Antioxidant Effects of Protocatechuic Acid and Protocatechuic Aldehyde: Old Wine in a New Bottle

Abstract

Phenolic compounds are naturally present as secondary metabolites in plant-based sources such as fruits, vegetables, and spices. They have received considerable attention for their antioxidant, anti-inflammatory, and anti-carcinogenic properties for protection against many chronic disorders such as neurodegenerative diseases, diabetes, cardiovascular diseases, and cancer. They are categorized into various groups based on their chemical structure and include phenolic acids, flavonoids, curcumins, tannins, and quinolones. Their structural variations contribute to their specific beneficial effects on human health. The antioxidant property of phenolic compounds protects against oxidative stress by up-regulation of endogenous antioxidants, scavenging free radicals, and anti-apoptotic activity. Protocatechuic acid (PCA; 3,4-dihydroxy benzoic acid) and protocatechuic aldehyde (PAL; 3,4-dihydroxybenzaldehyde) are naturally occurring polyphenols found in vegetables, fruits, and herbs. PCA and PAL are the primary metabolites of anthocyanins and proanthocyanidins, which have been shown to possess pharmacological actions including antioxidant activity in vitro and in vivo. This review aims to explore the therapeutic potential of PCA and PAL by comprehensively summarizing their pharmacological properties reported to date, with an emphasis on their mechanisms of action and biological properties.

Molecular mechanisms associated with the chemoprotective role of protocatechuic acid and its potential benefits in the amelioration of doxorubicin-induced cardiotoxicity: A review

“…PCA has also been compared to its precursor molecule, protocatechuic aldehyde (PLA)—the parent anthocyanin compound from which PCA is directly generated [18] , [19] . Findings not only demonstrate the antioxidant, anti-cell death, and other pharmacological properties of PCA in rats but these properties of PCA, when compared with those of PLA, were also found to be significantly higher [18] , [19] . Interestingly, the pharmacological properties of PCA, including its metal-chelating properties, show that these DIC events are negatively regulated by PCA [19] .…”

Solvent polarity dictates the anti‐inflammatory potency and mechanism of two purslane ( Portulaca oleracea ) seed extracts

“…The antioxidant assessments of purslane seed extracts revealed that MOH‐extract is more effective as radical‐scavenger, whether in hydrogen atom transfer (HAT) assays like ORAC, or in electron transfer (ET)‐based assays including DPPH, ABST, FRAP and metal chelation. This is not surprising considering the higher content of phenolic compounds that was confirmed by HPLC quantification results, identifying 19 peaks of different phenolic/polyphenolic and flavonoid compounds, particularly protocatechuic acid, a major metabolite of anthocyanins found in green tea and known as potent radical quencher (Zhang et al, 2021). However, the starking result was that the fixed oil extract showed a remarkable reducing capacity of phosphomolybdate, with the minimum IC50 value recorded (50.82 ± 3.4 μg/ml) compared with MOH‐extract that showed a weak reducing capacity with a very high IC50 value (1866 ± 73.8 μg/ml) despite its superior radical‐scavenging power pronounced in other assays, and even to ascorbic acid (134.42 ± 13.4 μg/ml).…”

Anthocyanin: a review of plant sources, extraction, stability, content determination and modifications

“…In addition, Zhang et al . (2021a, 2021b) detected six anthocyanins and their contents in blueberry by HPLC triple quadrupole mass spectrometry. In the positive ion mode, the scanning range was ( m / z ): 100–600.…”

“…This shows that anthocyanins are more stable at low temperature. However, it is worth noting that, although high temperatures degrade anthocyanins and reduce their content, the degradation products are procatechin and catechin, which still have antioxidant effects (Zhang et al, 2021a(Zhang et al, , 2021b. Therefore, high temperatures cannot significantly affect its antioxidant properties.…”