Category Archives: Medicine

Why medicinal plants could play an important role in treating malaria

Jeremiah Waweru Gathirwa, Kenya Medical Research Institute and Ruth Monyenye Nyang’acha,, Kenya Medical Research Institute

It will take effective prevention, accurate and timely diagnosis and treatment to successfully eliminate malaria. But none of this will help if the causative agents become resistant to the drugs used for treatment. The Conversation Africa’s Health and Medicine Editor Joy Wanja Muraya spoke to Dr. Jeremiah Waweru Gathirwa and Ruth Monyenye Nyang’acha researchers at the Kenya Medical Research Institute about the country’s work towards using medicinal plants as a potential anti-malarial drugs. The Conversation

What is the place of medicinal plants in Africa generally and in Kenya more particularly?

Most communities heavily rely on medicinal plants to prevent and treat diseases. About 80% of people in Africa depend on traditional medicine. Traditional healers prescribe medicinal plants to treat various illnesses. These plants are an accessible and affordable form of treatment for communities across the continent.

Medicinal plants have ingredients that can treat a condition or disease or can be used to manufacture useful drugs.

Herbal medicines are an important part of culture and traditions all over the continent and beyond. For centuries people have used their knowledge about the environment to treat various ailments. For example, the Chinese herbalists have used extracts of the Qinghao plant; Artemisia annua also known as sweet wormwood for malaria treatment for over 1,500 years.

The old-age use of herbal medicines is true of several communities in Kenya – where malaria is among the ailments they’ve treated.

Why is it important to consider medicinal plants as potential sources of anti-malarial drugs?

Malaria is preventable and treatable. But it’s a major public health problem in Kenya: there are an estimated 6.7 million new cases and 4,000 deaths each year.

It accounts for 15% of all out patient attendance in Kenya’s health facilities’ admissions.

Drug resistance has led to most of the malaria drugs in the market becoming ineffective in treating the disease. There is therefore an urgent and continuous call to search for new antimalarial agents.

Most of the drugs used to treat malaria are either derived from plants or are products of natural sources.

For example quinine, an antimalarial, comes from the medicinal plant Cinchona succirubra. Artemisinin is derived from Artemisia annua, another medicinal plant. These previous successes underscores the importance of medicinal plants in the fight against malaria and as a rich reservoir from which new antimalarial drugs can be developed.

Scientific evaluation for safety, efficacy and quality of medicinal plant preparations is important in safeguarding users. From our research, we found out that that medicinal plants are a potential source of new antimalarial drugs or preparations.

What did the study set to achieve? What were the findings?

The aim of the study was to identify and evaluate the safety of sampled medicinal plants in treating malaria. We selected 48 plants through interviews with traditional healers from malaria endemic zones in Kenya. The areas included Siaya in western Kenya, Mwea in Central Kenya and regions in the coastal belt.

These plants have historically been used by traditional health practitioners to treat malaria and we subjected them to laboratory tests in search of their anti parasitic properties.

We also investigated whether the plants were used singly or in combination with others. After testing all the selected plants for their antimalarial efficacy, we found the following six plant species to have the highest potential.

*Azadirachta indica

*Fagaropsis angolensis

*Rhus natalensis

*Zanthoxylum usambarense

*Cissampelos pareira

*Grewia plagiophylla

These medicinal plants depicted the highest ability to kill the malaria parasite.

We tested the effect of combining some plant extracts against a multi-drug resistant malaria parasite, Plasmodium falciparum and observed that in some cases the plants depicted higher efficacy when in combination as opposed to the single extracts.

Some of the tested plants showed mild toxicity against cultured mammalian cells. This is a test that involves growing human cells in the laboratory and exposing them to the plant extracts to test whether the extracts will have a negative effect to the growth of the cells as an indication of poisonous effect. All the other tested plant extracts were found to be safe.

The safety results of the medicinal plants were impressive because they showed that they were able to select the malaria parasites and effectively kill them.

What’s promising about your research?

