Research in full colour

"Natural plant pigments seem to be medically active, and have many mores uses than colouring our food", says Professor Øyvind Moksheim Andersen of the Dept. of Chemistry. He has specialized in a combination of chenistry and nature, and runs several research projects on medicines and food.

ASBJØRN LEIRVÅG

Consumer surveys show that colour is important when we choose foods. A fresh, natural appearance is particularly important in fruit and vegetables, jam and soft drinks. In order to prolong shelf life, food companies make use of a wide range of additives, but Moksheim Andersen can think of alternative strategies.

"There are still a lot of natural pigments in foodstuffs that we know too little about. We have tried to explain why strawberry jam, for instance, loses its colour so quickly, while blueberry jam stays blue for such a long time. Pigment stability is obviously a central question here."

Moksheim Andersen says that food companies are keenly interested in his research, since they are always on the lookout for natural pigments that will enable them to reduce their use of potentially hazardous artificial pigments. Nowadays, pigments derived from black grapes are most often used commercially, but plums, cranberries, blackcurrants, elderberries and red cabbage are also in use.

Positive effects

Interdisciplinary thinking has enabled chemists, medical doctors and botanists at the University of Bergen to identify the potential of plant pigments such as the water-soluble antocyans which are the basis of most blue, purple and red plant pigments. The red colour of foxgloves and the blue of cornflowers are caused by the same type of pigment.

"Human beings have long been eating food that contains pigments without doing any harm to their health. This made us wonder whether such substances might actually have positive effects on our bodies". Moksheim Andersen collaborates with Professor Knut Jan Andersen of Haukeland Hospital on studies of the effects of specific pigments and related compounds on enzymes and cell cultures used in cancer research. It has already been shown that the antocyan pigments have a positive effect on the capillary system, and that they help to prevent the blood platelets from clotting, thus reducing the danger of thromboses. Blueberry pigments have also been successful in healing burns.

Building blocks

Moksheim Andersen’s speciality is isolating and identifying the structures of naturally occurring pigments. He compares his methodology to making tea: "Just as pouring water over tea-leaves gives us tea, we add a solvent such as alcohol to flowers or berries in order to extract their pigments. The resulting mixture is fractioned and washed by special separation techniques. The next stage is to identify the chemical structure of the individual pigments".

Each pigment consists of several building blocks, which form a skeleton that can actually be taken apart and put together again in various combinations. Around 300 antocyans have been identified in plants, all of them based on about 20 different building blocks. A typical antocyan contains two to four such blocks. This concept has given the chemists in Bergen, who are regarded as world leaders in isolating and identifying natural pigments, ideas for other applications.

Basically curious

"Walking on the hills, I have often wondered about the interactions that occur in nature; why are colours different in different types of tissue, and why do they change with the seasons? What sort of signals do colours convey? We know that the combination of colour, shape and scent attracts insects to pollinate flowers, but do we have more to learn from the functions of other components of plants?"

Since a plant cannot move around, it has to look after its own interests in other ways. Ordinary plants have about ten times as many connections with their environment as animals. Chemical communication is a basic concept in Moksheim Andersen’s way of thinking.

"Many fruits and berries increase their production of pigments as they ripen. Their bright colours attract birds, for example, which help to spread their seeds over a wide area. Many people believe, quite wrongly, that the leaves of many plants redden in the autumn simply because their chlorophyll breaks down. But the colour change is also due to the production of red pigment in the leaves, and we don’t really know why this happens.

"Chemical analyses of plant components can also be of use in medical research, because many interactive process in nature will be explained at the basic molecular biology level. This will mean that collaboration involving chemists, biologists and the medical profession will be able to make important contributions to curing AIDS; cancer, heart disease and allergies", believes Moksheim Andersen, who has seen for himself how AIDS is killing a huge proportion of the people of Uganda. He emphasizes that time and money are critical input factors, and that although new medicines have yet to emerge from this process, the results are already very promising.