Judul: Aktivitas antioksidan dan kandungan kimiawi ekstrak daun wungu (Graptophyllum pictum L. Griff.)
Abstrak: Graptophyllum pictum L. Griff., a plant that originated from Papua and Polynesia, is believed to have antioxidant activity. This study aimed to examine of antioxidant activity and chemical content of Graptophyllum pictum L. Griff. leaves. Also, it was designed to determine the best extracting solvent that provides the highest antioxidant activity. This study used four different solvents, which were the solvent water, ethanol 30%, ethanol 70%, and ethanol 96%. Extracts of each solvent were studied to determine the presence or absence of the antioxidant activity and chemical content by using vitamin C as a comparison. The antioxidant activity of water extract, ethanol 30%, ethanol 70%, and ethanol 96% extract were determined using the DPPH (2,2 diphenyl-1-picryl-hydrazyl) with a spectrophotometer at a wavelength of 517 nm. Phytochemical test showed that water extract, ethanol 30%, ethanol 70%, and ethanol 96% Graptophyllum pictum L. Griff. leaves contain alkaloids and flavonoids. Ethanol 30% and ethanol 70% extract were contained saponin. Ethanol 70% and ethanol 96% extract contained tannins and steroids. Antioxidants activity test (IC50) of four types of solvents showed that the antioxidant activity is not active on four types of solvent used, but ethanol 70% extract of Graptophyllum pictum L. Griff. leaves has a weak antioxidant activity with IC50 of 257.79 ppm. It can be concluded that water, ethanol 30%, ethanol 96% extract Graptophyllum pictum L. Griff. leaf have no antioxidant activity as measured using the DPPH method.
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Judul: Antidiabetic activity and analysis of phytochemistry aqueous and ethanol extract of purple leaf (Graptophyllum pictum (L.) Griff)
Abstrak: Daun wungu (Graptophyllum pictum (L.) Griff) merupakan salah satu tanaman dari famili Acanthaceae. Tanaman lain yang berada dalam satu famili dilaporkan memiliki aktivitas antidiabetes melalui mekanisme inhibisi enzim α- glukosidase, sehingga diduga daun wungu juga memiliki aktivitas antidiabetes tersebut dan diamati kandungan fitokimianya. Aktivitas antidiabetes daun wungu dilakukan dengan menentukan besarnya daya hambat ekstrak daun wungu terhadap enzim α-glukosidase, intensitas warna yang dihasilkan dibaca serapannya pada panjang gelombang 400 nm dengan microplate reader dan dihitung persentase daya hambat ekstrak daun wungu terhadap enzim α- glukosidase. Maserasi daun wungu dilakukan dengan menggunakan empat jenis pelarut, yaitu etanol 96, 70, dan 30% serta air. Hasil yang diperoleh menunjukkan nilai inhibisi α-glukosidase oleh ekstrak etanol 96, 70, 30 dan air berturut-turut 61.09%, 66.11%, 58.55% dan 40.13%. Analisis fitokimia menunjukkan bahwa ekstrak dengan pelarut etanol 96% dapat mengekstraksi senyawa alkaloid, flavonoid, tanin dan steroid; pelarut etanol 70% mengekstraksi alkaloid, flavonoid, tanin, saponin dan steroid; pelarut etanol 30% mengekstraksi alkaloid, flavonoid dan saponin; dan pelarut air mengekstraksi alkaloid dan flavonoid. Ekstrak etanol 96% dan 70% merupakan dua ekstrak dengan persentase inhibisi α- glukosidase diatas 50%, yaitu sebesar 61.09% dan 66.11% sehingga dapat dikatakan bahwa kedua ekstrak tersebut berpotensi sebagai antidiabetes. Pelarut yang dapat mengekstraksi seluruh senyawa yang diharapkan adalah etanol 70%.
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Judul: Dynamics Model for Rural and Urban Economic Growth
Abstrak: Lewis theory of structural change has focused on mechanisms that allow countries to transform their domestic economic structure to a more modern economy. The proposed model deals with the mechanism of interaction between rural and urban Economic. This model is concerned with the process of labor transfer from rural to urban areas. This study aims to model the dynamics of economic growth in rural and urban areas, including determining the equilibrium solution and to carry out simulation of the model. The simulation results show that the transfer of labor from rural to urban areas will increase the rate of change of capital so that structural changes can be realized. In addition, increased propensity to save in rural areas will also accelerate structural change
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