Mylene M. Uy

Antioxidant hydroxycinnamic acid derivatives isolated from Brazilian bee pollen

One novel and three known hydroxycinnamic acid derivatives having antioxidant activities were isolated from a Brazilian bee pollen. They were identified as kaempferol 3-O-[2-O-p-coumaroyl]-α-L-arabinopyranoside, N1, N5, N10-tri-p-coumaroyl spermidine, N1, N5, N10, N14-tetra-p-coumaroyl spermine, and monocaffeoyl-tri-p-coumaroyl spermine, respectively. The structure of the kaempferol glycoside was established on the basis of spectroscopic and chemical investigations. Among the isolated compounds, monocaffeoyl-tri-p-coumaroyl spermine showed the strongest free radical-scavenging activity, which was almost identical to that of α-tocopherol. On the other hand, the antioxidant effect of tri-p-coumaroyl spermidine on autooxidation of linoleic acid was strongest and nearly equal to that of α-tocopherol.

Exiguamide, a new spirocyclic sesquiterpene from the marine sponge Geodia exigua that inhibits cell fate specification during sea urchin embryogenesis

A new nitrogen-containing bicyclic spirosesquiterpene designated exiguamide which inhibited cell fate specification during sea urchin embryogenesis has been isolated from the marine sponge Geodia exigua. Its structure was determined by interpretation of spectral data and X-ray crystallographic analysis.

Anti-fertilization activity of a spirocyclic sesquiterpene isocyanide isolated from the marine sponge Geodia exigua and related compounds.

(−)-10-epi-Axisonitrile-3, a spirocyclic sesquiterpene isocyanide obtained from the marine sponge Geodia exigua, immobilized sperm of sea urchin and starfish to block fertilization at the minimum effective concentration of 0.4 μg/ml. On the other hand, fertilized eggs developed normally to the gastrula stage in the presence of a 250-times higher concentration of the isocyanide. Analysis by 31P NMR revealed an accumulation of phosphocreatine and a depletion of inorganic phosphate in the isocyanide-treated sperm, suggesting that (−)-10-epi-axisonitrile-3 inhibited the phosphocreatine shuttle participating in the high-energy phosphate metabolism, thereby immobilizing sperm to block fertilization. No analogs of (−)-10-epi-axisonitrile-3 containing different functionalities or isocyanides with different carbon skeleton exhibited such activity.

Ficusnotins A–F: Rare diarylbutanoids from the leaves of Ficus nota

Six diarylbutanoids, designated as ficusnotins A-F, with a rare carbon skeleton consisting of two aromatic rings separated by an unbranched C4-chain have been isolated from the leaves of Ficus nota (Blanco) Merr. (Moraceae). The structures were determined on the basis of spectroscopic data, as well as X-ray crystallographic analysis. The isolated compounds were evaluated for their antibacterial activity against Bacillus subtilis.