Sesquiterpenoids from the roots of Aucklandia costus and their anti-inflammatory activities.

Five undescribed sesquiterpenoid dimers, aucklandiolides A-E (1-5), one new sesquiterpenoid glycoside, ß-cyclocostunolide-15-ß-D-glucopyranoside (6), and seventeen known analogues (7-23) were isolated from the roots of Aucklandia costus. Their structures were elucidated by comprehensive HRESIMS and NMR spectroscopic data analysis, and their configurations were confirmed by the computational calculations of ECD and NMR chemical shifts. Aucklandiolides A and B are the first examples of dimeric sesquiterpenoids with a unique 6/6/6/5/6/6 ring system originated from a proposed Diels-Alder cycloaddition between two eudesmane sesquiterpenoids. Besides, compounds 9-11, 20, and 22 showed significant inhibition of nitric oxide production in LPS-stimulated RAW 264.7 cells at a concentration of 20 µM.

Calycindaphines A-J, Daphniphyllum alkaloids from the roots of Daphniphyllum calycinum.

Ten new Daphniphyllum alkaloids, calycindaphines A-J (1-10), together with seventeen known alkaloids were isolated from the roots of Daphniphyllum calycinum. Their structures were established by extensive spectroscopic methods and compared with data from literature. Compound 1 is a novel alkaloid with a new rearrangement C22 skeleton with the 5/8/7/5/5 ring system. Compound 2 represents the second example of calyciphylline G-type alkaloids. Compound 10 is the first example of secodaphniphylline-type alkaloid absent of the oxygen-bridge between C-25/C-29. The possible biogenetic pathways of 1 and 2 were also proposed. All the isolated compounds were evaluated for their bioactivities in three cell models. Compounds 22, 23, and 26 showed significant NF-κB transcriptional inhibitory activity at a concentration of 50 µM. Compounds 16 and 18 exhibited significant TGF-ß inhibitory activity in HepG2 cells. Compounds 24 and 26 induced autophagic puncta and mediated the autophagic marker LC3-II conversion in HEK293 cells.

Hydroquinone colorimetric sensing based on platinum deposited on CdS nanorods as peroxidase mimics.

Pt deposited on CdS nanorods (Pt/CdS) have been prepared via the UV light photoreduction method. The Pt/CdS nanocomposites possess highly significant peroxidase-like activity with the assistance of the colorless substrate 3,3,5,5-tetramethylbenzidine (TMB). In the presence of peroxidase mimic Pt/CdS, TMB is quickly oxidized into a typical blue product (oxTMB, which has an obvious absorption at 652 nm) by H2O2 only in 3 min, which is easily detected visually. The catalytic activity of Pt/CdS originates from the accelerated electron transfer between the reactants. Combining the peroxidase-like activity of Pt/CdS with the blue change of TMB, a fast colorimetric sensing platform for detection of H2O2 has been constructed with a linear range 0.10-1.00 mM and a detection limit of 45.5 µM. The platform developed is further used to detect hydroquinone (HQ) in the range1.0-10 µM with a lower detection limit of 0.165 µM. The colorimetric platform has a potential to detect HQ residue in real water samples with recoveries ranging from 83.56 to 91.76%. Graphical abstract.

Porphyrin functionalized Co(OH)2/GO nanocomposites as an excellent peroxidase mimic for colorimetric biosensing.

5,10,15,20-Tetrakis(4-carboxyl phenyl)porphyrin (Por) modified Co(OH)2 deposited on the surface of GO nanocomposites (Por/Co(OH)2/GO) were prepared and characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and XRD. For the first time, H2TCPP/Co(OH)2/GO is found to have enhanced peroxidase-like activity and catalyze the oxidation of the substrate 3,3,5,5-tetramethylbenzidine (TMB) by hydrogen peroxide (H2O2). Notably, the colorless TMB rapidly transformed into blue oxTMB in just 60 s, which was easily observed visually. The catalytic kinetics of H2TCPP/Co(OH)2/GO is in accord with the Michaelis-Menten equation. The catalytic mechanism of H2TCPP/Co(OH)2/GO nanocomposites is attributed to hydroxyl radicals (˙OH), due to decomposition of H2O2, which is verified by using terephthalic acid as a fluorescent probe. What's more, H2O2 can be detected in a wide linear detection range from 5 to 35 mM with a detection limit of 0.385 mM. Furthermore, based on the excellent peroxidase-like activity of H2TCPP/Co(OH)2/GO, a colorimetric sensor is established to sensitively detect glutathione (GSH) in a linear range from 10 to 300 µM with a low detection limit of 9.5 µM.