The guishe is a by-product of the fiber extraction from Agave lechuguilla. This material has no commercial value, although it contains metabolites that could be used as a resource for producing high-value products. This study optimized the DPPH^• (2,2-diphenyl-1-picrylhydrazyl) antioxidant activity through microwave-assisted extraction (MAE) of polyphenolic compounds from Agave lechuguilla residues. The MAE process was optimized using a Box-Behnken design, with extraction time (5–15 min), temperature (40–50 °C), and solvent: sample ratio (1:20–1:30 m/v) as independent variables. In contrast, the dependent variable was DPPH^• free radical scavenging activity. As a result, the highest antioxidant activity was at 8 min of irradiation, extraction temperature of 45 °C, and solvent: sample ratio 1:30 w/v, obtaining a total flavonoid content of 19.25 ± 0.60 mg QE/g DW, a total polyphenol content of 6.59 ± 0.31 mg GAE/g DW, a DPPH^• free radical scavenging activity of 73.35 ± 1.90%, and an ABTS^+• ([2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonate)]) free radical scavenging activity of 91.93 ± 0.68%.

This study explores the bioconversion of diosgenin by Yarrowia lipolytica P01a, focusing on enhancing the antioxidant, antifungal, and herbicidal activities of the resulting extracts. The bioconversion process, involving glycosylation and hydroxylation, produced significant amounts of protodioscin and soyasaponin I. The extracts showed superior antioxidant activity, with up to 97.02% inhibition of ABTS· radicals and 33.30% inhibition of DPPH· radicals at 1000 mg L⁻¹ of diosgenin. Antifungal assays revealed strong inhibitory effects against Botrytis cinerea, Alternaria sp., and Aspergillus niger, with maximum inhibition rates of 67.34%, 35.63%, and 65.53%, respectively. Additionally, the herbicidal activity of the bioconverted extracts was comparable to commercial herbicides, achieving 100% inhibition of seed germination in both monocotyledonous and dicotyledonous plants. These findings suggest that the Y. lipolytica P01a-mediated bioconversion of diosgenin could provide a sustainable and eco-friendly alternative for developing natural biofungicides and bioherbicides.

Different strategies have been assessed for the revalorization of guishe to obtain biomolecules. The juice obtained after the mechanical extraction of guishe is rich in phytochemicals and sugars which can be converted to other products. The objective of the present study was to evaluate the production of hydrogen and butanol at different guishe juice concentrations (and therefore, different sugar concentrations) via fermentation in batch mode using Clostridium acetobutylicum ATCC 824. Fermentation assays were performed in triplicate under anaerobic conditions at 35 °C for 142 h. Guishe juice was supplemented with all components of synthetic medium (salts, vitamins and reducing agents), except glucose, and diluted at different concentrations: 20%, 40%, 60%, 80% and 100%. For comparison purposes, a control was carried out in a synthetic medium using glucose as carbon source. Results showed a maximum butanol concentration of 5.39 g/L using 80% guishe juice, corresponding to a productivity and yield of 0.04 g/L h⁻¹ and 0.24 g/g, respectively. Meanwhile, the highest productivity (1.16 L H₂/L d⁻¹; 1.99 mmol H₂/L h⁻¹) and yield (18.4 L/kg) of hydrogen were obtained with 40% guishe juice. This study demonstrates the potential of guishe juice to be used as a low-cost substrate for hydrogen and butanol production.