Abstract:
This study aims to determine the efficacy of Spirulina platensis extracts on microbial inhibition and antioxidative activity based on green solvent and green chemistry with chemical composition analysis. The Spirulina was extracted with six different solvents, i.e. water, 95% ethanol, methanol, water and 95% ethanol ratio 3:1, 1:1 and 1:3. As the results, only extracts from water and 95% ethanol in the ratios of 1:1, 3:1 and 1:3 were able to inhibit Ps. aeruginosa respectively. Ps. aeruginosa was considered a resistant strain and causes a high mortality rate. Therefore, Spirulina extract may be an alternative for control or inhibition in order to reduce the hazard of infection. The chemical composition analysis of spirulina extract by TLC technique (Silica gel, 100% methanol) found that Spirulina extracts showed activity against Ps. aeruginosa with Rf 0.15, which were not found in all inactive extracts. So, it was indicated that the compound was an active compound against Ps. aeruginosa. Moreover, the compound at Rf 0.15 assumed was an alkaloid by Dragendroff's reagent test and also showed DPPH antioxidant activity with the TLC technique. The antioxidant activity test of ABTS and DPPH by absorbance was reported as IC50 (ug/ml) so it was found that spirulina extracts using water and ethanol at the ratio of 1:3 gave the best antioxidant activity, followed by 3:1 and 1:1, respectively. Analysis of the pigment content of the Spirulina extract was found the highest phycocyanin content using water extraction. While ethanol and methanol as an extractant gave high amounts of chlorophyll A and carotenoids. This clearly showed the difference in the amount of pigment in different solvents which was useful for application in the future. In addition, TLC fingerprint could also be used to facilitate simple qualitative analysis for S. spirulina extracts.