Evaluation of Colubrina Asiatica extract using microwave-assisted extraction as saponin-based foaming agent

Since past decades, herbal plants have been used widely by indigenous or even urban people for disease treatment, or taken orally as appetizers. This includes Colubrina asiatica (C. asiatica) which is also known as Peria Pantai. Previous studies reported that this plant contains high amount of active compounds that are responsible for foaming ability and various bioactivities. However, these active compounds are sensitive towards many factors; temperature, pH, light and other factors in the production line. This study was conducted to optimize the microwave assisted extraction (MAE) process of C. asiatica using response surface methodology (RSM) through Box-behnken Design. The foam properties including surface tension, foam ability and stability, film drainage and wetting ability were also evaluated. The parameters used in RSM were irradiation time (3,5 and 7 minutes), solvent to solid ratio (10,20 and 30 mL/g) and power (300,400 and 500 W). The experimental data of MAE from RSM were analysed to identify the factors that affect the extraction yield. The C. asiatica extract was characterized by using total saponin content (TSC), foam properties evaluated based on surface tension, foam ability, foam stability, film drainage and wetting ability while the antibacterial activity was assessed by using agar diffusion method. The optimal extraction condition was irradiation time at 6.06 min irradiation time, solvent to solid ratio of 28.31 mL/g and microwave power of 445 W. A non-conventional (UAE) and conventional extraction method (SE) were conducted based on the optimal conditions from previous study. Under the optimal conditions, C. asiatica extract yielded 43.1 % of crude extract for MAE, 25.32 % for UAE, and 40.93 % for SE. Total saponin content obtained via MAE, UAE and SE under this condition was 15.36, 13.12 and 10.45 mg ESE/g (milligram Escin/gram) respectively. Evaluation of foam properties showed that surface tension of MAE extract dropped to 44.3 mN/m. Surface tension of MAE dropped nearest to range of good detergent which is 32-37 mN/m. MAE extract showed the highest foam height (10.2 cm) and R5 value of foam height showed the value of 87.3% which indicate that MAE extract possessed good foam ability and stability characteristics. R5 is the ratio of the height of the foam at 5 min to that at 0 min. Rate of film drainage was the slowest for MAE extract (78 %) followed by UAE and SE. No significant difference was observed in rate of film drainage among these three extracts (P>0.05). The wetting ability study showed that MAE, UAE and SE extract solution needed 4.2, 7.3, and 16.1 minutes to penetrate the cotton yarn which were too long and this indicated that these extracts had weak wetting ability. These extracts were subjected to antibacterial activity and MAE extract showed excellent inhibition of E.coli and B. subtillis growth (11 and 13 mm). The quantification of saponin using HPLC analysis also revealed that MAE extract contained saponins from group of oleanolic acid (9.57%), ursolic acid (5.64%) and betulinic acid (3.93%). The extraction of C. asiatica leaves by using MAE was proven to provide better quantity and quality of the saponin extract. The C. asiatica extracts by using MAE produced the highest amount of extract yield in the shortest time compared to UAE and SE. MAE extract also has good quality in term of foaming properties and antimicrobial activity due to the presence of saponin. The finding of the study revealed that saponin from C.asiatica extract has the potential to be a natural foaming agent as an alternative to the conventional chemical-based foaming agent used in personal care, cosmeceutical, pharmaceutical and food industries