Browsing by Author "Prastya, ME"

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    Citric acid-glycerol-based NADES for microwave-assisted extraction enhances the polyphenols level of Eleutherine bulbosa mill. Urb. Bulbs
    (Open Science Publishers LLP, 2024-09) Ahmad, I; Shakti, SOP; Prabowo, WC; Hikmawan, BD; Arifuddin, M; Angelina, M; Prastya, ME; Okselni, T; Alwi, RS; Sadikin, R; Iswahyudi, I; Febrina, L; Herman, H; Junaidin, J; Faisal, M; Samsul, E; Ibrahim, A; Mun’im, A
    Natural deep eutectic solvent combined with Microwave-assisted extraction (MAE) is considered as a potential green substitute for conventional extraction methods because of its selectivity and shorter extraction time. Eleutherine bulbosa Mill Urb. (E. bulbosa) bulbs, is renowned for having a high concentration of bioactive substances, primarily phenolics compounds with various therapeutic characteristics. This study aims to increase the level of total phenolics content (TPC) in E. bulbosa bulbs extract by applying a citric acid-glycerol (CA-Gly)-MAE and to optimize its extraction conditions using response surface methodology-based box-behnken design. In this study, we extracted dried samples under various conditions including microwave irradiation time and power, solid–liquid, sample-solvent ratio, and CA-Gly ratio. The measurements of TPC value were done spectrophotometrically and gallic acid was used as standard reference. The recommended optimum conditions were at 50% microwave power for 15 minutes, ratio of 1:14 g/ml, and CA-Gly ratio of 1:1 g/g, resulting in a predicted TPC value of 74.749 ± 3.716 mg GAE/g DW extract. Confirmation experiments were conducted using the recommended optimal extraction parameters, and the obtained TPC value was 84.653 ± 0.918 mg GAE/g DW extract. Our result demonstrates the potential of the CA-Gly-MAE for obtaining a higher yield of polyphenols from E. bulbosa bulbs.
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    Soil bacteria from Muna Island, Southeast Sulawesi, Indonesia: Antibacterial and antibiofilm activities, and the presence of antibiotic-biosynthetic genes
    (Open Science Publishers LLP, 2024-06) Hening, ENW; Priyanto, JA; Prastya, ME; Astuti, RI; Hasidu, LOAF; Jamilah
    Unexplored soil bacteria isolated from Muna Island, Southeast Sulawesi, Indonesia, provide a new source of active molecules serving as prospective antibacterial agents. In the present research, the antibacterial and antibiofilm activities of bacterial isolates obtained from Muna Island were evaluated. Based on the preliminary screening through the antagonism assay, 5 out of the 15 isolates exhibited various spectra of antibacterial activities. At a concentration of 80 mg/ml, metabolites extracted from the two selected isolates, M7 and P1 inhibited the growth of the five multidrug-resistant strains. These extracts exhibited minimum inhibitory concentration and minimum bactericidal concentration values of 312.5 ?g/ml to more than 10,000 ?g/ml. An analysis of the 16S rRNA sequences revealed that the corresponding isolates were closely related to Bacillus aerius strain 24K and Priestia (Bacillus) aryabhattai strain B8W22, with >97% similarity. Some genes involved in antibiotic biosynthesis, such as mlnA, baeR, srfA, dfnD, and bacD, were also present in the bacterial genome. Liquid chromatography-tandem mass spectrometry analysis of the most potent M7 extract showed that it contained several antibacterial compounds, such as cyclo(D-Pro-L-Tyr), marinoquinoline G, and rancinamycin Ib.