In vitro efficacy of Bryophyllum pinnatum leaf extracts as potent therapeutics

Leaf extracts of Bryophyllum pinnatum (BPEs) are used in several countries. Contextually, evaluation of the therapeutic potential of these was carried out in this study to explore antioxidant and antityrosinase potential through different in vitro methods. The radical scavenging properties of BPEs were studied using various techniques, based on the 1,1-diphenyl-2-picrylhydrazyl (DPPH) dot blot thin-layer chromatography (TLC) method, electron paramagnetic resonance (EPR) spectroscopy, metal chelation, β-carotene bleaching, inhibition of DNA breakage on agarose gel, and lipid peroxidation inhibition using liver and brain microsomes. EC₅₀ values of the results reflected that aqueous-methanolic BPE was the most active one. Antibrowning potential of the fresh leaf extract showed an antityrosinase property, with EC₅₀ values of enzymatic assay of tyrosinase inhibitory activity further advocating the findings.     

Effects of aqueous leaf extract of Bryophyllum pinnatum on guinea pig tracheal ring contractility

Aqueous leaf extract of Bryophyllum pinnatum Lam (Crassulaceae) is used as a cough remedy and for the prophylaxis of asthma. Since drugs used for the prophylaxis of asthma may be acting on airway smooth muscles, we investigated the effects of aqueous leaf extract of the plant on the contractile responses of isolated tracheal rings. Guinea pigs were grouped into non-sensitized, ovalbumin (OA)-sensitized, OA-sensitized but 200 mg/kg/day x 21 extract-treated, and OA-sensitized but 400 mg/kg/day x 21 extract-treated. The extract was administered orally. Tracheal rings obtained from the four groups were mounted in organ baths and used to test spasmolytic and antispasmodic effects of the extract on histamine or carbachol-induced contractions. Concentrations of 0.125-1.0 mg/ml of the extract did not relax histamine or carbachol-induced precontractions. The presence of 0.25-1.0 mg/ml of the extract in organ baths significantly reduced the maximal contractile responses (Emax) to cumulative concentrations of histamine or carbachol irrespective of the experimental group. pD2 values were significantly reduced for histamine and carbachol in rings obtained from 400 mg/kg/day x 21 extract-treated group. It is concluded that aqueous leaf extract of B. pinnatum possesses antispasmodic effects on the guinea pig tracheal rings. The results lend credence to the use of the extract for the prophylaxis of asthma in ethnomedicine.Keywords: Bryophyllum pinnatum; Tracheal rings; Anti-asthmatic; Antispasmodic; Herbal medicine.     

Radical scavenging activity of ribonuclease inhibitor from cow placenta

Cow placenta ribonuclease inhibitor (CPRI) has been purified 5062-fold by affinity chromatography, the product being homogeneous by sodium dodecyl sulfate-gel electrophoresis. The chemiluminescence technique was used to determine the radical scavenging activities of CPRI toward different reactive oxygen species (ROS) including superoxide anion (O2-*), hydroxyl radical (OH*), lipid-derived radicals (R*), and singlet oxygen (1O2). CPRI could effectively scavenge O2-*, OH*, R*, and 1O2 at EC50 of 0.12, 0.008, 0.009, and 0.006 mg/ml, respectively. In addition, the radical scavenging activities of CPRI were higher than those of tea polyphenols, indicating that CPRI is a powerful antioxidant.     

中华补血草多酚提取物对自由基的清除能力

采用超声波辅助浸提—大孔树脂吸附法从中华补血草[ Limonium sinense (Girard) Kuntze]根、根茎、叶和花中获得多酚提取物,并对它们的得率和组成成分进行了初步分析;在此基础上,比较研究了不同部位多酚提取物对DPPH·、·OH和O2的清除能力.实验数据表明:中华补血草根、根茎、叶和花多酚提取物的得率分别为12.42％、5.98％、5.27％和3.98％,差异明显;多酚提取物中总酚、原花色素、黄烷醇和总黄酮含量变化幅度较大,分别为51.87％ ～61.60％、5.62％～39.47％、3.69％～12.46％和2.53％ ～35.97％;其中,总酚、原花色素和黄烷醇含量均以根多酚提取物最高,总黄酮含量以花多酚提取物最高,均与其他部位多酚提取物有显著差异.随质量浓度提高,4个部位多酚提取物对3种自由基的清除率总体上逐渐增大;其中根多酚提取物对DPPH·的清除作用最强,半数清除质量浓度(ρSC50)为38.52 μg·L-1,显著低于阳性对照芦丁和BHT(ρSC50分别为67.40和74.25 μg·L-1);花多酚提取物对·OH和O2的清除能力最强,ρSC50分别为53.51和74.00 μg·L-1,均低于芦丁;总体上,4个部位多酚提取物对DPPH·的清除能力由强至弱依次为根、根茎、叶、花,对·OH和O2的清除能力由强至弱依次为花、根、叶、根茎.结果显示:中华补血草不同部位多酚提取物均具有较强的自由基清除能力,其中,根和花多酚提取物中高含量的原花色素和黄酮类成分分别与其自由基清除能力密切相关.     

