Sample records for 1,2,3-trihydroxybenzene

  1. Organization of the interior of molecular capsules by hydrogen bonding.

    Atwood, Jerry L; Barbour, Leonard J; Jerga, Agoston


    The enclosure of functional entities within a protective boundary is an essential feature of biological systems. On a molecular scale, free-standing capsules with an internal volume sufficiently large to house molecular species have been synthesized and studied for more than a decade. These capsules have been prepared by either covalent synthesis or self-assembly, and the internal volumes have ranged from 200 to 1,500 A(3). Although biological systems possess a remarkable degree of order within the protective boundaries, to date only steric constraints have been used to order the guests within molecular capsules. In this article we describe the synthesis and characterization of hexameric molecular capsules held together by hydrogen bonding. These capsules possess internal order of the guests brought about by hydrogen bond donors within, but not used by, the framework of the capsule. The basic building blocks of the hexameric capsules are tetrameric macrocycles related to resorcin[4]arenes and pyrogallol[4]arenes. The former contain four 1,3-dihydroxybenzene rings bridged together by -CHR- units, whereas the latter contain four 1,2,3-trihydroxybenzene rings bridged together. We now report the synthesis of related mixed macrocycles, and the main focus is on the macrocycle composed of three 1,2,3-trihydroxybenzene rings and one 1,3-dihydroxybenzene ring bridged together. The mixed macrocycles self-assemble from a mixture of closely related compounds to form the hexameric capsule with internally ordered guests. PMID:11943875

  2. Study on effects of lead on the antioxidant activities of Aloe vera%铅污染对芦荟抗氧化活性影响的研究

    蔡卓; 卢登峰; 梁信源; 莫创荣; 杜良伟; 莫利书; 黄富嵘


    The variation of the antioxidant enzyme system of Aloe vera under the stress of different Pb concentrations was studied using pot experiments. The scavenging abilities of the potted Aloe vera to ·OH and O2- o were determined by flow injection chemiluminescence method using methylene blue-Fenton system and 1,2,3 -trihydroxybenzene system. The effects of lead pollution on the enzymatic activity of Aloe vera were evaluated. The results showed that at a relatively low lead pollution level, the enzymatic activity of polluted Aloe vera was higher than that of the un-polluted, and increased with the increase of lead concentration in Aloe vera body; while at a relatively higher lead pollution level, the enzymatic activity of polluted Aloe vera was lower than that of the un-polluted, and the activity decreased with the increase of lead concentration in Aloe vera body. These indicated that at a low pollution level the physiological response of Aloe vera antioxidant enzyme system to heavy metal stress resulted in the rise of enzymatic activity of Aloe vera; while at a high pollution level, the self protection system of Aloe vera is damaged, which in turn led to the damage of antioxidant enzyme system, and then results in the decrease of the enzymatic activity.%采用盆栽试验,对芦荟在不同浓度Pb胁迫下抗氧化酶系统的变化进行了研究.用流动注射化学发光分析法,以亚甲基蓝-Fenton体系、鲁米诺-邻苯三酚体系分别测定盆栽芦荟体内抗氧化酶清除·OH和清除O2-·的能力,进而评价铅污染对芦荟生物活性的影响.结果表明,在相对低浓度铅污染水平下,芦荟提取酶的活性均比无污染时的对照值有所升高,并与芦荟体内铅含量成正相关;而在相对较高浓度铅污染下,提取酶的活性均比对照值有所下降,与芦荟体内铅含量成负相关.说明在低浓度铅毒害作用下,芦荟体内抗氧化酶系统对重金属胁迫的生理的响应使其活性有所上升