Judul: ACE inhibitor activities and characterities of endophytic streptomyces sp. AEP-1 from pegagan (Centella asiatica)
Abstrak: Hipertensi merupakan gangguan sistem peredaran darah yang menyebabkan kenaikan tekanan darah di atas normal, yaitu 140/90 mmHg. Obat kimia paten yang digunakan sebagai obat hipertensi antara lain adalah obat dari golongan inhibitor Angiotensin Converting Enzyme (ACE). Inhibitor ACE bekerja dengan menghambat ACE dalam membentuk angiotensi II dan mendegradasi bradikinin sebagai substrat kompetitif. ACE meregulasi keseimbangan antara penyempitan pembuluh oleh angiotensin II dan pelebaran pembuluh darah oleh bradikinin. Pegagan (Centella asiatica) telah lama digunakan sebagai obat herbal untuk mengatasi hipertensi. Dari beberapa hasil penelitian diketahui bahwa mikrob endofit mampu menghasilkan senyawa yang sama seperti yang dihasilkan oleh inangnya. Streptomyces sp. AEP-1 endofit tanaman pegagan terbukti mampu menghasilkan senyawa inhibitor ACE dengan aktivitas yang tinggi sebesar 279,2%, sehingga potensial untuk digunakan sebagai obat anti hipertensi. Namun demikian, karakterisasi senyawa inhibitor ACE Streptomyces sp. AEP-1 belum dikaji. Penelitian ini bertujuan mengetahui kemampuan Streptomyces AEP-1 endofit tanaman Pegagan dalam menghasilkan inhibitor ACE melalui kajian aktivitas dan karakterisasi. Isolat AEP-1 ditumbuhkan pada media YMA, WA, YSA, OM dan diinkubasi pada suhu ruang selama 28 hari. Untuk mencari aktivitas inhibitor ACE optimum, isolat dikulturkan pada media YMB dan di panen pada hari ke-0, 5, 10, 15, dan 20 untuk diambil supernatan dan biomassanya. Supernatan yang didapat diukur aktivitas inhibisinya terhadap ACE secara in vitro menggunakan metode inhibitor ACE assay dengan HHL sebagai substrat. Protein dalam ekstrak kasar diendapkan menggunakan aseton 80% kemudian di fraksinasi menggunakan kromatografi filtrasi gel dan diukur bobot molekulnya dengan SDS-PAGE.
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Judul: Aktivitas antihipertensi aktinomiset endofit asal tanaman pegagan dan belimbing wuluh
Abstrak: Endophytic actinomycetes lives in the plant tissue without causing a negative impact. Several medicinal associates with endophytic microbe which may produce similar bioactive compounds to their host plant. Inhibition of Angiotensin Converting Enzyme (ACE) is one of the effective antihypertension mechanism. The potency of endophytic actinomycetes from the medicinal plant used as ACE inhibitor needs to be elucidated. The research aimed to isolate endophytic actinomycetes from rhizome, stem, leaf of pegagan (Centella asiatica) and also from fruit of belimbing wuluh (Averrhoa bilimbi), and assess their capability to produce bioactive compound which can function as ACE inhibitor. The endophytic actinomycetes were isolated from surface sterilized plant parts, grounded and plated in Humic-acid Vitamin-B agar (HV) medium. The purified isolates were grown on International Streptomyces Project No.2 (ISP2) medium, and the crude extract which consisted of extracellular bioactive compound, was used for in vitro assay of ACE inhibitor activity. Twelve isolates of endophytic actinomycetes were successfully isolated from pegagan leaves (three isolates) and belimbing wuluh fruits (nine isolates). The data showed that nine isolates (AEP-1, AEP-2, AEP-3, AEB-1, AEB-3, AEB-5, AEB-6, AEB-7, and AEB-8), had various ACE inhibitor activities, and belonged to Streptomyces spp.. Three other isolates (AEB-2, AEB-4, and AEB-9) belonged to non-Streptomyces, and also showed various ACE inhibitor activities,. Meanwhile, free endophytic microbes of tissue culture seedling of pegagan did not show any ACE inhibitor activity. The AEP-1 isolated from pegagan had the highest percentage (279.2%) followed by AEB-5 isolated from belimbing wuluh (222,92%) of ACE inhibitor activity, exceeding the ACE inhibition activity of captopril (0.01 mg/mL) which was 61.5% and captopril (0.02 mg/mL) was 66.7%. The data indicate that endophytic actinomycetes isolated from leaf of pegagan and fruit of belimbing wuluh capable of producing ACE inhibitory compound.
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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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