Antioxidative and cytotoxic potential of some Chenopodium L. species growing in Poland

The cytotoxic and antioxidant properties of lipophilic compounds extracted from different parts of four Chenopodium L. (Chenopodium album, Chenopodium hybridum, Chenopodium rubrum and Chenopodium urbicum) species were evaluated. The highest phenolic content was found in herb and seeds of all examined plants. Large amounts of free polyphenols were observed in herb extracts of C. album (3.36 mg/g DW), seeds of C. urbicum (3.87 mg/g DW) and roots of C. urbicum (1.52 mg/g DW). The cytotoxic activities of the extracts were assessed against human lung carcinoma A-549 and ovarian carcinoma TOV-112D and normal human fibroblast cell lines. Our study demonstrated that the extracts from the herb of C. rubrum and C. urbicum had the best antioxidant effect of all the extracts analyzed. Most of the extracts tested exhibited low cytotoxicity. However, the extracts from herb and seeds of C. album and C. hybridum showed the significant antiproliferative effect on the TOV-112 cell line.It can be concluded that antioxidant activity and phenolic composition differ mainly between plant parts and are quite similar between the plants, when the same plant part is analyzed. Thus, the Chenopodium extracts could be used as a readily accessible source of natural antioxidants, and may be used in the pharmaceutical industry and for food supplements production.     

Purification, antioxidant and moisture-preserving activities of polysaccharides from papaya

Polysaccharides extracted from papaya are a group of heteropolysaccharides, and their antioxidant activities and moisture-preserving activities were investigated employing various established in vitro systems. Available data obtained with in vitro models suggested that among the three samples, the second fraction (named after P2) showed significant inhibitory effects on superoxide, hydroxyl and DPPH radical; its reducing power was also the strongest. Data also reveal that P2 has strong in vitro moisture absorption and retention capacities as compared to hyaluronic acid and glycerol. These results clearly establish the possibility that polysaccharides extracted from papaya could be effectively employed as a type of natural moisturizer. However, comprehensive studies need to be conducted in experimental animal models.     

毛竹对大气臭氧浓度倍增的生理响应

为了给气候变化背景下的竹林培育应对策略提供理论依据,以毛竹 （Phyllostachys edulis） 为材料,运用开顶式气室 （OTCs） 模拟当前环境背景大气O3浓度（NF,40~45nL·L-1）的倍增1倍（TR1,92~106nL·L-1）和倍增2倍（TR2, 142~160nL·L-1）情景,分析叶片光合色素、脂质过氧化及抗氧化酶等生理指标的变化规律。结果表明：大气O3浓度倍增处理90d时,毛竹叶片Chl、Car含量和SOD活性显著降低,叶片相对电导率和可溶性蛋白、MDA、O2-含量及POD活性显著升高。叶片O2-含量与SOD活性、光合色素含量呈极显著负相关,而与叶片相对电导率、POD活性和MDA、可溶性蛋白含量呈显著正相关。研究表明大气O3浓度倍增会导致毛竹叶片老化加快,光合色素降解或合成受阻,膜脂过氧化,膜结构和氧化系统破坏,影响毛竹的正常生长。本文从抗性生理方面揭示了毛竹对大气臭氧胁迫的耐受性,为竹子应对气候变化研究提供了参考。     

Isolation and the characterization of the degradation products of the mediator ABTS-derived radicals formed upon reaction with polyphenols

Two degradation products were obtained from the incubation of the widely used 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), ABTS, radical cations with the polyphenols, (+)-catechin, (-)-epicatechin, and phloroglucinol in acetate buffer (pH 5). The products were purified by reversed-phase chromatography and characterized by UV-visible detection, mass spectrometry, and (1)H NMR spectroscopy. The data allowed us to identify the degradation products as 3-ethyl-6-sulfonate benzothiazolinone imine and the corresponding sulfoxide, 3-ethyl-6-sulfonate benzothiazolone. Elemental composition strongly supported the proposed structures. Our results unequivocally demonstrated that ABTS radicals are not as stable as usually claimed because they could be degraded upon interaction with polyphenols, in addition to being reduced by these antioxidants back to the parent compound. Therefore, it is concluded that caution must be exercised in using ABTS radicals as a basis for the evaluation of antioxidant capacities of pure compounds and/or complex mixtures.     

