Simultaneous Analysis of Six Polymethoxyflavones and Six 5‑Hydroxy-polymethoxyflavones by High Performance Liquid Chromatography Combined with Linear Ion Trap Mass Spectrometry

Polymethoxyflavones (PMFs) and monohydroxylated polymethoxyflavones (OH-PMFs) exist exclusively in the citrus genus, particularly in citrus peels. Currently, due to the broad application of PMFs and OH-PMFs in nutraceuticals, pharmaceuticals, and functional foods, their identification and quantification will be of great significance and the first criteria to meet. We have developed a validated method with high performance liquid chromatography coupled with linear ion trap mass spectrometry. The method was fully validated in linearity, precision, accuracy, and recovery. Six PMFs and their monohydroxyl counterparts, six 5-OH-PMFs, were simultaneous analyzed within 20 min for the first time. The LOD (limit of detection) and LOQ (limit of quantitation) were calculated as 0.02–0.23 and 0.05–0.76 μg/mL, respectively. The method was performed on the samples of acid treated citrus peel extracts. The citrus peel extracts with high content of PMFs and 5-OH PMFs may provide reliable and economical resources in biological activity studies and development of health beneficial products

Pu-erh Tea Extract Attenuates Nicotine-Induced Foam Cell Formation in Primary Cultured Monocytes: An in Vitro Mechanistic Study

In this study, the mechanisms by which pu-erh tea extract (PETE) attenuates nicotine-induced foam cell formation were investigated. Monocytes were purified from healthy individuals using commercial antibodies coated with magnetic beads. We found that the nicotine-induced (1–10 μM) expression of oxidized low-density lipoprotein receptors (ox-LDLRs) and α9-nAchRs in monocytes was significantly attenuated by 24 h of PETE (10 μg/mL; ∗, <i>p</i> < 0.05) cotreatment. Nicotine (1 μM for 24 h) significantly induced the expression of the surface adhesion molecule ICAM-1 and the monocyte integrin adhesion molecule (CD11b) by human umbilical vein endothelial cells (HUVECs) and triggered monocytes to differentiate into macrophages via interactions with the endothelium. After treatment with nicotine (0.1–10 μM for 24 h), the HUVECs released chemotactic factors (IL-8) to attract monocytes into the tunica intima of the artery, and the monocytes then transformed into foam cells. We demonstrated that PETE treatment (>1 μg/mL for 24 h; ∗, <i>p</i> < 0.05) significantly attenuates nicotine-induced (1 μM) monocyte migration toward HUVECs and foam cell formation. This study suggests that tea components effectively attenuate the initial step (foam cell formation) of nicotine-induced atherosclerosis in circulating monocytes