Radical scavenging properties of genistein

The reactivity of genistein toward reactive radical species has been investigated by means of pulse radiolysis. The values of rate constants, respectively 2.3 x 10(10) M(-1)s(-1) and 1.3 x 10(10) M(-1)s(-1) for the reaction with hydroxyl radical at pH 8.3 and 3.0, are close to diffusion limit indicating that genistein is a potent hydroxyl radical scavenger. The reactivity of genistein towards one-electron oxidants has also been investigated. The rate constants k = 4.6 x 10(9) M(-1)s(-1) (pH 8.3) and 6.7 x 10(8) M(-1)s(-1) (pH 7.6) have been determined for the reaction of genistein with *N3 and Br2*- radicals, respectively. For both oxidants the rate constants at pH 3 does not exceed 10(8) M(-1)s(-1). The differences in reactivity of genistein towards the oxidants at different acidity of the solution have been assumed to arise from the acid-base equilibria of genistein. The dissociation constants for genistein (pKa: 7.2, 10.0, and 13.1) have been evaluated spectroscopically. The influence of acid-base equilibria on bond dissociation energy and ionization potential for genistein has also been investigated by means of DFT calculations. It has been concluded on the basis of these calculations that monoanionic form of genistein existing at physiological pH is more powerful radical scavenger than the neutral molecule.     

Radical scavenging activities of niacin-related compounds

We investigated whether niacin-related compounds had radical-scavenging activity by electron spin resonance methods. Many compounds, but not trigonelline, had radical-scavenging activity against hydroxyl radicals. However, for the nitric oxide radical and 1,1-diphenyl-2-picrylhydrazyl radical, only nicotinic acid hydrazide and isonicotinic acid hydrazide had scavenging activities. These results suggest that the moiety of hydrazide might have an important role in scavenging abilities of various radicals.     

A reevaluation of the peroxynitrite scavenging activity of some dietary phenolics

Peroxynitrite is implicated in many diseases. Hence, there is considerable interest in potential therapeutic peroxynitrite scavengers. Diet-derived phenolics have been claimed to be powerful peroxynitrite scavengers. However, the reactivity of peroxynitrite can be significantly modified by bicarbonate and this has not been considered in evaluations of the scavenging activity of phenols. Bicarbonate (25 mM) significantly decreased the ability of several phenolic compounds (caffeic acid, o- and p-coumaric acid, gallic acid, ferulic acid) but not others (catechin and epicatechin) to inhibit peroxynitrite-mediated tyrosine nitration. Bicarbonate (25 mM) also decreased the ability of catechin, epicatechin, quercetin and ferulic acid but not chlorogenic acid, gallic acid, caffeic acid and o-coumaric acid to inhibit peroxynitrite-mediated alpha(1)-antiproteinase inactivation. These results show that physiological concentrations of bicarbonate substantially modify the ability of dietary phenolics to prevent peroxynitrite-mediated reactions. When assessing compounds for peroxynitrite scavenging, experiments should be conducted in the presence of bicarbonate to avoid misleading results.     

Allelopathic potential of the phenolics from the roots of Pluchea lanceolata

Aqueous leachates of roots of the perennial weed Pluchea lanceolata (DC.) C. B. Clarke, its root-incorporated soil and rhizosphere soil, interfered with the seedling growth of certain plant species. The soils from the rhizosphere zone of this plant had significantly higher total phenolics and HPLC analysis revealed that phenolic fractions represented by retention times of 1.6, 1.9, 2.5 (simple phenol, chlorogenic acid and phloroglucinol respectively), 3.7 and 4.3 min were contributed by roots of the weed to the soil. The phenolic fraction represented by the retention time 3.3 (formononetin 7-O-glucoside) was detected in the weed's rhizosphere soils and not in the rootincorporated soils. UV spectral studies established the presence of phloroglucinol, simple phenol, chlorogenic acid, formononetin 7-O-glucoside, and methylated coumarins in the root leachate, which affect the seedling growth of mustard ( Brassica juncea ). Present research established the allelopathic potential of P. lanceolata roots, and the possible involvement of allelopathy in its interference success.     

