New classes of carborane-appended 5-thio-D-glucopyranose derivatives.

A series of carborane-appended 5-thio-D-glucopyranose (5-TDGP) derivatives containing one to two 5-TDGP moieties were synthesized via click cycloaddition reaction as well as following the traditional methods. Among the carboranyl-5-TDGP derivatives, the decapitated nido-carboranyl derivative 18 was found to be highly water-soluble and therefore its preliminary biodistribution study was conducted. A comparative biological evaluation of 18 versus its carboranyl-D-glucopyranose analog 19 with human hepatocellular carcinoma cells (SK-Hep1) indicated 5-TDGP to be a better boron carrier than normal D-glucopyranose. The carboranyl-5-TDGP 18 showed a nearly two fold increase in cellular boron accumulation than carboranyl-D-glucopyranose analog 19 over a period of 2 h. The accumulation of both 18 and 19 was found to occur in a temperature dependent manner. The higher accumulation of 18 suggested excellent promise for it to be a candidate for further evaluation as a future BNCT agent.