Coumaric acid

Coumaric acids are natural metabolites belonging to the family of hydroxycinnamic acids, and p-CouA (4-hydroxycinnamic acid) is the most abundant isomer. p-CouA is a yellowish-green crystalline powder with a molecular formula of C9H8O3.27,28. In plants, p-CouA exists in free or conjugated forms and is a precursor of other phenolic compounds.

p-CouA is widely found in edible plants, mushrooms, vegetables (eg, tomatoes, carrots, garlic, onions, potatoes), fruits (eg, grapes, apples, pears), grains (eg, wheat, oats, rice, corn, peanuts), and in beverages (eg, teas, coffee) {ref}

Synergy

"cytotoxic activity was related to the synergistic anticancer effects of the mixture of coumaric acid, kaempferol, apigenin, hydroxyursolic, ursolic, and betulinic acid plus the stilbenes resveratrol " {ref}