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: Determination of Total Phenolics and Flavonoids Content of Ethyl Acetate and Water of Red Betel Extract (Piper crocatum Ruiz & Pav.) and Their Inhibition of Tyrosinase Enzyme
Abstrak: Sirih merah (Piper crocatum Ruiz & Pav.) memiliki senyawa potensial seperti flavonoid yang dapat berperan sebagai inhibitor tirosinase. Penelitian ini bertujuan untuk menentukan kadar total fenolik dan flavonoid ekstrak sirih merah berdasarkan perbedaan pelarut serta aktivitas inhibisinya terhadap enzim tirosinase. Ekstrak yang mampu menginhibisi enzim tirosinase mampu bekerja sebagai agen pemutih, yang bisa digunakan dalam suatu krim pemutih. Metode ekstraksi yang digunakan yaitu maserasi untuk pelarut etil asetat dan perebusan untuk pelarut air, dilanjutkan dengan uji kadar total fenolik, flavonoid, dan uji inhibisi tirosinase yang berpotensi sebagai agen pemutih. Hasil yang diperoleh pada penelitian ini menunjukkan ekstrak etil asetat menjadi sampel terbaik dengan nilai total fenolik sebesar 56,255 mg GAE/g DW, kadar total flavonoid sebesar 48,631 mg QE/g DW, dan berpotensi sebagai penghambat tirosinase dengan nilai IC50 1600,38 mg/L. Sementara ekstrak air memiliki nilai kadar total fenolik sebesar 44,2 mg GAE/g DW, kadar total flavonoid sebesar 39,812 mg QE/g DW, dan berpotensi sebagai penghambat tirosinase dengan nilai IC50 1764,39 mg/L., Red betel (Piper crocatum Ruiz & Pav.) is a plant with flavonoid-like potential compound that can act as tyrosinase inhibitor. This research aimed to determine the total phenolic and flavonoid concentration of red betel extract based on different solvents and its inhibition activities against the tyrosinase enzyme. Extract capable of inhibiting the tyrosinase enzyme had potential to act as a whitening agent, which could then be utilized in a whitening cream product. The extraction methods include: maceration for the ethyl acetate solvent; and boiling for the water solvent, continued with measuring the phenolic and flavonoid content, with the tyrosinase inhibition test for solvents with whitening agent potential. Results indicated that the ethyl acetate solvent was the best sample with a total phenolic value of 56,255 mg GAE/g DW, total flavonoid content of 48,631 mg QE/g DW, and the potential to inhibit tyrosinase with an IC50 value of 1600,38 mg/L. Meanwhile, the water extract resulted in a total phenolic value of 44,2 mg GAE/g DW and a total flavonoid content of 39,812 mg QE/g DW, with the potential to inhibit tyrosinase with an IC50 value of 1764,39 mg/L.
Keyword: flavonoid, phenolic, red betel, solvent, tyrosinase

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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