In contrast with animals, plants respond to their environment by sinthesising a large
array of secondary compounds with very different chemical properties and uses. The most
interesting group of natural products is alkaloids, of wich about six thousand are well known
and have been found to be distributed among many plant families. The roles of alkaloids
in plant metabolism or plant physiology are supposed to be growth regulators, storage reservoirs
of nitrogen, end products of metabolism or waste products, or plant-protecting
agents toward parasites and competitors or against attack by predators
