Judul: Phytochemical Analysis, Antioxidant Activity, and Collagenase Inhibition of Red Betel Leaf Extract (Piper crocatum Ruiz & Pav.) In Vitro.
Abstrak: Sirih merah (Piper crocatum Ruiz & Pav.) merupakan tanaman dengan berbagai kandungan senyawa aktif. Penelitian ini bertujuan menentukan komponen fitokimia, aktivitas antioksidan, dan inhibisi kolagenase ekstrak etil asetat dan air daun sirih merah. Pengukuran kadar air dilakukan dengan metode pengeringan. Ekstraksi dilakukan dengan metode maserasi untuk pelarut etil asetat dan metode perebusan untuk pelarut air. Metode LC-MS digunakan dalam identifikasi senyawa aktif. Metode DPPH digunakan dalam uji antioksidan. Uji inhibisi kolagenase dilakukan dengan 1,10-Fenantrolin sebagai kontrol positif. Kadar air diperoleh sebesar 8.12 ± 0.63%. Nilai rendemen ekstrak etil asetat dan air berturut-turut sebesar 7.71 ± 0.35% dan 27.88 ± 0.59%. Senyawa dugaan dengan kelimpahan relatif terbesar pada kedua ekstrak yaitu Schisandrin B dan 2-(4-Allyl-2,6-dimethoxyphenoxy)-1-(3,4,5-trimethoxyphenyl)-1-propanol. Nilai IC50 penghambatan DPPH pada ekstrak air sebesar 1098.99 ppm dan ekstrak etil asetat sebesar 1378.59 ppm. Persen inhibisi kolagenase ekstrak etil asetat dan air tidak berbeda nyata, yaitu berturut-turut sebesar 89.9% dan 89.09%., Red betel (Piper crocatum Ruiz & Pav.) is a plant with various active compounds. This study aimed to determine the phytochemical components, antioxidant activity, and inhibition of the collagenase extract of ethyl acetate and red coat leaf water. Measurement of moisture content is carried out by the drying method. Extraction is carried out by the maceration method for ethyl acetate solvents and boiling methods for water solvents. The LC-MS method is used in the identification of active compounds. The DPPH method is used in the antioxidant test. The collagenase inhibition test was performed with 1,10-Phenantrolin as a positive control. The moisture content obtained is 8.12 ± 0.63%. The yield values of ethyl acetate and water extracts were 7.71 ± 0.35% and 27.88 ± 0.59%, respectively. The suspected compounds with the greatest relative abundance in both extracts are Schisandrin B and 2-(4-Allyl-2,6-dimethoxyphenoxy)-1-(3,4,5-trimethoxyphenyl)-1-propanol. The IC50 value of DPPH inhibition in aqueous extract is 1098.99 ppm and in ethyl acetate extract is 1378.59 ppm. The percentage of collagenase inhibition for ethyl acetate and water extracts is not significantly different, which is 89.9% and 89.09% respectively.
Keyword: antioxidant, collagenase, DPPH, LC-MS, 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: 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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