Nanoenkapsulasi Ekstrak Kelopak Bunga Rosella (Hibiscus sabdariffa) Hasil Ekstraksi Berbantu Gelombang Mikro Sebagai Bahan Antibakteri dan Antioksidan
Purbowati, Ike Sitoresmi Mulyo
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Roselle has used as medicine because they contain bioactive medicine because they contain bioactive compound such as phenols. The present study was designed to develop Microwave Assisted Extraction (MAE) on phenolics extraction from roselle calyx which gave maximum yield, higher antioxidant and antibacterial activity, and maintain stability of roselle bioactive compounds through the application of nano-encapsulation technology. Scope of this research was divided in three stages of experimental activities. Firstly, investigated of solvent influence on characteristics of toxicity, antibacterial and antioxidant activities. Secondly, determined the optimum condition of Microwave Assisted Extraction and characterized the extract on optimum conditions, and thirdly, applied of nano-encapsulation technique to improved the stability roselle extract. The aims of the first research was to find solvent with the best extract characteristics of toxicity, antibacterial and antioxidant activity. Qualitative method was used to determine the phytochemical calyx content, Brine Shrimp Lethality for toxicity tests. Antibacterial tests were done against Staphylococcus aureus and Escherichia coli using disc diffusion method. Total antioxidant activity was determined by the ferric thiocyanate method. The results showed that bioactive compounds in Roselle calyx were flavonoid, phenolic compounds, tannin, alkaloid, and steroid. Ethanol 70% could extract the phenolics 19.45 + 0.32 mg/g compared with ethyl acetate and hexane, which only could extract the fenolik compound respectively 7.51 + 0.49 mg/g and 2.73 + 0.31 mg/g. It means that ethanol 70% is more effective than the other solvents. The ethanol 70% extract was found to be potential against brine shrimp with LC50 value below 1000 ppm, 510.613 ppm. On the other hand with ethyl acetate and hexane were respectively 1241.983, and 1718.446 ppm. Ethanol 70% and ethyl acetate extract had antibacterial activity, showed by inhibitory zone 7.7 + 2,01b mm and 7,53 + 2,19 bmm for S aureus and 13.28 + 3,30b mm, 12,35 + 3,13b mm against to E coli. There was no inhibitory zone for crude hexane extract. EC50 value for ethanol 70%, ethyl acetate and hexane were 4393.2; 5879,16 ;4813,92 ppm respectively. Roselle calyx was an excellent source of phenolic compounds. In this study, microwave-assisted extraction was employed to extract the phenols from Roselle calyx. The aims for the second stage were to determined the optimum condition of microwave assisted extraction, and characterized of the antibacterial and antioxidant activity extract from optimum condition. For the efficiency of extraction by using response surface methodology, the effects of microwave output power, ethanol concentration, and extraction time on total phenols yield were investigated and the optimal conditions were determined as follows: microwave output power 250 W, etanol concentration 78,36% and extraction time 4.91 min. The estimated values for total fenoliks yield, 24,61 mg/g was obtained at those conditions. A verification experiment at the optimum condition, consisting of 4 runs, was performed and the practical yield of 23.77 + 0.25 mg/g total fenoliks was higher than using conventional method 19.84 + 0.46 mg/g.. Compared with conventional method, total phenolics, antosianin, and vitamin C and yield of microwave assisted extraction were 23.77 + 0.25, 14.80 + 0.08, 10.74 + 0,14 mg/g and 22.09 + 3.3 % which are higher and significantly different within 95% confidence level than conventional extraction (19.84 + 0.46, 9,28 + 0.04, 9.99 + 0.16 mg/g and 16,18 + 1,9%, respectively) The third stage, the extract which was in liquid form, has some weaknesses, such as unstable in enviromental changes, low flexibility uses and trouble in material handling and transportation. For these reasons, nano-encapsulation technique was an alternative way to prolong the stability of the roselle extract using β-cyclodextrins as matrix agent. The aims of these research were characterization of total phenolics, antioxidant and antibacterial activity of nano-encapsulation and the stability of the extract and nano-encapsulation against the change of pH, temperature and boiling time. Nano-capsules of roselle extract was containing phenolics 4,53 + 0,26 mg/g, antosianin 2,99 + 0,18 mg/g, vitamin C 2,77 + 0,04 mg/g and water content 5,16 + 0,03%, antioxidant activity 49%, antibacterial activity against E coli dan S aureus showed by clearance zone around the disc, expectively were 3,5 + 0,5 mm, 2,5 + 0,2 mm. Nanocapsules were more resistence against the enviroment changes than the liquid extract. The stability test against the enviroment changes shows that, the nanocapsules form are more stable than the extract, showed by the slope of linier regression of nanocapsules form for phenolics, antioxidant and antibacterial activity against E coli and S aureus respectively were: 0,111; 1,307; 0,291; 0,131 which were lower than the extract 2,825; 7,634;1,760; 1,636. Nanocapsules were more resistence against temperature and boiling time than the liquid extract. The stability test against temperature and boiling time showed that the nanocapsules form were more stable than the extract, showed with the slope of linier regression of nanocapsules for phenolics, antioxidant and antibacterial activity against E coli and S aureus were: 1,3315; 0,3162; 0,0439; 0,0333 which are lower than the extract : 1,5864; 0,5389; 0,1783; 0,1728, respectively.