Judul: Antioxidant and Antiaging Activities of the Extracellular Metabolites from Endophytic Bacteria Niallia nealsonii DCL1 from Clove Leaf
Abstrak: Tanaman cengkeh (Syzygium aromaticum) merupakan salah satu rempah berharga Indonesia karena memiliki banyak manfaat seperti pengawet makanan dan keperluan medis. Pada penelitian sebelumnya, enam bakteri endofit telah diisolasi dari daun cengkeh. Salah satu isolatnya adalah DCL1 yang merupakan bakteri Gram positif dan telah teridentifikasi sebagai Niallia nealsonii. Penelitian ini bertujuan menentukan aktivitas antioksidan serta antipenuaan dari metabolit ekstraseluler DCL1. Metabolit ekstraseluler diekstraksi dari kultur N. nealsonii DCL1 pada jam ke-28 dan jam ke-40 menghasilkan rendemen masing-masing 0,01% dan 0,009%. Data menunjukkan bahwa ekstrak DCL1 jam ke-40 memiliki kandungan total senyawa fenol (93,54 mg asam galat/g ekstrak) dan flavonoid (12,09 mg kuersetin/g ekstrak) lebih tinggi daripada ekstrak jam ke-28. Selain itu, ekstrak jam ke-40 menunjukkan aktivitas antioksidan lebih kuat dibandingkan ekstrak jam ke-28 yang secara in vitro dianalisis berdasarkan metode 2,2-diphenyl-1-picrylhydrazyl (DPPH) (IC50 222 µg/mL) dan 2,2′-azino-(bis(3-ethylbenzotiazolin-6-sulfonic-acid)) (ABTS) (IC50 511,43 µg/mL). Ekstrak tersebut juga dapat memperpanjang viabilitas khamir Schizosaccharomyces pombe dibandingkan tanpa perlakuan ekstrak. Hasil analisis LC-MS/MS menunjukkan adanya beberapa senyawa potensial yaitu gallic acid dan N-carbamoyl-2,3-dihydroxybenzamide. Hasil penelitian ini memperlihatkan bahwa ekstrak jam ke-40 memiliki potensi sebagai agen antipenuaan yang dapat diaplikasikan sebagai sumber formulasi produk biofarmasi atau kosmetik., Clove plant, Syzygium aromaticum, is one of Indonesia’s most valuable spices that are known to have abundant benefits such as food preservatives and medical purposes. In a previous study, six endophytic bacteria were successfully isolated from clove leaf. One of the isolates, namely DCL1 is Gram-positive bacteria and has been identified as Niallia nealsonii. This study aimed to determine antioxidant and antiaging properties of extracellular metabolites of DCL1. Extracellular metabolites were extracted from N. nealsonii DCL1 culture at 28 h and 40 h with yields of 0,01% and 0,009%, respectively. Data shows that DCL1 40 h extract has higher phenolic (93,54 mg gallic acid equivalents/g extract) and flavonoid (12,09 mg quercetin equivalents/g extract) than 28 h extract. In addition, 40 h extract showed higher antioxidant activities than 28 h extract in vitro as analyzed by 2,2-diphenyl-1-picrylhydrazyl (DPPH) (IC50 222 µg/mL) and 2,2′-azino-(bis(3-ethylbenzotiazolin-6-sulfonic-acid)) (ABTS) (IC50 511,43 µg/mL) assays. Furthermore, extract could prolong cell viability of yeast Schizosaccharomyces pombe better than without treatment. LC-MS/MS analysis showed the presence of some potential compounds including gallic acid and N-carbamoyl-2,3-dihydroxybenzamide. This study indicated that 40 h extract has potential as an antiaging agent which could be applied as a source for biopharmaceutical or cosmeceutical product formulations.
