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
Journal Title
Journal ISSN
Volume Title
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.
Description
Keywords
Volatile and non volatile compounds, corn silk