Publications by authors named "Raymond Malabed"

Article Synopsis
  • Cholesteryl-β-D-glucoside (ChoGlc), a glycolipid found in brain tissue, alters how cholesterol interacts with sphingomyelin (SSM) membranes, affecting the membrane's structure and fluidity.
  • Research methods like differential scanning calorimetry and solid-state NMR showed that ChoGlc is mixed similarly to cholesterol in SSM but reduces cholesterol's influence on the ordering of SSM chains due to its different orientation in membranes.
  • Molecular dynamics simulations indicate that the presence of the glucose moiety in ChoGlc disrupts interactions between sphingomyelin and sterols, potentially influencing the stability and distribution of lipid domains in biological membranes.
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OSW-1, a unique steroidal saponin isolated from the bulbs of , has potent cell-growth inhibition activity. In this study, we conducted fluorescence measurements and microscopic observations using palmitoyloleoylphosphatidylcholine (POPC)-cholesterol (Chol) bilayers to evaluate the membrane-binding affinity of OSW-1 in comparison with another steroidal saponin, digitonin, and the triterpenoid saponin, soyasaponin Bb(I). The membrane activities of these saponins were evaluated using calcein leakage assays and fitted to the binding isotherm by changing the ratios of saponin-lipids.

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The objective of this research was to find the possible pharmacognosy of the bark of the Philippine Wall. ex G.Don (AM).

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Article Synopsis
  • Theonellamides (TNMs) are antifungal compounds derived from marine sponges that show increased affinity for membranes when cholesterol or ergosterol is present.
  • In aqueous environments, TNM-A forms oligomers instead of remaining monomeric as it does in DMSO, and this study used NMR techniques to understand how TNM-A interacts with sterols like 25-hydroxycholesterol (25-HC).
  • The findings suggest that the cholesterol complex with TNM-A makes it more hydrophobic, leading to enhanced membrane penetration and disruption, and highlights that 25-HC can effectively replace cholesterol in experimental studies.
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Amphidinols are polyketide metabolites produced by marine dinoflagellates and are chiefly composed of a long linear chain with polyol groups and polyolefins. Two new homologues, amphidinols 20 (AM20, 1) and 21 (AM21, 2), were isolated from Amphidinium carterae collected in Korea. Their structures were elucidated by detailed NMR analyses as amphidinol 6-type compounds with remarkably long polyol chains.

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OSW-1 is a structurally unique steroidal saponin isolated from the bulbs of Ornithogalum saundersiae, and has exhibited highly potent and selective cytotoxicity in tumor cell lines. This study aimed to investigate the molecular mechanism for the membrane-permeabilizing activity of OSW-1 in comparison with those of other saponins by using various spectroscopic approaches. The membrane effects and hemolytic activity of OSW-1 were markedly enhanced in the presence of membrane cholesterol.

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