SYNTHESIS OF THE ANTIGEN BOVINE SERUM-ALBUMIN ERGOSTEROL AND ITS IMMUNOCHARACTERIZATION

Fungal contamination of agricultural commodities leads to their spoila ge and renders them unfit for human consumption. Ergosterol, a predomi nant sterol in most fungi and a major constituent of the cell membrane , has been established as a reliable biochemical marker for fungal gro wth. Various chemical and physico-chemical methods to quantify ergoste rol as an index of fungal contamination are in practice. Yet, immunoas says are the methods of choice in food analysis due to their increased specificity, sensitivity and rapidity. This paper reports the synthes is of an antigen, bovine serum albumin-ergosterol conjugate, and its i mmunocharacterization. Ergosterol was converted to ergosterol hemisucc inate (EHS) by succinylation. Subsequently, EHS was conjugated to bovi ne serum albumin by the mixed anhydride reaction. The molar ratio was found to be 1:28. Antisera raised against the synthesized antigen in r abbits was characterized by rite Ouchterlony double-diffusion techniqu e and an antibody capture assay. Olichterlony analysis showed a titre of 1:2. Further, characterization by an antibody capture assay, using 50 ng well (10 ng equivalent of ergosterol) of the antigen, gave a tit re of 1:4000 dilution of antiserum, with an absorbance of 1.0 at 405 n m. The synthesized antigen may find art application in the development of an immunoanalytical method for ergosterol quantification as a meas ure of food quality in relation to fungal contamination.