Antioxidant capacity of polyphenolic extracts from leaves of Crataegus laevigata and Crataegus monogyna (Hawthorn) subjected to drought and cold stress

Extraction of p-hydroxyacetophenone and catechin from Norway spruce needles. Comparison of different extraction solvents

The phenolic compounds p-hydroxyacetophenone and catechin have been extracted from Norway spruce needles with pure methanol, 80 and 50% (v/v) aqueous methanol, pure acetonitrile, 80% (v/v) aqueous acetonitrile, and pure water. Extraction efficiency of the individual solvents was compared. Although 80% aqueous methanol is the solvent most frequently used for extraction of soluble phenolic compounds from needles, it was found that pure methanol is a more suitable extraction solvent. Surprisingly, a two-step procedure based on the extraction of crushed needles with water then re-extraction with methanol proved a good alternative to direct extraction with methanol. Extraction of uncrushed spruce needles might indicate that relatively more p-hydroxyacetophenone than catechin was located in the surface layer of the needle.

Applied environmental stresses to enhance the levels of polyphenolics in leaves of hawthorn plants

In this investigation, two species of Crataegus (hawthorn) were chosen because their polyphenolic constituents have recently received greater attention for the treatment of patients with severe heart disease. One-year-old plants of hawthorn (Crataegus laevigata and C. monogyna) were subjected to water-deficit (continuous water deprivation), cold (4 degrees C), flooding (immersion of roots of plants in water) or herbivory (leaf removal) stress treatments (each of 10 days duration) in order to assess their effects on levels of polyphenolics, namely (-)-epicatechin, catechin, chlorogenic acid, vitexin, vitexin-2"-O-rhamnoside, acetylvitexin-2"-O-rhamnoside, hyperoside, quercetin, and rutin in the leaves. The working hypothesis followed is that one or more of these stress treatment will elicit increases in the levels of these polyphenolics. Cold stress causes increases in levels of vitexin-2"-O-rhamnoside, acetylvitexin-2"-O-rhamnoside, hyperoside, and quercetin in both Crataegus species. Water-deficit stress increased the productivity of chlorogenic acid, catechin, and (-)-epicatechin in both hawthorn species. Flooding and herbivory caused no net increases, and in some cases, decreases in levels of polyphenolics. These studies indicate that either water-deficit stress or cold stress treatments, or a combination of the two, can be used to enhance the levels of desired polyphenolics in the leaves of these two hawthorn species in a photobioreactor system. These results may have significance for hawthorn in adapting to water-deficit or cold stress and are important considerations for the use of hawthorn in the treatment of heart disease in humans.

Protective Effect of Buckwheat Polyphenols Against Long-Lasting Impairment of Spatial Memory Associated With Hippocampal Neuronal Damage in Rats Subjected to Repeated Cerebral Ischemia

In the present experiment, we studied the action of buckwheat polyphenol (BWP, from Fagopyrum esculentum MOENCH) in a repeated cerebral ischemia model, which induced a strong and long-lasting impairment of spatial memory in 8-arm radial maze with hippocampal CA1 cell death in rats. BWP (600 mg/kg, continuous 21-day p.o.) significantly ameliorated not only the impairment of spatial memory in the 8-arm radial maze, but also necrosis and TUNEL-positive cells in the hippocampal CA1 area subjected to repeated cerebral ischemia (10 min x 2 times occlusion, 1-h interval) in rats. In order to investigate the mechanism of BWP protective action, we measured the release of glutamate and NO(x)(-) (NO(2)(-) + NO(3)(-)) production induced by repeated cerebral ischemia in the rat dorsal hippocampus using microdialysis. A 14-day BWP treatment significantly inhibited the excess release of glutamate after the second occlusion. In addition, the BWP remarkably suppressed a delayed increase in NO(x)(-) (NO(2)(-) + NO(3)(-)) induced by repeated cerebral ischemia in the dorsal hippocampus as determined in vivo by microdialysis. However, the 14-day treatment did not affect hippocampal blood flow in either intact rats or rats subjected to repeated ischemia measured by lasser Doppler flowmeter. These results suggested that BWP might ameliorate spatial memory impairment by inhibiting glutamate release and the delayed generation of NO(x)(-) in rats subjected to repeated cerebral ischemia.