Antibacterial compounds from the mushroom Ganoderma colossum from Nigeria.

Three colossolactones (colossolactone E, colossolactone B and 23-hydroxycolossolactone E) were isolated and characterized from an n-hexane:dichloromethane (2:7) extract of Ganoderma colossum using chromatographic techniques. The antimicrobial activity of the three compounds was then tested against Gram-positive and Gram-negative bacteria. The activity was evaluated by the thin-layer chromatography agar overlay method. The results showed that colossolactone E and 23-hydroxycolossolactone E were active against Bacillus subtilis and Pseudomonas syringae. Colossolactone B was not active against the bacteria. Their structures were elucidated by spectroscopic methods. Potency of the compounds against bacteria tested supports the use of this mushroom in therapeutic medicine.