Abstract
The present study aimed at developing an original pre-column HPLC assay allowing rapid characterization of nitric oxide (NO) scavengers from complex plant extracts. Sodium nitroprusside (SNP) was employed as a NO donor and spiked with an aqueous extract from Aloysia triphylla leaves prior to HPLC analysis. Relying on the ability of radical scavenging constituents to be oxidized upon reaction with radicals, this assay successfully allowed direct identification of three potential NO scavengers, including verbascoside, isoverbascoside, and luteolin-7-O-diglucuronide. These three phenolics were also individually assessed for their NO scavenging activities by using a Griess colorimetric assay. With respective IC50 values of 56 ± 4, 51 ± 3, and 69 ± 5 µg/mL, verbascoside, isoverbascoside, and luteolin-7-O-diglucuronide were all reported as potent NO scavenging compounds, confirming the efficiency of the SNP spiking HPLC assay. The present method can, thus, be considered as a valuable and effective approach for speeding up the discovery of NO scavenging constituents.
Highlights
Nitric oxide (NO) is an important signaling molecule with dual effects
A. triphylla aqueous extract (ATAE) was first assessed for its nitric oxide (NO) scavenging activity by using common colorimetric evaluation. This method relies on the principle that, in aqueous solution and at physiological pH, Sodium nitroprusside (SNP) spontaneously generate NO radicals, which subsequently react with oxygen to produce nitrite ions that can be estimated with Griess reagent
The present study demonstrates, for the first time, that ATAE exerts potent NO scavenging effects, as attested by its low IC50 value of 231 ± 17 μg/mL
Summary
Nitric oxide (NO) is an important signaling molecule with dual effects. Generated by nitric oxide synthases through the conversion of L-arginine to L-citrulline, NO plays a key role in regulating vasodilation, neurotransmission, and the immune system, as well as cardiovascular and renal functions [1,2,3]. In most cases, sufficient to exert these beneficial effects. Overproduction of this free radical may induce several undesired deleterious effects, including inflammatory and autoimmune diseases [4,5]. The search for substances capable of preventing overproduction of NO has, received increasing attention, and numerous extracts of edible and/or medicinal plants have been shown to exert potent NO scavenging activities [6,7]. There is a need to develop new approaches capable of Molecules 2018, 23, 1574; doi:10.3390/molecules23071574 www.mdpi.com/journal/molecules
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