The kinetics and mechanisms of the complex formation and antioxidant behaviour of the polyphenols EGCg and ECG with iron(III)

(-)-Epigallocatechin-gallate ((-)-EGCg) and (-)-epicatechin-gallate ((-)-ECG) are important antioxidants which are found in green tea. The kinetics and mechanisms of the reactions of a pseudo-first order excess of iron(III) with EGCg and ECG have been investigated in aqueous solution at 25 degrees C and an ionic strength of 0.5M NaClO(4). Mechanisms have been proposed which account satisfactorily for the kinetic data. These are consistent with a mechanism in which the 2:1 metal:ligand complex initially formed on reaction of iron(III) with the ligand subsequently decomposes in an electron transfer step. Complex formation takes place at two separate binding sites via coupled reactions. Rate constants of 4.28(+/-0.06) x 10(6) M(-2) s(-1) and 2.83(+/-0.04) x 10(6) M(-2) s(-1) have been evaluated for the reaction of monohydroxy Fe(OH)2+ species with EGCg and ECG, respectively while rate constants for of 2.94(+/-0.4) x 10(4) M(-2) s(-1) and 2.41(+/-0.25) x 10(4) M(-2) s(-1) have been evaluated for the reaction of Fe3+ species with EGCg and ECG, respectively. The iron(III) assisted decomposition of the initial iron(III) complex formed was also investigated and the rate constants evaluated. Both the complex formation and subsequent electron transfer reactions of iron(III) with EGCg and ECG were monitored using UV-visible spectrophotometry. All of the suggested mechanisms and calculated rate constants are supported by calculations carried out using global analysis of time dependant spectra. The results obtained show that one molecule of either EGCg or EGC is capable of reducing up to four iron(III) species, a fact which is consistent with the powerful antioxidant properties of the ligands.     

A Novel Method Using 8-hydroperoxy-2′-deoxyguanosine Formation for Evaluating Antioxidative Potency

Degenerative diseases such as cancer are induced by oxidative genetic damage. Antioxidants can scavenge reactive oxygen species, but to prevent disease, they must do so quickly, before the DNA bases are damaged. In the present study, a novel method was established for evaluating the potency of antioxidants employing 2'-deoxyguanosine as a target and 2,2'-azobis(2-amidinopropane) dihydrochloride as a reactive oxygen generator. The reaction formed one product linearly with time. This product was a novel 8-hydroperoxy-2'-deoxyguanosine (8-OOHdG). Using this system, 81 antioxidants occurring in our diet were assayed for activity to suppress the formation of 8-OOHdG by high-performance liquid chromatography (HPLC). The system was useful for the evaluation of antioxidative potency, compared to another method utilizing 1,1-diphenyl-2-picrylhydrazyl (DPPH). Further, it was enabled to examine the synergism of antioxidants. The formation of 8-OOHdG started only after the antioxidants had been consumed. Ascorbic acid, quercetin, and epigallocatechin gallate together delayed the formation by the sum total of the delay times of each factor alone. The proposed method is simple and easy, and can evaluate which dietary antioxidants inhibit reactive oxygen species more quickly than the DNA bases are damaged.     

A novel method using 8-hydroperoxy-2'-deoxyguanosine formation for evaluating antioxidative potency

Degenerative diseases such as cancer are induced by oxidative genetic damage. Antioxidants can scavenge reactive oxygen species, but to prevent disease, they must do so quickly, before the DNA bases are damaged. In the present study, a novel method was established for evaluating the potency of antioxidants employing 2'-deoxyguanosine as a target and 2,2'-azobis(2-amidinopropane) dihydrochloride as a reactive oxygen generator. The reaction formed one product linearly with time. This product was a novel 8-hydroperoxy-2'-deoxyguanosine (8-OOHdG). Using this system, 81 antioxidants occurring in our diet were assayed for activity to suppress the formation of 8-OOHdG by high-performance liquid chromatography (HPLC). The system was useful for the evaluation of antioxidative potency, compared to another method utilizing 1,1-diphenyl-2-picrylhydrazyl (DPPH). Further, it was enabled to examine the synergism of antioxidants. The formation of 8-OOHdG started only after the antioxidants had been consumed. Ascorbic acid, quercetin, and epigallocatechin gallate together delayed the formation by the sum total of the delay times of each factor alone. The proposed method is simple and easy, and can evaluate which dietary antioxidants inhibit reactive oxygen species more quickly than the DNA bases are damaged.