The study identified plants that have medicinal qualities that kill the malaria causing parasite. Our study also confirmed that combining some medicinal plants with other species, as is done in traditional medicine, works.

The preliminary results showed that there’s great potential of developing safe and efficacious antimalarial medicines from the natural extract of local plants.

Adopting medicinal plants as sources of antimalarial treatment will be beneficial for Kenya because the drugs would be cheaper to produce, more cost effective for patients and easily accessible.

What are the next steps to making this a reality?

Kenya Medical Research Institute is working to develop a safe and effective antimalarial drug based on these natural products. We are working to establish appropriate dosages and mode of administration for effective treatment in humans. This is guided by reports from the laboratory and animal experiments.

A well conducted clinical trial of the best performing antimalarial preparations will be conducted prior to advocating the same for clinical application in primary health care.

We are also working with communities where these high value medicinal plants are found so as to encourage their preservation as sources of raw materials for the preparation of antimalarial medicines. We also hope to begin cultivating these plants as a future source of the raw material and as an income generating activity for the engaged communities.

Jeremiah Waweru Gathirwa, Researcher in Chemical Biology, Biochemistry, and Medicinal Chemistry, Kenya Medical Research Institute and Ruth Monyenye Nyang’acha,, Medical Parasitologist, Research Officer,, Kenya Medical Research Institute

This article was originally published on The Conversation. Read the original article.

Is the 2015 Nobel Prize a turning point for traditional Chinese medicine?

Marta Hanson, Johns Hopkins University

I’m sure I’m not the only one surprised by the announcement that half of the 2015 Nobel Prize in Physiology or Medicine has gone to a researcher who spent her entire career researching traditional Chinese medicine. Based at the Chinese Academy of Traditional Chinese Medicine in Beijing (now the China Academy of Chinese Medical Sciences) since 1965, scientist Youyou Tu, her colleagues, and home institution may well be just as stunned today as I am.

Being granted the Lasker Award is often a good predictor of Nobel Prize prospects. Tu received one in 2011 for her discovery of Artemisinin as an alternative malaria cure to the standard chloroquine, which was quickly losing ground in the 1960s due to increasingly drug-resistant parasites. Scientific research on the pharmaceutically active properties of traditional Chinese medicinals, however, has never been a predictor for such widespread international recognition.

Traditional medical knowledge anywhere in the world has not even been on the radar for Nobel Prize prospects. Until now, that is. So how should we interpret this arguably seismic shift in international attention on traditional Chinese medicine?

Watch the announcement of the winners and the following Q&A.

Discoveries to be made in historical record

In the question-and-answer session after the announcement at the Karolinska Institute, which awards the Nobels, one of the panelists emphasized not just the quality of Tu’s scientific research, but also the value of recorded empirical experience in the past.

The antifebrile effect of the Chinese herb Artemisia annua (qinghaosu 青蒿素), or sweet wormwood, was known 1,700 years ago, he noted. Tu was the first to extract the biologically active component of the herb – called Artemisinin – and clarify how it worked. The result was a paradigm shift in the medical field that allowed for Artemisinin to be both clinically studied and produced on a large scale.

Youyou Tu.
China Stringer Network/Reuters

Tu has always maintained that she drew her inspiration from the medical text of a fourth-century Chinese physician and alchemist named Ge Hong 葛洪 (circa 283-343).

His Emergency Formulas To Keep at Hand (Zhouhou beijifang 肘後備急方) can best be understood as a practical handbook of drug formulas for emergencies. It was a book light enough to keep “behind the elbow” (zhouhou), namely, in one’s sleeve, where Chinese men sometimes carried their belongings. We can discern from Ge’s astute description of his patients’ symptoms that people then suffered not only from malaria but also from other deadly diseases including smallpox, typhoid and dysentery.

Beyond recording the fever-fighting qualities of Artemisia annua, Physician Ge also wrote about how Ephedra sinica (mahuang 麻黃) effectively treated respiratory problems and how arsenic sulphide (“red Realgar,” xionghuang 雄黃) helped control some dermatological problems.

