pyridines vitamin B6 Any member of the group of pyridines that exhibit biological activity against vitamin B<small>₆</small> deficiency. Vitamin B<small>₆</small> deficiency is associated with microcytic anemia, electroencephalographic abnormalities, dermatitis with cheilosis (scaling on the lips and cracks at the corners of the mouth) and glossitis (swollen tongue), depression and confusion, and weakened immune function. Vitamin B<small>₆</small> consists of the vitamers pyridoxine, pyridoxal, and pyridoxamine and their respective 5'-phosphate esters (and includes their corresponding ionized and salt forms). B vitamin