Pharmacognosy and Plant-Derived Medicines: From Willow Bark to Aspirin

Yes, many well-known medicines began with plants. Aspirin traces back to willow bark, and the malaria drug artemisinin was found in a plant used in Chinese medicine. But a purified medicine, made and measured in a laboratory, is a different product from the plant it came from. This page explains the history and the limits. It is information only and not a reason to use a plant in place of a medicine.

What pharmacognosy means

The U.S. National Library of Medicine's subject heading describes pharmacognosy as the science of drugs prepared from natural sources, including preparations from plants, animals and other organisms. [1] A review of pharmacy history says descriptions of plants in early plant books (herbaria) led to the development of pharmacognosy, and that the first department for it opened in Padua in 1545. [2]

Examples named by the sources

The table lists medicines that sources link to plants. "Plant source" is what the source says, not a recommendation to use the plant.

Artemisinin: a traditional lead, then laboratory work

The 2015 Nobel Prize in Physiology or Medicine press release says Tu Youyou, working in China in the late 1960s, turned to traditional herbal medicine to look for new malaria treatments. [5] It says a large screen of herbal remedies in infected animals led to the plant Artemisia annua, and that she discovered artemisinin, a drug that has significantly reduced deaths from malaria. [5] In her Nobel lecture, Tu said the active substance was first isolated and tested in the 1970s in China. [6]

Here traditional use gave researchers a place to start (traditional use only), and the later steps were animal and human testing of one isolated compound. The tea or the whole plant was not what the Nobel committee described.

Plants as a source of medicines overall

• A review of drugs approved from 1981 to 2019 found that using natural products, or synthetic versions of their structures, to develop drugs is "still alive and well", and that the anti-infective area depends on natural products and their structures. [7] The same review also notes some disease areas where no drugs are derived from natural products. [7]
• A book chapter estimates that about 25% of drugs prescribed worldwide are derived from plants. [3] It is an estimate quoted from other work, so treat it as approximate.
• NCCIH puts it this way: nature gave us aspirin, morphine and other medicines derived from plants, but not all products from nature have been shown to be effective. [8]

Why the plant is not the medicine

A drug made from one purified compound has a known, measured amount. NCCIH notes that an herbal supplement may contain dozens of chemical compounds and that not all of its ingredients may be known. [8] A result for the drug does not transfer to a tea, a capsule or the raw plant. The reverse is also true.

Proper evidence not found for the claim that "taking the whole plant is as good as the medicine made from it". We looked at the NCCIH, Nobel Prize and review sources cited here, and none supports it.