The bioactive compounds present mostly in fruits and vegetables carry out various bodily functions related to health and well-being. Its effects are considered to be antioxidant, antidiabetic, antiaging, and anticancer.
Many studies have looked for ways to optimize the uptake of bioactive compounds by organisms and increase their bioavailability – the proportion that enters the bloodstream after absorption. One way is to coat compounds with other materials and package them down to the nanometric scale (a nanometer is one billionth of a meter). Nanoencapsulation, as this technique is known, ensures slow release of compounds so that they take longer to digest and can defend against attack by gut microbiome bacteria.
An investigation conducted by a duo of researchers at the Faculty of Pharmaceutical Sciences, University of São Paulo (FCF-USP) in Brazil is one of these studies. Working in the school’s Department of Food Science and Experimental Nutrition, they have produced several articles on the subject – most recently, published in International Journal of Biological Macromoleculesis a literature review on pectin-based nanoencapsulation plus a description of new technologies developed under the auspices of the Center for Food Research (FoRC), Center for Research, Innovation and Dissemination (RIDC) supported by FAPESP.
“We use pectin extracted from residues of albedo and citrus fruit peels, with a level of purity that allows humans to ingest it and does not contain any harmful chemicals,” said João Paulo Fabi, co-author and professor at FCF-USP. Albedo is the layer of white spongy material inside orange and lemon peels, for example.
“In addition to our literature review, we describe a new technology for nanoencapsulation of bioactive compounds using pectin. This necessitates the production of a pectin-lysozyme complex as a protective outer layer for very sensitive bioactive compounds called anthocyanins.” he explained, adding that lysozyme is “a safe edible substance obtained from egg whites and used to increase the stability of the final product”.
Anthocyanins are water-soluble pigments belonging to the flavonoid family. They are phenolic compounds found in all plants and are responsible for the red, blue and purple colors seen in flowers, fruits, leaves, stems and roots.
The authors say their methodology can be used to encapsulate other water-soluble bioactive compounds. “We tested anthocyanins for their challenging sensitivity to many factors, such as light, temperature, pH, and gut bacteria,” said Thiécla Katiane Osvaldt Rosales, another author. He is currently a postdoctoral researcher at the Nuclear and Energy Research Institute (IPEN).
According to the researchers, the main advantage of their methodology is that no other compounds are added apart from pectin, lysozyme and anthocyanins. “We take three compounds from natural sources and mix them in the laboratory to form a new product, without adding salts, ligands or anything else that is potentially toxic. In addition, the nanoparticles are not too small. Very small nanoparticles can penetrate barriers and cell membranes, enter DNA and have toxic effects. The size we get is safe.” said Fabi.
Rosales describes the process they developed to produce nanoparticles. “Pectin and lysozyme are heated separately. An increase in temperature partially changes their structure, and they interact better when heated. They are then cooled rapidly to reach a temperature that is harmless to anthocyanins, which are sensitive and quite unstable. The three substances are mixed in an aqueous suspension and stirred for one hour. The result is anthocyanin which is encapsulated. The suspension is then filtered to separate the content that is not encapsulated,” he says.
Special care is taken with factors such as temperature and pH. “We tested the parameters for optimization purposes, especially pH. If the pH is too high, the anthocyanins will be damaged. Also can’t be too low. We found pH 5 to be optimal for intermolecular interactions,” he explained. “We also tested the duration and intensity of the agitation. We decided to manage all the details, however small, because they make a difference when it comes to the formation of stable particles. We have filed a patent for the methodology.”
Finally, the encapsulation was tested for efficacy in a laboratory-simulated digestive system to mimic gastric and intestinal phases. “The result is that some of the anthocyanins are released during the digestive process, at the end of gastric digestion, and some remain in the nanostructures, with the possibility of releasing this residue in the gut or being absorbed along with the nanostructures. We believe this is a good result. Partial and gradual release suggests absorption of the compound begins before entering the intestine, with residual nanoencapsulation possibly released in the intestine or absorbed completely with little structural change.” said Rosales.
The next step is animal testing. “We tested the in vitro method and obtained results showing that the nanoparticles are safe for consumption. We have evidence that cells can absorb it in a non-toxic way and that pectin protects anthocyanins and their properties. We now have to test it. in animals, observing the process of oral ingestion, absorption of anthocyanins using specific markers for absorption, and the routes followed in the organism. It is important to verify its absorption rate and biological purpose.” he says.
The nanoparticles are primarily intended for use as a dietary supplement. “They can be added to food and dietary supplements, but industrial mass production is required to get them into supplements,” said Fabi.
It should be noted that this method does not require expensive equipment or procedures. “In addition, the materials used for the nanocapsules, which are derived from orange peel by-products, will lower producer costs. The pectin we used in our study is commercially available and used by the food industry, mostly for gelling. in jams or as a thickener,” said Rosales.