Judul: Total Tannin Content and Antioxidant Activity of Red Betel Leaf Extracts (Piper crocatum) From Bogor, Bandung, Solo and Malang Using FRAP Method
Abstrak: Sirih merah merupakan salah satu tanaman yang telah banyak diteliti sebagai sumber antioksidan. Tujuan penelitian ini untuk menentukan kadar total tanin dan aktivitas antioksidan ekstrak daun sirih merah dari 4 daerah di Indonesia yaitu Bogor, Bandung, solo dan Malang. Ekstraksi dilakukan menggunakan metode maserasi dengan etanol 70% sebagai pelarut. Rendemen ekstrak etanol didapatkan rentang antara 8,27 hingga 14,19 dengan rendemen terbaik didapatkan oleh sirih merah Malang. Pengukuran kadar total tanin menggunakan metode titrasi dan pengukuran aktivitas antioksidan menggunakan metode FRAP. Hasil penelitian menunjukkan ekstrak etanol daun sirih merah memiliki rentang kadar total tanin antara 20,33 hingga 64,91 mg/g tanin dan rentang aktivitas antioksidan antara 2,54 hingga 3,45 mg TE/g. Hasi kadar total tanin dan aktivitas antioksidan tertinggi didapatkan pada daun sirih merah Bandung dengan nilai 64,90 mg/g tanin dan 3,45 mg TE/g ekstrak. Korelasi pearson tidak dapat dilakukan karena sebaran data kadar total tanin tidak normal., Red betel (Piper crocatum) is one of the plants that has been extensively researched as a source of antioxidants. The purpose of this study was to determine the total tannin content and antioxidant activity of red betel leaf extract from 4 regions in Indonesia, namely Bogor, Bandung, Solo, and Malang. Extraction was carried out using the maceration method with 70% ethanol as the solvent. The yield of ethanol extract ranged between 8.27 to 14.19, with the best yield obtained from Malang red betel. The measurement of total tannin content was performed using the titration method, and the measurement of antioxidant activity was conducted using the FRAP method. The results showed that the ethanol extract of red betel leaves had a total tannin content range between 20.33 to 64.91 mg/g tannin and an antioxidant activity range between 2.54 to 3.45 mg TE/g. The highest total tannin content and antioxidant activity were obtained from red betel leaves from Bandung, with values of 64.90 mg/g tannin and 3.45 mg TE/g extract, respectively. Pearson correlation could not be performed because the distribution of total tannin content data was not normal.
Keyword: Antioxidant, FRAP, Red Betel, Tannin

Judul: Total Phenolics, Flavonoids, and ɑ-Glucosidase Inhibitory Activity of n-Hexane, Ethyl Acetate and Methanol Extracts of Red Betel (Piper crocatum)
Abstrak: Sirih merah (Piper crocatum) mempunyai berbagai senyawa dengan kemampuan penghambatan enzim ɑ-glukosidase. Penelitian ini bertujuan menentukan ekstrak yang memiliki tingkat kandungan fenolik dan flavonoid yang optimal, serta penghambatan tertinggi pada enzim α-glukosidase. Metode maserasi bertingkat digunakan untuk mengekstraksi senyawa bioaktif sirih merah menggunakan pelarut-pelarut dengan peningkatan kepolaran (n-heksana, etil asetat, metanol). Pengujian dilakukan terhadap kadar fenolik total, flavonoid, serta kemampuan inhibisi ɑ-glukosidase. Hasil pengukuran total kadar fenolik, flavonoid, dan aktivitas penghambatan α-glukosidase menunjukkan nilai yang secara signifikan berbeda (p<0,05) pada semua ekstrak dengan total kadar fenolik dan flavonoid tertinggi pada ekstrak n-heksana berturut-turut sebesar 25,68 ± 0,29 mg GAE/g dan 65,84 ± 0,96 mg QE/g. Sementara itu, ekstrak metanol daun sirih merah memiliki daya hambat diantara semua ekstrak dengan nilai persen inhibisi α-glukosidase sebesar 43,87 ± 1,83%., Red betel leaf (Piper crocatum) had various compounds with the ability to inhibit α-glucosidase enzymes. The research aimed to determine the extract with optimal levels of phenolic and flavonoid content, as well as the highest inhibition of α-glucosidase enzyme. A multistage maceration method was used to extract bioactive compounds from red betel leaf using solvents with increasing polarity (n-hexane, ethyl acetate, methanol). Tests were conducted on the total phenolic content, flavonoids, and α-glucosidase inhibition ability. The measurement results of the total phenolic content, flavonoids, and α-glucosidase inhibition activity showed significantly different values (p<0,05) in all extracts with the highest total phenolic and flavonoid content in n-hexane extract, respectively, at 25,68 ± 0,29 mg GAE/g and 65,84 ± 0,96 mg QE/g. Meanwhile, the methanol extract of red betel leaf had inhibitory power among all extracts with a percentage inhibition of α-glucosidase at 43,87 ± 1,83%.
Keyword: ɑ-glukosidase/ɑ-glucosidase, antidiabetes/antidiabetic, fenolik/phenolic, flavonoid/flavonoid, sirih merah/red betel

Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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