curcumin

n. (Chem.) The coloring principle of turmeric, or curcuma root, extracted as an orange yellow crystalline substance, C14H14O4, with a green fluorescence. [ 1913 Webster ]

☞ It possesses acid properties and with alkalies forms brownish salts. This change in color from yellow to brown is the characteristic reaction of tumeric paper. See Turmeric paper, under Turmeric. [ 1913 Webster ]