Cytotoxic Effect of Clinacanthus nutans Standardised Fraction (SF1) in Combination with Cisplatin Against Human Cervical Cancer Cell Line (SiHa)
Abstract
Cervical cancer is one of the most commonly diagnosed malignancies in the world, and it is correlated to HPV infection and invasion. Surgery, chemotherapy, and radiotherapy are common therapies, but serious adverse effects have been reported. A standardised fraction from the medicinal plant Clinacanthus nutans was successfully isolated and known as SF1. SF1 has shown cytotoxic action against cervical cancer cell lines, SiHa in a previous study [1].
Therefore, this study aims to further elucidate the effect of SF1 in combination with cisplatin against SiHa in order to increase the selectivity of the treatment, hence, minimising the side effects of cisplatin. The MTT assay was used to analyse the cytotoxicity of the combination treatment, and its combination index value was calculated using the Chou-Talalay method based on the median-effect equation. A cell survival test (clonogenic assay) was conducted to evaluate the reproducibility of cancer cells after being treated.
The combination treatment had enhanced cytotoxic action and inhibited SiHa’s cell proliferation the most (IC50 value = 5.10 µg/mL) compared to the individual cytotoxic activity of SF1 (IC50 value = 9.60 mL) and cisplatin (IC50 value = 3.6 µg/mL) (Figure 1). The combination also showed an antagonism effect with CI values of 2.60 to 1.5 with the fractional inhibition of Fa = 0.50 to 0.90. When it pertains to toxicity, the antagonistic action of the combination treatment is preferred, as one drug reduces the adverse effects of another. The outstanding result showed that the combination treatment of SF1 with cisplatin enhances efficacy compared to the mono-therapy approach because it targets key pathways in a characteristically antagonism manner. This paves the way for further study on the mechanisms of action for the combination treatment of SF1 and cisplatin.
