General Description

p-Coumaric acid is a compound found in plants and mushrooms, with mushrooms having significantly higher levels of free p-Coumaric acid. It can exist as free or bound forms, with the bound forms exhibiting greater biological activity. p-Coumaric acid exhibits significant antioxidant and anticancer activities, with similar antioxidant activity as caffeic acid and ferulic acid in food systems and cells. Its anti-cancer properties make it a promising candidate for further research and development in cancer treatment, as it exhibits cytotoxic effects on various tumor cell lines and inhibits angiogenesis-related signaling pathways.

Figure 1. p-Coumaric acid

Dietary Sources

p-Coumaric acid is a compound found in plants, with varying levels depending on the plant source. Free p-Coumaric acid is present at a relatively low level in plants, but some mushroom species, such as Ganoderma lucidum and Termitomyces heimii, have high levels of free p-Coumaric acid, reaching several milligrams per gram, which is nearly a thousand times higher than in fruits. Bound p-Coumaric acidcan be classified as water soluble or water insoluble based on their solubility in water or ethanol aqueous solution. In the water-soluble portion, p-Coumaric acid is conjugated to small molecules like monosaccharides, oligosaccharides, glycerol, organic acids, and amines through esterification. These p-Coumaric acid conjugates exhibit higher abundance and stronger biological activities compared to free p-Coumaric acid. Water-insoluble p-Coumaric acid refers to p-Coumaric acid esterified to long-chain alkyl alcohols, polysaccharides, lignin, or etherified linked to lignin. In summary, dietary sources of p-Coumaric acid include plants and mushrooms, with mushrooms having significantly higher levels of free p-Coumaric acid. p-Coumaric acid can exist as free or bound forms, with the bound forms exhibiting greater biological activity. ¹

Biological Activities

Antioxidant Activity

The phenyl hydroxyl group in p-Coumaric acid is responsible for its antioxidant activity. Compared to its analogs, p-Coumaric acid has a lower scavenging capacity for DPPH, superoxide anion radicals, and H2O2. However, studies show that p-Coumaric acid exhibits similar antioxidant activity as caffeic acid and ferulic acid in food systems and cells. In an in vitro study, Mathew et al compared the reduction potential and free radical scavenging capacity of p-Coumaric acid with 15 other antioxidants. Their results showed that p-Coumaric acid had lower scavenging capacity for DPPH, superoxide, and ABTS radicals, and reducing power than caffeic acid, sinapic acid, and ferulic acid. However, in food systems and cells, p-Coumaric acid showed similar or even higher capacity for eliminating reactive oxygen species than ferulic acid in human lung (A549) and colon adenocarcinoma (HT29-D4) cell lines, indicating that p-Coumaric acid may perform differently in complicated systems such as foods and cells. In summary, while p-Coumaric acid has lower scavenging capacity for certain radicals compared to other antioxidants, it exhibits similar antioxidant activity as caffeic acid and ferulic acid in food systems and cells. ²

Anticancer Activity

p-Coumaric acid has demonstrated significant anti-cancer activity. It exhibits antimutagenesis effects by protecting against reversion mutations induced by H2O2 and 2-amino-3-methylimidazo[4,5-f]quinoline in Salmonella typhimurium strains TA98 and TA102. p-Coumaric acid scavenges hydroxyl radicals, thereby preventing mutagenesis caused by H2O2. Additionally, it reduces the affinity of 2-amino-3-methylimidazo[4,5-f]quinoline to DNA through hydrogen bonding, inhibiting frame-shift mutations. Furthermore, p-Coumaric acid and its conjugates have cytotoxic effects on various tumor cell lines, including neuroblastoma, colon, lung, breast, and liver cancer cells. Antioxidants like p-Coumaric acid can inhibit tumor cell growth by depleting reactive oxygen species, which are essential for tumor cell proliferation. Several studies have shown that p-Coumaric acid moderately inhibits the growth of tumor cell lines, such as neuroblastoma N2a and human lung A549 and colon HT29-D4 cells. It also inhibits angiogenesis-related signaling pathways and reduces the expression of angiogenic factors, thus impeding the permeability, proliferation, migration, and tube formation of endothelial cells. Overall, p-Coumaric acid possess promising anti-cancer properties, making them potential candidates for further research and development in cancer treatment. ³

Reference

1. Pei K, Ou J, Huang J, Ou S. p-Coumaric acid and its conjugates: dietary sources, pharmacokinetic properties and biological activities. J Sci Food Agric, 2016, 96(9): 2952-2962.

2. Mathew S, Abraham TE and Zakaria ZA. Reactivity of phenolic compounds towards free radicals under in vitro conditions. J Food Sci Technol, 2015, 52: 5790–5798.

3. Tehami W, Nani A, Khan NA, Hichami A. New Insights Into the Anticancer Effects of p-Coumaric Acid: Focus on Colorectal Cancer. Dose Response, 2023, 21(1): 15593258221150704.