Polyphenol contents and antioxidant activities of extracts from flowers of two Crataegus azarolus L. varieties.

Phenolic contents of the ethyl acetate extracts prepared from floral buds and opened flowers harvested on Crataegus azarolus trees native in two localities were performed. The antioxidant activity was measured by DPPH' (2,2-diphenyl-picrylhydrazyl), ABTS+ (2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radicals scavenging using spectrophotometric method. The C. azarolus var. aronia (Willd.) Batt., producing yellow fruits, was richer in total phenols (1638.7 +/- 89.9 mg acid gallic/100 g dry weight) according to C. azarolus var. eu-azarolus Maire (1415.5 +/- 23.8 mg acid gallic/100 g dry weight), producing red ones. Ethyl acetate extract from opened flowers has less content in total phenols, proanthocyanidins and flavonoids compared to this from floral buds. Floral buds from the two C. azarolus varieties occurring in Siliana-Djebel Serdj showed the highest radical scavenging activities (2431.8 +/- 32.7 and 2267.7 +/- 22.7 micromol Trolox/100 g dry weight). Hawthorn from Tunisia contains eight antioxidants of phenolic type (chlorogenic acid, hyperoside, rutin, spiraeoside, isoquercitrin, quercetin, (-)-epicatechin and the dimer procyanidin B2). These compounds identified specially in floral bud extracts presented a strong radical-scavenging activity.

Hawthorn extracts inhibit LDL oxidation.

Polyphenol-rich diet decreases cardiovascular risk. LDL oxidation is the primary event in atherosclerosis plaque formation and antioxidants such as polyphenols were shown to inhibit LDL oxidation and atherosclerosis development. Hawthorn (Crataegus) and derived pharmaceuticals are rich in polyphenols and already prescribed to treat moderate heart failure, nervousness and sleep disorders. Extracts either from fresh plant parts (flower buds, flowers, young leaves or green fruits) or from dried pharmaceutical parts (flowers and flowering tops) were previously shown to be effective inhibitors of lipoperoxidation and scavengers of oxygen species. In this study, the capacity of total and ethyl-acetate extracts from dried pharmaceutical flowers, tops and fruits to inhibit Cu(2+)-induced LDL oxidation was tested. This capacity was positively linked to their content in total polyphenols, proanthocyanidins (global and oligomeric forms), as well as to their content in two individual phenolics: a flavanol, the dimeric procyanidin B2 and a flavonol glycoside, hyperoside. Flavanol-type phenolics showed to be higher active than the majority of the flavonoids tested in inhibiting Cu(2+)-induced LDL peroxidation. This study suggests that hawthorn could be a source of polyphenols able to inhibit LDL oxidation.

Effects of Rosa canina fruit extract on neutrophil respiratory burst.

Respiratory burst leads polymorphonuclear neutrophils (PMN) to produce reactive oxygen species (ROS) such as superoxide anions (O(2)(o-)), hypochlorous acid (HOCl) and hydrogen peroxide (H(2)O(2)) which may possess deleterious effects for the organism. Rosa canina fruits are well known to contain a large amount of vitamin C which is antioxidant. This study was focused on the polyphenolics contained in rose hips to evaluate their antioxidative properties. We prepared a rose hip extract deprived of vitamin C. The extract contained mainly phenolics such as proanthocyanidins and flavonoids. We investigated its effects directly against (O(2)(o-)), HOCl and H(2)O(2) and investigated its effects on isolated PMN. For that, in vitro inflammatory conditions were reproduced by stimulating PMN with stimuli having different transductional pathways, in order to determine a possible mechanism of action. The results showed that the extract can inhibit ROS tested in acellular and cellular systems. The IC(50) obtained were 5.73 mg/L, 1.33 mg/L and 2.34 mg/L respectively for (O(2)(o-)), HOCl and H(2)O(2) in acellular experiments. For cellular experiments, the IC(50) were quite similar. Thus, the extract did not present an effect on PMN metabolism. Therefore, the antioxidative effects of Rosa canina are due not only to vitamin C but also to polyphenolics.

