Zero Point of Charge Determination of Monoionic Montmorillonites by Transport Number Method

The zero points of charge (ZPC) of a natural bentonite and those of its homoionic forms (Na, Ca and Al) were determined by the transport number method. The influence of the interlayer cation was observed in the different pH values of the ZPC obtained. No influence of the water contains was observed.     

Efficient preparation of catechin thio conjugates by one step extraction/depolymerization of pine (Pinus pinaster) bark procyanidins

The skin penetrating antioxidant cysteamine derivative of (-)-epicatechin as well as other thio conjugates were efficiently obtained with high yields from pine (Pinus pinaster) bark by simultaneous one pot extraction and depolymerization using water and cysteamine hydrochloride. The influence of the concentration of bark, acid, and cysteamine, as well as the reaction time on the total conversion, was studied. The total conversion into the epicatechin and catechin conjugates was as high as 47 g/kg pine bark with 1666 g cysteamine/kg bark and 28 g/kg with 166 g cysteamine/kg bark. A fast cleanup step by absorption/desorption on XAD-16 greatly facilitated further purification of the active major component. At a pilot scale, 4beta-(2-aminoethylthio)epicatechin (1) (conversion 263 g, purity 35% by reversed phase high-performance liquid chromatography/weight) was obtained from 17 kg of pine bark after simultaneous extraction/depolymerization followed by cleanup with the polymeric resin in approximately 10 h. The results show that pine (P. pinaster) bark is a suitable source of flavanols for the preparation of active thio derivatives. Conditions are given for the fast and efficient preparation of the conjugates.     

Procyanidin fractions from pine (Pinus pinaster) bark: radical scavenging power in solution, antioxidant activity in emulsion, and antiproliferative effect in melanoma cells

Pine (Pinus pinaster) bark is a rich source of procyanidin oligomers. From a total polyphenolic extract, we have generated fractions of different procyanidin composition. The mixtures, devoid of gallate esters, were active as free radical scavengers against ABTS(*+), DPPH, and HNTTM. Pine bark fractions were tested for antioxidant activity in solution (hydrogen donation and electron transfer) and emulsion (inhibition of lipid peroxidation) and compared with their galloylated counterparts from grape origin. While galloylation clearly influenced the free radical scavenging efficiency in solution, it did not seem to play a determinant role in protection against lipid peroxidation in emulsion. The fractions were very mild inhibitors of cell proliferation. Because gallate esters appear to interfere with crucial cell functions, gallate free pine procyanidins may be the innocuous chemopreventative agents of choice for many applications in food and skin protection.