Judul: Isolation and Characterization of Non-Biflavonoid faction from Araucaria hunsteinii K. Schum Leaves and Their Bioactivity as Antibacterial
Abstrak: Meningkatnya penyakit disebabkan bakteri disertai resistensi terhadap antibiotik menyebabkan permasalahan medis. Pemanfaatan senyawa antibakteri yang bersumber dari tumbuhan merupakan alternatif penyelesaian masalah tersebut. Tumbuhan genus Araucaria memiliki 19 spesies dengan lima spesies telah diuji aktivitas antibakterinya. A. hunsteinii K. Schum merupakan salah satu spesies yang dapat ditemukan di Kebun Raya Bogor. Kandungan biflavonoid dan terpenoid pada tumbuhan ini sudah pernah dilaporkan, tetapi informasi terkait senyawa non-biflavonoid dan aktivitas antibakterinya belum diteliti. Pada penelitian ini, fraksi non-biflavonoid difraksionasi dengan kromatotron dan kromatografi kolom gravitasi Sephadex LH-20 serta dimurnikan dengan kromatografi lapis tipis preparatif. Isolat (T5 dan T6) dikarakterisasi dengan LC-MS dan dalam kedua fraksi tersebut masing-masing teridentifikasi 4 dan 11 senyawa dugaan termasuk seskuiterpena. Uji antibakteri menggunakan bakteri Staphylococcus aureus, Kocuria rhizopila, dan Escherichia coli menunjukkan potensi aktivitas antibakteri., Increased bacterial diseases, accompanied by antibiotic resistance, cause medical problems. Antibacterial compounds from plants are an alternative solution to this problem. Araucaria genus has 19 species, five of which have been tested for antibacterial activity. A. hunsteinii K. Schum is a species that can be found in Bogor Botanical Garden. Biflavonoids and terpenoids in this plant have been reported, but information related to non-biflavonoid compounds and their antibacterial activity has yet to be studied. In this research, the isolation of non-biflavonoids was performed by fractionating it through chromatotron and Sephadex LH-20 column chromatography and purified by preparative thin-layer chromatography. The isolates (T5 and T6) were characterized using LC-MS; in two fractions, 4 and 11 identified compounds were identified, including sesquiterpenes. Antibacterial tests using the bacteria Staphylococcus aureus, Kocuria rhizopila, and Escherichia coli showed potential antibacterial activity.
Keyword: antibakteri, Araucaria hunsteinii, daun, terpenoid

Judul: Biflavonoid dari Daun Araucaria hunsteinii serta Telaah Aktivitasnya sebagai Antivirus
Abstrak: Biflavonoid merupakan dimer flavonoid yang terhubung melalui ikatan C-C atau C-O-C. Metabolit ini diketahui memiliki berbagai aktivitas hayati, seperti antidiabetes, antibakteri, antikanker, antivirus, antifungi, dan antioksidan. Biflavonoid telah diisolasi dari delapan spesies dari genus Araucaria dan sebagian besar ditemukan pada daun. Araucaria hunsteinii merupakan salah satu spesies yang tumbuh di Kebun Raya Bogor. Kandungan biflavonoid dan aktivitas hayati dari tumbuhan ini belum pernah dilaporkan sebelumnya. Oleh karena itu, penelitian ini bertujuan mengisolasi biflavonoid dari A. hunsteinii. Sampel daun diekstraksi dengan aseton, kemudian difraksionasi dengan kromatografi kolom gravitasi (KKG) Sephadex LH-20, dan dilanjut dengan KKG silika gel. Berdasarkan spektrum inframerah, ultraviolet-sinar tampak, dan resonans magnetic inti 1D dan 2D, dua biflavonoid telah diidentifikasi, yaitu 4',7,7''-tri-O-metilkupresuflavon dan 4''',7,7''-tri-O-metilagathisflavon. Biflavonoid tersebut telah ditemukan di spesies lainnya pada genus ini, tetapi baru pertama kali ditemukan spesies A. hunsteinii. Berdasarkan studi pustaka, biflavonoid berpotensi sebagai antivirus influenza, SARS-Coronavirus, demam berdarah, virus herpes simpleks, dan hepatitis B., Biflavonoids are flavonoid dimers that are connected through C-C or C-O-C bonds. These metabolites are known for various biological activities, such as antidiabetic, antibacterial, anticancer, antiviral, antifungal, and antioxidant. The biflavonoids isolated from eight species of the Araucaria genus are mostly found in the leaves. Araucaria hunsteinii is one of the Araucaria grow in the Bogor Botanical Gardens. The biflavonoids content and the biological activity of this species have not been reported. This research aimed to isolate its biflavonoids. The leaf samples were extracted in acetone, then fractionated using Sephadex LH-20 column chromatography (CC), and continued with silica gel CC. Analysis of the infrared, ultraviolet-visible, 1D- and 2D-nuclear magnetic resonance spectra revealed two biflavonoids, identified as 4',7,7''-tri-O-methylcupressuflavone and 4''',7,7''-tri-O-methylagathisflavone. These biflavonoids have been reported in other species within the genus, but they are first discovered in A. hunsteinii. Based on the literature study, these biflavonoids are potential antiviral for influenza, SARS-Coronavirus, dengue, herpes simplex virus, and hepatitis B agents.
Keyword: antivirus, Araucaria, Araucaria hunsteinii, biflavonoid

Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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