As gasoline prices jumped, CHEMRAWN turned its focus to how South Africa (and the rest of the continent) might harvest some of its fuel from agricultural products.

From the late 1970s to the early 1990s, South Africa was “ahead of its time” in the hunt to find a way to convert cellulosic biomass to fuels and chemicals, according to Emile van Zyl, a Stellenbosch University microbiologist and organizer of the program’s biofuels portion, which is sponsored by the South African National Energy Research Institute. After the end of apartheid, most of these programs were abandoned in favor of funding other, more pressing priorities.

The current resurgence in interest here is underscored by yesterday and today’s packed sessions on biofuels, during which scientists from South Africa as well as Brazil, the U.S., and Europe discussed locally available feedstocks as well as technologies to convert cellulosic biomass to fuels.

Despite the enthusiasm in the room, it seems unclear at the moment whether biofuel production in South Africa will take off. Today the South African government announced that it has decided to scale back its biofuel dreams because of concerns about food security. The new plan limits the number of crops that can be used as feedstocks (ruling out corn, for example) and sets a production target of just 2%.

It’s no wonder, then, that Africa’s chemists are eager to eke increasingly more sophisticated and economically valuable products out of the continent’s flora.

These efforts are afoot across the continent, but one local example is Lizette Joubert of South Africa’s Agricultural Research Council here in Stellenbosch. One of Joubert’s prime targets is the indigenous herbal tea commonly known as rooibos.

Rooibos, which I’ve been drinking for several years but only on this trip realized came from South Africa, is produced from the Aspalathus linearis plant. It is quite popular among South Africans; in addition, some 11,000 tons of the stuff are exported to the international market each year. Joubert has been working to identify and characterize the various bioactive natural products found in this tea, which is widely touted for its superior antioxidant properties.

Among the molecules present in rooibos, she pointed to aspalathin, a dihydrochalcone and powerful antioxidant that is unique to this plant. With the global antioxidant market topping $3 billion in 2005, she argued that South Africa should further exploit rooibos and other indigenous teas such as honeybush to create novel antioxidant ingredients for cosmetics, food, and nutraceuticals.

Gabriel Bwembya, a chemist at the University of Swaziland, reported his efforts to profile various nutrients in indigenous leafy vegetables from Swaziland. Bwembya used high-performance liquid chromatography and atomic absorption spectroscopy to analyze the nutrient content of local greens known as ligusha (Corchorus olitorus), inkhakha (Momordica involucrata), imbuya (Amaranthus spinosus), shuchuza (Bidens pilosa), and umsobo (Solanum nigrum).

He concluded that these greens are a terrific source of vitamin A as well as iron, calcium, and zinc. By spreading the word, Bwembya hopes to get Swazis to eat more of these vegetables, which are cheaper than other vegetable sources of these nutrients.

In Uganda, chemist Vincent Makokh of the Uganda Industrial Research Institute, in Kampala, is using ultraviolet-visible spectroscopy to measure levels of the antioxidant lycopene in tomatoes. Urban residents in Kampala buy their fruits and vegetables at local markets, where hawkers sell two main varieties of shelf-ripened tomatoes. “We hope to be able to advise residents which tomatoes are more nutritious,” he said.

Finally, O. Tibe and Jo Amarteifio of Botswana College of Agriculture, in Gabarone, reported that their analytical measurements show that several wild indigenous plants—marama bean (Tylosema esculentum), mogose (Bauhinia petersiana), morula (Sclerocarya birrea), and leswe (Ceropegia rendalii)—are an excellent, low cost source of protein. They, like Bwembya and Makokh, are trying to use their results to get Botswanans to eat these vegetables.

WEED WHACKERS Witch weed (top, purple flowers) chokes a maize field. When certain witch-weed-fighting legumes are interspersed (bottom), the maize grows tall. (Zeyaur Khan)

Previously, Zeyaur Khan of the International Center of Insect Physiology & Ecology (ICIPE) in Mbita found that interspersing maize with Desmodium legumes, which are commonly grown for fodder, prevents witch weed from taking hold. Salome M. Guchu, a student at ICIPE in Nairobi, described her team’s efforts to track down how these legumes keep witch weed in check.

