Diverse effects of ascorbic acid and palmitoyl ascorbate onHelicobacter pylorisurvival and growth

Abstract

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.

Role of sialidase in Mycoplasma alligatoris-induced pulmonary fibroblast apoptosis

“…One candidate is 6-O-palmitoyl-L-ascorbic acid (AP) (Tabak et al, 2003), but in a series of similar preliminary experiments co-incubation with 100 μg/ml AP, the highest concentration without cytotoxic effects, failed to protect against M. alligatoris-induced primary fibroblast apoptosis measured as described above (our unpublished data). In addition, even potent competitive inhibitors like DANA probably cannot completely extinguish bacterial surfaceassociated sialidase activity directly at the intimate host-pathogen interface during infection.…”

Effects of ascorbic acid, citric acid, lactic acid, NaCl, potassium sorbate and Thymus vulgaris extract on Staphylococcus aureus and Escherichia coli

“…Richter et al (1988) reported that addition of ascorbate to aerobically growing cultures of E. coli B caused only a short pause in growth, and no subsequent change in the rate of growth. Tabak et al (2003) reported that 10-20 mg/ ml ascorbic acid inhibited Helicobacter pylori growth under microaerophilic conditions. Also, it is possible that E. coli strains tested utilized this compound.…”

Sodium Ascorbate Kills Candida Albicans in Vitro Via Iron-Catalyzed Fenton Reaction: Importance of Oxygenation and Metabolism

“…A few studies also show that ascorbate could function as a potential anti-infective agent, but the literature is scarce and sometimes conflicting [11][12][13][14][15]. Vilcheze and colleagues in 2013, reported that 4 mM ascorbate could sterilize both drug-susceptible and drug-resistant Mycobacterium tuberculosis, however several weeks of incubation was required for ascorbate to exert its effects in vitro.…”

“…On the other hand, when cultures were treated with ascorbate in an anaerobic chamber, ascorbate had no effect on M. tuberculosis viability [11]. In another study by Tabak et al it was shown that 100 mM ascorbate incubated for 48 h was able to decrease viability of Helicobacter pylori by four orders of magnitude in liquid medium under microaerophilic conditions [12]. Ojha et al studied the effect of ascorbate on growth and pathogenicity markers of ascorbate on C. albicans [16].…”