Cellular bound beta-carotene quenches singlet oxygen in man

It is often postulated that a major role of carotenoids in biology and medicine involves their ability to quench a toxic form of oxygen, known as singlet oxygen, although direct observations of such mechanisms do not exist. Using beta-carotene, bound to lymphocytes taken from human blood, we have used a direct, pulsed laser, physical chemical technique and, separately, a biological method to show a particularly efficient quenching reaction of singlet oxygen by carotene in a cellular environment.