Characterization of stress degradation products of curcumin and its two derivatives by UPLC–DAD–MS/MS

Curcumin and its two derivatives of PB-3 and DY-1 were subjected to the forced degradation studies under the conditions of hydrolysis (acidic and alkaline), oxidation, photolysis, and thermal stress recommended by ICH Q1A (R2) by means of UPLC-DAD-MS/MS. Three analytes and their degradation products were separated on a column of ACQUITY UPLC (R) BEH C-18 (100 mm x 2.1 mm, 1.7 mu m) with an in-line filter prior to the column using acetonitrile and 10 mM ammonium acetate buffer (pH adjusted to 3.5) as a mobile phase. Both curcumin and DY-1 showed extensive degradation under alkaline condition and gave rise to two degradation products for curcumin and three for DY-1, respectively, while no degradation product was observed under other tested conditions. PB-3 was found to be unstable in acid and alkaline conditions, two degradation products in acidic hydrolytic condition and one in alkaline condition were obtained, while it was stable in photolytic, oxidative and thermal stress conditions. The degradation products of three analytes were characterized as follows by analyzing the mass fragmentation patterns of curcumin and mass analysis of the degradation products: ferulic acid and vanillin for curcumin, 3-methoxyl-4-[3-(1-tetrahydropyrrolyl)propoxyl] benzoic aldehyde, 2,2-di-(1-phenylmethyl)-3-oxo-5-[3-methoxyl-4-(3-tetrahydropyrolylpropoxyl)] pent-4-enoic acid, and tetrapyrolyl propoxyl methoxyl phenyl prop-2-enoic acid for PB-3, 3-oxo-5-[4-hydroxyl-5-methoxyl-3-(1-morpholinylmethyl)] pent-4-enoic aldehyde, 3-oxo-5-(4-hydroxyl-5-methoxyl-3-(1-morpholinylmethyl)) pent-4-enoic acid and 2-hydroxyl-3-methoxyl-5-(7-(3-methoxyl-4-hydroxylphenyl)-3,5-dioxo-4,4-dimethyl hept-1,6-dienyl) benzoic acid for DY-1, respectively. The degradation pathways of curcumin and its derivatives were presented in addition. (C) 2016 The Authors. Published by Elsevier B.V. on behalf of King Saud University.