A STUDENT at Yaounde University in Cameroon has isolated an active substance, drawn from a tree native to Cameroon, that may be effective against Aids, the university said in a statement on Saturday.”The solution to problems provoked by Aids may come from Yaounde University,” rector Jacques Fame Ndongo said, adding that the substance apparently prevents the multiplication of the HIV virus, which leads to Aids. The substance, discovered by student Pascal Wafo during research for a doctoral thesis, comes from the mfo tree, whose Latin name is Enantia chlorantia. Observers warned that so far none of many “miracle drugs” announced by African researchers had proven to be effective against Aids.