Physiological Availability of Dehydro-L-Ascorbic Acid and Palmitoyl-L-Ascorbic Acid

Ritter, E. De; Cohen, N.; Rubin, Saul H.

doi:10.1126/science.113.2944.628

Cited by 27 publications

(13 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…29 Ascorbic acid is rapidly absorbed from the small intestine; after ingestion of 1.25 g, the peak serum concentration is reached at 2 h and then declines over a 5 -6 h period in a monophasic pattern. 30 The ascorbic acid transport system from the intestine is saturable, in that there is disproportionate absorption at higher doses.…”

Section: Discussionmentioning

confidence: 99%

Ascorbic Acid Enhances Hypoxic Ventilatory Reactivity in Elderly Subjects

Pokorski

Marczak

2003

J Int Med Res

View full text Add to dashboard Cite

The reducing properties of ascorbic acid in the carotid body make it a likely modifier of hypoxia-sensing mechanisms. This open-label study aimed to determine the effect of ascorbic acid on the hypoxic ventilatory response (HVR) in a population of elderly women, in whom both hypoxic reactivity and ascorbic acid levels may be deficient. We examined the HVR to progressive eucapnic hypoxia in 18 healthy females aged 60 -80 years, before and after 10 days' ascorbic acid supplementation, given as a sustained release preparation of 1 g twice daily. Respiratory variables were recorded breath by breath, and hypoxic sensitivity was assessed from the linear slopes of minute ventilation and mouth occlusion pressure plotted against oxygen saturation. We found that ascorbic acid increased the HVR by a mean of 44%, this effect being driven by a higher occlusion pressure. We conclude that augmentation of hypoxic reactivity by ascorbic acid may have therapeutic potential in pathologies associated with hypoxia, which frequently develop in old age.

show abstract

Section: Discussionmentioning

confidence: 99%

Ascorbic Acid Enhances Hypoxic Ventilatory Reactivity in Elderly Subjects

Pokorski

Marczak

2003

J Int Med Res

View full text Add to dashboard Cite

show abstract

“…In a human study, the urinary excretion rate of ascorbic acid, after AP given in a solid form as a suspension in water, on an equimolar basis, is similar to that after ascorbic acid administration [6]. This points to 100% availability of the palmitate ester, but the excretion of ascorbic acid is erratically dependent on hydration, renal blood flow, its reabsorption, and other factors.…”

Section: Discussionmentioning

confidence: 81%

“…Samples were analyzed on precoated HPTLC silica gel 60-angstrom plates (Merck), using benzene:methanol:acetic acid (16:3:1, v/v/v) as solvents. The plates were developed with 3% FeCl 3 and 5% K 3 [Fe(CN)] 6 , and the resolved ascorbate bands were immediately photocopied. The bands of AP were separated from those of AA with no overlap (not shown).…”

Section: Controlsmentioning

confidence: 99%

Ascorbyl Palmitate as a Carrier of Ascorbate into Neural Tissues

Pokorski

Marczak

et al. 2003

J Biomed Sci

View full text Add to dashboard Cite

We have investigated the hypothesis that a lipid-soluble derivative of ascorbic acid, ascorbyl-6-palmitate (AP), could serve as a carrier of ascorbate into neural tissues. Ascorbate could then exert its physiological effects in the biomembranes that are the target sites of the cellular signaling pathways which are normally hardly accessible to this water-soluble compound. The potential role of AP would require that it penetrates into tissues. The major objective of the study was to determine whether ascorbate could be recovered from cerebral cortex and carotid body tissues, both sensitive to the hypoxic stimulus, after AP given by gavage. Biological samples were analyzed by HPLC for the determination of ascorbate. We found that ascorbate was recovered from the tissues studied. Its content was higher in both tissues, by nearly an order of magnitude, after ingestion of AP than after ingestion of ascorbic acid, and the ascorbate level was higher in the carotid body than in the cortex. Hypoxia decreased the ascorbate content which implies physiological activity of ascorbate carried alongside the AP molecule. The lipophilic AP was able to cross biological barriers and satisfied the tissue demand for ascorbate better than the hydrophilic form. AP should be considered as the preferred form of transport of ascorbate into neural tissues. The results of this study suggest wider pharmacological applications of ascorbyl palmitate.

