Apart from natural-product-derived modern medicine, natural products are also
used directly in the ‘natural’ pharmaceutical industry that is growing rapidly in
Europe and North America, as well as in the traditional medicine programmes
being incorporated into the primary health care systems of Mexico, The
People’s Republic of China, Nigeria and other developing countries.
6.1.3 Drug discovery and natural products
Although drug discovery may be considered to be a recent concept that
evolved from modern science during the 20th century, in reality the concept
of drug discovery dates back many centuries, and has its origins in nature.
Time and time again, humans have turned to Mother Nature for cures, and
discovered unique drug molecules. Thus, the term natural product has
become almost synonymous with the concept of drug discovery. In modern
drug discovery and development processes, natural products play an
important role at the early stage of ‘lead’ discovery, i.e. discovery of the
active (determined by various bioassays) natural molecule, which itself or
its structural analogues could be an ideal drug candidate.
Natural products have been a wellspring of drugs and drug leads. It is
estimated that 61 per cent of the 877 small molecule new chemical entities
introduced as drugs worldwide during 1981–2002 can be traced back to or
were developed from natural products. These include natural products (6 per
cent), natural product derivatives (27 per cent), synthetic compounds with
natural-product-derived pharmacophores (5 per cent) and synthetic compounds designed on the basis of knowledge gained from a natural product,
i.e. a natural product mimic (23 per cent). In some therapeutic areas, the
contribution of natural products is even greater, e.g. about 78 per cent of
antibacterials and 74 per cent of anticancer drug candidates are natural
products or structural analogues of natural products. In 2000, approximately
60 per cent of all drugs in clinical trials for the multiplicity of cancers were of
natural origins. In 2001, eight (simvastatin, pravastatin, amoxycillin, clavulanic acid, clarithromycin, azithromycin, ceftriaxone, cyclosporin and paclitaxel) of 30 top selling medicines were natural products or derived from natural
products, and these eight drugs together totalled US$16 billion in sales.
Despite the outstanding record and statistics regarding the success of natural
products in drug discovery, ‘natural product drug discovery’ has been neglected
by many big pharmaceutical companies in the recent past. The declining
popularity of natural products as a source of new drugs began in the 1990s,
because of some practical factors, e.g. the apparent lack of compatibility of
natural products with the modern high throughput screening (HTS) programmes,
where significant degrees of automation, robotics and computers are used, the
complexity in the isolation and identification of natural products and the cost and
6.1 INTRODUCTION TO NATURAL PRODUCT DRUG DISCOVERY PROCESS
285
used directly in the ‘natural’ pharmaceutical industry that is growing rapidly in
Europe and North America, as well as in the traditional medicine programmes
being incorporated into the primary health care systems of Mexico, The
People’s Republic of China, Nigeria and other developing countries.
6.1.3 Drug discovery and natural products
Although drug discovery may be considered to be a recent concept that
evolved from modern science during the 20th century, in reality the concept
of drug discovery dates back many centuries, and has its origins in nature.
Time and time again, humans have turned to Mother Nature for cures, and
discovered unique drug molecules. Thus, the term natural product has
become almost synonymous with the concept of drug discovery. In modern
drug discovery and development processes, natural products play an
important role at the early stage of ‘lead’ discovery, i.e. discovery of the
active (determined by various bioassays) natural molecule, which itself or
its structural analogues could be an ideal drug candidate.
Natural products have been a wellspring of drugs and drug leads. It is
estimated that 61 per cent of the 877 small molecule new chemical entities
introduced as drugs worldwide during 1981–2002 can be traced back to or
were developed from natural products. These include natural products (6 per
cent), natural product derivatives (27 per cent), synthetic compounds with
natural-product-derived pharmacophores (5 per cent) and synthetic compounds designed on the basis of knowledge gained from a natural product,
i.e. a natural product mimic (23 per cent). In some therapeutic areas, the
contribution of natural products is even greater, e.g. about 78 per cent of
antibacterials and 74 per cent of anticancer drug candidates are natural
products or structural analogues of natural products. In 2000, approximately
60 per cent of all drugs in clinical trials for the multiplicity of cancers were of
natural origins. In 2001, eight (simvastatin, pravastatin, amoxycillin, clavulanic acid, clarithromycin, azithromycin, ceftriaxone, cyclosporin and paclitaxel) of 30 top selling medicines were natural products or derived from natural
products, and these eight drugs together totalled US$16 billion in sales.
Despite the outstanding record and statistics regarding the success of natural
products in drug discovery, ‘natural product drug discovery’ has been neglected
by many big pharmaceutical companies in the recent past. The declining
popularity of natural products as a source of new drugs began in the 1990s,
because of some practical factors, e.g. the apparent lack of compatibility of
natural products with the modern high throughput screening (HTS) programmes,
where significant degrees of automation, robotics and computers are used, the
complexity in the isolation and identification of natural products and the cost and
6.1 INTRODUCTION TO NATURAL PRODUCT DRUG DISCOVERY PROCESS
285