Protocatechuic acid abrogates oxidative insults, inflammation, and apoptosis in liver and kidney associated with monosodium glutamate intoxication in rats.

Rami B Kassab,Ola A Habotta,Ehab M Abdella,Khalid E Hassan,Khalaf F Alsharif,Ahmad H Mufti,Maha S Lokman,Mohammad Algahtani,Abdulrahman Theyab,Ali O Al-Ghamdy,Maha A Alshiekheid,Roua S Baty,Ashraf Albrakati,Mohamed M Omran,Amira A Bauomy,Heba A Elmasry,Ahmed E Abdel Moneim

doi:10.1007/s11356-021-16578-4

Abstract

Monosodium glutamate (MSG), a commonly used flavor enhancer, has been reported to induce hepatic and renal dysfunctions. In this study, the palliative role of protocatechuic acid (PCA) in MSG-administered rats was elucidated. Adult male rats were assigned to four groups, namely control, MSG (4 g/kg), PCA (100 mg/kg), and the last group was co-administered MSG and PCA at aforementioned doses for 7 days. Results showed that MSG augmented the hepatic and renal functions markers as well as glucose, triglycerides, total cholesterol, and low-density lipoprotein levels. Moreover, marked increases in malondialdehyde levels accompanied by declines in glutathione levels and notable decreases in the activities of superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase were observed in MSG-treated group. The MSG-mediated oxidative stress was further confirmed by downregulation of nuclear factor erythroid 2-related factor 2 (Nrf2) gene expression levels in both tissues. In addition, MSG enhanced the hepatorenal inflammation as witnessed by increased inflammatory cytokines (interleukin-1b and tumor necrosis factor-α) and elevated nuclear factor-κB (NF-κB) levels. Further, significant increases in Bcl-2-associated X protein (Bax) levels together with decreases in B-cell lymphoma 2 (Bcl-2) levels were observed in MSG administration. Histopathological screening supported the biochemical and molecular findings. In contrast, co-treatment of rats with PCA resulted in remarkable enhancement of the antioxidant cellular capacity, suppression of inflammatory mediators, and apoptosis. These effects are possibly endorsed for activation of Nrf-2 and suppression of NF-kB signaling pathways. Collectively, addition of PCA counteracted MSG-induced hepatorenal injuries through modulation of oxidative, inflammatory and apoptotic alterations.

Highlights

Many chemicals have been recently introduced in food technology such as colorants, preservatives, stabilizers, emulsifiers, sweeteners, and flavor enhancers (Acar)
Marked increases in MDA levels accompanied by declines in GSH levels and notable decreases in the activities of superoxide dismutase (SOD), CAT, GSH peroxidase (GPx), and GSH reductase (GR) were observed in Monosodium glutamate (MSG)-treated group
Rats received the treatment with protocatechuic acid (PCA) displayed notable declines (P < 0.05) in the aforementioned markers when compared with MSG-administered rats

Summary

Introduction

Many chemicals have been recently introduced in food technology such as colorants, preservatives, stabilizers, emulsifiers, sweeteners, and flavor enhancers (Acar). Monosodium glutamate (MSG), the sodium salt of glutamic acid, is one of the frequently used flavor enhancers (E621) to increase food palatability and taste (Mahieu et al 2016). By acting on particular glutamate receptors in the taste buds, it enhances markedly the taste and palatability of food (Hassan et al 2020). It elicits the “umami” taste experience that is recognized in high glutamate foods as meat, fish, cheese, and some vegetables (del Carmen Contini et al 2017). Despite of being reported as safe for human according to the last FDA reports, using of MSG as a food additive is still disputed (Shukry et al 2020). Former reports have revealed that the consumption of MSG was associated with human metabolic syndrome, obesity, and arterial hypertension in addition to various damages in the liver, brain, thyroid, and kidney (Elbassuoni et al 2018, Mekkawy et al 2020, Nahok et al 2019)

Methods

Results

Discussion

Conclusion