Why Nigeria’s antibiotic leads stall at the lab bench

Lagos, Nigeria—In 2012, a small research team at Lagos State University (LASU) watched a crude extract from a medicinal plant called scent leaf kill Staphylococcus aureus on an agar plate. The zone of inhibition was clear, reproducible, and, in some tests, comparable to that of gentamicin, a potent antibiotic. The plant extract was equally devastating to Salmonella typhi, a bacterium that causes typhoid fever. The scientists wrote up their findings, published the research in the East African Journal of Science and Technology, and moved on.

Thirteen years later, that extract is still just that. Though peer-reviewed journals have also documented the plant’s antimicrobial activity, what isn’t known is the molecule that’s responsible for this activity, or whether it could ever be made into a drug.

This is where promising natural product leads in Nigeria die: in the gap between bioassay and chemistry. “We’re stuck in the middle. We can show you how it works. But we can’t tell you why,” says Habeeb Adebodun Bankole, a LASU biochemistry professor who led the 2012 research on Ocimum gratissimum, known locally as efinrin.

Of 47 Nigerian papers on natural products published between 2010 and 2015 that reported antimicrobial activity, 42 stopped at the crude extract stage, according to C&EN’s analysis of the scientific literature.

The reason is obvious—a lack of technology and consistent funding for natural product development in Nigeria.

Meanwhile, the human cost of this gap is sobering. According to a 2023 study in the Lancet, antimicrobial resistance led to an estimated 64,000 deaths in Nigeria in 2019, which is slightly higher than that of other African countries. At the same time, the cost of imported antibiotics has risen steeply, in some cases by as much as 1,000%, because of currency devaluation and supply chain disruptions.

The crude extracts that Bankole and team isolated from scent leaf and another Nigerian plant, utazi (Gongronema latifolium), “need to be investigated further to identify the particular compound that is responsible,” says Ifeyinwa Adaka, a lecturer in the pharmaceutical chemistry department at the University of Nigeria Nsukka, who wasn’t involved in the research.

“That will enrich the body of antibiotics,” she says by email, “especially now that [antimicrobial resistance] is prevalent.”

A crop that outpaces the science

Walk through any of Lagos’s marketplaces at dawn, and you will find scent leaf farmers unloading crates, the air heavy with the herb’s sharp aroma. Before they’re sold in fist-sized bunches of broad, fuzzy leaves, the plants originate in plots on the city’s outskirts.

Like many sellers, Bashiru Mohammed begins the day wading through the muddy scent leaf fields to cut stems. He is dressed for wet work: rubber boots, rolled jeans, a faded T-shirt, and a towel flung around his neck. After collecting the day’s harvest, he packs the leaves into boxes and takes a bus or a bike to the city.

“It takes 21 to 28 days for the leaf to grow to maturity for harvest, though it requires a lot of water,” Mohammed says on his low-lying farm, where rows of deep-green scent leaf stand knee high, glossy with early-morning dew. Fortunately, “water is not a problem.”

When he arrives at the sprawling, open-air Oshodi Market, women in brightly hued head scarves call out prices beneath zinc roofs and tarpaulins. Generators hum. Buses hoot. The air mixes smells of diesel, earth, and fresh greens. 

“Efinrin o! Fresh efinrin,” they say, offering bundles of scent leaves for 200 naira (about 15 cents). The plant, a type of basil, is mixed into soups to infuse a peppery flavor, brewed into tea to settle stomachs, and chewed raw to ease toothaches.

Though no official economic statistics are available, scent leaf is likely one of the more lucrative crops in Nigeria. From traditional healers to people preparing their evening meal, market demand is high, Mohammed says: “The leaf is used for many purposes.”

A Herculean task for Nigerian chemists

To understand why scent leaf is not a commercial antibiotic, however, you must follow the chemistry. Crude plant extracts are not single drugs; they are complex mixtures of dozens or hundreds of molecules. To make a drug, you must separate the molecules, identify which one kills bacteria, and determine its structure, says Adaka, who studies medicinal plants.

That work requires specific equipment, including instruments for thin layer chromatography (TLC), mass spectrometry (MS), and nuclear magnetic resonance (NMR) spectroscopy.

In short: TLC tells you the number of molecules in a sample, MS tells you their weights, and NMR tells you how they are built. Without all three, you cannot file a patent, optimize a lead, or submit a drug for regulatory review.

