Study of alpha-lipoic acid penetration in the human aqueous after topical administration.

PURPOSE: To determine the concentration of alpha-lipoic acid in the aqueous and investigate if its topical instillation can increase quantities. METHODS: A total of 70 patients selected to undergo cataract surgery were randomly divided into two groups. Group 1 was used as a control group; for the patients in Group 2, a single instillation of alpha-lipoic acid eye drops (1%) was administered. Immediately before surgery, an aliquot of 40-120 microL of aqueous was aspirated. The individual aspirations were combined to constitute pools representing time intervals with respect to administration. The levels of alpha-lipoic acid in the aqueous were measured using gas chromatography/mass spectrometry. RESULTS: Pool 0 was created by combining the samples of aqueous obtained from the patients in Group 1, the control group; and the level of alpha-lipoic acid was 27.5 + 2.6 ng/mL. In the other pools, the time interval between the administration of the eye drops and sampling was, respectively, 23 min, 53 min, 72 min, 93 min and 114 min; and the level of alpha-lipoic acid was 33.0 + 10.8 ng/mL, 52.0 + 2.5 ng/mL, 86.7 + 2.5 ng/mL, 91.2 + 2.5 ng/mL and 80.3 + 2.5 ng/mL. CONCLUSION: Our study demonstrates the presence of alpha-lipoic acid in the aqueous and indicates that its concentration increases after it is administered in the form of eye drops, reaching maximum values after around 93 min. The concentrations that are achieved in the anterior chamber allow us to theorize the possibility of exploiting the antioxidant properties of alpha-lipoic acid.

The bacterial aetiology of rosy discoloration of ancient wall paintings.

The inventory of microorganisms responsible for biological deterioration of ancient paintings has become an integral part of restoration activities. Here, the microbial agent of rosy discoloration on medieval frescoes in the Crypt of the Original Sin (Matera, Italy) was investigated by a combination of microscopic, molecular and spectroscopic approaches. The bacterial community from three rosy-discoloured painting sites was characterized by 16S rRNA gene-based techniques. The eubacterial population was prevalently composed of Actinobacteria, among which Rubrobacter radiotolerans-related bacteria accounted for 63-87% of the 16S rRNA gene pool per sampled site. Archaea, with prevalence of Haloarchaea-related species, were detected in one of the three sites where they accounted for < 0.1% of the total 16S rRNA gene pool. Raman spectroscopy confirmed the identity between R. radiotolerans carotenoids (bacterioruberins) and pigments responsible for colour alteration of frescoes. This investigation provides the first evidence of a causal relationship between heavy contamination by Rubrobacter-related bacterioruberin-producing bacteria and rosy discoloration of ancient wall paintings.