Microalgae excrete antioxidant compounds as a defense system to protect themselves from the danger of ultraviolet rays. These compounds also can be used as the organic materials of cosmetics or medicines. This study aimed to determine the antioxidant activity of marine microalgal extracellular metabolite extract of Spirulina sp.. Extracellular metabolites were extracted from the residual media filtrate from the harvesting. The qualitative antioxidant test’s results using the thin-layer chromatography technique and 2,2-diphenylpycrilhydrazil (DPPH) reagent showed antioxidant activity. Moreover, the component identification using ninhydrin and Dragendorff reagent in thin layer chromatography test showed alkaloid and peptide compounds. To support the results, the identification using infrared spectrum analysis showed the peaks at 1117 cm-1 (C-N and C-C stretching), 1458 cm-1 (C-H bending of methyl group), 1635 cm-1 (C=O stretching of amide group), and 3454 cm-1 (N-H stretching of amine and amide groups).
Getih-getihan (Rivina humilis L.) plants can be used as antibacterial, antioxidant and natural pesticides. Most of the biological activities of natural products originated from secondary metabolites contained therein. Studies have shown the effects of leaves, branches, and fruits extract of R. humilis towards biological activities. However, identifying the phytochemical compounds of R. humilis L. fruit is less discussed. Here we proposed research on the identification of secondary metabolite compounds of R. humilis L. fruit extract using phytochemical screening tests and spectroscopic method. The extraction of R. humilis L. fruit was proceeded by maceration method using methanol solvent. The series of phytochemical screening tests signified the presence of alkaloids, terpenoids, tannins and flavonoids. Furthermore, we applied FT-IR analysis to confirm the existence of functional groups in the secondary metabolite compounds. A broad absorption band showed the hydroxyl groups (O-H) at 3265 cm-1. The sharp band at 1632 cm-1 exhibited the C=C stretching band. The presence of C-N (stretching) was signified by the absorption band at 1237 cm-1, while the C-H bond in CH3 terminals (alkanes, alkyl group) was exhibited at 1401 cm-1. All the functional groups confirmed in the FT-IR analysis corroborated the phytochemical test results.
Indonesia has a diversity of hot spring as a habitat of bacteria. One of the hot springs is Natar hot spring, Lampung. This study is to report the characteristics of a bacterium called Nat1 isolate that produces amylase to degrade raw starch from Natar hot spring. Water samples were taken from hot springs with a temperature of 45°C and a pH of 7.0. Nat1 was isolated by screening on the medium of Starch-Luria Bertani at 37°C. Its amylase-producing bacteria showed an optimum amylolytic activity of a crude enzyme of Nat1 isolate in soluble starch was 267.2774 U/mL at 60°C. Genotypic identification results using the 16S rRNA gene showed that the Nat1 isolate is identified as Panninobacter phragmatetus. A crude enzyme of Nat1 isolate showed a novel amylase ability and could degrade the raw starch substrates, such as corn and sago, with the amount of reducing sugar for each raw starch, 37.0688 µmol/mg, and 24.2697 µmol/mg. In conclusion, Nat1 amylase is potentially used in industry for its ability to degrade raw starch directly.
Polypropylene/sugarcane bagasse silica (PP/SiO2) composites have been synthesized. The sol gel method with 1 M NaOH was used to synthesize silica from bagasse ash. The results showed that the silica yield was 52.8%. The resulting silica was blended with polypropylene with a mass ratio variation of 1:5, 1:10, 1:15, 1:20, and 1:25 to obtain PP/SiO2 composites. Composites in variations of 1:5 and 1:10 produce fragile plastic, whereas composites in variations 1:15, 1:20, and 1:25 produce strong and homogeneous plastic. The water resistance test showed that PP/SiO2 with variations of 1:15, 1:20,and 1:25 had good water resistance (> 94%), whereas variations of 1:5 and 1:10, the resistance to water dropped to 80-87%. FT-IR was used to characterize polypropylene, silica synthesized from bagasse ash, and PP/SiO2 composites (1:25) to observe functional group changes. FT-IR analysis showed that silica was successfully synthesized from bagasse ash. This is indicated by a band that widened at a wavenumber of 3400-3600 cm-1, which is characteristic of the O-H strain on water. This band is confirmed by a band with a wavenumber of 1660 cm-1 which is a bend in the O-H in a water molecule. Other silica characteristics can be seen in bands with wavenumbers of 1075 cm-1 and 950 cm-1, which are strains of Si-O, and bands with a wavenumber of 460 cm-1, which is a bend of Si-O. The spectra of polypropylene and PP/SiO2 were also similar. The similarity between the polypropylene and PP/SiO2 spectra indicates that SiO2 spreads homogeneously in polypropylene.
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