A Clinical Study to Assess the Safety, Tolerability and Pharmacokinetics of Oral SRT2104 Capsules Administered to Healthy Elderly Subjects for 28 Days

The primary objective is to determine the pharmacokinetics, safety and tolerability of SRT2104 in healthy elderly subjects following single and 28 days dosing. The secondary objectives of the study are: 1. To contrast changes in leg muscle function following repeat doses of SRT2104 or placebo: Endurance exercise tolerance 31P MRS measures of mitochondrial oxidative capacity in the gastrocnemius muscle 2. To test for a change in the ratio of visceral to subcutaneous body fat following repeat doses of SRT2104 relative to placebo using MRI 3. To estimate any changes in insulin sensitivity (using mOGTT) following repeat doses of SRT2104 or placebo 4. To test for dose-related effects on the exploratory pharmacodynamic measures above