Optimisation of extraction parameters of Aquilaria malaccensis on in vitro antiurolithiatic activities using Response surface methodology (RSM)

The prevalence of urolithiasis has become a concerning issue in Malaysia. Its treatment normally relies on medical processes which are costly and can trigger reoccurrence. Traditional healers have used Aquilaria malaccensis (agarwood) to treat urolithiasis; however, the extraction parameters that result in optimum effectiveness have not been determined. Hence, this research aims to optimise the extraction parameters of A. malaccensis stem on in vitro antiurolithiatic activities by applying response surface methodology (RSM) and central composite design (CCD). The studied parameters were solvent concentration (X1), extraction temperature (X2) and extraction time (X3). Their effects on antiurolithiatic activities (turbidity assay, Y1; titrimetric assay, Y2) were also investigated. The presence of phenols, alkaloids and terpenoids was assessed both qualitatively and quantitatively. The quadratic model was selected for both antiurolithiatic activities as the R2 values achieved were close to 1 and were significantly affected by each studied parameter (p < 0.05). The optimum extraction condition of A. malaccensis stem extract was 100% ethanol, 30.0°C extraction temperature and 30 min extraction time. The extract demonstrated antiurolithiatic activities measured at 83.58 ± 0.75% (turbidity assay) and 86.57 ± 0.80% (titrimetric assay). The phytoconstituents in A. malaccensis stem extracts showed positive correlations with both antiurolithiatic activities. This research has established the reliability of RSM to optimise extraction conditions of A. malaccensis stem to exhibit high antiurolithiatic activities.