Specialized metabolites of the United States lichen Niebla homalea and their antiproliferative activities
- Author:
- Zhang Y., Tan C.Y., Spjut R.W., Fuchs J.R., Kinghorn A.D. & Rakotondraibe L.H.
- Year:
- 2020
- Journal:
- Phytochemistry
- Pages:
- 180: 112521 [7 p.]
- Url:
- https://doi.org/10.1016/j.phytochem.2020.112521
Three undescribed stictanes, nieblastictanes A, two flavicanes, nieblaflavicanes A and B, together with three
already reported stictanes, along with the known compounds (+)-usnic acid, sekikaic acid, divaricatic acid, and
divaricatinic acid methyl ester were isolated from an ethyl acetate extract of the western North American lichen
Niebla homalea. The structures of the new and known compounds were established by spectroscopic methods
including nuclear magnetic resonance spectroscopy, mass spectrometry and electronic circular dichroism.
Among the compounds isolated, usnic acid exhibited moderately potent antiproliferative activities against the
A2780 ovarian (IC50 3.8 μM) and MCF-7 breast cancer (IC50 6.8 μM) cell lines. A plausible mode of formation of
the chlorine-containing compound nieblastictane C is provided and the contribution of the isolated compounds to
the chemotaxonomy of United States lichen species of the genus Niebla is also discussed.
Keywords: Niebla homalea; Ramalinaceae; Lichen; Strictanes; Flavicane.
- Id:
- 32878
- Submitter:
- zdenek
- Post_time:
- Wednesday, 04 November 2020 10:51