Background:Fucoxanthin is a potential tumor cytotoxic compound. However, mechanisms underlying the activities are unclear.Aim:This in silico study aimed to predict the main mechanism of fucoxanthin; whether with its binding to p53 gene, CDK2, or tubulin.Materials and Methods:In silico was studied by using Autodock-Vina's algorithms. The mechanisms being analyzed by comparison of fucoxanthin and native ligands binding energies in p53 gene (1RV1), CDK2 (1AQ1), and three binding sites of tubulin (1JFF-paclitaxel, 1SA0-colchicine, and 1Z2B-vinblastine site).Results:Autodock-Vina's algorithms were valid, as re-docking the native ligands to their receptors showed a RSMD value less than 2 A with binding energies of -11.5 (1RV1), -14.4 (1AQ1), -15.4 (1JFF), -9.2 (1SA0), and -9.7 (1Z2B) kcal/mol. Docking of fucoxanthin to subjected receptors were -6.2 (1RV1), -9.3 (1AQ1), -8.1 (1JFF), -9.2 (1SA0), and -7.2 (1Z2B) kcal/mol. Virtual analysis of fucoxanthin and tubulin binding structure showed the carboxyl moiety in fucoxanthin make a hydrogen bound with 355Val (2.61 A) and 354Ala (2.79 A) at tubulin.Conclusion:The results showed that binding energy of fucoxanthin could only reach the same level as with colchicine ligand in tubulin. Therefore, it may predict that the most probable fucoxanthin main mechanism is to bind tubulin, which causes microtubules depolimerization and cell cycle arrest.

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 57  LC-MS metabolomic analysis of environmental stressor impacts on the metabolite diversity in Nephthea spp.Abstract Context: The soft coral Nephthea spp. is a source of terpenoid class that potentially has pharmaceutical properties. However, metabolite diversity and cytotoxic activity of this species are varied among coral reefs from various sites. Aim: To analyze the water quality in Nephthea spp. environment as a possible factor causing a difference in its metabolite diversity. Settings and Design: Nephthea spp. from seven sites were taken in October 2010 at the Alor District of Marine Protected Area, Indonesia. Materials and Methods: Water quality assessment was analyzed in situ and indexed by Canadian Council of Ministry Environment-Water Quality Index (CCME-WQI) method. Meanwhile, metabolite diversity was analyzed by a LC-MS metabolomic method, using C18 reversed phase and gradient water-acetonitrile system. Statistical Analysis Used: Spearman's rho and regression analysis were applied to correlate the water quality index to ecological index (richness, diversity, and evenness) from LC-MS results. Results: The water quality index had a significant positive correlation and strong linear regression determinant to the total metabolite (R 2 = 0.704), particularly to semipolar metabolite richness (R 2 = 0.809), the area of terpenoid class in the organism. Conclusion: It can be concluded that water quality may serve as a major factor that affects the amount of richness in Nephthea spp. metabolites. When the water quality is lower, as environment stresses increases, it may affect the metabolite richness within direct disrupt of metabolite biosynthesis or indirect ecological means. Terpenoids are known as a soft coral antipredator (coral fishes), the amount of which depends on the water quality.

Key words: fucoidan, brown seaweed, bioactivity, L-fucose ABSTRAK Fukoidan adalah senyawa polisakarida yang secara substansional terdiri atas L-fukosa dan golongan ester sulfat, terutama terdapat pada rumput laut coklat. Dalam jangka waktu sepuluh tahun terakhir, bioaktivitas dari fukoidan telah banyak diteliti. Bahkan belakangan ini telah diteliti aplikasi fukoidan untuk obat. Dalam beberapa tahun terakhir, struktur fukoidan telah berhasil diidentifikasi dan bioaktivitasnya berhasil diketahui. Fukoidan mempunyai banyak bioaktifitas antara lain sebagai antikoagulan, antioksidan, antikomplementari, anti pembengkakan, pelindung lambung, dan pengatur kadar lipid darah. Review ini memberikan ringkasan beberapa kemajuan penelitian isolasi dan bioaktivitas fukoidan dari beberapa jenis rumput laut coklat penghasil fukoidan.

Recently, research to explore marine bioactive compounds especially marine medicines and cosmetics shows increasing trend due to the diversity of the chemical structures and their bioactivities. 9 In the