Antimicrobial secondary metabolites of an endolichenic Aspergillus niger isolated from lichen thallus of Parmotrema ravum

Abstract

A new 6-benzyl-γ-pyrone (1), named aspergyllone was isolated from the culture filtrates of an endolichenic fungus Aspergillus niger Tiegh, obtained from lichen thallus Parmotrema ravum (Krog & Swinscow) Serus, collected in India. 1 was isolated for the first time from an endolichenic fungus together with six other known metabolites identified as aurasperones A (2) and D (3), asperpyrone A (4), fonsecinone A (5), carbonarone A (6) and pyrophen (7). The compounds were tested against a panel of human, plant, food borne and fish pathogens. Aspergyllone showed strong selective antifungal activity against Candida parapsilosis (Ashford) Langeron & Talice, with an IC₅₀ of 52 µg/mL. Aurasperone A and pyrophen showed moderate to strong antimicrobial activity inhibiting seven different test pathogens, being pyrophen active with IC₅₀ ranging from 35 to 97 µg/mL.

Keywords:

• Endolichenic fungus
• Parmotrema ravum
• Aspergillus niger
• aspergyllone
• antimicrobial activity

Acknowledgements

S.P. acknowledges Department of Science and Technology (DST), Government of India and European Molecular Biology Organization (EMBO) for providing financial assistance in the form of INSPIRE fellowship and short term internship respectively. The work was carried out in part in the frame of Programme STAR 2017 financially supported by Università di Napoli Federico II and Compagnia di San Paolo.

Disclosure statement

The authors declare no conflict of interest.