Biomedical subjects

G Rosenblat

Publications and source records attributed to G Rosenblat.

4 recordsLinked to original sources

PubMed2003

Diverse effects of ascorbic acid and palmitoyl ascorbate on Helicobacter pylori survival and growth.

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.

Aerobiosis↗

PubMed1999

Palmitoyl ascorbate: selective augmentation of procollagen mRNA expression compared with L-ascorbate in human intestinal smooth muscle cells.

The effect of 6-O-palmitoyl ascorbate on procollagen mRNA levels, collagen synthesis, and collagen secretion was investigated and compared with the effect of L-ascorbate in human intestinal smooth muscle (HISM) cells in vitro. Collagen synthesis, determined by the incorporation of 3H-proline into pepsin-resistant, salt-precipitated collagen, increased in a concentration-dependent manner in response to palmitoyl ascorbate. There was a twofold increase in collagen synthesis at 2.5 and 5 microM. By contrast, L-ascorbate was required at 4-5 times the concentration for the same response. However, at 20 microM, both palmitoyl and L-ascorbate induced similar 2.7-fold increases in collagen synthesis. Palmitoyl ascorbate induced a 1.6- and 3.5-fold increase in steady-state levels of procollagen I and III mRNA levels respectively, whereas L-ascorbate had no effect. Palmitoyl ascorbate and L-ascorbate induced similar increases in the amounts of newly synthesized procollagen secreted into the medium and in the amounts of collagen types I, III and V accumulating in the cell layer. There was no effect of either palmitoyl ascorbate or L-ascorbate on the activity of a procollagen alpha2 (I) promoter construct transiently transfected into HISM cells. Palmitoyl ascorbate augments HISM cell procollagen synthesis and mRNA levels more efficiently than L-ascorbate. This property may be due to the greater resistance of the ascorbate ester to oxidation and suggests that palmitoyl ascorbate could be an important agent for studies of collagen synthesis in vitro.

Ascorbic Acid↗

PubMed1998

Cactus flower extracts may prove beneficial in benign prostatic hyperplasia due to inhibition of 5alpha reductase activity, aromatase activity and lipid peroxidation.

The cactus flower is deemed to be helpful in benign prostatic hyperplasia (BPH) therapy, although there is no published information regarding its clinical effect in patients and on the mechanism of its biological activity. The present study evaluated the ability of cactus flower extracts to exert an effect on BPH through possible inhibition of such processes as lipid peroxidation, androgen aromatization and testosterone reduction. Cactus flower extracts indeed inhibited aromatase and 5alpha reductase activity in cultured foreskin fibroblasts, and also in human placental and prostatic homogenates. The inhibitory activity in both instances was associated with the dichloromethane or ethanol (methanol) extracts, while a marked antioxidative activity was associated with the aqueous extract. The finding that cactus flower extracts interfere concurrently in vitro with aromatase and reductase activity as well as with free radical processes suggests that these substances may prove beneficial in BPH treatment.

5-alpha Reductase Inhibitors↗

PubMed1998

Acylated ascorbate stimulates collagen synthesis in cultured human foreskin fibroblasts at lower doses than does ascorbic acid.

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.

Acylation↗