Hydrogen peroxide scavenging, antioxidant and anti-radical activity of some phenolic acids.

Some water-soluble phenolic acids were investigated as antioxidants, scavengers of hydrogen peroxide (H(2)O(2)) and scavengers of 1,1-diphenyl-2-picrylhydrazyl radical (DPPH(*)). The strongest antioxidant, scavenging of H(2)O(2) and DPPH(*) radical activity was exhibited by 3,4,5-trihydroxybenzoic (gallic) acid and 1,2,3-trihydroxybenzene (pyrogallol) with three hydroxyl groups bonded to the aromatic ring in an ortho position in relation to each other. Phenolic acids with two hydroxyl groups bonded to aromatic ring in the ortho position, such as 3,4-dihydroxycinnamic (caffeic), 3,4-dihydroxybenzoic (protocatechuic) and 2,3-dihydroxybenzoic (o-pyrocatechuic) acids, showed strong antioxidant and anti-radical activity; however, it was lower than that of 3,4,5-trihydroxybenzoic acid or 1,2,3-trihydroxybenzene. 3,5-Dihydroxybenzoic (alpha-resorcylic) and 2,4-dihydroxybenzoic (beta-resorcylic) acids with two hydroxyls bonded in the meta position in relation to each other showed moderate antioxidant and low DPPH(*) and hydrogen peroxide scavenging activity. Compounds with one hydroxyl group such as 3-hydroxybenzoic, 4-hydroxyphenylacetic and 2-hydroxybenzoic (salicylic) acids, exhibited the lowest anti-radical and antioxidant activity. The results obtained show that the antioxidant and anti-radical activity of phenolic acids correlated positively with the number of hydroxyl groups bonded to the aromatic ring. The model of an ortho substitution of hydroxyl groups to the aromatic ring seems to be adequate for antioxidant and H(2)O(2) or DPPH(*) scavenging activity of phenolic acids.

Phenolic extracts from meadowsweet and hawthorn flowers have antioxidative properties.

From the flowers of meadowsweet and inflorescence of hawthorn the whole set of phenolic acids and flavonoids was analysed by TLC. Phenolic compounds were determined both as free ones and those liberated by hydrolysis. Moreover, ethyl ether and ethyl acetate extracts obtained from the analysed plants before and after alkaline and enzymatic hydrolyses were evaporated under reduced pressure and residues were analysed for their antioxidative properties. The weakest antioxidative activity was observed with the remaining residue after evaporation of ethyl ether extract obtained from enzymatically (beta-glucosidase) hydrolysed hawthorn inflorescence water extract. The strongest antioxidative activity was noticed with the remaining residues after evaporation of ethyl ether extracts obtained from non-hydrolysed and hydrolysed in alkaline conditions of meadowsweet flower water extracts. The residues from meadowsweet flowers exhibited stronger antioxidative properties than residues obtained from hawthorn inflorescence and can be recommended as margarine preservatives.

Flavonoids from some species of the genus Cucumis.

From the leaves of Cucumis sativus the following C-glycosides were isolated and identified: isovitexin 2"-O-glucoside, isovitexin, isoorientin, 4'-X-O-diglucosides of isovitexin and swertiajaponin. In the flowers of the above species chromatographically (HPLC, TLC) the presence of kaempferol 3-O-rhamnoside and 3-O-glycosides of kaempferol, quercetin, isoramnetin was revealed. The flavonoids complexes occuring in other species of Cucumis: C. metuliferus, C. myriocarpus and six cultivar varieties of C. sativus chromatographically (HPLC, TLC) were campared.

Essential oil from herb and rhizome of Peucedanum ostruthium (L. Koch.) ex DC.

Essential oil from herb and rhizome of Peucedanum ostruthium (L.Koch.) ex DC underwent qualitative and quantitative analyses. The content of the oil obtained by hydrodistillation was 0.95% in the herb and 1.25% in the rhizome (per dry weight basis). Gas chromatography (GC) with MS detection and flame ionisation detection showed that the oil from the rhizome contains 39 compounds, of which 29 were identified. Gas chromatography with flame ionisation detection in chiral columns against standard compounds showed the presence of enantiomers of some of the components of the oil. Compounds present in largest quantities are: sabinene (35.2%) of which (+) sabinene accounts for (96.54%) and 4-terpineol (26.6%) of which (+) 4-terpineol accounts for (65.8%). 44 components were found in the herb essential oil, of which 39 compounds were identified. Compounds present in largest quantities were beta-caryophyllene (16.1%) and alpha-humulene (15.8%). The content of sabinene in the herb oil was 4.7%. The following compounds were present in the herb oil only as enantiomers: (+) sabinene (4.7%), (-) limonene (4.4%), (-) beta-pinene (0.4%). A coumarin (osthole) was detected in both essential oils (5.5% in herb oil and 5.1% in rhizome oil).

