Optimisation of the Extraction Process of a Flavonoid-rich Extract from the Leaves of Abutilon indicum with Anti-inflammatory Activity and Cytotoxicity against Selected Cancer Cell lines

Abstract

In recent years, increasing attention has been directed toward the study of flavonoids isolated from medicinal plants, due to their broad pharmacological properties and lower toxicity than synthetic agents. This study aimed to optimise the extraction process for a flavonoid-rich extract from Abutilon indicum (L.) leaves and to evaluate its sweet taste, anti-inflammatory, and cytotoxic activities. A Box–Behnken Design under Response Surface Methodology (RSM) was employed to investigate the effects of ethanol concentration, extraction temperature, ultrasound time, and solvent-to-material ratio. Total flavonoid content was determined using the aluminium chloride (AlCl₃) colourimetric method. The optimised extract was assessed for in vitro anti-inflammatory activity by measuring nitric oxide (NO) inhibition in LPS-induced RAW264.7 macrophages and for cytotoxicity against three human cancer cell lines—HepG2 (liver), SK-LU-1 (lung), and MKN7 (gastric)—using the Sulforhodamine B (SRB) assay. Under the optimal extraction conditions (68.5 % ethanol, 50 °C, 20 minutes ultrasound), the extract yielded a total flavonoid content of 306.55 ± 4.62 mg QE/g. The extract exhibited anti-inflammatory activity with a cell protection rate of 54.92 ± 2.29 %, and demonstrated promising cytotoxicity against cancer cell lines with IC₅₀ values of 148.29 ± 4.55 µg/mL (SK-LU-1), 164.39 ± 6.94 µg/mL (HepG2), and 164.76 ± 7.73 µg/mL (MKN7). These findings suggest that Abutilon indicum leaves are a promising natural source of bioactive flavonoids with potential anti-inflammatory and anticancer effects.