Synephrine, from bitter orange (citrus aurantium) extract.The synephrine in the product comes from the fruit extract of an evergreen fruit tree, the bitter orange. Bitter orange is native to asia, but can also be found in mediterranean areas. Synephrine is most often extracted from the skin of the fruit, and its leaves are often used to make essential oils. Synephrine occurs in many products, but is typically contained in thermogenic formulations. It is also popular as a synergist for caffeine