Quercetin, rutin, and their combinations modulate penile phosphodiesterase-5′, arginase, acetylcholinesterase, and angiotensin-I-converting enzyme activities: a comparative study

Abstract

This study demonstrates the effects of rutin and quercetin and their various combinations on phosphodiesterase-5 (PDE-5), arginase, acetylcholinesterase (AChE), and angiotensin-I-converting enzyme (ACE) activities in vitro. The effects of the flavonoids against Fe2+- and sodium nitroprusside (SNP)-induced lipid peroxidation in rats’ corpus cavernosum tissues were also investigated. Quercetin and rutin were dissolved in dimethylsulfoxide (DMSO) to a final concentration of 1 mM each. Thereafter, their combinations (50% quercetin + 50% rutin [Q1:R1]; 75% quercetin + 25% rutin [Q3:R1]; 25% quercetin + 75% rutin [Q1:R3]) were prepared. Our findings revealed that both flavonoids inhibited PDE-5, arginase, AChE, and ACE activities. Rutin exhibited significantly higher inhibitory effects on PDE-5, AChE, and ACE activities compared to quercetin. Considering the combinations, Q1:R3 was more potent compared to Q1:R1 and Q3:R1. Both flavonoids inhibited Fe2+- and SNP-induced lipid peroxidation in rat’s corpus cavernosa tissues. Rutin also showed higher inhibitory effects on Fe- and SNP-induced lipid peroxidation. Similarly, the combinatorial effects of the flavonoids revealed that Q1:R3 significantly inhibited malondialdehyde (MDA) production compared to Q1:R1 and Q3:R1. In conclusion, our findings suggest that the combination of quercetin and rutin is more potent than their individual effect.