Delayed onset muscle soreness (DOMS) due to eccentric muscle activity is associated with inflammatory responses and production of reactive oxygen species (ROS) that sustain both inflammation and oxidative stress. Curcumin, a powerful promoter of anti-oxidant response, is one of the best-investigated natural products, and is now commercially available as a lecithin delivery system (Meriva®, Indena SpA, Milan) with improved bio-availability. The aim of this study was to test whether curcumin could attenuate damage from oxidative stress and inflammation related to acute muscle injury induced by eccentric continuous exercise This was a randomised, placebo-controlled, single-blind pilot trial. Twenty male healthy, moderately active volunteers were randomised to curcumin given as the Phytosome® delivery system 1 g twice daily (200 mg curcumin b.i.d.) or matching placebo. Supplementation was initiated 48 hours prior to a downhill running test and was continued for 24 hours after the test (4 days in total). Muscle damage was quantified by magnetic resonance imaging, laboratory tests and histological analyses on muscle samples obtained 48 hours after the test. Patient-reported pain intensity was also recorded. Subjects in the curcumin group reported less pain in the lower limb as compared with subjects in the placebo group, although significant differences were observed only for the right and left anterior thighs. Significantly fewer subjects in the curcumin group had MRI evidence of muscle injury in the posterior or medial compartment of both thighs. Increases in markers of muscle damage and inflammation tended to be lower in the curcumin group, but significant differences were only observed for interleukin-8 at 2 h after exercise. No differences in markers of oxidative stress and muscle histology were observed Curcumin has the potential for preventing DOMS, as suggested by its effects on pain intensity and muscle injury. Larger studies are needed to confirm these results and further clarify the mechanism of action of curcumin.

Protein carbonylation (PC) is a marker of reactive oxygen species-mediated alterations induced by external stimuli such as UV and blue light irradiation. In this study, we investigated the protective effect of Vitachelox^®, a mixture of three standardized natural extracts rich in polyphenols, against PC induced by blue light irradiation in human keratinocytes. We tested eight experimental conditions, including Vitachelox^® 0.01% and 0.005% w/v, used for 6 or 24 h before irradiation, and a solution of N-acetylcysteine (NAC) as positive control of protection. PC was evaluated by fluorescence microscopy in situ and by absolute quantification (Carbonyl Score) upon protein extraction and separation. Both the in situ visualization study and the carbonyl score showed a considerable increase in protein oxidative damage upon blue light irradiation, and a decrease in PC in the presence of Vitachelox^®. In particular, Vitachelox^® 0.005% showed superior results compared to NAC in terms of carbonyl score and protein quality, and it was estimated to exert a protective action against blue-light irradiation ranging from 72% (24 h) to 82% (6 h). The protective antioxidant effect of Vitachelox^®, together with the anti-inflammatory and anti-microbial properties previously reported, make this natural active ingredient a valuable tool in the maintenance of healthy skin.