Judul: Pengaruh naungan dan pemupukan MgSO4.H2O terhadap produksi antosianin daun dewa (Gynura pseudochina (L.) DC)
Abstrak: Daun dewa merupakan tanaman obat yang banyak manfaatnya karena mengandung senyawa bioaktif antara lain golongan flavonoid. Antosianin termasuk golongan flavonoid yang dapat berfungsi untuk mengobati beberapa jenis penyakit khususnya tumor atau kanker pada manusia. Tanaman daun dewa mengandung berbagai senyawa kimia, antara lain saponin, flavonoid, minyak atsiri, dan antikoagulan. Oleh karena itu daun dewa mempunyai banyak kegunaan dan salah satunya adalah untuk mengatasi stroke. Cahaya merupakan faktor penting bagi pertumbuhan dan perkembangan tanaman, karena selain berperan dominan pada proses fotosintesis, juga sebagai pengendali, pemicu dan modulator respon morfogenesis khususnya pada tahap awal pertumbuhan tanaman. Spektrum cahaya yang dibutuhkan tanaman berkisar antara panjang gelombang 400-700 nm, yang biasa disebut photosynthetically active radiation (PAR). Disamping pengaturan intensitas cahaya (naungan) untuk mendukung pertumbuhan di lapang, pemberian unsur hara melalui pemupukan sangat penting untuk mekanisme produksi bioaktif (flavonoid/ antosianin) pada tanaman daun dewa. Magnesium dan sulfur yang merupakan unsur hara yang akan dicobakan pada penelitian ini memiliki peran spesifik pada mekanisme produksi senyawa flavonoid. Sulfur dalam bentuk SO4 2- merupakan elemen esensial dalam sintesis protein dan produksi senyawasenyawa metabolit sekunder dalam tanaman seperti flavonoid dan terpenoid, sedangkan magnesium dapat membentuk senyawa cianidin Mg-compleks yang merupakan salah satu aglikon antosianin. Penambahan kandungan Mg dalam tanah dapat dilakukan dengan pemberian pupuk Mg yaitu kieserit (magnesium sulfate/ MgSO4.H2O) dengan kandungan 29% Mg dan 23% S. Penentuan dosis magnesium dan sulfur yang tepat untuk meningkatkan kandungan flavonoid daun dewa sangat penting untuk diketahui.
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Judul: Isolasi Komponen Bioaktif Flavonoid dari Tanaman Daun Dewa (Gynura pseudochina (Lour) DC)
Abstrak: This research was including of isolation of flavonoid component from leaf and rhizoma of daun dewa plant, followed by bioassay test of larvae mortality of Artemia salina Leach and antikhamir to Saccharomyces cerevisiae. Extraction process of antocyanin flavonoid was done by maceration using HCl in MeOH solvent, whereas another flavonoid was done maceration too, but with two steps, first, using MeOH – H2O (9:1) and second, using MeOH – H2O (1:1). Filtrate obtained from these steps was collected together and dried using rotavapour. Extract that obtained from this process was partitied using n-hexan, chloroform, diethylether, ethylacetic and n-buthanol solvent, respectively. Its residue was soxhletated using petroleum ether and methanol. The existency of flavonoid was traced by phytochemical test, its bioavailabiolity was traced by toxicity test using A. salina Leach larvae (BSLT test) and antikhamir activity test to Saccharomyces cerevisiae with spectrometer UV-Vis and FTIR, GC-MS and HPLC. The result of phitochemical test of fresh leaf extract of daun dewa plant could not detect the anthocyanin flavonoid group. The result of BSLT test of leaf powder extract showed that buthanol fraction has the highest value of LC50 = 832.12297 ppm, in rhizoma powder extract, the ethylacetic showed the highest value of LC50 was 723.44205 ppm, but in those both extract did not show antikhamir activity to S. cerevisiae khamir. Separation of buthanol fraction was using TLC preparative with silica gel 60 F254 as a stationer phase and BAW as a mobile phase. It was resulted 7 fractions. Fraction 4 and 7 had LC50 value 7.80408 and 208.51563 ppm, respectively. The result of structure identification of fraction 4 and 7 with spectrometer UV-Vis and FTIR gave a clue that fraction 4 and 7 could be presumed contain of flavonoid group compound and these fractions had functional group such as OH, C=O ketone, C=C aromatic and C-O. The results of GC and HPLC showed fraction 4 and 7 obtained was not pure. From the result of HPLC analysis, the content of quercetine in fraction 4 was 2.7458 mg/g.
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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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