Pleiotropy and Synergy

Bioactivity resulting from the synergistic interaction of several compounds to a target is undoubtedly a drawback in HTS, a hit discovery strategy based on 

Within mixtures of natural products, interactions are the norm rather than the exception and Nature seems to have known very well that there can be strength in numbers and that there are not only active compounds but also supportive ancillary constituents. Thus, the response of the mammalian immune system to a stimulus depends on the concerted effect of a host of cytokines and not on the activity of just one, while the mandibular pheromone of the queen honey bee is a mixture of nine compounds, all required to elicit its multiple action on worker bees and drones.54 

A library of pure natural products will always be less chemically diverse compared to a library of extracts and will not generally benefit from the bioactivity clues that the ethnopharmacological selection of the starting plant material can afford. 

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