Chemical composition of guarana flowers and nectar and their ecological significance

The plant species Paullinia cupana Kunth (Sapindaceae), commonly known as guarana, originates from the central Amazonian Basin and has a long history of local use for its stimulant properties. It is currently commercialized worldwide for its health beneficial properties. The seeds chemical composition has been extensively studied over the years. However, the chemistry of guarana flowers, particularly the nectar content, have been barely investigated. From an ecological perspective, floral nectar and pollen are the primary food rewards for pollinators. In the present study, we investigated the chemical composition of nectar and whole pistillate, and staminate guarana flowers harvested separately. Although guarana is well known for its high concentration of caffeine in its seeds, to the best of our knowledge, this is the first report of caffeine and other methylxanthines as the main constituents of the nectar. The significant difference between guarana floral chemistry, which is more diverse and complex, and nectar chemical profile, which primarily contains methylxanthines, suggests that the presence of these compounds in guarana nectar may have an impact on plantpollinator interactions, which can affect the fitness of both plants and flower visitors