Gallic acid: a versatile antioxidant with promising therapeutic and industrial applications

Abstract

Oxidative stress, a result of an overproduction and accumulation of free radicals, is the leading cause of several degenerative diseases such as cancer, atherosclerosis, cardiovascular diseases, ageing and inflammatory diseases. Polyphenols form an important class of naturally occurring antioxidants, having innumerable biological activities such as anticancer, antifungal, antibacterial, antiviral, antiulcer and anticholesterol, to name a few. Among various polyphenols, gallic acid (3,4,5-trihydroxybenzoic acid), a naturally occurring low molecular weight triphenolic compound, has emerged as a strong antioxidant and an efficient apoptosis inducing agent. Starting from the bioavailability and the biosynthetic pathway of gallic acid, this review includes various in vitro, in vivo and in silico studies providing the mode of action, radical scavenging activity, ability to inhibit lipid peroxidation, maintenance of endogenous defense systems and metal ion chelation by this triphenolic molecule, along with a comprehensive overview of factors responsible for its high antioxidant activity. Gallic acid derivatives have also been found in a number of phytomedicines with diverse biological and pharmacological activities, including radical scavenging, interfering with the cell signaling pathways and apoptosis of cancer cells. The diverse range of applications of this simple polyphenol is due to a fine amalgam between its antioxidant and prooxidant potential. The existing literature on this dual behavior of gallic acid and its derivatives is reviewed here. This is followed by an account of their potential clinical and industrial applications.

Microwave-assisted green synthesis of superparamagnetic nanoparticles using fruit peel extracts: surface engineering, <em>T</em>₂ relaxometry, and photodynamic treatment potential

“…Peels of pomegranate, lemon, orange, and apple are the major sources of vitamins C and A, 10 whereas pomegranate peels contain antioxidants, especially polyphenols. 41,42 Using fruit waste as a cheaper bioreductant is a fascinating, simple, and green approach.…”

“…Broad absorbance peak may likely result from various capping agents coming from different natural compounds. 10,27,29,42,45 The proceeding reaction could be envisioned via color changes in the resulting colloidal solution. Phytochemicals bound to the surface of bio-SPIONs are rich in hydrophilic hydroxyl groups that allowed the NPs to disperse and distribute homogenously in aqueous media (Table S1).…”

“…[8][9][10] Moreover, these processes mostly end up with hydrophobic nanoparticles (NPs), which are often subjected to surface engineering, making them water dispersible. [11][12][13] The absorption of NPs produced by hydrophobic polymers is greater than that of NPs produced by hydrophilic polymers.…”

β‐cyclodextrin encapsulated polyphenols as effective antioxidants

“…GA forms a free radical at the C4 hydroxyl position which is stabilized by the two adjacent AOH groups via intramolecular hydrogen bonding. [79] This ease of formation of free radicals and subsequent stabilization makes GA an essential candidate for prevention of oxidative stress. Our experiment showed that the other two polyphenols (ECG and EGCG) possess greater antioxidant activity over GA both in the free and encapsulated state.…”

Modelling of Protective Mechanism of Iron(II)-polyphenol Binding with OH-related Molecular Descriptors

“…HE protective action of polyphenols is well known, [1][2][3][4][5] but the mode of their action has not yet been sufficiently explained. There are general reaction mechanisms for scavenging of radicals by polyphenols, such as single-step hydrogen atoms transfer (HAT), single electron transfer followed by proton transfer (SET-PT) and sequential proton loss electron transfer (SPLET).…”