Natural products are small molecules produced by living organisms including plants, invertebrates and microorganisms. They are also known as secondary metabolites being non-essential for life; but they play key roles in defence and cell to cell communication. They represent a unique chemical space with compounds distributed in a broad diversity of chemical classes. They have been evolving with nature together with the activities that have been optimized together with the targets.
Pharmaceutical companies have been using natural products for decades as one of the major sources for discovery of novel bio-active compounds and today more than 50% of the molecules in development are still natural products, semi-synthetic derivatives or have been inspired in these scaffolds. Today, natural products are still an untapped reservoir with more than 90% of the microbial sources still underexplored and with biosynthetic potential that by far exceeds the initial estimations. This is why natural products still represent one of the major sources of chemical diversity and one of the starting points for the discovery of novel antibiotics.