Fast Separation and Sensitive Quantitation of Polymethoxylated Flavonoids in the Peels of Citrus Using UPLC-Q-TOF-MS

Abstract

A rapid, sensitive, and efficient ultraperformance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) method has been developed to analyze polymethoxylated flavonoids (PMFs) in 14 Citrus peels, including 7 Citrus reticulata (C. reticulata) and 7 Citrus sinensis (C. sinensis). In this study, fast separation can be achieved within 12 min and 42 PMFs have been identified including 33 flavones and 9 flavanones. Most C. reticulata were shown to contain more than 20 PMFs, except Guangxihongpisuanju (GX) containing only 12 PMFs, while most C. sinensis contained fewer than 20 PMFs, except Edangan (EG) containing as many as 32 PMFs. To our knowledge, there are few reports about the quantitation of PMFs using the MS response. Here, a MS quantitative method was established and systematically validated in linearity, precision, and recovery. The linearity was from 1.25 ng/mL to 1.0 μg/mL with the limit of detection (LOD) as low as 75 pg/mL and the limit of quantitation (LOQ) as low as 0.25 ng/mL. Up to 13 PMFs, more types than ever before, were undoubtedly identified and quantitated according to the PMF standards. The results showed that the contents of PMFs in the C. reticulata were generally higher than those in the C. sinensis. This study is systematic for analyzing PMFs and is of great significance because it can provide guidance on utilization of both PMFs and citrus germplasm resources in the future.

Characterisation and classification of Citri Reticulatae Pericarpium varieties based on UHPLC‐Q‐TOF‐MS/MS combined with multivariate statistical analyses

“…They possess the basic aglycone structure and vary in the number and position of hydroxyl groups (‐OH) and/or methoxyl groups (‐OCH 3 ) on the A, B and C rings of the aglycone. Furthermore, they tend to form the diagnostic fragments of [M + H – n CH 3 ] + , [M + H – 2CH 3 – H 2 O] + , [M + H – 2CH 3 – CO] + , and so on . Here, a total of 37 PMFs were screened in CPR.…”

Efficient analysis of phytochemical constituents in the peel of Chinese wild citrus Mangshanju (Citrus reticulata Blanco) by ultra high performance liquid chromatography–quadrupole time‐of‐flight‐mass spectrometry

“…The RDA cleavage of C‐ring yielded the ions at m/z 136.0159 ([ 1,3 A + –CH 3 ]) and 121.0284 ([ 1,2 A + –CH 3 –CO]), indicating that A‐ring contained one hydroxyl group and B‐ring contained two hydroxyl groups and one methoxyl group. So compound 32 was tentatively assigned as 3′,4′‐dihydroxy‐7,5′‐dimethoxyflavone, which has been reported before in citrus . Compound 52 with the [M+H] + ion at m/z 299.0912 was similar to compound 32 and was suggested to be 5‐hydroxy‐7,4′‐dimethoxyflavone.…”

“…According to their structure difference, PMFs can be divided into polymethoxylated flavones, polymethoxylated flavanones, polymethoxylated chalcones, and so on. As for the identification of PMFs, the basic procedure is summarized as shown in Figure and was reported previously by our group . Besides, the fragmentation pattern of polymethoxylated flavones was different from that of polymethoxylated flavanones/chalcones.…”

“…identified 32 bioactive compounds in Ponkan peel, such as flavonoid‐ O ‐glycosides, flavone‐ C ‐glycosides, and polymethoxyflavones based on UHPLC–Q‐TOF‐MS and the separation was achieved within 7 min . Recently, our group analyzed and identified 42 polymethoxylated flavonoids (PMFs) in 14 citrus peels using UHPLC–Q‐TOF‐MS with a fast separation of 12 min . Many reports on phytochemical constituents in citrus are based on commercial citrus cultivars, whereas studies on Chinese wild citrus genotypes are much fewer, especially concerning their distinctive compounds .…”

Evaluation of chemical components in Citri Reticulatae Pericarpium of different cultivars collected from different regions by GC–MS and HPLC

“…In recent studies, lots of attention is being paid to flavonoids because of its anticancer, antioxidant, anticonvulsant, and anti-inflammatory properties (Chang et al, 2015;Devi et al, 2015;Dimpfel, 2006;Fu et al, 2017), whereas few on volatile oils which have abundantly valid biological activities on CRP (Duan et al, 2016;Yi, Dong, Liu, Yi, & Zhang, 2015). So far, there were a group of analyses of flavonoids including constituents and contents, and the results indicated obvious differences in CP and GCP (Lin, Li, Ho, & Lo, 2012;Liu et al, 2013;Xing, Zhao, Zhang, & Li, 2017;Zhang et al, 2012;Zheng et al, 2009Zheng et al, , 2013.…”