Widely distributed in plants, flavonoids reduce the incidence of cancer and cardiovascular disease. In this study, flavonoid content and composition in members of the Prunus genus were evaluated using liquid chromatography with diode array and electrospray ionization mass spectrometric detection (UPLC-DAD-ESI/QTOF-MS). Flavonoids in plants of the Prunus genus include the basic structures of kaempferol, quercetin, and catechin, and exist as mono-, di-, or tri-glycoside compounds mono-acylated with acetic acid. A total of 23 individual flavonoids were isolated and confirmed, three of which appear to be newly identified compounds: quercetin 3-O-(2″-O-acetyl)neohesperidoside, quercetin 3-O-(4″-O-acetyl)rutinoside, and kaempferol 3-O-(4″-O-acetyl)rutinoside. Japanese apricot and Chinese plum contained the highest amounts of flavonoids in the Prunus genus. During the ripening stage of Japanese apricot, the total flavonol content was reduced, while the catechin content was increased.

The chili pepper (Capsicum annuum L.) is a food source that is rich in flavonoids such as luteolin and apigenin. Flavonoids are known to have anti-inflammatory and antioxidant activities; however, studies on the flavonoids composition identified and the anti-inflammatory and antioxidant effects in pepper leaves (PL) and fruits (PF) are insufficient. In the present study, we investigated the antioxidant and anti-inflammatory effects in vitro, and the flavonoids contents of the PL and PF. Pepper extracts showed radical scavenging activities and ameliorated the lipopolysaccharide (LPS)-stimulated inflammatory response by decreasing nitric oxide production and interluekin-6 and tumor necrosis factor alpha levels in RAW 264.7 cells, with more effective activities noted for PL than for PF. Furthermore, PL extracts markedly inhibited the LPS-induced production of reactive oxygen species accumulation. The flavonoid profile and content of pepper were dependent on the part, with PL showing higher total flavonoids than PF. In particular, the content of luteolin glycosides in PL was twice that in PF. Thus, PL may be useful to prevent oxidative stress and inflammation-related diseases.

Most previous studies have been focused on the variation of tea chemical composition by fermentative processes as well as different cultivars and regions. The detailed changes of flavonoid profiles were described for the first time by each processing step of green and black tea leaves in this study. A total of 24 flavonoid derivatives including catechins, theaflavins, and flavonols were separated and identified from the tea samples based on UPLC-DAD-QToF/MS data and constructed library. Among these, the fragmentation pathway of theaflavins was proposed specifically in positive ionization mode for structural interpretation. During leaf processing, the individual flavonols were changed as diverse patterns according to their aglycone types and glycosylated forms, but their total content showed a slight difference. EGCG and ECG were increased after roasting approximately twofold higher than that of fresh leaves (EGCG, 2709.5 →6085.6; ECG, 1548.0 →2318.2 mg/100 g dry weight, respectively) in green tea while considerably decreased their contents due to oxidation and conversion to theaflavins after fermentation during black tea processing. Especially, the drying steps also found to be factor to influence positively to increase the flavonoid contents in both tea processing. Therefore, this result indicated that detailed conditions of each processing step played important roles in changing the flavonoid profiles from tea leaves.

Zingiberaceae is the large diverse family comprised of rhizomatous plants with a higher concentration of phenolic compounds. The normal ginger (Zingiber officinale Rosc.) and black ginger (Kaempferia parviflora Wall.) belongs to this family and have similar morphological characteristics of rhizome, but their phenolic composition revealed differently. On this study, the phenolic composition of normal ginger (from Ethiopia and Korea) and black gingers (from Korea and Thailand) were profiled using ultra performance liquid chromatography coupled with diode array detector, quadrupole time-of-flight mass spectrometry (UPLC–DAD–QToF–MS). The result revealed that gingerol-related phenolic acid was detected only in normal gingers while, the methoxyflavones were identified exclusively in black gingers. 6-gingerol, 8-gingerol, 10-gingerol, 1-dehydro-6-gingerdione, and diacetoxy-8-gingerdiol were the major constituents among 18 phenolic acids detected from normal gingers, and 3,5,7,3′,4′-pentamethoxyflavone and 5,7,4′-trimethoxyflavone were confirmed as predominant constituents among 13 methoxyflavones from black gingers. The total phenolic content was 434.7 and 698.1 mg/100 g dry weight (DW) in Korean and Ethiopian sample, respectively. The total methoxyflavone concentration was 4388.0 mg/100 g DW and 3940.2 mg/100 g DW in Korean and Thai black ginger sample, respectively. The higher concentration of methoxyflavones is from advanced biosynthetic pathway related to accumulated color of black ginger. In addition, new possible structural fragmentation was proposed for gingerol homologous series as additional pathway under the positive ionization mode, and further rationalized that ferulic acid moiety is the biosynthetic precursor. The result suggested that despite the morphological similarity, normal and black ginger showed distinct biosynthetic difference to synthesis their major secondary metabolites.