Andy J Pérez

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A bioassay-guided fractionation of Agave offoyana leaves led to the isolation of five steroidal saponins (1-5) along with six known saponins (6-11). The compounds were identified as (25R)-spirost-5-en-2α,3β-diol-12-one 3-O-{α-l-rhamnopyranosyl-(1→3)-O-β-d-glucopyranosyl-(1→2)-O-[β-d-xylopyranosyl-(1→3)]-O-β-d-glucopyranosyl-(1→4)-O-β-d-galactopyranoside}(More)
A fingerprint of steroid saponins, the major constituent in 80% methanolic fraction from the male flowers of Phoenix dactylifera has been established. Under ESI-MS/MS conditions, the fragmentation patterns of [M - H]- ions exclusively displayed signals corresponding to the cleavage of the glycosidic bonds, thus allowing a rapid identification of 21(More)
Five azukisapogenol glycosides (1-5) have been isolated from the aerial parts of alsike clover (Trifolium hybridum L.), and their structures were elucidated by combined spectroscopic, spectrometric (1D and 2D NMR; HRESIMS, ESI-MS/MS), and chemical methods. Three of them are new compounds and were identified as(More)
A careful NMR analysis, especially by 1D TOCSY and 1D ROESY, of a refined saponin fraction allowed us to determine the structure of three saponins from a polar extract of Agave brittoniana Trel. spp. Brachypus leaves. The use of 1D DOSY for the suppression of the solvent signal was useful to obtain the chemical shifts of anomeric signals. A full assignment(More)
For centuries oak wood (Quercus robur) has been used in aging of wines and spirits, which is based on pleasant flavors given to beverages by phenolics transferred to the liquid during the maturation process. Other metabolites, such as triterpenoids, can also be released. Searching for extractable triterpenoids in oak heartwood, 12 new, 1-12, and five known,(More)
For centuries wood containers have been used in aging of wines and spirits, due to the pleasant flavors they give to the beverages. Together with oak, sweet chestnut wood (Castanea sativa) have been often used for such purpose. The maturation process involves the transfer of secondary metabolites, mainly phenolics, from the wood to the liquid. At the same(More)
Several species of Brachiaria (Poaceae) currently cover extensive grazing areas in Brazil, providing valuable source of feed for a large cattle population. However, numerous cases of toxicity outbreaks in livestock have raised concerns on safety of using these plants, especially B. decumbens. In this study, chemometric analysis of ultrahigh-performance(More)
Tabletop computing is a new emerging interface that can be realized with low cost using depth sensor cameras such as the Microsoft Kinect. The optimization of the touch interface using depth measurements must take into account the size variations of a diverse population. In this study, we examine a sample population to understand the differences in hand(More)
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