Medicinal plants

Medicinal plants, also called medicinal herbs, have been used in traditional medicine since prehistoric times. Plants create many chemical compounds to protect themselves, and some of these can help humans.

The earliest records of herbs come from the Sumerian civilization around 3000 BC, and the Ebers Papyrus from ancient Egypt lists over 850 plant medicines. A Greek physician named Dioscorides wrote about over 600 plants that could be used as medicine, and his work helped guide medicine for many years.

Today, scientists study plants to find useful compounds, and some medicines like aspirin, digoxin, and quinine come from plants. Many people still use medicinal plants because they are easy to find and often cheaper than modern medicines. However, some plant medicines are not well regulated, and plants also face threats from climate change and loss of their natural homes.

History

Further information: History of herbalism and History of pharmacy

Plants, including many used as culinary herbs and spices, have been used as medicines since ancient times. These plants helped protect food from spoiling and were used by humans and even some animals when they felt unwell. Early humans used plants found around their homes, like nettle, dandelion, and chickweed.

In ancient Sumeria, people listed many healing plants, such as myrrh and opium, on clay tablets around 3000 BC. The ancient Egyptian Ebers Papyrus from around 1550 BC mentions over 800 plant medicines, including aloe, cannabis, and garlic.

From ancient times, many cultures used herbs for healing. For example, Ayurvedic medicine used plants like turmeric, and the Chinese pharmacopoeia recorded plants such as ephedra. The Greek doctor Dioscorides wrote a book called De materia medica around 60 AD, which listed over 600 plants for making medicines. This book was very important for many years.

During the Middle Ages, monasteries in Europe kept knowledge of healing plants alive by writing books and growing their own herbs. Later, books with pictures of plants, called herbals, became popular. New plants were discovered as people explored new lands, bringing useful herbs to different parts of the world.

In the 1800s, scientists began to study plants more closely. They found powerful medicines hidden inside plants, like morphine from the poppy. Even today, plants continue to help us find new medicines.

Context

Medicinal plants are used to help keep people healthy or to treat specific illnesses, either in modern medicine or traditional practices. Many drugs used today come from plants, and they are carefully tested to make sure they are safe. In many parts of the world, people rely mostly on traditional medicine, which often includes plants, to stay healthy.

These plants can help people, provide jobs for those who grow and sell them, and benefit society in many ways. However, it can be tricky to know which plants are safe and effective, and there isn’t always enough scientific research to guide their use.

Trade

Plants used for medicine and flavor are sold in many ways, such as in medicines, foods, drinks, and beauty products. Most of these plants are used in medicines and supplements, making up about 60% of all plant sales. In 2023, the world bought about US$68 billion worth of these plants each year, and this number grows by 10-20% every year.

China and India grow and sell the most of these plants. Other big buyers include the United States, the European Union, and Japan.

Phytochemical basis

Further information: Phytochemistry

Plants make special chemicals that help protect them, like keeping away bugs or animals that might eat them. These same chemicals can be helpful for people and are used in modern medicines when tested and proven safe. For example, daffodils have a chemical called galantamine that helps people with memory problems.

Scientists are learning more about these plant chemicals and how they work. They study many plants to understand which chemicals might be useful as medicines.

Alkaloids

Further information: Alkaloids

Alkaloids are strong chemicals found in many plants. They can be very bitter and sometimes harmful, but they are also used to make medicines. For example, medicines from nightshade plants include atropine, scopolamine, and hyoscyamine. Other examples are berberine from Berberis and Mahonia plants, caffeine from coffee plants, and many more.

The opium poppy is a source of morphine and codeine. Nicotine from tobacco works by attaching to special receptors in the body. Deadly nightshade contains tropane alkaloids like atropine, scopolamine, and hyoscyamine.

Glycosides

Further information: Glycosides

Some plants have special chemicals called anthraquinone glycosides, which are used in medicines to help with digestion. Plants like rhubarb, cascara, and Alexandrian senna have these chemicals.

Cardiac glycosides are strong medicines that help the heart beat better. They come from plants like foxglove and lily of the valley. Examples include digoxin and digitoxin, which are used to help with heart problems.

Senna alexandrina has been used for thousands of years to help with digestion. Foxglove contains digoxin, which was used for heart problems before scientists knew exactly how it worked. Digoxin is used to treat certain heart conditions.

Polyphenols

Further information: Polyphenol and Health effects of polyphenols

Polyphenols are chemicals found in many plants that help protect them from diseases and animals that might eat them. Some of these can act like hormones and have been used for many years to help with women's health issues, such as problems with fertility, monthly cycles, and changes during aging. Plants like Pueraria mirifica, kudzu, angelica, fennel, and anise are examples.

Many extracts from plants like grape seeds, olives, or maritime pine bark are sold as supplements or in cosmetics, but they do not have proven health benefits. In traditional Ayurveda medicine, the rind of the pomegranate, which contains polyphenols called punicalagins, is used as a medicine, although there is no scientific proof it works.

Angelica, which contains phytoestrogens, has been used for women's health issues.

Terpenes

Further information: Terpenes

Terpenes are strong-smelling chemicals found in many plants, especially resinous plants like conifers. They help keep away animals that might eat the plants and are used in essential oils for perfumes like rose and lavender, or for aromatherapy. Some terpenes have medicinal uses, like thymol, which is an antiseptic and was once used to treat worms.

The essential oil of common thyme contains thymol, which can kill germs and fungi. Thymol is one of many terpenes found in plants.

In practice

Main articles: Herbalism and List of plants used in herbalism

Medicinal plants need special care when grown because each kind has its own needs. Experts suggest rotating crops to keep pests and diseases away. Farmers can use methods that save water and keep the soil healthy.

People prepare medicinal plants in different ways to make them easier to use. One common way is to boil the plant in water to make a liquid. Another way is to crush the plant into a powder. Some plants are soaked in alcohol to make a strong solution.

Plants can help people stay healthy all over the world. In many places, people rely on plants for medicine because it is the only care they have. In other places, people choose to use plants along with other kinds of medicine.

Scientists have studied many plants to see which ones might help treat sickness. Some plants have been used for hundreds of years, and new research shows they might really work.

The World Health Organization works to make sure medicines from plants are safe and work well. Not all countries have strong rules for these medicines, but the WHO wants to help everyone have access to safe plant medicines.

The drug industry began with shops that mixed plants to make medicines. Many important medicines today come from plants. Scientists keep studying plants used by different cultures to find new medicines.

Plants can sometimes cause problems if not used properly. They can be harmful if too much is taken or if mixed with other medicines. It is important to use plant medicines carefully.

Herbal products sometimes do not tell people exactly what is inside or if it is safe. Companies sometimes make promises that are not true to sell more products. It is important to know the facts about these products.

Threats

When people take medicinal plants from the wild instead of growing them, these plants face many dangers. Big problems include climate change and habitat loss from building and farming. Another big danger is taking too many plants because many people want to use them as medicine. For example, when people learned how helpful a plant called taxol was, they took too many from the wild. To help these plants, people can grow them instead of taking them from nature, or create rules to make sure taking plants from the wild does not hurt them too much. In 2020, a report showed that 723 medicinal plants were in danger of disappearing partly because people took too many of them.