Identification and Quantification of Polymethoxylated Flavonoids in Different Citrus Species Using UPLC-QTOF-MS/MS and HPLC-DAD

Abstract

Many species from the genus Citrus are used in traditional medicine and contain polymethoxylated flavonoids. These compounds show anti-inflammatory and chemopreventive activities, among others, and therefore have a big potential to be developed as therapeutic agents or dietary supplements. Citrus species are different in their profile and yield of polymethoxylated flavonoids. Therefore, polymethoxylated flavonoids were identified and quantified in seven different Citrus species, including wild-type and commercially available species. All species were profiled using UPLC-QTOF-MS/MS analysis combined with mass spectral molecular networking. A total of 38 polymethoxylated flavonoids were detected and 8 of them were present in every species. As the yield of polymethoxylated flavonoids was different for each species, a generally applicable HPLC-diode array detection method was developed and validated according to the ICH guidelines to quantify the amount of nobiletin and the total amount of polymethoxylated flavonoids expressed as nobiletin. Analysis of the seven samples showed evidence that wild-type Citrus species (e.g., Citrus depressa) contain higher yields of polymethoxylated flavonoids compared to commercially available species (e.g., Citrus limon). Qualitative analysis revealed the broadest variety of different PMFs in C. depressa, Citrus reticulata, and Citrus reticulata × Citrus sinensis, which makes them interesting sources of polymethoxylated flavonoids for future development as therapeutic agents or dietary supplements.

Characterization of a Caffeic Acid 8-O-Methyltransferase from Citrus and Its Function in Nobiletin Biosynthesis

“…Citrus fruits are a good source of PMFs. In recent years, along with the development of UPLC and high-resolution mass spectrometry, PMF profiles were characterized in more than 100 citrus varieties. − In citrus fruit, PMF contents varied greatly among different varieties. Peng et al reported that C.…”

“…Because of the high amounts of PMFs, citrus peels, also known as chen pi or ju pi , have been used as herbal drugs in the traditional medicines for thousand years. Recently, along with the development of UPLC technology and high-resolution mass spectrometry, much progress has been made in the identification and qualification of PMFs in citrus. − In the study of Xing et al, a total of 42 PMFs were undoubtedly or tentatively identified in seven Citrus reticulata (C. reticulata) and seven Citrus sinensis (C.…”

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Nobiletin (3′,4′,5,6,7, is a polymethoxylated flavonoid specifically accumulated in citrus fruit with numerous beneficial effects to human health. In this study, a novel O-methyltransferase (CitOMT2) was isolated from three citrus varieties, Ponkan mandarin (Citrus reticulata Blanco), Nou 6 ("King mandarin" × "Mukaku-kishu"), and Satsuma mandarin (Citrus unshiu Marc.

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An integrated multi‐system to screen quality markers of blossom of Citrus aurantium L. var. amara Engl. via combining lipid‐lowering and expectorant assays

“…As shown in Figure S1A, compound 73, by the RDA producing a DPI at 151 Da and through the NL of 30 Da (CH 3 OH) and 28 Da (CO), was identified as tetrahydroxytrimethoxyflavone based on the literature (Li et al, 2022). Compounds 71, 93, 138 and 144 were analyzed with similar fragmentation behaviors of polymethoxylated flavonoids and then were identified through the literature (Brits et al, 2019(Brits et al, , 2021. with known types of coumarins (Xiao et al, 2020;Zhao, Guo, et al, 2020).…”

On‐site analysis and rapid identification of citrus herbs by miniature mass spectrometry and machine learning

“…12 Then, techniques like liquid chromatography-mass spectrometry (LC/MS) and GC/MS have become prevalent. [13][14][15] Alongside these, rapid identification methods for natural medicines, including Raman spectroscopy, electronic tongue, and electronic nose, [16][17][18] have been developed. However, GC/MS and LC/MS methods often necessitate complex sample preparation and prolonged chromatographic separation, limiting their mobility and applicability in field settings due to the cumbersome nature of the equipment.…”