What’s more, this equipment can cost hundreds of thousands of dollars per item. Only a handful of mass spectrometers are in Nigeria; the Institute of Genomics and Global Health at Redeemer’s University in Ede has one but has no formal program for advancing natural product research.

On a June afternoon in his laboratory, Bankole listens as centrifuges softly whir, a rotary evaporator emits a steady gurgle, and a blender breaks down fresh scent leaves. Revealing a setup on scarred wooden benches, Bankole shows a C&EN reporter his research essentials: analytical balances for weighing out milligrams of dried leaf extract and an ultraviolet–visible spectrophotometer blinking as it reads the latest sample. Fogged glassware emits the bitter smell of ethanol and solvents.

“We had no access to [high-performance liquid chromatography], no mass [spectrometer], no way to fractionate and track the active component,” Bankole says of his 2012 research into scent leaf. “The funding line ended at the bioassay.”

In the US and the EU, core facilities, contract research organizations, and specific US National Institutes of Health and National Institute of Allergy and Infectious Diseases programs support preclinical natural product development. In Nigeria, the handoff from research to drug development does not exist.

That’s why Adaka calls getting a drug to market a “Herculean task” in Nigeria. “To get these things done, researchers who are well funded send their samples from one institution to another for specific analysis, and sometimes the integrity and quality of these samples get compromised in transit,” she says.

A pattern, not an outlier

If the technical wall is equipment, the foundation under it is money.

Bobby Aguebor-Ogie, a senior bioscientist at the University of Benin, Ugbowo, puts it bluntly: “The major challenges about molecule or compound identification from natural products in Nigeria begin and end in funding.”

Most academic researchers have limited money, and many draw upon their own salaries to personally fund experiments, he says. At LASU, research such as Bankole’s is kept alive by a mix of private grants and funding from the Lagos state budget.

“Taking the work just beyond laboratories to encapsulation, tablet, or drug formation requires a lot of money, and without adequate funding, that part of research is really difficult,” Aguebor-Ogie says.

Scent leaf isn’t the only story of promising natural product research in Nigeria left to languish through a lack of funds. The medicinal plant Alstonia boonei is used to treat a variety of ailments, such as diarrhea and insomnia, and scientists at the University of Nigeria Nsukka have found that an ingredient in its bark kills off pathogenic bacteria, including Escherichia coli and Pseudomonas aeruginosa. Researchers at Ahmadu Bello University have also reported that a crude extract of Moringa oleifera, an invasive tree, can kill multidrug-resistant E. coli (PDF). Neither project has identified a responsible molecule, let alone advanced one toward the clinic.

Government support

To address the problem, the Nigerian government runs the Lagos State Science Research and Innovation Council (LASRIC), which manages and funds research on natural products. They’ve supported studies on a cultivated cowpea that can resist the parasitic weed Striga and the use of Crinum glaucum bulbs as treatment for coronavirus, says Lateef Alani, coordinator of the LASRIC secretariat.

Yet in an interview with C&EN, he acknowledges the same ceiling that Bankole described.

“These researchers stop at the lab bench without further work on molecule identification and commercialization of the products, basically because of limited funds and collaboration,” Alani says.

That’s why Alani is forming local and international partnerships to boost academic research, for instance by accelerating prototype development and ramping up production of potential drugs.

For example, the University of Cape Town’s Drug Discovery and Development Centre (H3D) offers shared access to natural product chemistry for collaborators in other African countries. India’s Council of Scientific and Industrial Research laboratories also contract out isolation work to African research groups.

“We have so many scientific research works in various institutions in Nigeria that can improve quality of life wasting on one shelf or the other. We should understand that most world innovations are products of academic research,” Alani says.

Closing the gap

To restart his LASU work, Bankole would need about $12,000–$18,000, between 3 and 4 months of chemists’ time, and of course the advanced technological equipment. Beyond that, his bioassay work—using a laminar flow hood, agar, and consumables—is relatively cheap, as is the plant itself, thanks to farmers such as Mohammed.

Bankole says the chemistry is more straightforward now than it was 13 years ago. With advances in thin-layer chromatography and bioassay-guided fractionation, he estimates that a competent natural product chemist could obtain semipurified fractions within weeks.

“I’m open to collaborating,” he says. “If someone has the facility, I’ll supply the plant material and the bioassay data. We know it works. We just need someone to tell us what it is.”

Emeka Onwuasoanya is a life sciences journalist in Nigeria.