Resonancia eugenol

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19 EUGENOL, AN ANTIFUNGAL COMPONENT IN CLOVE THAT CHECKS THE CONTAMINATION OF ASPERGILLI IN RICE Reddy CS, Reddy KRN, Mangala UN, Muralidharan K Fungal deterioration of stored seeds and grains is a chronic problem in the Indian storage system because of the tropical hot and humid climate. Harvested grains are colonized by various species of Aspergillus under such conditions leadingto deterioration and mycotoxin production. Infection of Aspergillus spp. was found on most paddy samples collected from different rice growing areas in India, either at or immediately after harvest or during storage. An investigation was carried out to isolate and characterize the antifungal component in clove, the extracts of which were found effective against Aspergilli in our earlier studies.Eugenol, a major component in clove was identified on TLC plate as dark colored spot with Rf 0.5 along with standard. This compound was purified by column chromatography. HPLC of this sample showed the eugenol peak at RT 5.03 with 79.3 percent purity. Based on the HPLC results, 1 g of powdered cloves contained 40 mg of eugenol. The proton and 13C NMR confirmed the identity of eugenol. IR spectrumof this sample showed OH functional group at 3462 cm-1 and the molecular weight was estimated at M/z 165 (m+1 peak) by mass spectrometry, which agreed with the eugenol composition, C10H12O2. For bioautography test, TLC plates were spray inoculated with Aspergillus flavus, A. parasiticus, A. niger and A. ochraceus. Eugenol on TLC inhibited mycelial growth of all four species of Aspergillus. In agardiffusion tests, eugenol produced inhibition zones ranging from 30 to 55 mm at 4.8 mg/disc depending on the Aspergillus spp. tested. On rice grains treated with eugenol at 2.4 mg/g aflatoxin B1 biosynthesis was completely inhibited. This is the first report on the inhibition of Aspergillus flavus, A. parasiticus, A. niger and A. ochraceus by eugenol obtained from clove. Clove is expensive, buteugenol can be commercially extracted from other sources such as Ocimum gratissimum, O. tenuiflorum, O.sanctum, Cassia fistula, Zieria smitii, Clarkia breweri, Ageratum conyzoides and whole tobacco, which are also known to be useful sources for eugenol.

EUGENOL, AN ANTIFUNGAL COMPONENT IN CLOVE THAT CHECKS THE CONTAMINATION OF ASPERGILLI IN RICE
C. S. Reddy*, K. R. N. Reddy, U. N. Mangala andK. Muralidharan Directorate of Rice Research, Rajendra Nagar, Hyderabad – 500 030, India.

INTRODUCTION Fungal deterioration of stored seeds and grains is a chronic problem in the Indian storage system because of the tropical hot and humid climate. Harvested grains are colonized by various species of Aspergillus under such conditions, leading to deterioration and mycotoxin production. Infectionof Aspergillus spp. was found on most paddy samples collected from different rice growing areas in India, either at or immediately after harvest or during storage. An investigation was carried out to isolate and characterize the antifungal component in clove, the extracts of which were found effective against Aspergilli in our earlier studies. MATERIALS AND METHODS Characterization of Eugenol: Thecrude extract of cloves was loaded on to column of silica gel and eluted with a gradient of hexane-dichloromethane. The fractions were spotted on TLC strip and developed to detect fluorescence under UV. Fractions (8-21) that showed fluorescence were combined, concentrated and the purity of eugenol was analysed by HPLC. The purified eugenol was re-suspended in methanol and analyzed by NMR, FTIR andEIMS to identify the chemical structure. Bioautographic assay of Eugenol: For bioautographic assay of eugenol, the TLC plates were sprayed with the spore suspension of Aspergillus flavus (DRAf009), A. parasiticus (DRAp032), A. niger (DRAn014) and A. ochraceus (DRAo013) and incubated in a moist and dark chamber at 250 C. The inhibitory zones were observed on the TLC plate and visualized under UV...