ISOLATION AND CHARACTERIZATION OF AN AFLATOXIN B1-LIKE SUBSTANCE

• Main Author: Asbiran, Nursal
• Format: Dissertations
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/8866
• Institution: Institut Teknologi Bandung

ABSTRACT: <br /> <br /> <br /> The aim of this work is to examine whether Aspergillus flavus always produces Aflatoxin B1 (AFB1) as it was explained in literatures. It has been reported recently that Indonesian food contain a considerable amount of Aflatoxin B1 exceeding the safety level. However, the cases of the liver diseases which are caused by Aflatoxin B1 is much lower than it is expected. <br /> <br /> <br /> An Aflatoxin B1-like substance has been isolated recently in our laboratory from peanut press cake after it has been cultivated with Aspergillus flavus. The purification was performed by extracting the raw material with amixture of chloroform, water and silica, followed by column chromatography using silica gel. The substance showed one blue fluorescence spot on a thin layer chromatographic (TLC) plate. The Rf of that substance is the same as that of AFB1. <br /> <br /> <br /> The investigation on absorption spectra in the ultraviolet region showed that the isolated substance had 2 peaks, viz. at 275 and 244 nm, while AFBI has 3 peaks, viz. at 360, 265 and 241 nm. It can be conluded so far that the difference in the spectra might be due to the difference in their structures. In this connection the ated substance was further called Aflatoxin BX (AFBX). as well as AFB1 were toxic towards Bacillus AFB megaterium. However, AFBx was less potent than AFB1. Both toxins were able to inhibit the respiration of rat liver homogenates. Further experiments revealed that AFB]. as well as AFBX possessed significant inhibitory effects on rat liver ATPases. Kinetics experiments showed that the Ki for AFB1 appeared to be 1.2 x 10 5 M, while for AFBx was 6.4 x 10-5 M. From these,experimantsl results it can be concluded that AFBx was less potent than AFB1. <br /> <br /> <br /> In the course of further investigation it was shown that L-cysteine, a substance which possesses a SH group was able to restore or diminish the inhibition. Therefore it can be concluded that AFBx as well as AFB]. are inhibitors of the so called SH enzymes including ATP-ases. Further it was found that both toxins have about the same chemical as well as physical characteristics. It is known that Aflatoxin analyses in Indonesian food are determined based on the assumption that the substance was Aflatoxin B1. So it is quite possible that the estimated AFB1 in Indonesian food might be AFBx as the major component which is less toxic. This could explain why incidence of liver diseases in Indonesia are relatively low and not in accordance with that high AFB1 content as assayed in food.