Hesperidin is a flavanone glycoside found in citrus fruits. Its aglycone form is called hesperetin. Its name is derived from the word "hesperidium", for fruit produced by citrus trees. Hesperidin was first isolated in 1828 by French chemist Lebreton from the white inner layer of citrus peels (mesocarp, albedo). As a flavanone found in citrus fruits (such as oranges, lemons or pummelo fruits), hesperidin is under laboratory research for possible biological properties. One area of research is focused on the possible chemopreventive effects of hesperidin, but there is no current proof that hesperidin has this role in human cancer mechanisms. Hesperidin was effective in an animal model of Alzheimer's, alleviating pathological changes induced by aluminum. Early research suggests that taking one tablet of a specific product (Daflon 500, Les Laboratoires Servier) containing hesperidin and diosmin by mouth for 45 days decreases blood sugar levels and improves blood sugarcontrol in women with type 2 diabetes. For Rheumatoid arthritis (RA): early research suggests that drinking a beverage containing alpha-glucosyl hesperidin for 12 weeks improves symptoms of RA. Orally, hesperidin can cause gastrointestinal side effects, including abdominal pain, diarrhea, and gastritis. Headache can also occur in some patients. The possible anti-inflammatory action of hesperidin is probably due to the possible anti-inflammatory action of its aglycone hesperetin. Hesperetin appears to interfere with the metabolism of arachidonic acid as well as with histamine release. Hesperetin appears to inhibit phospholipase A2, lipoxygenase and cyclo-oxygenase. There is evidence that hesperetin inhibits histamine release from mast cells, which would account for the possible anti-allergic activity of hesperidin. The possible hypolipidemic effect of hesperidin is probably due to hesperetin's possible action in lipid lowering. Hesperetin may reduce plasma cholesterol levels by inhibition of 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase, as well as acyl coenzyme A: cholesterol acytransferase (ACAT). Inhibition of these enzymes by hesperetin has been demonstrated in rats fed a high cholesterol diet. The mechanism of hesperidin's possible vasoprotective action is unclear. Animal studies have shown that hesperidin decreases microvascular permeability. Hesperidin, itself or via hesperetin, may protect endothelial cells from hypoxia by stimulating certain mitochondrial enzymes, such as succinate dehydrogenase. The mechanism of hesperidin's possible anticarcinogenic action is also unclear. One explanation may be the inhibition of polyamine synthesis. Inhibition of lipoxygenase and cyclo-oxygenase is another possibility.