Original Research ArticleIdentification of polyphenols in mulberry (genus Morus) cultivars by liquid chromatography with time-of-flight mass spectrometer

- A total of 28 polyphenols were identified in Chinese mulberry cultivars.
- Six polyphenols were identified for the first time in mulberry by HPLC-TOF-MS/MS.
- Two newly found polyphenols had antioxidant and α-glucosidase inhibitory activities.
- Mulberry polyphenols show potential for natural antioxidant developments.

Mulberry, often used both as a medicine and an edible fruit in China, has been found to contain large amounts of polyphenols. Ten representative mulberry fruits were chosen to determine their total phenolic contents, which were from 0.67 to 7.70 mg gallic acid/g fresh weight (FW). To identify the inherent polyphenol, high performance liquid chromatography coupled with quadrupole-time-of-flight mass spectrometer (HPLC-QTOF-MS) was performed, by which a total of 28 polyphenols were identified. Vanillic acid hexoside, 5-p-O-coumaroylquinic acid, 4,5-di-O-caffeoylquinic acid, luteolin hexoside, luteolin rutinoside, and quercetin rhamnosyl dihexoside were tentatively identified in mulberry fruits for the first time. Among them, luteolin hexoside and luteolin rutinoside showed significant positive (P < 0.01) correlation with DPPH and ABTS scavenging activities together with α-glucosidase inhibitory activity. Thus mulberries may be an interesting source of natural antioxidants in food applications.