Occurrence and Role of Alkaloids in Plants
The history of alkaloid research begins with morphine, a major alkaloid of opium poppy (Papaver somniferum). Since the isolation of morphine in the early nineteenth century mere has been a vigorous search for alkaloids or “plant alkalies” from the vegetable kingdom. Isolation of alkaloid is incomplete without structure determination and this final step was generally the synthesis of the alkaloid in question and successful synthesis were important milestones in the history of alkaloid research. Among the seed plants a greater variety of alkaloids has been found in Dicotyledons than in Monocotyledons or gynosperms. It has been estimated that about 15–30 percent of all plants species contain alkaloids. Alkaloid-producing plant families are found in the tropics, about three times more than in temperate zones, but this reflects the greater number of tropical plants generally since the ratio of tropical alkaloid families to total tropical families is the same as the ratio for temperate.