Abstract:
Fourier Transform Infrared (FTIR) spectroscopy is finding increasing biological application, for example in
the analysis of diseased tissues and cells, cell cycle studies and investigating the mechanisms of action of
anticancer drugs. Cancer treatment studies routinely define the types of cell-drug responses as either
total cell destruction by the drug (all cells die), moderate damage (cell deterioration where some cells
survive) or reversible cell cycle arrest (cytostasis). In this study the loss of viability and related chemical
stress experienced by cells treated with the medicinal plant, Plectranthus ciliatus, was investigated using
real time cell electronic sensing (RT-CES) technology and FTIR microspectroscopy. The use of plants as
medicines is well established and ethnobotany has proven that crude extracts can serve as treatments
against various ailments. The aim of this study was to determine whether FTIR microspectroscopy would
successfully distinguish between different types of cellular injury induced by a potentially anticancerous
plant extract. Cervical adenocarcinoma (HeLa) cells were treated with a crude extract of P ciliatus and
cells monitored using RT-CES to characterize the type of cellular responses induced. Cell populations
were then investigated using FTIR microspectroscopy and statistically analysed using One-way Analysis
of Variance (ANOVA) and Principal Component Analysis (PCA). The plant extract and a cancer drug control
(actinomycin D) induced concentration dependent cellular responses ranging from nontoxic, cytostatic
or cytotoxic. Thirteen spectral peaks (915 cm 1, 933 cm 1, 989 cm 1, 1192 cm 1, 1369 cm 1,
1437 cm 1, 1450 cm 1, 1546 cm 1, 1634 cm 1, 1679 cm 1 1772 cm 1, 2874 cm 1 and 2962 cm 1) associated
with cytotoxicity were significantly (p value < 0.05, one way ANOVA, Tukey test, Bonferroni)
altered, while two of the bands were also indicative of early stress related responses. In PCA, poor separation
between nontoxic and cytostatic responses was evident while clear separation was linked to
cytotoxicity. RT-CES detected morphological changes as indicators of cell injury and could distinguish
between viable, cytostatic and cytotoxic responses. FTIR microspectroscopy confirmed that cytostatic cells were viable and could still recover while also describing early cellular stress related responses on a
molecular level.
