Chemical profile and bioactivities of industrial wastes from Chenopodium quinoa seed

Abstract

This study aimed to investigate the effect of extraction methods and solvents (Soxhlet and supercritical fluid extraction, SFE) on the chemical profile (gas chromatography [GC]/mass spectrometry and GC/flame ionization detection) and antimicrobial, antioxidant, antitumor, and anti-inflammatory activities of quinoa Piabiru (QP) husk crude extracts. Soxhlet was applied using 100% water (QPSH2O), and ethanolic solutions of 50% ethanol (ethanol:water 50:50 v/v, QPSetOH50), 70% ethanol (QPSetOH70), and 99% ethanol (QPSetOH99) as solvents. SFE was applied using CO₂ and n-propane as solvents (QPSF). QPSH2O extract showed a higher concentration of phytosterols (stigmasterol, β-sitosterol, 7,8-epoxylanostan-11-ol,3-acetoxy) and carotenoids (rhodopin) and oleic acid, displaying intermediate thiobarbituric acid reactive substance (TBARS) antioxidant activity. Intermediate concentrations of ethanol (QPSetOH50 and QPSetOH70 extracts) increased the extraction yields and the antibacterial activity of the extracts (Pseudomonas aeruginosa, Salmonella enterica, Bacillus cereus, and Staphylococcus aureus). Higher concentrations of ethanol (QPSetOH99 extract) contributed to increased antioxidant activity as assessed by TBARS and higher recoveries of 4-(allyloxy)-2-methyl-2-pentanol, nonadecane, and lauric, myristic, palmitic, linoleic, stearic, arachidic, behenic, and lignoceric acids. Finally, the QPSF extract presented higher antioxidant activity by DPPH, ABTS, and ferric-reducing antioxidant power, higher content of 5-methoxy-2-pentanone, 5-methoxy-2-methyl-2-pentanol, 1-(1,3-dimethylbutoxy)-2-propanol, oxalic, undecanoic, myristoleic, tricosanoic, pentadecanoic, elaidic, 11-eicosenoic, and erucic acids, and better antifungal activity against Aspergillus brasiliensis than the other extracts. Crude extracts were not cytotoxic against non-tumor cells (Vero) and did not show antitumor or anti-inflammatory activities. Thus, antagonistic or synergistic effects of the phytochemical profile of quinoa husk crude extracts may present potential food and pharmaceutical applications.

Practical Applications: The exceptional nutritional properties of quinoa seeds have boosted their cultivation in more than 123 countries. However, quinoa husks are generally considered waste. This study, which is of utmost importance, demonstrates the potential of extracting bioactive compounds from quinoa husks via pressurized fluids, turning them into a health-promoting co-product. This approach could minimize the current shortage of new antibiotics, antifungals, antitumor agents, and anti-inflammatory substances in the pharmaceutical and food sectors. By converting quinoa husks into valuable bioactive extracts, we contribute significantly to developing effective natural compounds, underlining the significance of our collective work.