Anti-inflammatory and antinociceptive potential of major phenolics from Verbascum salviifolium Boiss

The potential effects of flavonoids, phenylethanoid and neolignan glycosides from the aerial parts of Verbascum salviifolium Boiss. were studied in the p-benzoquinone-induced writhing reflex, for the assessment of the antinociceptive activity, and in carrageenan- and PGE1-induced hind paw edema and 12-O-tetradecanoyl-13-acetate (TPA)-induced ear edema models in mice, for the assessment of the anti-inflammatory activity. Through bioassay-guided fractionation and isolation procedures ten compounds from the aqueous extract of the plant, luteolin 7-O-glucoside (1), luteolin 3'-O-glucoside (2), apigenin 7-O-glucoside (3), chrysoeriol 7-O-glucoside (4), beta-hydroxyacteoside (5), martynoside (6), forsythoside B (7), angoroside A (8), dehydrodiconiferyl alcohol-9'-O-beta-D-glucopyranoside (9) and dehydrodiconiferyl alcohol-9-O-beta-D-glucopyranoside (10), were isolated and their structures were elucidated by spectral techniques. Results have shown that 1, 2, 3 and 5 significantly inhibited carrageenan-induced paw edema at a 200 mg/kg dose, while 1, 2 and 5 also displayed anti-inflammatory activity against the PGE1-induced hind paw edema model. However, all the compounds showed no effect in the TPA-induced ear edema model. The compounds 1 and 2 also exhibited significant antinociceptive activity.     

Radical scavenging and NO-releasing properties of selected beta-adrenoreceptor antagonists

It is claimed that novel beta-adrenolytic drugs possess superior antioxidant properties as compared to classical selective or non-selective beta-adrenoceptor antagonists. Here we tested this notion by analyzing radical scavenging properties of selected beta-adrenolytic drugs and their ability to release nitric oxide in biological preparations. Selective beta1-adrenolytics such as nebivolol, atenolol, metoprolol and non-selective beta-adrenolytics with alpha1-receptor blocking properties such as carvedilol and labetalol were chosen for analysis. NO-releasing properties of nebivolol and carvedilol distinguished third generation beta-adrenolytics from their older counterparts while the reactivity towards hydroxyl and peroxyl radicals discerns only carvedilol but not nebivolol. Thus, superior clinical efficacy of third generation beta-adrenolytics may be related to their ability to release NO rather then to their direct antioxidant properties.     

Radical scavenging activity of phenylpropanoid glycosides in Caryopteris incana.

In our screening program for antioxidants from traditional drugs and foodstuffs, one new phenylpropanoid glycoside, incanoside, was isolated together with four known phenylpropanoid glycosides, verbascoside, isoverbascoside, phlinoside A, and 6-O-caffeoyl-beta-D-glucose from the whole plant of Caryopteris incana (Thunb.) Miq. On the basis of chemical evidence and spectral analysis data, the structure of incanoside was determined to be 1-O-(3,4-dihydroxyphenyl)ethyl-O-beta-D-glucopyranosyl (1-->2)-alpha-L-rhamnopyranosyl(1-->3)-6-O-caffeoyl-beta-D- glucopyranoside. The four phenylpropanoid glycosides exhibited potent radical scavenging activity against DPPH, hydroxyl (.OH), and superoxide anion (O2-.) radicals.     

Radical and superoxide scavenging activities of matairesinol and oxidized matairesinol

The radical and superoxide scavenging activities of oxidized matairesinols were examined. It could be assumed that the free benzylic position was important for higher radical scavenging activity. The different level of activity was observed between 7'-oxomatairesinol (Mat 2) and 7-oxomatairesinol (Mat 3). The activity of 8-hydroxymatairesinol was lower than that of matairesinol (Mat 1). The superoxide scavenging activity of the oxidized matairesinols was also demonstrated for the first time. It is assumed that the pKa value of phenol in the oxidized matairesinols affected this activity.     

