and mean degree of polymerization (mDP) of these fractions were then characterized by acid-catalysis followed by HPLC analysis. The antioxidant activity of each fraction was determined using a combination of chemical-based methods (DPPH, ABTS+ radical scavenging activity, ferric-reducing antioxidant power, and phosphomolybdate assay) and a cellular-based assay. All fractions tested were found to have high total phenolics contents and were rich in proanthocyanidins. The mDP of fractions (F1–F5) ranged from 1.92 to 9.25. When tested by the chemical-based assays, the antioxidant activity of the fractions did not depend on molecular weight of the phenolics. Conversely, when tested by the cellular-based assay the antioxidant activity actually decreased with increasing molecular weight of the proanthocyanidins. These experiments highlight the limitations of using chemical-based assays to establish the antioxidant activity of proanthocyanidins within biological systems.

The production of new blood vessels (angiogenesis) is an important stage in the growth and spread of cancerous tumors. Anti-angiogenesis is one strategy for controlling tumor progression. This study evaluated the antioxidant and anti-angiogenic activities of a proanthocyanidins (PAs) extract from Choerospondias axillaris peels. HPLC-MS analysis revealed that numerous oligomeric forms of the PAs were detected in the PAs extract, including dimers, trimers, tetramers, and flavan-3-ol monomers. The PAs extract possessed appreciable free radical scavenging activity (IC50/DPPH = 164 ± 7 μg/mL, IC50/ABTS = 154 ± 6 μg/mL), potent reducing power (0.930 ± 0.030 g AAE/g), and strong cellular antioxidant activity (EC50 = 10.2 ± 1.4 and 38.9 ± 2.1 μg/mL without or with PBS-wash, respectively). It could also retard various stages of angiogenesis, such as the migration of endothelial cells and the creation of tubes, without causing toxicity to the cells. With regard to intracellular signal transduction, the PAs extract attenuated the phosphorylation of Akt, ERK, and p38MAPK dose-dependently in endothelial cells from human umbilical veins. In transgenic zebrafish embryo, new blood vessel formation was suppressed by PAs extract in a concentration-dependent manner at 72 h post fertilization. Thus, these results suggest that PAs from C. axillaris peels could be a good source of natural inhibitors to target angiogenesis.

Pectic-oligosaccharides (POSs) were prepared from apple pectin by dynamic high-pressure microfluidization (DHPM). Operating under selected conditions (pectin concentration 1.84%, solution temperature 63 °C, DHPM pressure 155 MPa and number of cycles 6 passes), 32.92% of the pectin was converted into POS. The resulting POS contains 29.56% galacturonic acid and 58.53% neutral sugars. The prebiotic properties of POS were then evaluated using a fecal batch culture fermentation. The POS increased the number of Bifidobacteria and Lactobacilli, and produced a higher concentration of acetic, lactic, and propionic acid than their parent pectin. Furthermore, POS decreased the number of Bacteroides and Clostridia while their parent pectin increased them. Moreover, the effects of POS on the growth of these bacteria and production of short-chain fatty acids are comparable to those of the most studied prebiotic, fructooligosaccharide. These results indicated that the POS prepared by DHPM has a potential to be an effective prebiotic.Highlights► Pectic-oligosaccharide (POS) was prepared by dynamic high-pressure microfludization. ► POS is superior to pectin and comparable to oligofructose in prebiotic effects. ► POS prepared by dynamic high-pressure microfludization can be a useful prebiotic.