AMP-activated protein kinase (AMPK) is an important cellular fuel sensor. Activation of AMPK requires phosphorylation at threonine (Thr)-172, which resides in the activation loop of the alpha1 and alpha2 subunits. Several AMPK upstream kinases are capable of phosphorylating AMPK at Thr-172, including LKB1 and CaMKKbeta. AMPK has been implicated in the regulation of physiological signals, such as inhibition of cholesterol, fatty acid, protein synthesis, and enhancement of glucose uptake and blood flow. AMPK activation also exhibits several salutary effects on vascular function and improves vascular abnormalities. AMPK is activated by numerous drugs and xenobiotics. Some of these are in clinical use for the treatment of type 2 diabetes (e.g., metformin and thiazolidinediones), hypertension (e.g., nifedipine and losartan), and impaired blood flow (e.g., aspirin, statins, and cilostazol). Plant-derived xenobiotics or nutraceuticals that were claimed to have health benefits in diabetes or cancer have been reported to activate AMPK. These include resveratrol from red wine, epigallocatechin gallate from green tea, capsaicin from peppers, berberine, which is a yellow dye of the genus berberis, genistein from soy bean, and ginsenoside from ginseng panax. AMPK is also modulated by numerous hormones and cytokines that regulate energy balance at the whole body level, including leptin, adiponectin, ghrelin, and even thyroid hormones. This work shows that the precise mechanisms of AMPK kinase and AMPK interaction.