Traditional ingredients, modern drugs

Just because a compound has natural roots and has long been used in traditional medicine is no reason to take it lightly.

You might remember that in 2004, the FDA actually banned ephedra-containing dietary and performance-enhancing supplements. They’d been the cause not only of serious side effects but also several deaths. The ban remains in effect in the US despite a court challenge from ephedra manufacturers. Related drug ephedrine, however, is used to treat low blood pressure and is a common ingredient in over-the-counter asthma medicines.

Compounds long known by practitioners of traditional Chinese medicine to be effective are being isolated now in modern labs.
vkreay/flickr, CC BY-SA

As for Realgar, its toxicity was well-known in both ancient Greece and Chinese antiquity. In Chinese medical thought, though, skillfully administered toxins may also be powerful antidotes for other toxins. Realgar thus continues to be used in Chinese medicine as a drug that relieves toxicity and kills parasites. Applied topically, it treats scabies, ringworm and rashes on the skin’s surface; taken internally, it expels intestinal parasites, particularly roundworms.

Although biomedicine does not currently use Realgar or its related mineral arsenicals in treatments, Chinese researchers have been studying their anticancer properties for some time now. In 2011, a Chinese researcher at Johns Hopkins University, Jun Liu (with other colleagues), also discovered that the Chinese medicinal plant Tripterygium wilfordii Hook F (lei gong teng 雷公藤 “Thunder God Vine”) is effective against cancer, arthritis and skin graft rejection.

Tu’s groundbreaking work on artemisinin, in fact, can be seen as the tip of the iceberg of the extensive and global scientific study of pharmacologically active Chinese medicinals, including another successful antimalarial Dichroa febrifuga (changshan 常山) that has roots in the new scientific research on Chinese medicinals in 1940s mainland China.

It was validation of this traditional drug as an antimalarial in the 1940s, in fact, that set the foundation for Chinese leader Mao Tse Tung’s directive two decades later in the late 1960s to find a cure for malaria. Indeed, Tu’s research is best understood within the complex politics and history of top-down support from the Chinese government of Chinese medicine in mainland China during the long durée of the 20th century, and not just in the Maoist period.

Even outside mainland China, though, such research has yielded results. In the 1970s, for example, US and Japanese researchers developed the statin drugs used to lower cholesterol from studying the mold Monascus purpureus that makes red yeast rice, well, “red.”

Empirical evidence of the medical efficacy in the rich Chinese medical archive from centuries earlier similarly influenced the initial direction of this research.

Medically bilingual

So is this Nobel Prize for Tu’s discovery a signal that Western science has changed how it perceives alternative systems of medicine? Perhaps, but only slightly.

One of the Karolinska Institute panelists acknowledged that there are many sources from which scientists draw inspiration to develop drugs. Among them, we should not ignore the long history of experiences from the past. As he clarified, such sources may be inspirational, but the old herbs found there cannot be used just as they are. Don’t underestimate the sophisticated methods Tu used to extract the active Artemisinin compound from Artemesia annua, another one of the panelists concluded.

So the Nobel Prize is not only acknowledging this complete transformation of a Chinese herb through modern biomedical science into something powerfully efficacious, but also the millions of lives saved because of its successful application worldwide, particularly in the developing world.

But there’s something else that marks Tu as extraordinary vis-à-vis both her two fellow Nobel Laureates for medicine, William C Campbell and Satoshi Ōmura, and her more Western medically oriented colleagues in pharmacology. She embodies, in both her history and her research, what I call medical bilingualism – the ability not only to read in two different medical languages but to understand their different histories, conceptual differences, and, most importantly for this unexpected news, potential value for therapeutic interventions in the present.

This medical bilingualism is a quality that current researchers mining the same fine line between the empirical knowledge of traditional medical traditions and the highest level of modern biomedical science would be lucky to share with Nobel Laureate Youyou Tu.

The Conversation

Marta Hanson, Associate Professor of the History of Medicine, Johns Hopkins University

This article was originally published on The Conversation. Read the original article.