Antioxidant and antihypertensive activity of phenolic compounds

VALLEJO, CLAUDIA VERÓNICA; ARÉDEZ FERNÁNDEZ, PEDRO ADRIÁN; RODRÍGUEZ VAQUERO, MARÍA JOSÉ

Mar del Plata-Buenos Aires

Congreso; VIII CONGRESO DE MICROBIOLOGÍA GENERAL "SAMIGE"; 2012

SAMIGE

Recently, more attentions had been paid on phenolic compounds of fruits, and some publications have suggested they might play an important role on the antioxidant capacity of fruits. Dietary phenolic compounds of citric fruits include flavonoids (such as rutin and quercetin) and phenolic acids (such as gallic, protocatechuic, caffeic, p-coumaric and ferulic acids). Some authors found that phenolic compounds from herbs, wines and other sources presented radical scavenging activity. However, there are no reports available with respect to the inhibitory activity toward Angiotensin I-converting enzyme (ACE) of pure phenolic compounds. The objective of this study was to investigate the antioxidant and antihypertensive activities of individual phenolic compounds (phenolic acids: gallic, protocatechuic, vanillic, caffeic, syringic, coumaric and ferulic acids and flavonoids compounds: quercetin, quercitrin, rutin, myricetin, rhamnetin, kaempherol and ellagic acid). All phenolic compounds were dissolved in ethanol 99.8% and filter-sterilized through a 0.22 µm membrane filter, four concentrations were used for antioxidant experience (10, 20, 50 and 100 mg/l). The antioxidant activity was carried out using three methods, FRAP (Ferric-reducing antioxidant power) (Benzie and Strain, 1996), DPPH (1,1-diphenyl-2-picrilhydrazyl) (Von Gadow et al., 1997) and ABTS (2,2´-azinobis-(3-ethylbenzothiazoline-6-sulfonate)) (Re et al., 1999) assays. ACEI activity was determined with slight modifications of the method first described by Cushman and Cheung (1971) and later modified by Hernández-Ledesma et al. (2003). The results showed that all phenolic compounds posses antioxidant activity that increased when the concentration is higher. Between all phenolic compounds, gallic acid (100 mg/l) showed the highest values of ferric reducing power (3,032 µmol FeSO4/l) and radical scavenging activity (80%: DPPH and 95%: ABTS). The antioxidant activity of gallic acid at 50 mg/l is still higher than many phenolic compounds at 100 mg/l. Between flavonoid compounds, quercetin, myricetin and rhamnetin showed the highest antioxidant activity determine by FRAP (between 1,935 and 1,443 µmol FeSO4/l), DPPH (between 61,8% and 50%) and ABTS (between 83% and 77%). With respect to the antihypertensive activity, all phenolic compounds showed an inhibition of ACE higher than 40%. Ours results demonstrate that pure phenolic compounds, at concentrations found in fruit or juices, could be used as new sources of safe natural antioxidants and antihypertensive compounds.