Identification of volatile and non-volatile compounds of cornsilk and its association with diuretic properties in rats

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Date
2014-03
Authors
Mat Ali, Solihah @ Solinah
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Publisher
Universiti Sains Malaysia
Abstract
Identification of volatile and non volatile compounds of corn silk and its association with diuretic activity were investigated. Corn silk powder was heated at ten different combinations of time and temperature, including control corn silk powder (unheated) for identification of volatile compounds via GC-MS. Two types of corn silk extracts were used in the present study namely aqueous and methanolic to identify the presence of volatile and non-volatile compound using GC-MS and screening test, respectively. Each extract was orally fed to individual Sprague- Dawley rats for diuretic properties determination. After 24 h administration of extract, the level of urine excretion, pH, osmolality, Na+, K+ and Cl- were measured. The same parameters were observed for another four days to investigate the effect of repeated dosage on diuretic properties. Several phytochemical compounds had been identified in aqueous and methanolic extract of corn silk through screening method which contained flavonoids, phenols, tannins, phlobatannin, alkaloids, saponins and cardiac glycosides including terpenoids in methanolic extract. In addition, thirteen volatile compounds were identified in aqueous extract by gas GC-MS which consists of cis-2-pentenal, hexadecanoic acid, pyranone, 2-methylheptane, ethyl cyclopentane, furfural, methyl-5-furfural, acetic acid, lactone-G, 1-naphtol and tetrahydro-3-furanol. Meanwhile in methanolic extract, four volatile compounds were identified including 5-hydroxymethyl furfural, 4-methyl itaconate, acetic acid and 3-deoxy-d-mannoic acid lactone. These preheating treatments of corn silk powder resulted in unique aromatic odour due to the interaction of several volatile compounds. Preheating corn silk powder at 110 °C (15 min) was found to produce the most pleasant flowery odour among all treatments may be due to the presence of benzeneethanol. Vice versa, preheating corn silk powder at 135 °C (20 min) and 145 °C (15 min) gave strong caramelized odour, that probably contributed by 2-methyl, tetrahydrofuran-3-one and 2-acetylpyrrole. Aqueous and methanolic extract of corn silk significantly (p < 0.05) increased urine excretion at higher doses with respect to distilled water. The diuresis induced by aqueous extract was comparable to chlorothiazide and mannitol at doses of 600, 700 and 800 mg/kg (20.13, 19.63 and 20.00 ml, accordingly). Similar trait was observed in methanolic extract at doses of 40 and 60 mg/kg (18.25 and 18.87 ml, respectively). Aqueous and methanolic extract of cornsilk significantly (p < 0.05) increased Na+ excretion at doses of 500 – 800 mg/kg and 15 and 60 mg/kg, respectively. All doses of aqueous extract did not alter the excretion of K+, while methanolic extract doses at 15 and 16 mg/kg significantly (p < 0.05) decreased the K+ excretion in the urine. Both extracts showed potassiumsparing diuretic effect. There was no significant (p < 0.05) alteration observed in chloride, pH and osmolality aside from slight alkalization of urine in rats treated with corn silk extracts. The ED50 of aqueous and methanolic extract of corn silk were observed at 454.10 mg/kg and 16.64 mg/kg, respectively. Repeated oral administration for another four consecutive days of both extracts at all doses showed no significant (p < 0.05) value in all parameters when compared to day 1. Based on literature review, three compounds were identified to have potential association with diuretic activity namely pyranone, ethyl cyclopentane, and hexadecanoic acid.
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Keywords
Volatile and non volatile compounds, corn silk
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