Usnic acid induced changes in biomolecules and their association with apoptosis in squamous carcinoma (A-431) cells: A flow cytometry, FTIR and DLS spectroscopic study

Kumari, M and Kamat, S and Jayabaskaran, C (2022) Usnic acid induced changes in biomolecules and their association with apoptosis in squamous carcinoma (A-431) cells: A flow cytometry, FTIR and DLS spectroscopic study. In: Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy, 274 .

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Abstract

Many natural products induce apoptotic cell death in cancer cells, though studies on their interactions with macromolecules are limited. For the first time, this study demonstrated the cytotoxic potential of usnic acid (UA) against squamous carcinoma (A-431) cells and the associated changes in cell surface proteins, lipids and DNA by attenuated total reflection- fourier transform infrared spectroscopy (ATR-FTIR) and dynamic light scattering (DLS) spectroscopic studies. The IC50 for UA was 98.9 µM after treatment of A-431 cells for 48 h, while the IC50 reduced to 39.2 µM after 72 h of incubation time. UA induced oxidative stress in treated cells as confirmed by DCFHDA flow cytometry assay, depletion in reduced glutathione and increase in lipid peroxidation. The oxidative stress resulted in conformation change in amide I, amide II protein bands and DNA as observed by ATR-FTIR in UA treated A-431 cells. Shift in secondary structures of proteins from α helix to β sheets and structural changes in DNA was observed in UA treated A-431 cells. An increase in the band intensity of phospholipids, increased distribution of lipid and change in membrane potential was noted in UA treated cells, which was confirmed by externalization of phosphatidylserine to the outer membrane by annexin V-FITC/PI assay. Increase in mitochondrial membrane potential, cell cycle arrest at G0/G1 phase by flow cytometry and activation of caspase-3/7 dependent proteins confirmed the UA induced apoptosis in treated A-431 cells. FTIR and DLS spectroscopy confirmed the changes in biomolecules after UA treatment, which were associated with apoptosis, as observed by flow cytometry. © 2022

Item Type:	Journal Article
Publication:	Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy
Publisher:	Elsevier B.V.
Additional Information:	The copyright for this article belongs to the Elsevier B.V.
Keywords:	Amides; Biomolecules; Cell death; Cell membranes; DNA; Dynamic light scattering; Flow cytometry; Mitochondria; Phospholipids; Proteins; Spectroscopic analysis, Acid treated; Attenuated total reflection Fourier transform infrared spectroscopy; Dynamic light-scattering; Dynamic-light scatterings; FTIR; Natural products; Secondary structures; Spectroscopic studies; Squamous carcinoma; Usnic acid, Fourier transform infrared spectroscopy
Department/Centre:	Division of Biological Sciences > Biochemistry
Date Deposited:	22 Jun 2022 04:54
Last Modified:	22 Jun 2022 04:54
URI:	https://eprints.iisc.ac.in/id/eprint/73597

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