Flavonoids are a group of natural products isolated from a wide variety of plants, responsible for much of the natural colouring in vascular plants. A single plant may contain up to 50 different flavonoids, and the distribution of flavonoids within a plant family can yield useful classifying information about that family. Flavonoids exhibit a wide range of biological activity and currently are of particular interest in the pharmaceutical industry as potential anti-cancer agents. They find applications in the food industry as natural food colourings and in the analysis of wine, and as insect...