BDNF and major depressive disorder: Beside antioxidant action, each flavonoid found to follow one or more distinct pathways against the progression and advancement of depression through affecting neurotransmission receptors, BDNF levels, increasing neuronal growth, inhibiting certain enzymes activity, i.e., MAO and acetylcholinesterase, modulation of caspases 3 and 9, Bax, Bak and cytochrome C protein expression, modulation of calcium and potassium ions channels, maintaining brain plasticity and preventing potential dissipation of mitochondrial membrane [1,29,145].