The legume exerts its death grip on the parasitic weed by releasing a secondary metabolite (or mix of metabolites) that inhibits witch weed growth. By means of extraction, fractionation, and characterization of natural products from the legumes’ roots, Guchu eventually fingered a class of glycosylated flavones.

One might think the next step would be to use these isolated natural products for weed control. But Baldwyn Torto, a former USDA scientist who recently returned to his home country of Kenya to take a job at ICIPE, has different ideas. Kenyan farmers, he argued, are far more likely to plant a crop that blocks weed growth than to buy and use chemicals that inhibit witch weed growth. To that end, ICIPE scientists, in collaboration with Rothamsted Research, in the U.K., are now working to screen related legume species for those that boast the highest concentration of the most active glycosylated flavones.

So began today’s most provocative talk, given by Stellenbosch University geochemist Martin Fey. “The cynical answer is yes—if you want to attract research funds,” he continued. “But the real answer surely lies elsewhere. There are many constraints on food security in Africa, the least of these being scientific knowledge.”

Fey pointed out that Malawi’s remarkable turnaround came not by way of some new scientific discovery, product, or advance but simply by providing subsidized chemical fertilizers and good seeds. “I see too much of science being extended as the answer to Africa’s food security,” he added. “But I’m pretty sure that it’s not science we need.”

Later I asked Sospeter Muhongo, regional director of the International Council for Science here in Africa, what he had made of Fey’s argument. “We should not be questioning whether science is key to improving Africa’s food security,” he told me. “To restrict our tools to simple science is shortsighted. Considering our existing food shortages and growing population, we must look to modern and appropriate science and technology—for example, biotechnology—to increase our food supply in the future. There simply is no other way.”

RSC hopes the brand-new Pan Africa Chemistry Network will build on the archive’s success. The program aims to promote science and research throughout Africa by catalyzing connections between scientists, researchers, schools, and libraries across the continent. Agro giant Syngenta has committed approximately $2 million over the next five years to help fund the program.

One of the program’s first initiatives is to distribute 16,000 new undergraduate textbooks to universities in Ethiopia and Kenya. Future initiatives will be guided by local needs but are likely to include additional support for science education at all levels, funding for intra-African conferences and symposia, and travel and training grants.

Shem O. Wandiga of Kenya’s Center for Science & Technology Innovations is a part of the Africa-based committee that will help the Pan Africa Chemistry Network select projects to fund. He told me this morning that he welcomes the program as “a catalyst to help African scientists strengthen their capacities and capabilities.”

Africa is the only region in the world in which average per capita food production has fallen steadily over the past 40 years, according to the UN’s Food & Agriculture Organization. The situation is particularly precarious in sub-Saharan Africa, where poverty, nutrient-depleted soil, and an unruly and unpredictable water supply have left millions of people unable to feed themselves.

Chemical fertilizers and improved seed varieties might help. But even though “you can buy a Coca-Cola just about everywhere in sub-Saharan Africa, you simply can’t buy seed and fertilizer,” Sanchez said. Access to and subsidies for seed and fertilizer could lift starving African farmers from hunger, he argued.

As evidence, Sanchez pointed to Malawi’s recent and rapid transformation from food-aid recipient to food-aid donor. Just three years ago, the perennially poor and hungry country was scorched from drought and as many as 5 million of its citizens relied on foreign-supplied food aid to survive. In 2006–07, however, Malawi provided 10,000 tons of food aid to Lesotho and Swaziland.

Malawi’s dramatic food surpluses came about because the Malawi government, tired of begging for aid, decided to buck World Bank strictures and subsidize urea and other fertilizers as well as improved maize seeds for some farmers, Sanchez argued. Better rains helped the cause along but can’t explain the dramatically improved yields of those farmers who got the subsidies, he said. “Better rains are not enough when a nation suffers from critical deficiencies in soil nutrients.”

Malawi’s transformation “came down to chemistry,” noted Piet Steyn of Stellenbosch University, an organic chemist who organized CHEMRAWN XII. He hopes that the chemical research and technologies discussed here this week will have a similarly positive effect on sustaining food supplies throughout Africa in the years ahead.