Antioxidant capacity and phenolic compounds of Lonicerae macranthoides by HPLC-DAD-QTOF-MS/MS

Lonicerae macranthoides with strong antioxidant activity is commonly used in traditional Chinese medicine and folk tea/beverage. However, detailed information about its antioxidant activity and bioactive compounds is limited. Then at first, we comparatively evaluated total phenolic content (TPC), total flavonoid content (TFC) and antioxidant activities of water extract, petroleum ether, ethyl acetate and n-butanol fractions of L. macranthoides. Ethyl acetate fraction exhibited the highest level of TPC (207.38 mg GAE/g DW), TFC (53.06 mg RE/g DW) and the best DPPH center dot scavenge activity and reducing power. n-Butanol fraction showed the best ABTS(center dot+) and O-2(center dot-) scavenging activities. Interestingly, water extract, ethyl acetate and n-butanol fractions showed stronger antioxidant activities than positive control, butylated hydroxytoluene (BHT). After that, thirty-one antioxidant phenolic compounds, including twenty-two phenolic acids and nine flavonoids, were screened by DPPH center dot-HPLC experiment and then identified using HPLC-DAD-QTOF-MS/MS. It is noted that twenty-one compounds (1, 3-4, 6-17, 19, 23, 26, 28-29, and 31), as far as was known, were discovered from L. macranthoide for the first time, and eleven of them (3-4, 10-17, and 23) were reported in Lonicera species for the first time. Results indicated that L. macranthoides could serve as promising source of rich antioxidants in foods, beverages and medicines for health promotion. (C) 2016 Elsevier B.V. All rights reserved.