Judul: Ekstrak Sarang Semut (Hydnophytum formicarum) dan Potensinya sebagai Antihiperglikemik
Abstrak: Sarang semut (Hydnophytum formicarum) as an epiphyte of mangrove plant from Papua is increasingly popular to be used as antidiabetic medicine. Inhibition of α-glucosidase is one of mechanism of actions of an oral antidiabetic for diabetes mellitus treatment. The purpose of this research was to determine the antihyperglycemic activity of the sarang semut extract as α-glucosidase inhibitor. The research was performed in several steps: extraction of tuber of sarang semut, phytochemical test, α-glucosidase inhibition test, toxicity test using BSLT method. The phytochemical test indicated that methanol extract contained phenol and flavonoid, and water extract contained phenol, flavonoid, and tannin. Flavonoid concentration of methanol and water extracts were 0.559% (b/b) and 0.585% (b/b). Methanol extract inhibited α-glucosidase activity up to 98.55%, while water extract up to 9.37%. LC50 value of methanol extract was 735.02 ppm (categorized as a low toxic material), and water extract was 258166.58 ppm (as non toxic material).
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Judul: Kapang Endofit dari Tumbuhan Pesisir Sarang Semut (Hydnophytum formicarum) dan Potensinya sebagai Antihiperglikemik
Abstrak: Epiphytic plant sarang semut Hydnophytum formicarum is one of the coastal plants that used as traditional medicine. Microbial endophytic can produce secondary metabolite compounds similar to compounds produced by plants of its host. The purpose of this research was to determine the activity of the endophytic fungi extracts to inhibit α-glucosidase. This research included isolation, cultivation, extraction, characterization, and assay the antihyperglycemic activity. The results showed 7 types of endophytic isolates included 1A, 1B, 2A, 2B, 3, 6A and 6B with a different characterization. Endophytic fungus 3 and 6B were the selected isolate based on antagonism test. A fungal growth patterns showed that the stationary phase of the fungus was on the 21th day until 24th day. Phytochemical test on extracts of mycelium and culture media showed that the extracts containing flavonoids and phenols hydroquinone. The screening results showed that the fungal broth extract with concentration of 20000 ppm had α-glucosidase inhibitor activity 72.63%.
Keyword: α-glucosidase enzyme activity, sarang semut, endophytic fungi, antihyperglycemic

Judul: Bifurkasi Hopf pada Model Siklus Bisnis Kaldor Kalecki tanpa dan dengan Waktu Tunda
Abstrak: Business cycle model is one of dynamical system models in economic. One of the business cycles model is Kaldor-Kalecki model. Kaldor-Kalecki business cycle model that is written in delayed defferential equations, is a business cycle model that involves gross product and capital stock of a company. In this paper Kaldor-Kalecki business cycle model is analyzed using both nondelay and delay in time of capital stock. By Taylor expansion for the time delayed model, an analysis of stability around the fixed points has been done. Furthermore, by using Hopf bifurcation theorem, it can be shown that there exists periodic orbits and limit cycle. In the nondelayed model, changing the parameter of goods market could lead to the occurrence of Hopf bifurcation and the existence of limit cycle. Similarly, for the delayed model, it has been shown that changing the time delay parameter may result in the occurrence of Hopf bifurcation and limit cycle.
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