ABSTRACT
A novel Schiff base probe 4'-hydroxy-3'-((2-pyridin-2-ylmethylimino) methyl)-4-biphenyl carbonitrile (HPBC) for dual sensing of Zn2+and CN-was synthesized and characterized by various techniques such as UV-Vis, fluorescence, HRMS and NMR spectroscopy. HPBC was highly selective toward these two ions with different fluorescence signals in two different media. In EtOH-H2O(2:3,V/V;HEPES,pH 7.4),HPBC selectively bound Zn2+to form a 1:1 ligand/metal complex. Addition of Zn2+to the solution of HPBC resulted in a blue shift (△λ=15 nm) with a pronounced fluorescence enhancement at 468 nm, while there was no enhancement in the presence of other metal ions,especially Cd2+. HPBC displayed an"ON-OFF-ON"mode fluorescence change with alternative addition of Zn2+and EDTA. Hence, HPBC is a reversible and reusable sensor for Zn2+. The dynamic range of the assay is linear up to 4.0 μmol/L Zn2+ion and the limit of detection was 36.5 nmol/L,which was thousand fold lower than the WHO guideline (about 76 μmol/L) for drinking water. The fluorescence response of HPBC toward Zn2+was pH-dependent, and the maximal signal was observed at near neutral pH values, which makes it suitable for application in physiological conditions. Cell imaging studies demonstrate that this sensor is capable of sensing Zn2+in living cells. In DMSO-H2O (3:7,V/V) medium,addition of cyanide ion to HPBC led to deprotonation of the phenol hydrogen,resulting in a color change from colorless to pale yellow and a significant fluorescence enhancement at 510 nm. The probe exhibited high selectivity and sensitivity for CN- ion and the detection limit was 5.75×10-7mol/L. Finally,the use of a test strip of probe HPBC to detect cyanide was reported.
ABSTRACT
The dried whole plant of Pteris dispar were milled and extracted with 95% EtOH. The resulting dried extract was isolated by kinds of chromatographic column, including polyamide, Sephadex LH-20, preparative HPLC. As a result, ten diterpenes were isolated from the plant. By analyzing of ESI-MS and NMR spectroscopic data, the structures were established as geopyxin B(1), geopyxin E(2), ent-11α-hydroxy-18-acetoxykaur-16-ene(3), ent-14β-hydroxy-18-acetoxykaur-16-ene(4), neolaxiflorin L(5), ent-3β,19-dihydroxy-kaur-16-ene(6), ent-3β-hydroxy-kaur-16-ene(7), 7β,17-dihydroxy-16α-ent-kauran-19-oic acid 19-O-β-D-glucopyranoside ester(8), crotonkinin C(9)and crotonkinin C(10). Compounds 1-10 were obtained from P. dispar for the first time. Compounds 1 and 2 showed moderate activities against Bel-7402 with IC₅₀ values of 7.50 and 10.60 μmol•L⁻¹, and against HepG2 with IC₅₀ values of 6.68,11.80 μmol•L⁻¹, respectively.