Judul: Kuersetin dari Ekstrak Daun Jambu Biji Merah (Psidium guajava) dan Kinerjanya sebagai Penghambat Proliferasi Sel Kanker
Abstrak: Red guava leaf (Psidium guajava) extract has been known to inhibit cancer cell proliferation. However, further studies on the activity of flavonoids in red guava leaves as an anticancer agent has not been done. This study aims to test the inhibitory activity on Raji cells (ATCC CCL-86) by quercetin in guava leaves. Methanol crude extract was fractionated using vacuum liquid chromatography and column chromatography techniques to obtain fraction rich of quercetin. Fractionation of the crude methanol extract gave a fraction which shows a spot at Rf 0.675, which is similar to that of standard quercetin. Identification of quercetin fraction with liquid chromatography-mass spectrometry showed the fragment ion spectra of the quercetin (m/z 150, 151, 152). The quercetin fraction has been tested for its activity toward Raji cells and Vero cells. The quercetin fraction inhibited proliferation of Raji cells by 60%, at a concentration of 100 mg mL-1, but only inhibits the proliferation of Vero cells by 10%. This result indicates the quercetin fraction of guava leaf is able to inhibit the proliferation of Raji cells, but not toward Vero cells.
Keyword: quercetin, Psidium guajava, flavonoids, cancer cells proliferation

Judul: Formulasi ekstrak daun jambu (Psidium guajava) dan daun sirsak (Annona muricata) untuk menghambat proliferasi sel kanker
Abstrak: Daun jambu biji merah (Psidium guajava) mengandung senyawa kuersetin dan sirsak (Annona muricata) mengandung senyawa kaempferol yang masingmasing telah diketahui memiliki aktivitas antikanker. Tujuan penelitian ini adalah mengevaluasi efek sinergis campuran fraksi kaya-kaempferol dari daun sirsak dan fraksi kaya-kuersetin dari daun jambu biji merah dalam menghambat proliferasi sel kanker secara in vitro. Ekstrak metanol didapatkan melalui maserasi dengan sonikasi setelah sebelumnya sampel daun yang telah diserbukkan disoxhletasi menggunakan pelarut n-heksana. Ekstrak dari kedua daun masing-masing dipisahkan menggunakan kromatografi cair vakum sehingga didapatkan sebanyak 2.6% fraksi kaya-kaempferol dan 2.2% fraksi kaya-kuersetin. Kedua fraksi diformulasikan dalam berbagai formula (8:2, 6:4, 5:5, 4:6, 2:8) dan dilihat efek penghambatannya terhadap sel Vero (sel normal) dan Raji (sel kanker darah). Persen penghambatan sel Raji oleh formula kedua fraksi memiliki nilai di bawah 30%. Formula fraksi kaya-kaempferol dari daun sirsak dan fraksi kaya-kuersetin dari daun jambu tidak memiliki efek sinergis maupun antagonis dalam menghambat proliferasi sel Raji secara in vitro.
Keyword: Anticancer, Guava leaf, Kaempferol, Quercetin, Soursoup leaf, Anti kanker, Kuersetin, Kaempferol, Rendemen ektrak metanol, Sel kanker, Ektraksi

Judul: Penggunaan Metode Homotopi untuk Menyelesaikan Masalah Nilai Eigen pada Suatu Model Getaran
Abstrak: Most mathematical models of natural phenomena are nonlinear model. One of the nonlinear problems is a problem of vibration which can be considered as an eigen value problem. Here, the nonlinear factor appeared due to the external forces applied to the system. The vibration problem in this study, was solved using the homotopy method. The homotopy method is analytical approach in the nonlinear problems within the series form. The terms of the series were obtained based on a recursive formula in a high deformation. A convergent solution of the series dependent on both the homotopy parameter and the coefficient of nonlinear factors appeared in the model.
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