Dereplication of Bioactive Spirostane Saponins from Agave macroacantha

Abstract

A dereplication strategy using UPLC-QTOF/MS E , the HMAI method, and NMR spectroscopy led to the identification of five main steroidal saponins ( 1 – 5 ), including three previously unknown compounds named macroacanthosides A–C ( 3 – 5 ), in a bioactive fraction of Agave macroacantha . The major saponins were isolated, and some of them together with the saponin-rich fraction were then evaluated for phytotoxicity on a standard target species, Lactuca sativa . The inhibition values exhibited by the pure compounds were confirmed to be in agreement with the phytotoxicity of the saponin-rich fraction, which suggests that the saponin fraction could be applied successfully as an agrochemical without undergoing any further costly and/or time-consuming purification processes. The NMR data of the pure compounds as well as of those corresponding to the same compounds in the fraction were comparable, which indicated that the main saponins could be identified by means of this replication workflow and that no standards are required.

Dereplication of Bioactive Agave Saponin Fractions: The Hidden Saponins

“…Thus, the proposed structure for sugar S5Deox is S5Rha), which has previously been reported in A. macroacantha. 10 Finally, the only reported chain derived from S4 that is consistent with the fragmentation observed for S5Pent possesses a xylose at position 3 of glucose (Glc'), so it is proposed that at least one of the chains is…”

“…The most widely used technique to ascertain the contents of saponins in a given extract is UPLC/MS. − The molecular ion [M – H] − and the fragmentation patterns provide information on the sequential loss of sugar moieties, and the last and most intense fragment usually corresponds to the aglycone linked to the innermost monosaccharide …”

“…In a previous study, the bioactive fraction of A. macroacantha was dereplicated, and this led to the identification of five main saponins, four of which had the same sugar chain . The bioactive fractions of A.…”

Steroidal Saponins with Plant Growth Stimulation Effects; Yucca schidigera as a Commercial Source

“…Analysis of the UPLC-MS chromatograms for these two fractions displayed molecular ions and fragmentations that were consistent with steroidal saponin features ( Table 1 ). The fragmentation patterns usually observed for this kind of compound in negative mode are the precursor ion forming adduct with formate [M + HCOO] – and [M–H] – , the different losses of sugar residues and, as the last fragment, the aglycone with the sugar moiety directly linked to it, which is commonly a hexose residue [Aglycone–H + 162] – [ 23 ].…”

“…The exact masses of the saponins were measured using the method previously described in the bibliography [ 17 , 23 ]. A UPLC-QTOF ESI (Waters Xevo G2, Manchester, UK) high-resolution mass spectrometer (HRESI-TOFMS) was used to measure the exact masses.…”