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Inhibition of Autophagy Increases Cell Death in HeLa Cells through Usnic Acid Isolated from Lichens

Kumari, M and Kamat, S and Singh, SK and Kumar, A and Jayabaskaran, C (2023) Inhibition of Autophagy Increases Cell Death in HeLa Cells through Usnic Acid Isolated from Lichens. In: Plants, 12 (3).

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Official URL: https://doi.org/10.3390/plants12030519


The Western Ghats, India, is a hotspot for lichen diversity. However, the pharmacological importance of lichen-associated metabolites remains untapped. This study aimed to evaluate the cytotoxic potential of lichens of this region. For this, sixteen macrolichens were collected and identified from two locations in the Western Ghats. The acetone extract of Usnea cornuta (UC2A) showed significant cytotoxicity towards multiple human cancer cell lines. Interestingly, co-treatment with chloroquine (CQ), an autophagy inhibitor, increased the cytotoxic potential of the UC2A extract. A gas chromatography mass spectrometry (GCMS) study revealed usnic acid (UA), atraric acid and barbatic acid as the dominant cytotoxic compounds in the UC2A extract. Further, UA was purified and identified from the UC2A extract and evaluated for cytotoxicity in HeLa cells. The monodansyl cadaverine and mitotracker red double staining revealed the autophagy-inducing activities of UA, and the inhibition of autophagy was confirmed via CQ treatment. Autophagy inhibition increased the cytotoxicity of UA by 12–16% in a concentration-dependent manner. It also increased lipid peroxidation, ROS levels and mitochondrial depolarization and decreased glutathione availability. A decrease in zeta potential and a 40% increase in caspase 3/7 activity were also noted after CQ treatment of UA-treated cells. Thus, cytotoxicity of UA can be increased by inhibiting autophagy.

Item Type: Journal Article
Publication: Plants
Publisher: MDPI
Additional Information: The copyright for this article belongs to the Authors.
Keywords: apoptosis; autophagy; cytotoxicity; HeLa; macrolichens; secondary metabolites; usnic acid (UA); Western Ghats
Department/Centre: Division of Biological Sciences > Biochemistry
Date Deposited: 25 Feb 2023 07:46
Last Modified: 25 Feb 2023 07:46
URI: https://eprints.iisc.ac.in/id/eprint/80677

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