Polyacetylene Glycosides: Isolation, Biological Activities and Synthesis.

Polyacetylene glycosides (PAGs) constitute a relatively small class of secondary metabolites characterized by the presence of a sugar unit anomerically connected to a polyacetylene. These compounds are found in fungi, seaweed, and more often in plants. PAGs exhibit a wide range of biological and pharmacological activities and, as a result, the literature of these compounds has grown exponentially in recent years.

Resveratrol inhibition of lipid peroxidation.

To define the molecular mechanism(s) of resveratrol inhibition of lipid peroxidation we have utilized model systems that allow us to study the different reactions involved in this complex process. Resveratrol proved (a) to inhibit more efficiently than either Trolox or ascorbate the Fe2+ catalyzed lipid hydroperoxide-dependent peroxidation of sonicated phosphatidylcholine liposomes; (b) to be less effective than Trolox in inhibiting lipid peroxidation initiated by the water soluble AAPH peroxyl radicals; (c) when exogenously added to liposomes, to be more potent than alpha-tocopherol and Trolox, in the inhibition of peroxidation initiated by the lipid soluble AMVN peroxyl radicals; (d) when incorporated within liposomes, to be a less potent chain-breaking antioxidant than alpha-tocopherol; (e) to be a weaker antiradical than alpha-tocopherol in the reduction of the stable radical DPPH*. Resveratrol reduced Fe3+ but its reduction rate was much slower than that observed in the presence of either ascorbate or Trolox. However, at the concentration inhibiting iron catalyzed lipid peroxidation, resveratrol did not significantly reduce Fe3+, contrary to ascorbate. In their complex, our data indicate that resveratrol inhibits lipid peroxidation mainly by scavenging lipid peroxyl radicals within the membrane, like alpha-tocopherol. Although it is less effective, its capacity of spontaneously entering the lipid environment confers on it great antioxidant potential.

Compressed biodegradable matrices of spray-dried PLGA microspheres for the modified release of ketoprofen.

A spray-drying technique was used to prepare poly(lactide-co-glycolide) (PLGA) drug loaded microspheres. Ketoprofen was chosen as a model NSAID drug. The microspheres were characterized in terms of morphology, drug content and release behaviour. The spray-dried particles were subject to a direct compression process for the preparation of biodegradable matrix tablets. The spray-dried powders were found to have good compaction properties. Tablets were also prepared from a mixture of microspheres and microcrystalline cellulose, mannitol and hydroxypropylmethylcellulose or sodium alginate. The release of ketoprofen in phosphate buffer (pH 7.4) was significantly sustained, indicating the suitability of using tabletted spray-dried PLGA microspheres for controlled drug delivery. The results show that spray-dried PLGA particles have promising properties as direct compression and release controlling excipients in matrix tablets for oral administration.

Spray-dried microspheres containing ketoprofen formulated into capsules and tablets.

In this study, microspheres were prepared by a spray-drying technique using solutions of ketoprofen and two polymers, cellulose acetate butyrate (CAB) and hydroypropylmethylcellulose phthalate (HPMCP), in different weight ratios. Different total concentrations were used in the feed solutions: 3, 6 and 9% w/v. The spray-dried microparticles were characterized in terms of shape (SEM), size (light scattering method), production yield and encapsulation efficiency. They were formulated into capsules; tablets were prepared by direct compression of the microparticles mixed with maltose and, in some cases, hydroypropylmethylcellulose (HPMC). In vitro release studies were performed both at acidic and neutral pHs. The spray-drying process of solutions of ketoprofen with polymeric blends of cellulose derivatives leads to microparticles which, depending on their final formulation (capsules or tablets), can give a rapid or prolonged drug release. The formulations here described can be proposed for the oral administration of NSAIDs.