Steroidal saponins have shown beneficial health effects. Agave spp. leaves and rhizomes are sources of these compounds, but their presence has not been reported in the aguamiel. Aguamiel is the sweet edible sap from mature agave, and its quality is influenced by the plant ripening stage. The purpose of this research was to identify and quantitate saponins in aguamiel from Agave americana and Agave salmiana at two ripening stages. Saponins and sapogenins were identified with HPLC/ESI-MS/TOF and quantitated with HPLC/ELSD. Results proved the presence of saponins derived from kammogenin, manogenin, gentrogenin, and hecogenin. The saponin content in aguamiel from immature A. salmiana was 2-fold higher (478.3 protodioscin equivalents (PE) μg/g aguamiel (DM)) compared with A. americana (179.0 PE μg/g aguamiel (DM)). In both species, saponin content decreased when plants reached sexual maturity. This should be considered before evaluating the effects of Agave spp. as a source of bioactive saponins.

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The phenolic, flavonoid, and antioxidant contents of methanol extracts of nine samples of Mexican cactus ( Opuntia spp.) cladodes processed into flours were studied. Opuntia undulata contained the highest amount of phenols [905.08 ± 64.51 μg of gallic acid equivalents (GAE)/g]. The oxygen radical absorbance capacity (ORAC) of the cladode flour extracts indicated that Opuntia robusta var. Gavia [738.8 ± 89.9 μmol of Trolox equivalents (TE)/g] contained the highest antioxidant capacity. ORAC values significantly correlated to total phenols but not to flavonoid contents and were comparable to cranberries and blackberries. Glycosidic forms of isorhamnetin and kaempferol were identified via high-performance liquid chromatography-photodiode array (HPLC-PDA) and HPLC-mass spectrometry (MS), with isorhamnetin being the most abundant flavonol in all samples, except for Opuntia lindheimeri . The effectiveness of acid hydrolysis varied among species because of the different flavonol profiles. For some varieties, the triglycosidic forms were partially acid-hydrolyzed, giving an increase in the content of diglycosides. Optimization of hydrolysis for each species is required to estimate the total amount of each flavonol.

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The aim of this work was to evaluate the effect of ultrasound on supercritical fluid extraction for the recovery of antioxidants and saponins from agave bagasse as a green extraction technique. When a mass load of 0.086 g/cm 3 was used, ultrasound effect was not observed, due to sample swelling and compaction within the cell. For 0.043 g/cm 3 , the intensification effect of ultrasound was significant (p<0.05) and its magnitude depended on the transducer geometry. For a multiplate transducer geometry, antioxidant capacity increased from 12.18±1.01 to 20.91±1.66 µmol TE/g; and saponins from 19.05±1.67 to 61.59±1.99 µg/g, when ultrasound was applied. Although the amount of bioactives extracted is low, the use of a multiplate transducer design was able to intensify the supercritical fluid extraction of phytochemicals from agave bagasse. Consequently, this type of transducer can become an alternative for the application of ultrasound on the supercritical fluid extraction of other suitable agro-industrial by-products.