Developmental and reproductive toxicity (DART) end points are important hazard end points that need to be addressed in the risk assessment of chemicals to determine whether or not they are the critical effects in the overall risk assessment. These hazard end points are difficult to predict using current in silico tools because of the diversity of mechanisms of action that elicit DART effects and the potential for narrow windows of vulnerability. DART end points have been projected to consume the majority of animals used for compliance with REACH; thus, additional nonanimal predictive tools are urgently needed. This article presents an empirically based decision tree for determining whether or not a chemical has receptor-binding properties and structural features that are consistent with chemical structures known to have toxicity for DART end points. The decision tree is based on a detailed review of 716 chemicals (664 positive, 16 negative, and 36 with insufficient data) that have DART end-point data and are grouped into defined receptor binding and chemical domains. When tested against a group of chemicals not included in the training set, the decision tree is shown to identify a high percentage of chemicals with known DART effects. It is proposed that this decision tree could be used both as a component of a screening system to identify chemicals of potential concern and as a component of weight-of-evidence decisions based on structure-activity relationships (SAR) to fill data gaps without generating additional test data. In addition, the chemical groupings generated could be used as a starting point for the development of hypotheses for in vitro testing to elucidate mode of action and ultimately in the development of refined SAR principles for DART that incorporate mode of action (adverse outcome pathways).
A novel series of carboxylic acids containing a substituted piperidine were synthesized and tested for inhibition of selected matrix metalloproteinases. Multiple analogues prepared based on this novel design were found to inhibit the target MMPs (MMP-2, -3, -8, -9, and -13) with unprecedented, low nanomolar potency while, at the same time, sparing MMP-1 and MMP-7. Solubility and plasma protein binding of several members of this new series of carboxylic acids were also investigated.Introduction. The matrix metalloproteinases (MMPs) are a family of zinc-containing enzymes that are capable of degrading many proteinaceous components of the extracellular matrix. 1 The enzymes have been implicated in several pathological processes including arthritis, 2,3 tumor growth and metastasis, 4 periodontal disease, 5 multiple sclerosis, 6 and congestive heart failure. 7,8 Considerable research has been devoted to the discovery of potent MMP inhibitors, which may act as potential disease modifying agents in a number of important pathologies. 9,10
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