Phenolic acids and depsides from some species of the Erodium genera.

Six natural polyphenolic compounds, brevifolin carboxylic acid, brevifolin, ellagic acid, methyl gallate, gallic acid and protocatechuic acid have been isolated from the methanol extract of the whole plant of Erodium cicutarium (L.) L.'Hérit. (Geraniaceae). Structures were determined by conventional methods of analysis and confirmed by MS and NMR spectral analysis. The distribution of these compounds in the other species of the Erodium genera (E. botrys, E. chium, E. ciconium, E. cicutarium, E. glutinosum subsp. dunense, E. gruinum, E. manescavi, E. pelargoniiflorum, E. petraeum) were examined by HPLC with a RP-18 column, and MGD-TLC methods on unmodified silica gel and silica gel chemically modified with polar and nonpolar groups (HPTLC-Si 60 LiChrospher, HPTLC-NH2, HPTLC-DIOL, HPTLC RP-18W).

Comparative analysis of phenolic acids in mistletoe plants from various hosts.

Phenolic acids present in mistletoe plants collected from various hosts were analysed with the use of HPLC. The following numbers of compounds were found in the mistletoe plant material gathered from respective hosts: Sorbus aucuparia- 12 compounds; Acer plantanoides--14 compounds: Malus domestica, Pyrus communis and Populus nigra--13 compounds each; Quercus robur--15 compounds. Altogether 21 phenolic acids were chromatographically identified in the tested material. The compounds were either free or combined as esters or glycosides. Comparative chromatography revealed qualitative differences in the investigated compounds between the various plant materials. For example o-coumaric acid was only found in mistletoe hosted by Quercus robur. Digallic acid was only found in the plant material hosted by Acer plantanoides. Qualitative and quantitative composition of mistletoes hosted by Malus domestica and Pyrus communis showed considerable similarities as far as phenolic acids were concerned. Moreover. vanillic acid. absent in all other batches of plant material, seemed to be characteristic of the above mistletoes. Quantitative HPLC analysis demonstrated a considerable content of salicylic acid (39.55 mg%) in mistletoe hosted by Sorbus aucuparia. Apart from the above material, this compound was only present in small quantities in plants hosted by Populus nigra (15.63 mg%) and Quercus robur (2.63 mg%).

Antifungal biflavones from Cupressocyparis leylandii.

From the leaves of Cupressocyparis leylandii (Cupressaceae) cupressuflavone, 4-O-methylcupressuflavone, amentoflavone, 7-O-methylamentoflavone, 4-O-methylamentoflavone and hinokiflavone were isolated. 1H- and 13C-NMR data for 4-O-methylcupressuflavone are given for the first time. The biflavones from cultivar varieties of C. leylandii (Naylor's Blue, Castlewellan Gold) were chromatographicaly (HPLC) compared. The antifungal activity of cupressuflavone and 4-O-methylcupressuflavone against Alternaria alternata, Cladosporium oxysporum, Fusarium culmorum and F. avenaceum was assayed.

The effect of some flavonoids on non-enzymatic lipid oxidation and enzymatic oxidation of arachidonic acid.

Twenty flavonoids isolated from plants or transformed into methyl or acetyl derivatives were tested with regard to their influence on cyclooxygenase from the ram seminal vesicle microsomes and lipoxygenase from soya beans. Moreover, their antioxidant properties were evaluated by estimating the amount of the malonylaldehyde formed from arachidonic acid. Only rhamnetin and myricetin inhibited the soybean lipoxygenase. Most of the tested flavonoids stimulated cyclooxygenase at a high (100 microM) substrate concentration, myricetin being the most potent. Rhamnetin was the strongest antioxidant, while myricetin was about ten times weaker. Structural requirements for the cyclooxygenase stimulation, lipoxygenase inhibition and antioxidant properties were different in the case of the twenty tested flavonoids.

Effect of plant extracts on the in vitro interferon synthesis.

The extracts of roots and rhizomes of Angelica and Peucedanum genera, known in popular medicine for their various activities, were investigated in search of non-virus interferon inducers. It has been found that none of the extracts tested, induce interferon in human cell cultures. However, the extract from Peucedanum verticillare augmented the yield of interferon in the in vitro human fibroblast cell culture and human leukocytes suspensions when Sendai or NDV viruses were used as inducers. The increase of interferon yield was observed when the plant extract was administered at the time of interferon messenger RNA synthesis.