Gingerol is the active constituent of fresh ginger. Chemically, gingerol is a relative of capsaicin and piperine, the compounds which give chilli peppers and black pepper their respective spicyness. It is normally found as a pungent yellow oil, but also can form a low-melting crystalline solid. Cooking ginger transforms gingerol into zingerone, which is less pungent and has a spicy-sweet aroma. When ginger is dried, gingerol undergoes a dehydration reaction forming shogaols, which are about twice as pungent as gingerol. This explains why dried ginger is more pungent than fresh ginger. Gingerol administered by intraperitoneal injection has been used to induce a hypothermic state in rats. Gingerol seems to be effective in an animal model of rheumatoid arthritis. Gingerol has been investigated for its effect on cancerous tumors in the bowel, breast tissue, ovaries, the pancreas, among other tissues, with positive results.