Synephrine

Deionized water was used for HPLC-Q-TOF-MS and HPLC-Q-TOF-MS/MS analysis and was purified using a Milli-Q system (Merck Millipore, Billerica, MA, USA). HPLC-grade acetonitrile and formic acid were purchased from Merck (Darmstadt, Germany) and ROE (Newark, New Castle, USA), respectively. Methanol (AR) was purchased from the National Institutes for Food and Drug Control (Beijing, China). The seventeen reference substances (seven flavonol glycosides, three flavonols, two polymethoxyflavonoids, three coumarins, one alkaloid, and one limonin), including synephrine (15), neoeriocitrin (36), poncirin (39), eriocitrin (40), naringin (42), naringenin (43), narirutin (44), neohesperidin (51), hesperidin (56), apigenin (59), hesperitin (61), xanthotoxol (71), scopoletin (76), auraptene (80), limonin (79), nobiletin (85), and tangeretin (87) were purchased from Shanghai Yuanye Bio-Technology Co., Ltd. (Shanghai, China).

The peach leaf orange was picked from Longmaxi Village, Quyuan Town, Zigui County (Hubei, China) on 3 September 2019; the Qingzhuan tea (loose tea) was provided by Zigui Yihong Tea Co., Ltd. (Hubei, China)
Folin phenol, ninhydrin, methanol, anhydrous ethanol, anthrone, sulfuric acid, potassium dihydrogen phosphate, disodium hydrogen phosphate, sodium carbonate, oxalic acid, ethyl acetate, n-butanol, stannous chloride, Coomassie brilliant blue G250, sodium chloride, and phosphoric acid were all of analytical grade and purchased from China Pharmaceutical (Group) Shanghai Chemical Reagent Company (Shanghai, China). Bovine serum albumin BSA, α-glucosidase, α-glucoside, rutin, limonin, synephrine, hesperidin, and cyclohexanone standard products were purchased from Shanghai Yuanye Biotechnology Co., Ltd. (Shanghai, China). ABTS, FRAP, and DPPH antioxidant kits were purchased from Suzhou Keming Biotechnology Co., Ltd. (Suzhou, Jiangsu, China). α-amylase activity detection reagent cartridges were purchased from Solarbio Co., Ltd. (Beijing, China).

SMD, used for gastrointestinal dysmotility in China (approval number: guo-yao-zhun-zi Z20025044; specification: 10 mL/division), was obtained from Hunan Hansen Pharmaceutical Company, Ltd. (Yi Yang, China). HSA was acquired from Sigma Chemical Co. (St. Louis, MO, USA), standards, including arecaidine, arecoline, norisoboldine, linderane, costunolide, dehydrocostus lactone, synephrine, rutin, limonin, eriocitrin, narirutin, naringin, hesperidin, heohesperidin, poncirin, naringenin, hesperetin, nobiletin, tangeretin, and sorbic acid with a purity of over 98%, were purchased from Yuan-ye Bio-Technology Co., Ltd. (Shanghai, China). The formic acid, acetonitrile, and methanol used for HPLC analysis were chromatographic grade and purchased from Sinopharm Chemical Reagent Co., Ltd. (Shanghai, China).