Judul: Profil Flavonoid, Tanin, dan Alkaloid dari Ekstrak Daun Sirih Merah (Piper crocatum)
Abstrak: Piper crocatum is Indonesia’s medicinal plant that has been proven to have anti-hyperglycemic, antioxidative, and anticancer activities. Hence, the aim of this study was to determine and analyze flavonoid, tannin, and alkaloid profiles of 30 % ethanol and water extracts of Piper crocatum leaves. Flavonoid, tannin, and alkaloid profiles were measured using spectrophotometry, titrimetry, gravimetry and LC-MS techniques. Phytochemical identification proved that both of extracts contain flanovoids, tannins, and alkaloids. Measurement of flavonoids quantitatively showed that the highest value was found in ethanol 30 % extract, 6.09 ± 0.26 mg QE/g. The highest quantitative tannin and alkaloid present in the water extract with a value of 3.97 ± 0.08 mg/g and 543.75 ± 3.17 mg/g. LC-MS analyze, the highest flavonoid compounds expected in water extract. The highest tannin and alkaloid compounds were expected in ethanol 30 % extract.
Keyword: tannins., Piper crocatum, flavonoids, alkaloids

Judul: Ekstrak dan Fraksi Daun Sirih Merah (Piper crocatum Ruiz & Pav) sebagai Antioksidan dengan Metode 2,2-difenil-1-pikrilhidrazil.
Abstrak: Sirih merah (Piper crocatum Ruiz & Pav) merupakan tanaman obat potensial yang memiliki khasiat untuk beberapa jenis penyakit seperti hiperglikemia, kanker, asam urat, dan hipertensi. Senyawa aktif yang berperan sebagai antioksidan dapat digunakan sebagai pencegah dan obat penyakit degeneratif. Penelitian ini bertujuan menentukan aktivitas antioksidan tertinggi dari ekstrak dan fraksi daun sirih merah. Ekstraksi dilakukan dengan maserasi menggunakan etanol 70%, selanjutnya ekstrak kasar difraksinasi dengan 3 pelarut, yaitu n-heksana, etil asetat, dan air. Uji antioksidan dilakukan dengan metode DPPH dan identifikasi untuk sampel yang memiliki senyawa antioksidan teraktif menggunakan instrumen LC-MS. Berdasarkan hasil penelitian ekstrak maupun fraksi memiliki aktivitas sebagai antioksidan. Aktivitas antioksidan tertinggi terdapat pada fraksi etil asetat dengan nilai IC50 13.15 μg/mL. Fraksi etil asetat dan ekstrak etanol 70% termasuk sebagai antioksidan sangat kuat. Analisis senyawa aktif dengan LC-MS menunjukkan bahwa fraksi etil asetat mengandung lima senyawa berdasarkan kelimpahan paling tinggi, yaitu 60.58 (m/z), 701.54 (m/z), 701.67 (m/z), 440.82 (m/z), dan 482.93 (m/z).
Keyword: antioksidan, DPPH, LC-MS, Piper crocatum, sirih merah

Judul: Dynamic New Keynesian Model for Unemployment and Inflation Rate.
Abstrak: This paper deals with a scientific analysis of the equilibrium level of hiring, employment and unemployment. The basic model being used is a standard new Keynesian model, which states that utility function depends on consumptions and working hours. Utility maximization refers to a standard labour supply equation, with the marginal cost’s dynamics on new Keynesian model simply reflects movements in real wages and productivity. Furthermore, trade-off between output and inflation stabilization can be considered using the new Keynesian Phillips curve. Dynamic general equilibrium model is a model that can be used to study interactions between market imperfections and nominal rigidities, which is capable of overcoming the main shortcoming of the standard new Keynesian model. In the general equilibrium model there are three groups of the economy agents, namely households, firms and monetary authority. The results of this research science that bargaining processes between firms and workers will yield optimal wage. Increase in labour will cause wages to fall, but the unemployment rate can be reduced. An increase in the firm’s monopoly power will shift the labour demand curve downward, which will reduce the number of workers that firm is willing to hire for any given bargained wage.
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