Brazil’s Caatinga Yields Natural Antioxidants Through Green Extraction of Barbatimão Phenolics

Deep in northeastern Brazil, one of the world’s most overlooked biomes may hold the key to replacing a family of controversial synthetic food additives. Scientists at the Regional University of Cariri argue that the Caatinga, a dry forest ecosystem found exclusively in Brazil, is a rich and largely untapped reservoir of phenolic compounds, plant-derived molecules capable of slowing the oxidative reactions that spoil fats and oils in food. Writing in the journal Discover Green Chemistry, the team, led by Maria Alice Macêdo Ribeiro and José Galberto Martins da Costa, uses the endemic tree Stryphnodendron rotundifolium, popularly known as barbatimão, as a model for how this biodiversity could be transformed into clean-label antioxidant ingredients for the food industry.

The industrial problem they target is both old and enormous. Oxidation is one of the principal mechanisms of food deterioration, degrading nutritional quality, altering flavor, aroma and color, and shortening shelf life, particularly in lipid-rich products. To fight it, manufacturers have long relied on synthetic antioxidants such as butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA) and tert-butylhydroquinone (TBHQ). Yet mounting evidence of potential health risks, combined with a consumer shift toward natural ingredients and transparent ‘clean label’ products, has intensified the search for plant-based alternatives that can do the same job without the baggage of synthetic chemistry.

Phenolic compounds are the leading candidates in that search. This broad class of plant secondary metabolites includes flavonoids, phenolic acids and tannins, and their antioxidant power arises from a set of complementary chemical mechanisms: they scavenge free radicals, chelate transition metal ions that catalyze oxidation, and interrupt the chain reactions by which lipid peroxides propagate. When these mechanisms operate in a food matrix, lipid oxidation is delayed and shelf life is extended. The challenge is that plants produce these compounds as defensive responses to environmental stress, so their abundance depends heavily on where and how a species grows, and extracting them efficiently without damaging them has been an enduring technical obstacle.

This is where the Caatinga becomes strategically interesting. The biome’s plants endure high temperatures, intense solar radiation and prolonged water deficit, conditions that push them to biosynthesize phenolics as adaptive protection against oxidative stress. In other words, the very harshness that makes the Caatinga inhospitable appears to make its flora chemically rich. Barbatimão exemplifies the point. A member of the Fabaceae family, the species concentrates tannins, particularly in its bark, alongside flavonoids such as rutin and catechins and phenolic acids including gallic and caffeic acids. Its bark has a long history of empirical use in teas, tinctures and sitz baths for wounds, ulcers, gastritis and inflammatory conditions, and modern laboratory studies have shown that bark and leaf extracts exhibit pronounced free radical scavenging, lipid peroxidation inhibition and metal chelation activity.

Despite this promise, the authors argue that the technological valorization of Caatinga antioxidants has been held back by conventional methodology. Most published work relies on extraction systems built around volatile organic solvents that are poorly selective, energy-intensive and difficult to translate to food-grade applications, a mismatch with both green chemistry principles and current regulatory and consumer expectations. Conventional hydroalcoholic extraction, the standard approach in barbatimão research to date, may also leave complex phenolic fractions, such as high-molecular-weight condensed tannins, insufficiently extracted or chemically degraded during processing, meaning the full antioxidant arsenal of the plant has likely been underestimated.

The proposed solution is a pairing of two green technologies: natural deep eutectic solvents (NADES) and ultrasound-assisted extraction (UAE). NADES are tunable liquid systems formed by combining hydrogen bond acceptors, such as choline chloride, with hydrogen bond donors, including organic acids like lactic and citric acid, polyols such as glycerol, amino acids and sugars. Their effectiveness rests on extensive hydrogen-bonding networks and polarity matching, which favor the solubilization of hydroxylated aromatic structures, precisely the architecture of flavonoids, phenolic acids and condensed tannins. Choline chloride–organic acid and choline chloride–polyol combinations have already demonstrated high efficiency in pulling quercetin derivatives, gallic acid and catechins out of plant matrices.

Selectivity is the standout advantage. Because solvent composition can be rationally designed, acidic NADES systems tend to favor phenolic acids, while polyol-based systems are more effective for flavonoids and bulky tannins. This design flexibility means researchers can target specific bioactive fractions rather than accepting whatever a generic solvent happens to dissolve. The main technical limitation of NADES, their relatively high viscosity, which slows mass transfer, can be mitigated by adding water or by coupling the solvent with ultrasound. Acoustic cavitation disrupts cell walls, enhances solvent penetration into the plant tissue and accelerates mass transfer. Under optimized NADES–UAE conditions, recent studies across diverse plant materials report significant increases in total phenolic content and antioxidant activity, often exceeding conventional organic solvents while cutting extraction time and solvent consumption.

Applying this technology to barbatimão would be unprecedented, and the authors argue it could unlock underexplored phenolic fractions and clarify antioxidant mechanisms such as metal chelation and lipid oxidation inhibition that current extracts capture only partially. The food applications are equally forward-looking: many NADES constituents are non-volatile, low in toxicity and, in some cases, edible, which raises the possibility of using extracts directly or with minimal downstream processing, reducing costs and environmental impact while supporting clean-label claims. Computational tools are accelerating the design stage too, with approaches such as COSMO-RS, a Conductor-like Screening Model for Real Solvents, and machine learning enabling researchers to predict solvent–solute interactions and rationally tailor solvents to specific phenolic targets before any benchwork begins.

Significant hurdles remain before Caatinga antioxidants reach industrial shelves. Solvent viscosity, compound recovery, sensory impact on foods, and compliance with food safety regulations must all be systematically evaluated, and while NADES components are often regarded as safe, dedicated regulatory frameworks for their direct use in food systems are still under development, underscoring the need for toxicological and safety studies. The authors outline a research roadmap: rational optimization and scale-up of NADES systems with sustainability metrics such as energy efficiency, solvent recyclability and life cycle assessment; advanced chemical profiling using HPLC-DAD-MS/MS and metabolomics to identify bioactive fractions; and validation in real food matrices with kinetic and mechanistic analyses of antioxidant performance during processing and storage. Within that roadmap, S. rotundifolium serves as a proof-of-concept species, a demonstration of how one of Earth’s harshest and least-studied biomes can supply the sustainable, science-grounded ingredients that the food industry increasingly demands.

Subject of Research: Phenolic-based natural antioxidants from Caatinga plants as sustainable food additives using green extraction technologies

Article Title: Natural antioxidants from the Caatinga with insights from Stryphnodendron rotundifolium as a model for phenolic-based food additives

Article References: Ribeiro, M. A. M., Ferreira dos Santos, I. R., de Lima Pereira, J. F., Xenofonte, J. V. F., & da Costa, J. G. M. (2026). Natural antioxidants from the Caatinga with insights from Stryphnodendron rotundifolium as a model for phenolic-based food additives. Discover Green Chemistry, 1(1), Article 17. https://doi.org/10.1007/s44509-026-00019-x

Image Credits: AI Generated

DOI: 10.1007/s44509-026-00019-x

Keywords: phenolic compounds, Caatinga biome, Stryphnodendron rotundifolium, natural antioxidants, NADES, ultrasound-assisted extraction, green chemistry, food additives, tannins, clean label, Natural, antioxidants