5 January 2011

Uncovering the chemical secrets of plants

By Enzo Palombo

Areas of natural wilderness, such as the tropical Borneo rainforest, are striking for their beauty and sheer vastness. What may not be immediately obvious to the casual observer is that such areas are also domains of chemical warfare.

In the never-ending battle for survival, plants have armed themselves with an almost endless array of chemicals which are used to fight attackers such as bacteria, insects, fungi, and in some cases mammals.

What is probably not known is that these chemicals can be developed into new medicines, drugs and other useful compounds – if we know where to look and how to find them.

The use of plants as medicines is not a new idea. Plants have been used for medicinal purposes throughout human history and about 80 per cent of people in developing countries use traditional medicines for their primary health care.

The first pharmaceuticals were derived from medicinal plants. Well-known examples include the anti-malarial drug quinine, which is found in the Quinine Bark tree from South America, and the painkiller morphine from the Opium Poppy.

More recently the powerful anti-flu drug, Tamiflu was derived from shikimate, a chemical found in Star Anise, which is used in Traditional Chinese Medicine.

There is estimated to be over half a million plant species around the world, so how do we find the right ones to investigate further and hopefully discover new medicines?

By targeting medicinal plants rather than searching at random, there is a significantly increased chance of finding useful compounds.

Large-scale studies investigating the potential of medicinal plants have reported a high correlation
between the traditional medicinal use of the plants and the presence of active compounds within extracts made from those plants.

For example, plants used traditionally as antiseptics have been found to inhibit the growth of many different species of bacteria.

This traditional knowledge includes details such as the season during which a particular plant species has healing properties, which part of the plant contains this biological activity, and where a particular species grows that makes it more active than other plants of the same species.

So why do we need new medicines?

With the threat posed by diseases such as cancers and infections ever-increasing, there is a general need for new and useful ‘bioactive’ compounds which are highly effective, possess low toxicity and have minor environmental impact.

Given the abundance of plant life on earth, of which only one percent has been chemically investigated, there is great potential for discovering new bioactive compounds.
Unfortunately, according to the United Nations, current extinction rates of plants and animals mean that the world is losing one major drug every two years – even before they are discovered.

Many researchers around the world continue to study plants and the chemicals they make with the anticipation of discovering the next generation of wonder drugs. It is hoped that this research will help to promote the need to conserve these precious natural resources and preserve the traditional knowledge of how plants can be used in the treatment of diseases.

There is also a greater realisation that benefit-sharing is an important outcome of this research.

Many scientists are now very conscious that without the traditional knowledge that helped to identify the right plants to study, much of the research would be impossible.

As such, scientists, research institutions and indigenous groups are entering into partnerships so that the profits of any future commercialisation of plant-based products will be returned to the traditional communities from where the knowledge was obtained.

Biotechnologists at Swinburne University of Technology in Melbourne, Australia are working with the Sarawak Biodiversity Centre in Kuching to identify plant chemicals that have the potential to be developed into new drugs to combat infectious diseases such as influenza, dengue fever, diarrhoea and other diseases caused by infectious bacteria and bacteria and fungi.

Borneo has been recognised as one of the world’s top biodiversity ‘hotspots’ so the chances of finding new chemicals that can be turned into drugs in the many plants that inhabit the tropical rainforests is great. Of course, the traditional knowledge about the medicinal uses of these plants is vital in directing the scientists to the plant species of interest.

In this way, the plant research undertaken by biotechnologists around the world will derive benefits that will help save lives, promote conservation of the environment, maintain biodiversity on earth and help to preserve the precious traditional knowledge of indigenous people.

Enzo Palombo is an associate professor within the Faculty of Life and Social Sciences, Swinburne University of Technology, Melbourne, Australia.