N-methylpyridoxamine: novel canine vitamin B6 urine metabolite.

Cation-exchange HPLC analysis of urine from dogs given large daily doses of pyridoxamine revealed an unidentified metabolite hypothesized to be N-methylpyridoxamine. Identity was established by N-methylpyridoxamine synthesis and HPLC comparison to the canine metabolite. Compound synthesis was confirmed by IR, NMR, UV-vis and emission spectroscopy.

Use of chlorite to improve HPLC detection of pyridoxal 5'-phosphate.

The sensitivity of fluorescent detection of the biologically active form of Vitamin B-6, pyridoxal 5'-phosphate (PLP), in biological samples has been improved approximately four-fold by adopting chlorite as a post-column derivatization reagent (instead of bisulfite) in high-performance liquid chromatography (HPLC) separation. Chlorite oxidizes PLP to the more fluorescent 4-pyridoxic acid 5'-phosphate, and avoids the toxicity and heating of the cyanide procedure. Detection of another major metabolite, 4-pyridoxic acid (4-PA), is not effected.

Elevation of plasma homocysteine in natural menopause can not be explained by a lack of vitamin coenzyme availability: relevance to the risk of cardiovascular disease.

Unlabelled: The risk of cardio vascular disease (CVD) doubles after menopause. Plasma homocysteine (hCy) is a risk factor which is influenced by vitamins B12,B6 and folate. The present study was conducted to examine the relationship of plasma hCy to the three vitamins and other contributing variables in early natural menopause.

B-6 vitamers and 4-pyridoxic acid in the plasma, erythrocytes, and urine of postmenopausal women.

Background: Although many studies have reported reduced vitamin B-6 status with aging, little information is available about the specific effects of menopause.

Objective: We aimed to examine vitamin B-6 metabolism in premenopausal and early postmenopausal women.

Design: We examined dietary intake and vitamin B-6 metabolites in the plasma, erythrocytes, and urine of 30 premenopausal women (x +/- SD age: 41.