Can you please specify your question:- What metabolite do you want to visualize?-Are you going to monitor it in live cells during cultivation period or  use staining technique for microscopy?

A fluorescence microscopy might be very helpful for certain secondary metabolites in fungi.

Thank you Maria for your reply..i was particularly interested in visualizing the localization of secondary metabolites of Aspergilus, such as Aflatoxins, Vesicolorin A and Aflatrem, using staining technique for microscopy..

Thank you Andrei. I am aware of the fluorescence microscopy technique for this purpose..but I am not sure as to how to go about this whole thing, as its something i have never done before..

Fluorescent microscopy demand special hardware, light filters, camera and may demand quite complicated tchniques. I mean immunocytochemistry. Though it work really good.

Unfortunately, I have not any links directly dconcerned with  compounds you meant but maybe following paper might be useful for you.

You may also use a culture of Paramecium caudatum as a model  to estimate toxin presence and amounts as it is very sensitive to various toxins.

I noticed that many years ago some colleagues of my Institution made an antibody against A. flavus AFB. If you will be able to obtain this ab, maybe you could perform an immunogold analysis to detect the intracellula localization of AFB....

Thank a tonne Maria for the paper! Thank you Francesca for the technique..will surely look into it..Thnx again!