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Background and Aim: Fermented milk can be used to produce antihypertensive peptides. Lactic acid bacteria (LAB) with its proteolytic system hydrolyze milk protein during fermentation to produce several peptides, which include antihypertensive bioactive peptides. This study aimed to investigate the ability of indigenous LAB for the production of angiotensin-I-converting enzyme inhibitory (ACE-I) peptides in fermented milk and to characterize the ACEI peptides. Materials and Methods: Reconstituted milk (11%) inoculated with ten LAB isolates, and then incubated at 37°C until it reaches pH 4.6. The evaluation was carried out for LAB count, lactic acid concentration, peptide content, and ACE-I activity. The low molecular weight (MW) peptides (<3 kDa) were identified using Nano LC Ultimate 3000 series system Tandem Q Exactive Plus Orbitrap high-resolution mass spectrometry. Results: The result showed that the ten LAB isolates were able to produce ACE-I in fermented milk with the activities in the range of 22.78±2.55-57.36±5.40%. The activity of ACE-I above 50% produced by Lactobacillus delbrueckii BD7, Lactococcus lactis ssp. lactis BD17, and Lactobacillus kefiri YK4 and JK17, with the highest activity of ACE-I produced by L. kefiri YK4 (IC50 0.261 mg/mL) and L. kefiri JK17 (IC50 0.308 mg/mL). Results of peptide identification showed that L. kefiri YK 4 could release as many as 1329, while L. kefiri JK 17 could release 174 peptides. The peptides produced were 95% derived from casein. The other peptides were from α-lactalbumin, β-lactoglobulin, and serum amyloid A. The peptides produced consisted of 6-19 amino acid residues, with MWs of 634-2079 Dalton and detected at 317-1093 m/z. A total of 30 peptides have been recognized based on literature searches as ACE-I peptides (sequence similarity: 100%). Conclusion: L. kefiri YK4 and JK17 are the potential to be used as starter cultures to produce the bioactive peptide as ACE-I in fermented milk.

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Determination of uric acid concentration in human urine and blood is needed to diagnose several diseases, especially the occurrence of kidney disease in gout patients. Therefore, it is needed to develop a simple and inexpensive method for uric acid detection. The purpose of the research was to observe the use of Indonesian microbe that was immobilized on natural zeolite as a source of uricase for uric acid biosensor. Selection of mediators and determination of optimum condition measurement, the stability and kinetic properties of L. plantarum uricase were performed using carbon paste electrode. Cyclic voltammetry was employed to investigate the catalytic behavior of the biosensor. The result indicated that the best mediator for measurement of L. plantarum uricase activity was Qo (2,3-dimethoxy-5-methyl-1,4 benzoquinone). Optimum conditions for immobilization of L. plantarum uricase on zeolite were obtained at pH 7.6, with temperature of 28 degrees C, using uric acid concentration of 0.015 mM and zeolite mass at 135 mg K(M) and V(Max) of L. plantarum uricase obtained from Lineweaver-burk equation for the immobilization uricase on zeolite were 8.6728 x 10(-4) mM and 6.3052 mM, respectively. K(M) value of L. plantarum uricase directly immobilized onto the electrode surface was smaller than K(M) value of L. plantarum uricase immobilized on zeolite. The smaller K(M) value shows the higher affinity toward the substrate. The Electrode when kept at 10 degrees C was stable until 6 days, however the immobilized electrode on zeolite was stable until 18 days. Therefore, Indonesian L. plantarum could be used as a uric acid biosensor.

Apo-glucose dehydrogenase existing in Escherichia coli is converted to the holoenzyme with exogenous pyrroloquinoline quinone (PQQ) and Mg(2+). Catalytic behaviour of the E. coli cells with the holoenzyme is characterized by a Michaelis-Menten-type equation with a catalytic constant of the cell and apparent Michaelis constants for D-glucose and an artificial electron acceptor added to the E. coli suspension. The catalytic constant is expressed as the product of the number of molecules of the enzyme contained in an E. coli cell (z) and the catalytic constant of the enzyme (k(cat)), which were determined to be 2.2x10(3) and 6.8+/-0.8x10(3) s(-1) (phenazine methosulphate as an electron acceptor) respectively. Kinetics of the in vivo holoenzyme formation can be followed by an enzyme-electrochemical method developed by us. The rate constants for the reactions of apoenzyme with PQQ (k(f,PQQ)) and with Mg(2+) (k(f,Mg)) were determined to be 3.8+/-0.4x10(4) M(-1).s(-1) and 4. 1+/-0.9 M(-1).s(-1) respectively. Equilibrium constants for the binding of apoenzyme to PQQ and Mg(2+) were determined as the dissociation constants K(d,PQQ(Mg)) and K(d,Mg) to be 1.0+/-0.1 nM and 0.14+/-0.01 mM respectively. The dissociation constants for Ca(2+) were also determined. The holoenzyme, once formed in E. coli, returns gradually to the apoenzyme in the absence of PQQ and/or Mg(2+) in solution. EDTA was effective to remove Mg(2+) from the enzyme in the cells to deactivate the enzyme completely, while PQQ remained in the E. coli cells.

Asam gelugur fruits of Garcinia often used to reduce body weight. Lengkuas and kencur are traditional herbal that potential for antiobesity because they could reduce the level of phospholipids, triglycerides, and cholesterol. The aim of the research was to evaluate the potencies of these herbal as antiobesity by measurement of their water and ethanol extracts capabilities as in vitro inhibitor of pancreatic lipase activity. The water and ethanol extracts of asam gelugur fruits contained saponins and alkaliods, respectively. The water extract of lengkuas rhizomes contained alkaloids, flavonoids, saponins, and quinones, while the ethanol extract contained alkaloids, flavonoids, saponins, and steroids. The water extract of kencur rhizomes contained saponins and quinones, while the ethanol extract contained alkaloids, flavonoids, steroids, and quinones. The highest inhibitory effect of all extracts was obtained from the ethanol extract of asam gelugur fruits with value of 86.3% at 150 ppm. The highest inhibitory effect of lengkuas extracts was from the ethanol extract at 200 ppm (56.2%). The highest inhibitory effect of kencur was showed by the ethanol extract with the value 37.6% at 300 ppm. These values were higher than the inhibitory effect of the positive control (Xenical ® ) at 100 ppm (10.6%).Kata kunci: asam gelugur, lengkuas, kencur, inhibitory effect, antiobesity

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