Remarkable African plant could revolutionize tuberculosis treatment

In the battle against tuberculosis, a global scourge that claims over 1.5 million lives annually, researchers are looking to a plant with deep roots in traditional medicine. African wormwood (Artemisia afra), long used in southern Africa to treat fevers, coughs, and other ailments, has emerged as a promising candidate in the fight against Mycobacterium tuberculosis (Mtb), the bacterium responsible for tuberculosis.

This discovery combines centuries of ethnobotanical knowledge with cutting-edge scientific innovation, offering a new angle in tackling one of the world’s most persistent public health challenges.

Tuberculosis, one of the oldest recorded human diseases, remains a major global health concern. The World Health Organization (WHO) reported 10 million new cases and over 1.6 million deaths in 2021, marking it as one of the deadliest infectious diseases. While effective therapies exist, their implementation is hampered by the disease’s complex treatment requirements.

Patients with drug-sensitive tuberculosis must undergo a standard six-month regimen of antibiotics, combining isoniazid, rifampin, pyrazinamide, and ethambutol during the intensive phase, followed by a continuation phase with fewer drugs. For drug-resistant strains, treatment duration can extend up to two years, with higher costs, severe side effects, and reduced efficacy.

A significant challenge in tuberculosis treatment arises from Mtb’s ability to enter a dormant, non-replicating state. When stressed by antibiotics or the immune system, the bacteria slow their metabolism and reduce cellular activity, making them resistant to traditional therapies. These hibernating cells pose a significant barrier to eradication, as they can reactivate after treatment, leading to relapses and continued transmission.

The WHO’s “End TB Strategy” aims to eliminate tuberculosis by 2050. Achieving this goal requires innovative treatments that can target both actively replicating and dormant bacteria, particularly in regions where resources are limited and access to healthcare is uneven.

Nature has long been a source of inspiration for drug discovery. Many of today’s antibiotics, antivirals, and antimalarials originate from natural products, demonstrating the potential of plants, fungi, and microorganisms to yield life-saving compounds. Among these, plants in the Artemisia genus have played a pivotal role in traditional medicine.

The Artemisia genus encompasses over 500 species, including Artemisia annua and Artemisia afra. A. annua is celebrated for producing artemisinin, a potent antimalarial compound. However, A. afra, a species native to southern Africa, lacks detectable levels of artemisinin. Despite this, it has been traditionally used to treat fevers and respiratory illnesses, including symptoms consistent with tuberculosis.

Recent studies, published in the Journal of Ethnopharmacology have confirmed that A. afra possesses significant antibacterial properties. Researchers have demonstrated that extracts from the plant are effective against Mtb, even under conditions mimicking the bacterium’s dormant state. These findings suggest that A. afra contains unique compounds with therapeutic potential.

Joshua Kellogg, an assistant professor at Penn State and co-corresponding author of the study, emphasized the plant’s significance. “Multiple species of Artemisia have been used for centuries in traditional medicine, and our research shows that their potential extends far beyond what we previously understood,” he said.

To identify the bioactive compounds responsible for A. afra’s antibacterial effects, researchers used advanced biochemometric techniques. This approach combines chemical profiling with biological testing, enabling scientists to pinpoint specific molecules linked to therapeutic activity.

The research team began by extracting compounds from A. afra using dichloromethane (DCM), a solvent that isolates lipophilic substances. They then fractionated the extract into simpler chemical mixtures and tested each fraction against Mtb in laboratory conditions. These tests assessed the minimum inhibitory concentration (MIC) required to halt bacterial growth and evaluated the compounds’ effectiveness in both aerobic and hypoxic environments.

Machine learning models played a crucial role in this process. By correlating chemical profiles with biological activity, researchers narrowed their focus to a specific fraction containing an O-methylflavone. This compound demonstrated the rare ability to kill Mtb in both its active, replicating state and its dormant, hypoxic state.

“This dual activity is particularly significant,” Kellogg explained. “Most current treatments target actively dividing bacteria, leaving dormant cells untouched. The compound we identified shows promise in overcoming this limitation.”

The O-methylflavone compound exhibited minimal toxicity in human cell models, suggesting it could be developed into a safe therapeutic. However, its potency is currently too low for direct clinical application. Kellogg and his team are now exploring ways to modify the compound’s structure to enhance its effectiveness.

“While this compound alone may not be the answer, it provides a foundation for designing new drugs,” Kellogg said. “We’re also investigating whether similar molecules in A. afra could contribute to its overall antibacterial activity.”

The discovery of A. afra’s potential highlights the enduring value of traditional medicine. For centuries, healers in southern Africa have used the plant to treat symptoms associated with tuberculosis, such as persistent coughs and fevers. This long-standing practice provided the initial clues that led scientists to investigate the plant’s properties.

Traditional remedies often contain complex mixtures of bioactive compounds, which may work synergistically to produce therapeutic effects. Kellogg emphasized the importance of respecting and learning from these practices. “Ethnobotanical knowledge is a treasure trove of information,” he said. “By combining it with modern scientific tools, we can uncover new solutions to age-old problems.”

The findings also underscore the importance of biodiversity in drug discovery. Plants like A. afra thrive in specific ecosystems, and their medicinal properties are a direct result of their unique evolutionary histories. Protecting these ecosystems is not just an environmental imperative—it’s a matter of public health.

The journey from plant-based discovery to pharmaceutical development is long and complex. Compounds identified in the laboratory must undergo rigorous testing to determine their safety, efficacy, and stability. This process can take years, but the rewards are well worth the effort.

In the case of tuberculosis, the stakes are particularly high. The emergence of multidrug-resistant (MDR), extensively drug-resistant (XDR), and totally drug-resistant (TDR) strains has made the disease even more difficult to control. Innovative treatments are urgently needed to stay ahead in the arms race against bacterial evolution.

Kellogg and his team remain optimistic. “This is just the beginning,” he said. “Our work with A. afra has opened new doors, and we’re eager to explore what lies beyond. The potential to develop faster, more effective treatments for tuberculosis is within reach.”

As research continues, partnerships between scientists, healthcare providers, and traditional medicine practitioners will be crucial. By uniting diverse perspectives and expertise, the global community can move closer to achieving the WHO’s ambitious goal of eradicating tuberculosis by mid-century.

African wormwood, with its deep cultural roots and newfound scientific promise, serves as a symbol of hope. It reminds us that sometimes, the answers to our most pressing challenges lie hidden in plain sight, waiting to be rediscovered.

Note: Materials provided above by The Brighter Side of News. Content may be edited for style and length.

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