Structurally Diverse Bisbenzylisoquinoline Alkaloids with Antiadipogenic Activity through PPARγ Downregulation from the Embryo of Nelumbo nucifera Seeds.

Six undescribed and six known bisbenzylisoquinoline alkaloids were isolated from the embryo of Nelumbo nucifera seeds. Their structures were fully characterized by a combination of 1H, 13C NMR, 2D NMR, and HRESIMS analyses, as well as ECD computational calculations. The antiadipogenic activity of 11 alkaloids was observed in a dose-responsive manner, leading to the suppression of lipid accumulation in 3T3-L1 cells. Luciferase assay and Western blot analysis showed that the active alkaloids downregulated peroxisome proliferator-activated receptor gamma (PPARγ, a key antiadipogenic receptor) expression in 3T3-L1 cells. Analysis of the structure-activity relationship unveiled that a 1R,1'S configuration in bisbenzylisoquinoline alkaloids led to a notable enhancement in antiadipogenic activity. The resistance level against lipid accumulation highlighted a consistent pattern with the suppressive effect on the PPARγ expression. These activity results indicate that alkaloids from the embryo of N. nucifera seeds have a potential of antiobesity effects through PPARγ downregulation.

Constructing bifunctional metal-organic framework based nanozymes with fluorescence and oxidase activity for the dual-channel detection of butyrylcholinesterase.

Herein, we reported a novel strategy for the fabrication of bifunctional metal-organic framework based nanozymes (oxidized UiO-66-NH2@Ce), which displayed excellent oxidase mimic activity as well as fluorescence property. The bifunctional oxidized UiO-66-NH2@Ce possess excellent oxidase activity due to oxidase-like active Ce4+/Ce3+ sites, which makes the nanozymes have strong positive charge, resulting in a stronger affinity for the negatively charged chromogenic substrate 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS). Utilizing the bifunctional oxidized UiO-66-NH2@Ce, a sensitive fluorometric and colorimetric dual-channel detection strategy for butyrylcholinesterase (BChE) was fabricated for the first time. The oxidized UiO-66-NH2@Ce could catalyze the oxidation of colorless ABTS to green oxABTS, which in turn quench the fluorescence of oxidized UiO-66-NH2@Ce. Butyrylcholinesterase (BChE) can catalyze the hydrolysis of S-butyrylthiocholine iodide (BTCh) to produce thiocholine, which could prevent the oxidation of ABTS, resulting in the fluorescence of oxidized UiO-66-NH2@Ce recovered. Both the colorimetric and fluorometric dual-channel sensing platform displayed a sensitive response to BChE, and the limits of detection (LOD) for BChE could achieve as low as 0.056 and 0.050U/L, respectively. The dual-output assay for BChE detection displayed excellent application prospects.

TLC-electrostatic field induced spray ionization-MS analysis of diverse structural skeletons and its coupling with TLC bioautography for characterization of lipase inhibitory components in American ginseng.

Natural compounds with diverse structural skeletons have different ionization efficiencies and different mass spectrometry (MS) responses. Some key factors influencing the electrostatic field induced spray ionization (EFISI)-MS for a variety of natural compounds have been optimized and improved. Fifteen reference substances representing ten well-known skeletons of natural products including alkaloids, flavonoids, phenolic acids, lignans, coumarins, anthraquinones, monoterpenoids, sesquiterpenoids, diterpenoids and triterpenoids, were selected and investigated for their EFISI-MSn responses on TLC plates using a dot-blot test. The optimized ionization conditions for these compounds in the positive ion mode were achieved, together with their limits of detection. In addition, to avoid the limitation of some compounds being difficultly ionized in the positive ion mode, the negative ion mode of the TLC-EFISI-MS method was developed and optimized for the first time. By coupling with a TLC bioautographic assay, nine lipase inhibitory components in American ginseng (Panax quinquefolium roots) have been successfully identified/ tentatively identified in situ by their EFISI-MSn data and further confirmed by comparisons of their Rf values and MSn data with those of reference substances. These lipase inhibitory compounds were 24(S)-pseudo-ginsenoside F11, ginsenosides Rg1, Re, XVII, Rc, Rb2/Rb3, Rb1, Ro and malonyl-ginsenoside Rb1. This is the first report that the TLC-EFISI-MSn method is adapted to a broad-spectrum analysis of structural skeletons present in herbal medicines.

Direct coupling of thin-layer chromatography-bioautography with electrostatic field induced spray ionization-mass spectrometry for separation and identification of lipase inhibitors in lotus leaves.

In situ profiling compounds in complex matrices is important technology to develop in analytic chemistry. The aim of this study is to develop a direct coupling method of thin layer chromatography (TLC) to mass spectrometry (MS) via electrostatic field induced spray ionization (EFISI). We proposed a surface treatment method of normal-phase thin layer chromatography (TLC) plates with dimethyl silicone oil coating which successfully allowed TLC to couple to MS via EFISI. Different parameters affecting the ionization efficiency were investigated and optimized, including silicone oil concentrations, air-drying times, applied voltages, and TLC plate types. This optimized TLC-EFISI-MS method was successfully applied to examine lipase inhibitory components present in lotus leaves. Six active alkaloids including three aporphines and three benzylisoquinolines were profiled with their MSn (n = 4) data, or with a comparison with reference substances. This is the first report on the coupling EFISI-MS to TLC or TLC bioautography for in situ identification of active natural products.