Free radical scavenging and COX-2 inhibition by simple colon metabolites of polyphenols: A theoretical approach

•3-Hydroxyphenylacetic and 4-hydroxyphenylpropionic acid were theoretically studied.•These colon metabolites of polyphenols exert high free radical scavenging potency.•Docking analysis indicated dianions of these acids as potent inhibitors of COX-2.•As abundant metabolites, these acids could be effective in situ anticancer agents.