Metabolism of Pyrogallol to Purpurogallin by Human Erythrocytic Hemoglobin

Abstract

The aim of this study was to investigate the oxidoreductive reactions of human hemoglobin with pyrogallol and the metabolism of pyrogallol by the protein, which contains a protoporphyrin IX like cytochrome P-450. Pyrogallol, having three hydroxy groups at the adjacent positions in the benzene ring, oxidized human oxyhemoglobin to methemoglobin and reduced human methemoglobin to oxyhemoglobin. Since superoxide dismutase and catalase inhibited these reactions extensively, active oxygens such as superoxide and hydrogen peroxide were considered to be involved in the oxido-reductive reaction of human hemoglobin by pyrogallol. It was also found that the metabolism of pyrogallol to purpurogallin occurred quickly in human erythrocytes, i.e., when pyrogallol was added to human erythrocyte suspension, it oxidized intracellular hemoglobin and produced purpurogallin. The metabolism of pyrogallol to purpurogallin was explained by the pyrogallol oxidation with superoxide and hydrogen peroxide produced during the oxidoreductive reactions of human hemoglobin with pyrogallol. The present results show that human erythrocytes can metabolize pyrogallol, suggesting that the cells may be involved in the metabolism of some drugs in the human body.erythrocytes; hemoglobin; pyrogallol; purpurogallin © 2004 Tohoku University Medical Press Though drug metabolism has been shown to be carried out by cytochrome P-450 in the liver (Omura and Sato 1964;Lu et al. 1972), the contribution of erythrocytic hemoglobin, a protoporphyrin IX containing hemoprotein like cytochrome P-450, to drug metabolism is unlikely to attract much attention. Tomoda et al. (1977a) showed that aniline was metabolized to p-aminophenol by human erythrocytes, in the presence of catalytic amounts of methylene blue. Mieyal and Blumer (1976) demonstrated that oxyhemoglobin can hydroxylate aniline to p-ami-

Role of Single-Electron Oxidation Potential and Lipophilicity in the Antiplasmodial in vitro Activity of Polyphenols: Comparison to Mammalian Cells

“…The prooxidant character of antiplasmodial activity has been demonstrated for curcumin (Cui et al, 2007), and has been proposed for quercetin (Vennerstrom and Eaton, 1988). Although the pathways of polyphenol oxidation in P. falciparum are unclear, these compounds may be oxidized by oxyhemoglobin in erythrocytes with the concomitant formation of ROS (Stolze and Nohl, 1999;Miyazaki et al, 2004). (ii) Lower than expected mammalian cell cytotoxicity of flavonoids (Fig.…”

Conversion to purpurogallin, a key step in the mechanism of the potent xanthine oxidase inhibitory activity of pyrogallol

“…In addition to XO-inhibitory activity of pyrogallol [18], the potent XO-inhibitory activity of purpurogallin [19] has been reported: it has also been reported to have several other biological activities, such as antioxidant activity in liver, kidney and cardiovascular cells were reported [20][21][22][23]. Biological production of purpurogallin from pyrogallol has also been observed in human erythrocytes [24]. The identification of this new compound as purpurogallin was completed by comparing its retention time and UV-VIS spectra of synthetically prepared purpurogallin.…”

Enhanced functional properties of tannic acid after thermal hydrolysis

“…Even though microbial enzymatic process or human metabolism were reported to degrade tannin compounds into smaller products such as gallic acid and pyrogallol (Miyazaki et al, 2004;Roy & Abraham, 2006;Singh, Bhat, & Sharma, 2001;Tauber, 1953), industrially, gallic acid is mainly produced from tannins (gallotannin or tara tannin) by acid-/base-catalysed hydrolysis (Chen et al, 1995;Lu et al, 2008;Wang, 1995), and then thermally decarboxylated with a catalyst to produce pyrogallol. However, these processes may result in the creation of hazardous waste and are costly.…”

“…The oxidation of polyphenol molecules through in vivo and in vitro enzymatic reactions could enhance the bioavailability of pharmacologically active natural products (Matsuo, Tanaka, & Kouno, 2006;Miyazaki, Arai, Iwamoto, Takasaki, & Tomoda, 2004;Tauber, 1953).…”

“…Industrially, gallic acid is mainly produced from tannic acid by acid-/base-catalysed hydrolysis, and then thermally decarboxylated with a catalyst to produce pyrogallol which can be further oxidised to purpurogallin by enzymatic systems (Miyazaki et al, 2004;Roy & Abraham, 2006;Tauber, 1953). Production of gallic acid, pyrogallol and purpurogallin need multiple thermal/enzymatic preparation steps which may cause severe environmental pollution and are costly (Kambourakis et al, 2000;Lu et al, 2008;Roy & Abraham, 2006;Yoshida & Yamada, 1985).…”