Purification of caffeoylquinic acids from sweet potato leaves and their analysis by high performance liquid chromatography

Six caffeoylquinic acid ( CQA) derivatives were separated by semi- preparative high performance liquid chromatography (HPLC) from sweet potato leaves. The structures of prepared monomers were confirmed by 1H NMR and electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS) , and the components and total polyphenol contents of different sweet potato leaves were analyzed. The results demonstrated that sweet potato leaf polyphenols were mainly caffeoylquinic acid and its derivatives. The composition of different varieties of sweet potato leaves were basically the same, the main component were six CQA derivatives, including 3- CQA, 4- CQA, 5- CQA, 3, 4- di CQA, 3, 5- di CQA and 4, 5- di CQA, and the contents of total polyphenol were different in various groups. Overall, this HPLC method was accurate for investigation of the polyphenol contents and components in sweet potato leaves, and lay down a base for the choice of production material.