Coumarins – found as coumaric acid – are very powerful anti-oxidants that smell like either vanilla or freshly mown hay (it’s what smells nice after clover is cut). Because of this lovely smell, it’s often used in perfumes and fragrance oils.
Coumarins are good anti-inflammatories, and they reduce both oedema and redness on our skin. They are anti-bacterial and may offer anti-fungal activity. Some studies have shown promise using coumarins to treat Candida albicans, although “more study needs to be done” (in other words, they’re not sure).