Arylspiroborates Derived from 4-tert-Butylcatechol and 3,5-Di-tert-butylcatechol and Their Antimicrobial Activities : Arylspiroborates Derived from 4-tert-Butylcatechol and 3,5-Di-tert-butylcatechol and Their Antimicrobial Activities

This article provides minimum requirements for having confidence in the accuracy of EC50/IC50 estimates. Two definitions of EC50/IC50s are considered: relative and absolute. The relative EC50/IC50 is the parameter c in the 4-parameter logistic model and is the concentration corresponding to a response midway between the estimates of the lower and upper plateaus. The absolute EC50/IC50 is the response corresponding to the 50% control (the mean of the 0% and 100% assay controls). The guidelines first describe how to decide whether to use the relative EC50/IC50 or the absolute EC50/IC50. Assays for which there is no stable 100% control must use the relative EC50/IC50. Assays having a stable 100% control but for which there may be more than 5% error in the estimate of the 50% control mean should use the relative EC50/IC50. Assays that can be demonstrated to produce an accurate and stable 100% control and less than 5% error in the estimate of the 50% control mean may gain efficiency as well as accuracy by using the absolute EC50/IC50. Next, the guidelines provide rules for deciding when the EC50/IC50 estimates are reportable. The relative EC50/IC50 should only be used if there are at least two assay concentrations beyond the lower and upper bend points. The absolute EC50/IC50 should only be used if there are at least two assay concentrations whose predicted response is less than 50% and two whose predicted response is greater than 50%. A wide range of typical assay conditions are considered in the development of the guidelines. Copyright © 2010 John Wiley & Sons, Ltd.

The use of boron in small-molecule pharmaceuticals is increasing. Boron's ubiquitous occurrence in nature and the recent success of a boronic acid drug (Velcade®) in the clinic have alleviated many concerns over its use in pharmaceuticals. In addition, the unique physicochemical properties of boronic acids make them an attractive addition to the medicinal chemists toolbox. This tutorial review will discuss these properties and potential benefits for anyone interested in finding novel enzyme inhibitors. An exceptional class of boronic acids, the oxaboroles, will be highlighted and their properties and uses will be discussed in detail. Finally, the current paradigm for the reaction of boronic acids with enzyme nucleophiles will be summarized. This journal is © The Royal Society of Chemistry 2011