Alkaloids as MAO-A inhibitors: Towards the final solution for depression and anxiety

The acute phase of depression is often accompanied by anxiety, irritability and insomnia. As a result, the concomitant use of an anxiolytic agent with an antidepressant is often necessary. At the present there are drugs very effective in treating depression, however, much of them have more side effects, so they usually are not the first drugs used in patients. In this sense, monoamine oxidase inhibitors (MAOIs) like clorgyline, moclobemide or phenelzine and tranylcypromine are another early form of antidepressant. These drugs are most effective in people with depression who do not respond to other treatments, being the inhibition of one or both MAO-A and MAO-B isoforms the main reason in preventing the breakdown of monoamine neurotransmitters, thereby increasing their availability. In this review, we give a point of view of the use of alkaloids, either marine or terrestrial, with wide or selective effect on the treatment of depression and/or anxiety specially related with the MAO-A inhibition. Some examples and their pharmacological effects as MAO-A inhibitors by using plants and organic extract from natural sources, in order to be used in combating these behavior diseases, are mentioned.