Judul: . Literature Review Effect of Extraction Solvent on antihyperglycemic, Antioxidant, and Antibacterial Activities of Red Betel Leaf (Piper crocatum)
Abstrak: Sirih merah (Piper crocatum) merupakan salah satu tanaman yang banyak tersebar di Indonesia. Selain dikenal sebagai tanaman hias, sirih merah juga diketahui sebagai obat herbal tradisional yang memiliki banyak maanfaat untuk kesehatan, diantaranya sebagai antihiperglikemia, antioksidan, dan antibakteri. Penelitian ini bertujuan memberikan informasi mengenai pelarut terbaik dalam mengekstrak senyawa bioaktif daun sirih merah terhadap aktivitas antihiperglikemia, antioksidan, dan antibakteri. Ekstrak etanol 70% terbaik dalam menurunkan glukosa darah secara in vivo, sedangkan etil asetat dari ekstrak etanol 70% terbaik dalam menghambat α-glukosidase secara in vitro. Fraksi etil asetat dan ekstrak etanol 70% memiliki aktivitas antioksidan tertinggi dalam metode DPPH, FRAP, dan MDA-TBA, sedangkan fraksi n-heksana dari ekstrak etanol 70% memiliki aktivitas antioksidan tertinggi dalam metode CUPRAC. Dalam aktivitas antibakteri, ekstrak etil asetat dapat menghambat bakteri Staphylococcus aureus dan Escherichia coli dengan zona hambat tertinggi.
Keyword: antibacterial, antihyperglycemic, antioxidant, Piper crocatum, red betel

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: Analysis of Unequal Income Distribution with Cobb-Douglas Production Function
Abstrak: This paper studies the economic growth model by Moav (2002). Moav model shows the existence of unequal income distribution between low-income with high-income community. That kind of unequal income distribution is caused by uneven distribution of income. On this Moav model, there is one area called the threshold. Threshold becomes a benchmark to determining whether a society is categorized into low- or high- income community. The production function used in this paper is the Cobb-Douglas function. The dynamics of this model is described as difference equation of low-income, threshold, and high-income community. Simulation study on the model is carried out using Maple 13 and Mathematica 7.0 software. Overall, from the observed case, high-income community will reach a stable condition earlier, followed by the threshold, and then the low-income community.
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