Studies explore bioactive compounds in plants for disease prevention

Fruits and plant extracts contain bioactive compounds that can help treat or prevent diseases. To characterize and understand their mechanism of action, researchers from universities and research institutions in Brazil and Germany have conducted independent but complementary studies.

Some of the results were presented at a lecture session on the future of food and nutrition research on March 25th during FAPESP Week Germany at the Free University of Berlin.

According to Ulrich Dobrindt, a professor at the University of Munich in Germany, medicinal plants contain different types of phytochemicals (natural chemical substances) that neutralize bacterial infections in different ways, thereby boosting the host’s defenses. For this reason, there is growing interest in using extracts from these plants to treat and prevent urinary tract infections, one of the most common infections worldwide, which are currently treated with antibiotics.

“Although their anti-inflammatory, antipyretic and analgesic effects are well known, the active compounds of these plants – such as flavonoids, alkaloids and terpenoids – and their mechanisms of action on pathogen cells have yet to be characterized. Some are antibacterial, but many don’t have this effect,” said the researcher.

In order to further their understanding, German scientists have developed infection models to study the effects of plant extracts on the innate immune response and on the epigenetic regulation of gene expression (biochemical processes that activate and deactivate genes). In bladder cells, for example, they are studying the effect of traditional plants with urological activity, according to the German pharmacopoeia.

In collaboration with researchers at the Federal University of Minas Gerais (UFMG) in Brazil, it was found that some aqueous plant extracts (from species such as Solidago gigantea and Equiseti herba) significantly reduced the adhesion and survival of Escherichia coli in human bladder epithelial cells.

“We observed a drastic reduction in the adhesion and proliferation of this bacterium in bladder cells,” said Ulrich.

Fruit fibers

In Brazil, a group associated with the Food Research Center (FoRC) – one of FAPESP’s Research, Innovation and Dissemination Centers (RIDCs) – has focused on the technological prospection and evaluation of the biological effects on humans of non-digestible water-soluble polysaccharides (bioactive polysaccharides), such as pectins.

Found in papaya, passion fruit and citrus fruits, pectins make up a large portion of the fiber in these fruits and have been linked to a reduction in chronic non-communicable diseases.

However, some of the challenges in extracting these compounds from fruits such as papaya are that they ripen very quickly, resulting in softening of the pulp and chemical modification of the structures of its pectins, which are linked to biological effects such as modulation of the gut microbiota.

“During fruit ripening, enzymes are expressed that modify the structure of the pectins, reducing their beneficial biological effects. Passion fruit and citrus pectins, on the other hand, must be chemically modified in order to present beneficial activities in the intestine,” João Paulo Fabi, professor at the School of Pharmaceutical Sciences of the University of São Paulo (FCF-USP) and coordinator of the project, told Agência FAPESP.

To do this, the Brazilian researchers developed techniques to extract pectin from the albedo of oranges and passion fruit – the white part between the peel and the pulp that is normally discarded when the fruit is processed to make juice – and to modify it in the laboratory to reduce its molecular complexity in order to increase its biological activity.

The development resulted in a patent for the process of extracting pectin from fleshy fruits such as papaya and chayote. A second patent covering the modification of pectin from passion fruit by-products is in the process of being filed.

“We already have a prototype for extracting and modifying these pectins on a laboratory scale. The idea is to obtain a product, such as a flour rich in modified pectin, that could be consumed as a supplement or food ingredient,” said Fabi.

In partnership with other groups, the researchers conducted animal studies to demonstrate the correlation between modified pectins and increased biological activity.

“These preclinical studies can serve as a basis for the development of clinical trials [with modified pectins] as adjuvants to chemotherapy treatment of colon cancer or even as beneficial modulators of the intestinal microbiota,” the researcher said.