show abstract

“…It is less likely that differences in the bioavailability of ascorbic acid used in supplements explain these results, because natural and synthetic ascorbic acid are chemically identical, and studies have not found any differences in bioavailability. 4,[40][41][42][43][44] The median intake for participants in the lowest quintile of vitamin C from foods was close to the RDA (90 mg/day). Thus, we cannot exclude the possibility that use of vitamin C supplements may reduce risk of OPL for people deficient in vitamin C.…”

Section: Discussionmentioning

confidence: 99%

Prospective study of vitamins C, E, and A and carotenoids and risk of oral premalignant lesions in men

Maserejian

Giovannucci

Rosner

et al. 2006

Intl Journal of Cancer

View full text Add to dashboard Cite

Case-control studies indicate that vitamins C, E, A and carotenoids decrease risk of oral premalignant lesions (OPLs) and oral cancer, but clinical trials have failed to find protective effects of bcarotene and suggest that vitamin E may increase risk. The authors prospectively evaluated the association between intake of vitamins C, E, A and carotenoids and incidence of OPL. Participants were 42,340 men in the Health Professionals Follow-up Study who provided information on supplement use and diet every 2-4 years by food frequency questionnaire. The authors confirmed 207 clinically or histopathologically diagnosed OPL events occurring between 1986 and 2002 by medical record review. Multivariate-adjusted relative risks (RR) of OPL were calculated with proportional hazards models. Total intake of vitamin C, vitamin A or carotenoids was not significantly associated with OPL risk. Dietary vitamin C was significantly associated with reduced risk (quintile 5 vs. 1, RR 5 0.52, 95% CI 0.31-0.85, p trend 5 0.04), but no association with supplemental vitamin C was observed. Inverse associations were apparent for b-cryptoxanthin and a-carotene intake. No clear relationship emerged with b-carotene, lycopene or lutein/zeaxanthin. Vitamin E was associated with increased risk (quintile 5 vs. 1, RR 5 1.86, 95% CI 1.06-3.19), particularly among current smokers and with supplemental intake (currentsmokers, supplement dose tertile 3 vs. 1, RR 5 3.07, 95% CI 1.28-7.34, p trend 5 0.01). For current smokers, b-carotene also increased risk. Vitamin C from dietary sources, but not supplements, was associated with a reduced risk of OPL. The observed increased risk for current smokers with high vitamin E or b-carotene intake should be explored further. ' 2006 Wiley-Liss, Inc.Key words: leukoplakia; vitamin C; vitamin E; mouth neoplasms; diet A prominent contributor to the onset and development of oral cancer is damage to DNA and other cellular molecules by reactive oxygen species. Tobacco use, the primary known risk factor for oral cancer and precancerous lesions, also increases oxidative stress and therefore enhances the possibility of cancer-causing mutations, oxidization of lipids and proteins and alteration of signal transduction pathways that damage cells.1,2 Dietary micronutrients, such as vitamin E, vitamin C, b-carotene and lycopene, have potential chemopreventive properties that can neutralize or block reactive oxygen species and protect against cellular damage. 3-5Observational studies suggest that intake of antioxidants, primarily through consumption of fruits and vegetables, is associated with a decreased risk of oral cancer, but the evidence has been inconsistent. [6][7][8][9][10][11] Recent large clinical trials, however, saw significantly increased risks of head and neck cancer recurrence and second primary tumors with a-tocopherol (vitamin E) supplementation, 12 and failed to find any benefits of supplementation with vitamin A in oral cancer patients. 13 Such results suggest that more compelling evidence is needed before...

show abstract

Physiological Availability of Dehydro-L-Ascorbic Acid and Palmitoyl-L-Ascorbic Acid

Cited by 27 publications

References 9 publications

Ascorbic Acid Enhances Hypoxic Ventilatory Reactivity in Elderly Subjects

Ascorbic Acid Enhances Hypoxic Ventilatory Reactivity in Elderly Subjects

Ascorbyl Palmitate as a Carrier of Ascorbate into Neural Tissues

Prospective study of vitamins C, E, and A and carotenoids and risk of oral premalignant lesions in men

Contact Info

Product

Resources

About