Common beans are important food sources with high nutritional content. Bean seeds also contain phenolic compounds, which have antioxidant and anti-inflammatory properties that promote health. A study from the University of Illinois Urbana-Champaign and CIATEJ in Guadalajara, Mexico, explored the composition of seed coat extracts from black and pinto bean varieties unique to the Chiapas region of southern Mexico.
“These beans are preserved among Mayan communities and cultivated by indigenous farmers. They are heirlooms from previous generations and are important because of their cultural significance and contribution to biodiversity,” explained study co-author Elvira de Mejia, professor at the Department of Food Science and Human Nutrition ( FSHN), part of the College of Agricultural, Consumer and Environmental Sciences (ACES) at the U. of I.
The research team selected two varieties from among several collected in the Chiapas region because of their high phenolic content found in the seed coat pigment that gives the beans their dark red or black color.
“These phenolic compounds have the ability to keep oxidation and inflammation under control, which can help reduce the risk of chronic health problems such as cardiovascular disease, cancer and diabetes,” de Mejia said.
First, the researchers removed the bean seed shell and ground it for processing. They then analyzed the chemical composition of a crude extract, as well as an enriched extract that was purified to concentrate the phenolic content. They also measured the bean extracts’ antioxidant capacity and ability to inhibit free radicals through biochemical analyzes and in silico molecular docking, a form of computer simulation.
“We found that the black beans had high amounts of anthocyanin, especially delphinidin, petunidin and malvidin glucosides, which have antioxidant properties. The pinto beans had the highest total content of phenolic compounds and showed a high potential to inhibit enzymes that contribute to inflammation,” said David Fonseca Hernández, a doctoral student at CIATEJ, and lead author of the paper. Fonseca carried out the research as a visiting researcher in FSHN at the U. of I.
The seed husk extracts can be used as additives in the food industry or in cosmetics, Fonseca explained.
“My research focuses on skin health because there is great interest in new ingredients with bioactive properties for use in cream formulations. One of the main problems with skin aging is the oxidative stress caused by environmental factors. When the skin is exposed to air pollution and sunlight , it produces greater amounts of free radicals and inflammatory pathways are activated,” he said.
“We tested some markers related to inflammation, such as cyclooxygenase and inducible nitric oxide synthase. We had really good results showing that the extracts, especially from pinto beans, could inhibit and reduce the activity of these enzymes.”
The researchers also found that the process of enriching the extracts can further concentrate the anthocyanins and phenolic compounds, which is useful both for industrial and research purposes.
The study is part of a large project supported by CONAHCYT, Mexico’s National Science Foundation, explained study co-author Luis Mojica, research professor at CIATEJ and Fonseca’s advisor.
“One of the goals of the project was to find varieties with an interesting profile to use as a source of phytochemicals for the cosmetics industry. This industry is growing very fast and there is a demand for natural products to treat skin-related diseases or aging,” he said. “In our research, we compared about 60 varieties of common beans from southern Mexico, and these two varieties are three or four times higher than others in phenolic compounds and anthocyanins. These beans are very interesting for health; they are also high in other nutrients such as proteins, fibers and oligosaccharides.”
The project can help provide regional support by increasing wellness and developing Mexico’s southern region by conserving these unique bean varieties, the researchers said.
After following up on the study’s significant laboratory results, the next steps will be to test the extracts on cell tissue cultures and eventually in clinical trials.
Fonseca attended the U. of I. through I-MMAS, a program created to increase the recruitment of Mexican and Mexican-American students within the University of Illinois System.
“Our collaboration with Dr. Mojica’s research group through I-MMAS is meaningful because there is a large number of migrants from Guadalajara in Illinois, but also because of the quality of their work. Dr. Mojica’s laboratory conducts basic research, but they also work with industry to apply knowledge to solve practical problems Dr. Mojica completed his PhD in FSHN at the U. of I. Both he and David were very productive and successful students during their time here and we are very excited to continue our work with them,” de Mejia concluded.