PTGS2 and obesity due to melanocortin 4 receptor deficiency: These include the cancer chemopreventive activity of xanthohumol [25,26], estrogenic activity of 8-prenylnaringenin [25,27], cyclooxygenase-2 inhibition of humulone (an α-acid) [28], and prevention of diet-induced obesity of iso-α-acids [11].