Abstract:
The lichen host, Amandinea medusulina, collected from mangrove habitats in Sri Lanka, and its associated endolichenic fungi were
isolated and identified by rDNA-ITS
sequence analysis and morphological features. One of the fungal strains frequently isolated
from the lichen thalli was identified as Xylaria psidii. This study aimed at the isolation and identification of the cytotoxic compounds
present in this fungus. Secondary metabolites of X. psidii were first extracted into ethyl acetate and subsequently subjected to
bioassay-guided
fractionation to isolate the bioactive compounds. Sulforhodamine B assay against a lung cancer (NCI-H292)
cell
line was used to determine the differential cytotoxic activity. Bioassay-guided
fractionation led to the isolation of an active compound,
SS/02/29/08, showing moderate cytotoxicity (IC50 = 27.2 μg/mL). Its structure was elucidated by IR, 1D- and 2D-NMR,
and 13C-NMR
spectrophotometry and MS, in combination with HRMS, 13C NMR, HSQC, HMBC, and DQF-COSY.
The structure
of SS/02/29/08 was determined as (Z)-3-{(3-acetyl-
2-hydroxyphenyl)
diazenyl}-2,4-dihydroxybenzaldehyde
and identified as
a new compound. This novel compound has promising differential cytotoxic activity against human lung cancer cell line
(NCI-H292).
