lycopene , a biologically occurring carotenoid , exhibits the highest physical quenching rate constant with singlet oxygen ( kq = 31 x 10 ( 9 ) m-1 s-1 ) , and its plasma level is slightly higher than that of beta-carotene ( kq = 14 x 10 ( 9 ) m-1 s-1 ) .
C0007271
carotenoid
C0053396
beta-carotene