Exposing skin to ultraviolet (UV) radiation contributes to photoaging and to the development of skin cancer by DNA lesions and triggering inflammatory and other harmful cellular cascades. The present study tested the ability of unique lipid molecules, polyhydroxylated fatty alcohols (PFA), extracted from avocado, to reduce UVB-induced damage and inflammation in skin. Introducing PFA to keratinocytes prior to their exposure to UVB exerted a protective effect, increasing cell viability, decreasing the secretion of IL-6 and PGE(2), and enhancing DNA repair. In human skin explants, treating with PFA reduced significantly UV-induced cellular damage. These results support the idea that PFA can play an important role as a photo-protective agent in UV-induced skin damage.

Among many antioxidants used in the food, pharmaceutical and cosmetic industries, ascorbic acid (AA) is one of the most important. AA has been suggested to decrease the risk of gastric disease (gastritis, duodenal ulcer, and carcinoma) by direct action on Helicobacter pylori. However, there are limited studies on the possible role of AA and its derivatives such as palmitoyl ascorbate (PA) on the growth and survival of H. pylori. In the present study it was demonstrated in vitro that AA in the concentration range 10-20 mg x ml(-1) (50-100 mM) inhibited H. pylori growth in liquid medium under microaerophilic conditions. In contrast, under aerobic conditions AA in the concentration range 2-20 mg x ml(-1) (10-100 mM) significantly increased the survival of H. pylori presumably eliminating the toxic effect of reactive oxygen species on bacterial cells. The hydrophobic derivative of AA, PA (a food antioxidant), demonstrated a strong antibacterial effect, under both aerobic and microaerophilic conditions in the concentration range 0.04-0.4 mg x ml(-1) (0.1-1.0 mM). This effect was also tested on other bacterial strains: Escherichia coli, Proteus vulgaris, Proteus mirabilis, Pseudomonas aeruginosa, Enterococcus faecalis, Bacillus cereus, Bacillus subtilis, Staphylococcus aureus, Staphylococcus epidermidis, Clostridium sporogenes and Campylobacter jejuni. Among these bacterial strains, PA showed a similar inhibitory effect on B. cereus and B. subtilis as observed with H. pylori. The results suggest that PA may be considered an important AA derivative in eradication of H. pylori in vitro and in vivo and to decrease the risk for gastric diseases.

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Acylated derivatives of ascorbic acid were found to be active in a number of biochemical and physiological processes. In the present study we investigated the effects of 6-O-palmitoyl ascorbate on collagen synthesis by cultured foreskin human fibroblasts. Our observations indicate a marked stimulatory effect on collagen synthesis by 6-O-palmitoyl ascorbate in the concentration range of 5-20 microM, while the synthesis stimulated by ascorbic acid was maximal at concentrations of 20-100 microM. Cells treated with 10 microM palmitoyl ascorbate for 36 h exhibited a production of collagen threefold greater than those in the presence of 10 microM ascorbic acid, and it was about the same as in cells treated with 100 microM ascorbic acid. By 48 h differences were not significant. Acylated ascorbate impaired vitality of the treated fibroblasts at concentrations exceeding 20 microM in media supplemented with 0.5% FCS. However, most of the cytotoxic effect was neutralized by FCS at a concentration of 10%. The resistance of acylated ascorbate against oxidative degradation as well as the role of free radicals in the modulation of collagen synthesis by ascorbic acid and by its derivatives is discussed.

The active factor of lysy[ oxidase inhibition was separated from unsaponifiables of avocado seed oil and characterized by gas chromatography-mass spectrometry. Results indicated the presence of furan-containing lipids in the active factor mixture and also showed a structural difference compared to previously reported furan-containing lipids of avocado which relates to the length of the hydrocarbon chain substituent. Another structural difference evinced was the availability of the hydroxyl group in the aliphatic moiety of the investigated substances. A purified mixture of furan-containing compounds was tested in vitro for inhibitory activity on pure bovine aorta lysyl oxidase. It was shown that mixing furan-containing lipids in Tween 80 reversibly inhibited pure bovine aorta lysyl oxidase activity against tritiated recombinant tropoelastin with the 150 value of inhibition of 105 pM. These in vitro studies suggested that the mixture of avocado seed oil furan-containing lipids was not a substrate-specific inhibitor of lysyl oxidase, and it might prove to be useful as a potential antifibrotic drug. Moreover, the unique chemistry of the studied compound for [ysy[ oxidase inhibition should enable the designing of new probes of the active site of this important enzyme. JAOCS 72, 225-229 (1995).