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Oxalic acid and oxalate oxidase enzyme in Costus pictus D. Don

100%

Sathishraj R., Augustin A.

Acta Physiologiae Plantarum

2012

tom 34

nr 2

The leaves of Costus pictus are sour in taste due to the presence of oxalic acid in the leaves. Different stages of leaves were collected and the samples were designated as stage one, stage two and stage three. It was found that oxalate content and oxalate oxidase activity were maximum in second leaf stage followed by first leaf stage and third leaf stage. Drying causes substantial loss of oxalate content and complete loss of oxalate oxidase activity. With various solvents water recovered more oxalate followed by methanol and ethanol while oxalate oxidase activity was maximum in ethanol followed by methanol and water. The ethanol or methanol extract of second leaf stage of C. pictus can be used for isolating active principles. The oxalate oxidase from C. pictus can be used as a cheap source of oxalate oxidase enzyme which is used in oxalate determination in biological fluids. Moreover, the sensitivity of oxalate determination employing oxalate oxidase from C. pictus will be more as oxalate oxidase in C. pictus has Km 20 times lesser than the oxalate oxidase enzyme from barley seedling.

Green tea extracts lower serum folates in rats at very high dietary concentrations only and do not affect plasma folates in a human pilot study

51%

Augustin A., Frank J., Augustin S., Langguth P., Ohrvik V., Witthoft C. M., Rimbach G., Wolffram S.

Journal of Physiology and Pharmacology

2009

tom 60

nr 3

103-108

Green tea catechins (GTC) have been shown to inhibit the activities of enzymes involved in folate uptake. Hence, regular green tea drinkers may be at risk of impaired folate status. The present experiments aimed at studying the impact of dietary GTC on folate concentrations and metabolism. In a human pilot study (parallel design) healthy men consumed for 3 weeks 6 capsules (~670 mg GTC) per day (2 capsules with each principal meal) containing aqueous extracts of the leaves of Camellia sinensis (n=17) or placebo (n=16). No differences in plasma folate concentrations were observed between treatments. We further fed groups of 10 male rats diets fortified with 0, 0.05, 0.5, 1, or 5 g GTC/kg for 6 weeks. Only at the highest intake, GTC significantly decreased serum 5-methyl-tetrahydrofolate concentrations in rats, while mRNA concentrations of reduced folate carrier, proton-coupled folate transporter/heme carrier protein 1, and dihydrofolate reductase (DHFR) remained unchanged in intestinal mucosa. Using an in vitro enzyme activity assay, we observed a time- and dose-dependent inhibition of DHFR activity by epigallocatechin gallate and a green tea extract. Our data suggest that regular green tea consumption is unlikely to impair folate status in healthy males, despite the DHFR inhibitory activity of GTC.

Ograniczanie wyników

1 Acta Physiologiae Plantarum

1 Journal of Physiology and Pharmacology

2 Augustin A.

1 Augustin S.

1 Frank J.

1 Langguth P.

1 Ohrvik V.

1 Rimbach G.

1 Sathishraj R.

1 Witthoft C. M.

1 Wolffram S.

1 2012

1 2009

Wyniki wyszukiwania

Oxalic acid and oxalate oxidase enzyme in Costus pictus D. Don

Green tea extracts lower serum folates in rats at very high dietary concentrations only and do not affect plasma folates in a human pilot study