Jutti Levita

This book discusses about the simple basics of molecular modeling which is easily to be understood by beginners. It also explains about ligand representation, analysis of binding pocket, interaction of ligand and macromolecule, and the relationship between molecular modeling with in vitro and in vivo studies. Informations concerning molecular modeling freewares are also provided.

Some examples written in this book are based on the author’s experimental results which have been published in journals or presented in seminars.

Malaria parasite encodes several homologues of aspartic proteases such as plasmepsin I, II and IV which are responsible for degradation of host erythrocyte hemoglobin inside the parasite’s food vacuole, hence plasmepsins are novel targets for antimalarial drug discovery. Previous study concluded that Andrographis paniculata herbs extract has been proven to exert antimalarial activity. The molecular mechanism of this activity was not described. The objective of this paper was to investigate the interaction between andrographolide, a major constituent of Andrographis paniculata with the ligand binding domain of plasmepsin I, II and IV, to find the most favorable binding site as well as to predict the binding mode. Pepstatin, a protease inhibitor, was used as the standard. Docking studies showed that pepstatin gave better binding interactions to plasmepsin I, II and IV with binding affinity and inhibition constant values Ei = -10.3 kcal/mol; Ki = 0.02 uM  (plasmepsin I), Ei = -8.9 kcal/mol; Ki = 0.3 uM (plasmepsin II), Ei = -9.3 kcal/mol; Ki = 0.15 uM (plasmepsin IV), respectively while andrographolide showed Ei = -9.8 kcal/mol; Ki = 0.07 uM  (plasmepsin I), Ei = -8.7 kcal/mol; Ki = 0.42 uM (plasmepsin II), Ei = -8.8 kcal/mol; Ki = 0.35 uM (plasmepsin IV). According to the result, we concluded that andrographolide could be developed as protease inhibitor for antimalarial drug.

Andrographis paniculata or sambiloto is one of the most widely used medicinal herbs in Indonesia. The main bioactive chemical constituent, andrographolide, has been reported to have various pharmacological activities. Besides its function for medical purposes, the sambiloto herbs infusion is frequently taken to maintain health. This study was conducted to determine the bioavailability of sambiloto herbs infusion in rabbit plasma, stomach, and liver, calculated as total andrographolide. Fourteen male New Zealand white rabbits were used in this study. Sambiloto herbs infusions were administered orally at the dose 7.04mL/kg body weight to each rabbit. Blood samples were taken at intervals 0.0; 0.5; 1.5; 2.0; 3.0; and 5.0h after infusion administration. Sambiloto herbs infusion, which calculated as andrographolide, levels in plasma, stomach, and liver were analyzed by high performance liquid chromatography using C-18 column as stationary phase and a mixture of methanol-double distilled water (60:40) as mobile phase. Bioavailability parameters obtained were Cmax 0.5549µg/mL (in stomach), 0.2136µg/mL (in plasma), 0.0051µg/mL (in liver); while tmax 1h (in stomach), 1.5h (in plasma), 2h (in liver); and AUC 1.7451µg.h/mL (in stomach), 0.434µg.h/mL (in plasma), 0.0038µg.h/mL (in liver). These data showed that in healthy animals, sambiloto herbs infusion was fastly absorbed from the stomach, distributed in the circulation system, and metabolized in the liver, in subsequent process. Sambiloto herbs infusion showed good bioavailability in rabbit.

Nonivasive diagnosis of cancer can be provided by molecular imaging using hybrid modality to obtain better sensitivity, specificity and depiction localization of the disease. In this study, we developed a new molecular imaging agent, radiogadolinium(III)-DOTA-PAMAM G3.0-trastuzumab in the form of 147Gd-DOTA-PAMAM G3.0-trastuzumab, that can be both target-specific radiopharmaceutical in SPECT as well as targeted contrast agent in MRI for the purpose of diagnosis of HER-2 positive breast cancer. 147Gd radionuclide emits γ-rays that can be used in SPECT modality, but because of technical constraint, 147Gd radionuclide was simulated by its radioisotope, 153Gd. Gd-DOTA complex has also been known as good MRI contrast agent. PAMAM G3.0 is useful to concentrate Gd-DOTA compelexes in large quantities, thus minimizing the number of trastuzumab molecules used. Trastuzumab is human monoclonal antibody that can spesifically interact with HER-2. Synthesis of radiogadolinium(III)-DOTA-PAMAM G3.0-trastuzumab was initiated by conjugating DOTA NHS ester ligand with PAMAM G3.0 dendrimer. The DOTA-PAMAM G3.0 produced was conjugated to trastuzumab molecule and labeled with 153Gd. Characterization DOTA-PAMAM G3.0-trastuzumab immunoconjugate was performed using HPLC system equipped with SEC. The formation of immunoconjugate was indicated by the shorter retention time (6.82 min) compared to that of trastuzumab (7.06 min). Radiochemical purity of radiogadolinium(III)-DOTA-PAMAM G3.0-trastuzumab was >99% after purification process by PD-10 desalting column. Radiogadolinium(III)-DOTA-PAMAM G3.0-trastuzumab compound was stable at room temperature and at 2–8 0C as indicated by its radiochemical purity 97.6 ± 0.5%–99.1 ± 0.5% after 144 h storage.

Abstract: NF-kappaB plays a central role in coordinating the expression of various soluble proinflammatory mediators, such as cytokines and chemokines. In physiological conditions, NF-kappaB occurs within the cytoplasm and is retained by IkappaB, a protein inhibitor that masks the nuclear localization signal present in the NF-kappaB sequence.