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. 2025 Jul 31;26(15):7407.
doi: 10.3390/ijms26157407.

Setting Up a "Green" Extraction Protocol for Bioactive Compounds in Buckwheat Husk

Anna R Speranza  1 , Francesca G Ghidotti  1 , Alberto Barbiroli  1 , Alessio Scarafoni  1 , Sara Limbo  1 , Stefania Iametti  1
Affiliations

Setting Up a "Green" Extraction Protocol for Bioactive Compounds in Buckwheat Husk

Anna R Speranza et al. Int J Mol Sci. .

Abstract

Buckwheat, a gluten-free pseudocereal, is rich in dietary fiber, minerals, high-quality proteins, vitamins, and essential amino acids. Buckwheat husk, a by-product of dehulling, contains high levels of bioactive compounds such as polyphenols and dietary fibers. This study compares green extraction methods (ultrasound-assisted extraction, UAE; and microwave-assisted extraction, MAE) for recovering polyphenols from buckwheat husk. MAE improved polyphenol yield by 43.6% compared to conventional acidified methanol extraction. Structural and chemical analyses of the residual husk material using SEM, FTIR, and fiber analysis revealed that MAE alters husk properties, enhancing polyphenol accessibility. Thus, MAE appears an efficient and sustainable alternative to acid- and solvent-based extraction techniques. Extracts obtained via "green" methods retained strong antioxidant activity and showed significant modulation of inflammatory markers in human Caco-2 cells, highlighting the potential use of "green" buckwheat husk extracts for food and pharma applications. This work supports the valorization of buckwheat husk within a circular economy framework, promoting buckwheat husk as a valuable raw material for bioactive compound recovery in diverse applications.

Keywords: anti-inflammatory properties; buckwheat husk; extraction; microwave-assisted extraction; polyphenols; ultrasound-assisted extraction.

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Conflict of interest statement

The authors declare no conflicts of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.

Figures

Figure 1
Figure 1
Chromatograms of the extracts recorded at two different wavelengths: (a) 280 nm and (b) 350 nm. Met-HCl, Acidified methanol extracts; BA, Aqueous Acetic Acid Extract; UAE, Ultrasound-assisted extraction; MAE1, Microwave-assisted extraction first step; MAE2, Microwave-assisted extraction second step.
Figure 2
Figure 2
Cell viability at three different concentrations of the various extracts. The cell viability was calculated by comparing the optical density at 565 nm of treated cells to that of the control group (CTRL). Met-HCl, Acidified methanol extract; BA, Aqueous Acetic Acid Extract; UAE, Ultrasound-assisted extraction; MAE1, Microwave-assisted extraction first step; MAE2, Microwave-assisted extraction second step. Results are presented as means ± SD (n = 4). Data marked with the same letter are not significantly different (p < 0.05, Tukey’s test).
Figure 3
Figure 3
Anti-inflammatory properties of the various extracts at three different concentrations. Cells were then stimulated with IL-1β 20 ng/mL (CTRL) in the presence or absence of buckwheat extracts. IL-8 gene expression was quantified using qPCR and normalized to CTRL. Met-HCl, Acidified methanol extract; BA, Aqueous Acetic Acid Extract; UAE, Ultrasound-assisted extraction; MAE1, Microwave-assisted extraction first step; MAE2, Microwave-assisted extraction second step. Results are presented as means ± SD (n = 2). Data marked with the same letter are not significantly different (p < 0.05, Tukey’s test).
Figure 4
Figure 4
SEM micrographs of buckwheat husk before (a–d) and after microwave-assisted extraction second step MAE2 (e–h).
Figure 5
Figure 5
Van Soest analysis. Composition of the buckwheat husk before (untreated) and after microwave-assisted extraction second step (MAE2). Results are presented as means ± SD (n = 2). Data marked with the same letter are not significantly different (p < 0.05, Tukey’s test).
Figure 6
Figure 6
FTIR analysis of the before (untreated) and after (MAE2) microwave-assisted extraction of the buckwheat husk.
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