Keyword: antioksidan, antipenuaan, LC-MS/MS, N. nealsonii, S. pombe, antiaging, antioxidant

Judul: Antibacterial Activity of Endophytic Bacteria Isolates from Clove Leaf (Syzygium aromaticum) and Identification Based on Morphological and Physiological Characteristics
Abstrak: Infeksi bakteri patogen masih menjadi masalah utama dalam kesehatan yang banyak menimbulkan kematian. Bakteri endofit pada tanaman obat berpotensi sebagai agen penghasil antibakteri. Keberadaan bakteri endofit pada tanaman cengkeh (Syzygium aromaticum) memungkinkannya memproduksi senyawa bioaktif yang sama seperti yang terkandung dalam inangnya. Penelitian ini bertujuan menganalisis aktivitas antibakteri isolat bakteri endofit asal daun cengkeh dan karakterisasi isolat yang potensial. Metode penelitian dilakukan dengan peremajaan isolat dan bakteri uji, skrining potensi aktivitas antibakteri secara disc diffusion, karakterisasi morfologi dan fisiologi isolat paling potensial, penentuan kurva pertumbuhan, serta uji aktivitas antibakteri isolat potensial pada waktu inkubasi optimum. Hasil penelitian menunjukan bahwa isolat bakteri endofit dari daun tanaman cengkeh (Syzygium aromaticum) mempunyai aktivitas antibakteri terhadap bakteri patogen. Isolat DCL1 bersifat bakterisidal kuat terhadap Escherichia coli, sedangkan isolat DCL3 bersifat bakterisidal intermediet terhadap Pseudomonas aeruginosa. Dua isolat bakteri endofit asal daun cengkeh tersebut memiliki kesamaan karakteriskik dengan genera Bacillus berdasarkan karakter morfologi koloni, morfologi sel, dan aktivitas biokimia yang menghasilkan enzim katalase. Aktivitas antibakteri isolat bakteri endofit daun cengkeh DCL1 dan DCL3 paling baik pada jam ke-40 waktu inkubasi optimum berdasarkan kurva pertumbuhan., Pathogenic bacterial infection is still a major health problem that causes many deaths. Endophytic bacteria in medicinal plants have the potential as antibacterial agents. The presence of endophytic bacteria in the clove plant (Syzygium aromaticum) allows it to produce the same bioactive compounds as those contained in its host. This study aims to analyze the antibacterial activity of endophytic bacteria from clove leaves and characterize the potential isolates. The research method was carried out by rejuvenating isolates and testing bacteria, screening for potential antibacterial activity by disc diffusion, morphological and physiological characterizations of the most potential isolates, determining growth curves, and testing the antibacterial activity at optimum incubation times. Based on the results, endophytic bacteria from clove leaf (Syzygium aromaticum) have antibacterial activity against pathogenic bacteria. DCL1 isolate is strong bactericidal against Escherichia coli, while DCL3 isolate is intermediate bactericidal against Pseudomonas aeruginosa. The two isolates of endophytic bacteria from clove leaf have similar characteristics to the Bacillus genera based on colony morphology, cell morphology, and biochemical activity that produce catalase enzymes. The best antibacterial is shown by isolating DCL1 and DCL3 at 40 hours of optimum incubation time based on the growth curve.
Keyword: antibacterial, bioactive compound, disc diffusion, endophytic bacteria, pathogenic bacteria

Judul: Approximation of the Median of Poisson Distribution Using the Relation of Poisson-Gamma Distribution
Abstrak: A major drawback of median is that median cannot usually be defined in closed form, even in the cases where their distribution functions are known. This study gives an approximation of the closed form for the median of the Poisson distribution by using the relation of Poisson-Gamma distribution. The approximation uses elementary techniques based on the monotonicity of certain sequences involving tail probabilities of the Poisson distribution and the Central Limit Theorem. Furthermore, a closed form expression for the mean absolute deviation 􀜧|􀜰􀰒 􀵆 􀜯􀝁􀝀􁈺􀜰􀰒􁈻| is also studied. The median is relevant because of the fact that it minimizes the mean absolute deviation of a Poisson random variable (􀜰􀰒􁈻 by considering median as central tendency.
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