Abstract:
Endolichenic fungi are microorganisms living in the thalli of lichens that are analogous to
the plant endophytic species inhabiting the intercellular spaces of the hosts. The diversity
and prevalence of endolichenic fungi have not been studied extensively and there are only a
few recorded studies on isolations and identifications of endolichenic fungi. The
endolichenic fungi available in Sri Lanka are still an untapped source of bioactive natural
products since their identity and the chemistry of their secondary metabolites have not been
explored thoroughly. In our ongoing research programme on searching for new bioactive
compounds from endolichenic fungi, we have investigated an endolichenic fungi,
Curvularia trifolii and Penicillium citrinum isolated from the lichens, Usnea sp. and
Parmotreama sp. collected in the Hakgala Botanical Garden, Sri Lanka. Ethyl acetate
extracts of two endolichenic fungi, C. trifolii and P. citrinum led to isolation of four new
compounds, 1- 4. The structures of the new compounds were determined on the basis of
their 1D NMR, 2D NMR and FABMS spectroscopic data. The new compounds, 1 - 4
showed radical scavenging activities with IC50 values of 4.0±2.6 mg/mL, 1.3±0.2 mg/mL,
159.7±22.3 μg/mL and 68.6±4.3 μg/mL respectively in DPPH antioxidant assay and
antioxidant activity of the compound 2 was comparable to the standard antioxidant
compound, BHT. Moreover, the new compound, 2 were evaluated for their antiinflammatory
activity and exhibited significant activity comparable to the standard antiinflammatory
drug, Aspirin. The Compound 1 was evaluated for inhibition of cell
proliferation in a panel of five cancer cell lines NCI-H460, MCF-7, SF-268, PC-3M, and
MIA Pa Ca-2 and exhibited >90% inhibitory activity at 5 μg/mL with all the above cell
lines.
