Baogang Wang

Near-Infrared Phosphorus-Substituted Rhodamine with Emission Wavelength above 700 nm for Bioimaging

Phosphorus has been successfully fused into a classic rhodamine framework, in which it replaces the bridging oxygen atom to give a series of phosphorus-substituted rhodamines (PRs). Because of the electron-accepting properties of the phosphorus moiety, which is due to effective σ*-π* interactions and strengthened by the inductivity of phosphine oxide, PR exhibits extraordinary long-wavelength fluorescence emission, elongating to the region above 700 nm, with bathochromic shifts of 140 and 40 nm relative to rhodamine and silicon-substituted rhodamine, respectively. Other advantageous properties of the rhodamine family, including high molar extinction coefficient, considerable quantum efficiency, high water solubility, pH-independent emission, great tolerance to photobleaching, and low cytotoxicity, stay intact in PR. Given these excellent properties, PR is desirable for NIR-fluorescence imaging in vivo.

A Lysosome-Compatible Near-Infrared Fluorescent Probe for Targeted Monitoring of Nitric Oxide.

The requirement for nitric oxide (NO) of lysosomes has motivated the development of a sophisticated fluorescent probe to monitor the distribution of this important biomolecule at the subcellular level in living cells. A near-infrared (NIR) fluorescent Si-rhodamine (SiRB)-NO probe was designed based on the NO-induced ring-opening process of Si-rhodamine. The probe exhibits fast chromogenic and fluorogenic responses, and high sensitivity and selectivity toward trace amounts of NO. Significantly, the spirolactam in Si-rhodamine exhibits very good tolerance to H(+), which in turn brings extremely low background fluorescence not only in the physiological environment but also under acidic conditions. The stability of the highly fluorescent product in acidic solution provides persistent fluorescence emission for long-term imaging experiments. To achieve targeted imaging with improved spatial resolution and sensitivity, an efficient lysosome-targeting moiety was conjugated to a SiRB-NO probe, affording a tailored lysosome-targeting NIR fluorescent Lyso-SiRB-NO probe. Inheriting the key advantages of its parent SiRB-NO probe, Lyso-SiRB-NO is a functional probe that is suited for monitoring lysosomal NO with excellent lysosome compatibility. Imaging experiments demonstrated the monitoring of both exogenous and endogenous NO in real time by using the Lyso-SiRB-NO probe.

Synthesis and evaluation of novel azoles as potent antifungal agents

Using a rational approach to the design of antifungal agents, a series of azole agents with 1,3,4-oxadiazole side chains were designed and synthesized. The results of preliminary in vitro antifungal tests with eight human pathogenic compounds showed that all of the title compounds exhibited excellent activities against all of the tested fungi except Aspergillus fumigatus. Compounds 11e and 11f were found to be the most effective, with a minimum inhibitory concentration of 0.0039μg/mL, followed by voriconazole, which has a MIC of 0.0625μg/mL. The 1,3,4-oxadiazole side chain is not the major contributor but plays a role in eliciting the observed antifungal activity.

A six-membered-ring incorporated Si-rhodamine for imaging of copper(II) in lysosomes

The regulation of copper homeostasis in lysosomes of living cells is closely related to various physiological and pathological processes. Thus, it is of urgent need to develop a fluorescent probe for selectively and sensitively monitoring the location and concentration of lysosomal Cu(2+). Herein, a six-membered ring, thiosemicarbazide, was incorporated into a Si-rhodamine (SiR) scaffold for the first time, affording a SiR-based fluorescent probe SiRB-Cu. Through the effective Cu(2+)-triggered ring-opening process, the probe exhibits fast NIR chromogenic and fluorogenic responses to Cu(2+) within 2 min as the result of formation of a highly fluorescent product SiR-NCS. Compared with a five-membered ring, the expanded ring retains great tolerance to H(+), ensuring the superior sensitivity with a detection limit as low as 7.7 nM and 200-fold enhancement of relative fluorescence in the presence of 1.0 equiv. of Cu(2+) in pH = 5.0 solution, the physiological pH of lysosome. Moreover, the thiosemicarbazide moiety acts not only as the chelating and reactive site, but also as an efficient lysosome-targeting group, leading to the proactive accumulation of the probe into lysosomes. Taking advantage of these distinct properties, SiRB-Cu provides a functional probe suitable for imaging exogenous and endogenous lysosomal Cu(2+) with high imaging contrast and fidelity.

A New Method for Selective Deprotection of Anomeric N,O-Dimethylhydroxylamine Promoted by TMSCl

TMSCl was shown to be an efficient reagent for selective deprotection of the anomeric position protected as N,O-dimethylhydroxylamine glycoside. This deprotection condition was proved to be compatible with a number of protecting groups, such as the TBDPS, acetyl, benzyl, benzylidene, and benzoyl groups.

Design, synthesis and biological evaluation of azithromycin glycosyl derivatives as potential antibacterial agents.

A series of 11,12-cyclic carbonate azithromycin-4″-O-carbamoyl glycosyl derivatives were designed, synthesized, and evaluated as antibacterial agents to search for target compounds with excellent activity. The results of preliminary antibacterial tests against eight strains in vitro revealed that all of the title compounds exhibited improved activities with broad spectrum compared with the parent compound. The glycosylated side chains may be the pharmacophores responsible for the improved activity.