Phenolic compounds and antioxidant activities of buckwheat (Fagopyrum esculentum Moench) hulls and flour.

The interest of polyphenolics as therapeutic agents against diseases involving radical damage is growing. The phenolic contents of the hulls and flour from the seeds of Fagopyrum esculentum (French variety 'La Harpe') (total phenols, flavonoids, total flavanols, oligomeric proanthocyanidins) are compared with the antioxidative effects of the extracts against reactive oxygen species: hydrogen peroxide, hypochlorous acid, superoxide anion. The higher efficiency of the flour extract can be related to its higher flavanolic content rather than to flavonoids which are predominant in the hull extract.

Antimicrobial activity of aerial parts of Drosera peltata Smith on oral bacteria.

The antimicrobial activity of extracts of aerial parts of Drosera peltata Smith against oral bacteria was investigated using agar diffusion and dilution micromethods. The chloroformic extract, active against all the bacteria tested, showed the most significant antimicrobial properties. Plumbagin, isolated from the extract, is the active principle. Results obtained suggest that Drosera peltata extract could be used in the treatment of oral infectious diseases like dental caries and periodontitis.

Antioxidant activities of polyphenolic extracts from flowers, in vitro callus and cell suspension cultures of Crataegus monogyna.

Numerous plants synthesize among their secondary metabolites phenolic compounds which possess antioxidant effects. The aim of the present work was to assay the antioxidant activities of phenolics from Crataegus monogyna Jacq. flowers and in vitro tissue culture (calli and cell suspensions) extracts. In the case of tissue culture extracts, the phenolic production is studied at three different stages of one subculture period (initial growth period, increasing and maximal phenolic synthesis phases). Attention was paid to the main categories: flavonoids and proanthocyanidins, and to the principal individual components. Total phenolic amounts decrease in the order: fresh flowers > cell suspension cultures > callus cultures. The antioxidant activities of these different extracts against H2O2 and HOCl, have been determined in vitro. All the extracts are efficient and the scavenging capacity is clearly related to the total phenol content. The scavenging effects of the cell suspension extracts are similar to those of the flowers. Among individual compounds, the flavanol-type derivatives, specially the proanthocyanidin B2, are more efficient. Thus, in vitro plant tissues could be an interesting source of bioactive molecules.

Oxygen species scavenging activity of phenolic extracts from hawthorn fresh plant organs and pharmaceutical preparations.

Different extracts of fresh vegetative and reproductive organs from Crataegus monogyna harvested during a whole season and from some pharmaceutical hawthorn preparations exhibit in vitro antioxidant activities using three different models of oxygen reactive species generation (superoxide anion, hydrogen peroxide and hypochlorous acid). All the tested samples show low IC50 values, the most efficient being fresh young leaves, fresh floral buds and pharmaceutical dried flowers. The activities seem to be especially bound to the total phenolic proanthocyanidin and flavonoid contents.

Antioxidant activities of Crataegus monogyna extracts.

Interesting antioxidant activities of extracts from different vegetative and reproductive organs of Crataegus monogyna harvested at different stages of growth have been determined by the malondialdehyde-thiobarbituric acid (MDA) test on hepatic microsomal preparations and compared to the contents in total phenolics, proanthocyanidins, catechins, flavonoids, and phenolic acids. The best correlations were established with total phenols while activities in leaves seem to be influenced by flavonoids and in flowers and fruits by proanthocyanidins and catechins.

Procyanidin Production by Fagopyrum esculentum Callus Culture.

FAGOPYRUM ESCULENTUM CALLUS cultures grown on B5 medium synthesize procyanidins B2 (0.6-1.8 mg/g dry wt) and B2-3'- O-gallate (3.5-6.0 mg/g dry wt). Sucrose is a better source than other carbohydrates and moderate concentrations (3-4%) stimulate both growth and procyanidin synthesis. While darkness was not a limiting factor, light induced faster growth and increased procyanidin contents. Treatment with gallic acid strongly stimulated the procyanidin B2-3'- O-gallate production, but drastically inhibited growth, leading to a two-step-culture experiment combining convenient growth and increased galloylated dimer synthesis (up to 45 mg/g dry wt).