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The use of high water content (> 96%) hydrogels obtained from copolymerisation of bovine serum albumin and poly(ethylene glycol) as a controlled release system has been investigated. Such hydrogels allowed release of soluble and hydrophobic substances, even proteins. Release is shown to occur by a diffusion controlled mechanism, leading to half-life times of release ranging between 0.8 hour for theophylline and 4.2 hours for lysozyme, when a 2.4 mm thick disc of BSA-PEG (MW of 10000) was used. The effect of the porosity of the hydrogel on the diffusive properties of theophylline and hydrocortisone has been evaluated by varying the molecular weight of the poly(ethylene glycol). It was shown that poly(ethylene glycol) of high molecular weight leads to more porous hydrogels in which the diffusion is faster.

A family of hydrogels based on the crosslinking of bovine serum albumin (BSA) and activated poly(ethylene glycol) (PEG), were characterized. The swelling process was found to be dependent on the molecular weight of the PEG used and on the OH/NH2 molar ratio of the reagents. These hydrogels performed a volume expansion from 266 to 554% when PEG with molecular weights from 3,350 to 20,000 were used. The volume expansion was greater when the OH/NH2 molar ratio increased. Some anisotropy occurred during swelling since thinner devices swelled more than thicker ones, due to the difference of constraints in the hydrogels structure. Mechanical studies showed that these hydrogels were highly deformable and presented good elastic behavior since they broke only after 80% deformation. At this point, they needed a compression force ranging from 165 to 456 g/cm2 to break. The differentiation of two kinds of water in these highly swollen hydrogels was performed using DSC studies at low temperature. Free water (i.e., bulk water) was found to be the predominant form which filled the network, .and bound water (i.e., water engaged in interactions with PEG) tended to form a trihydrate complex (three molecules of water per ethylene oxide repeated unit). Three forms of water with different evaporating rates were detected by DSC studies at high temperature. This other form of water may be important for maintaining the hydrogen's form.

Oxydative cyclization of lapachol was attempted by feeding this compound into the culture broth of Beauveria sulfurescens and two ionophore-producing strains of Streptomyces albus and Streptomyces griseus. As a result, three compounds were obtained, lomatiol, lomatic acid and lomatiol acetate, only with B. sulfurescens and S. albus. The structures of these products were determinated by NMRand mass spectrometry. The stereochemistry is given by a comparison with butene analogs.