Radical scavenging activity of tea catechins and their related compounds

(-)-Epigallocatechin gallate was found to be the most effective scavenger among tea catechins for the superoxide anion, hydroxyl radical, and 1,1-diphenyl-3-picrylhydrazyl radical. Examination of the scavenging effects of tea catechins and their glucosides on superoxide anion showed that the presence of at least an ortho-dihydroxyl group in the B ring and a galloyl moiety at the 3 position was important in maintaining the effectiveness of the radical scavenging ability. Stoichiometric factors of tea catechins were estimated to be 2 for (+)-catechin and (-)-epicatechin, 5 for (-)-epigallocatechin, 7 for (-)-epicatechin gallate, and 10 for (-)-epigallocatechin gallate.     

Metal-chelating properties, electrochemical behavior, scavenging and cytoprotective activities of six natural phenolics

Chelation, electrochemical, antioxidant and cytoprotective properties of six phenolics - cynarin and caffeic, chlorogenic, ferulic, protocatechuic and rosmarinic acids were studied on the following models: (i) chelation of transition metals, (ii) quenching of the diphenylpicrylhydrazyl radical (DPPH), (iii) determination of half-wave potential, (iv) erythrocytes or mitochondrial membranes damaged by tert-butyl hydroperoxide (tBH) and (v) a primary culture of rat hepatocytes intoxicated by Cu(II) and Fe(III) or tBH. All phenolics suppressed cell membrane damage induced by transition metals or tBH. The protectivity correlated with their capacity to bind transition metals, to scavenge DPPH radical and with the value of half-wave potentials. In in vitro assays, the most promising was rosmarinic acid.     

Accumulation of phenolics and growth rate of barley seedlings (Hordeum vulgare L.)

Accumulation of phenolics in barley seedlings was examined in relation to elongation; the seedlings were cultivated at 5 °C or 26 °C in light or in darkness. It was found that a higher accumulation of phenolics (mainly saponarin) was accompanied by slower elongation. This relation was repeatedly observed regardless of whether growth retardation or stimulation was obtained by light and temperature conditions of growth or treatment with CCO orp-fluorophenylalanine (p-FPA), respectively. It is proposed that PAL and peroxidase activities are responsible for maintaining the level of phenolics in seedlings. These enzyme activities are differently influenced by temperature conditions of growth. It is also suggested that accumulation of saponarin may lead to slowing down the growth by stimulating IAA oxidase and lowering the auxin level in the tissues. Thus, phenolics may belong to the factors through which environmental conditions influence elongation of seedlings.     

Establishment of dedifferentiated callus of haploid origin from unfertilized ovaries of tea (Camellia sinensis (L.) O. Kuntze) as a potential source of total phenolics and antioxidant activity

This is the first report of induction of haploid callus with significant antioxidant activity from unpollinated ovary cultures of tea. Out of the five cultivars tested, TV18 gave the highest percentage of callus induction. Within 1 wk of induction, ovules swelled to almost double their original size, and white, friable callus emerged. A high cytokinin/auxin ratio, provided by 8.5 μM benzyl adenine and 4.5 μM 2,4-dichlorophenxyacetic acid, and high-temperature treatment (33°C) for 10 d in the dark promoted maximum callus induction. Callus was maintained on MS medium containing 22.2 μM benzyl adenine and 9.8 μM indolebutyric acid (callus line RM 1) in the light at 25°C. Well-developed tracheids were formed within 4 wk in callus subcultured on MS medium containing 1.8 μM thidiazuron and 5.0 μM 2,3,5-triiodobenzoic acid (line RM 2). Flow cytometric analysis revealed that most cells were haploid. Both RM 1 and RM 2 produced phenolic compounds with significant antioxidant capacity. Phenolic content showed a positive linear correlation with antioxidant activity. The total phenolic content of RM 1 was 3.47?±?0.21 gallic acid equivalents (GAE) mg/g dry weight and that of RM 2 was 2.39?±?0.12 GAE mg/g dry weight. Antioxidant activity was measured using IC₅₀, a measure of inhibitory concentration; a lower IC₅₀ value reflects greater antioxidant activity. The IC₅₀ value of RM 1 was 2,530 μg/ml and that of RM 2 was 3,170 μg/ml. The results suggested that the phenolic compounds contributed significantly to the antioxidant capacity of the in vitro cell lines.