The ALOIN A (barbaloin) is considered to be the most specific secondary phytoconstituent in Aloe species, widely distributed throughout the world. Barbaloin has been found to have a strong inhibitory effect on histamine release from mast cells. Orally administered barbaloin is poorly absorbed but is metabolized by intestinal microflora to aloe emodin, which is readily absorbed. Barbaloin is the main medicinal constituent of aloe vera, which has anti-inflammatory activity. Moreover, it has strong anti-oxidant and anti-tumor properties. For example, barbaloin inhibited the proliferation and metastasis of non-small cell lung carcinoma cells in vivo and in vitro. Barbaloin demonstrated a cardioprotective potential: barbaloin pretreatment attenuates myocardial ischemia-reperfusion injury. Plus, it might be used as an antiarrhythmic drug.