There are many compounds in plants that are active in animals and humans. In broad category, all of these compounds listed below are listed. But, lets take it one at a time.
Proanthocyanidins
Cyanogenic glycosides
Polysaccharides
Glucosinolates
Bitters
Alkaloids
Coumarins
Saponins
Phenols
Volatile oils
Flavonoids
Tannins
Anthraquinones
Cardiac glycosides
Proanthocyanidins: These molecules give the plants a deep color such as blue, purple and red. They are free radical scavengers and antioxidants and found in grapse, blackberries and other berries. Ariona berry has the highest level in fruits. Why this is important is because they help in neutralize reactive free radicals by donating an electron or hydrogen atom. They primarily work by interrupting chain reactions which would otherwise damage lipids, proteins, DNA or cell membrane. Take a look at the picture on how complex the molecule is and implies that except in plants these would be tough to produce in vitro. However, it works well as antioxidant and may have other effects that have not been documented yet.
