Hindawi Publishing Corporation Evidence-Based Complementary and Alternative Medicine Volume 2011, Article ID 969275, 7 pages doi:10.1155/2011/969275 Research Article Enhanced Antitumoral Activity of Extracts Derived from Cultured Udotea flabellum (Chlorophyta) Rosa Moo-Puc, 1, 2 Daniel Robledo, 1 and Yolanda Freile-Pelegrin 1 1 Department of Marine Resources, Cinvestav, Km 6 Carretera Antigua a Progreso, Cordemex, A.P. 73, 97310 M´ erida, YUC, Mexico 2 Unidad de Investigaci´ on M´ edica Yucat´ an, Unidad M´ edica de Alta Especialidad, Centro M´ edico Ignacio Garc´ ıa T´ ellez, Instituto Mexicano del Seguro Social; 41 No 439 x 32 y 34, Colonia Industrial CP, 97150 M´ erida, YUC, Mexico Correspondence should be addressed to Daniel Robledo, robledo@mda.cinvestav.mx Received 16 January 2011; Accepted 3 June 2011 Copyright © 2011 Rosa Moo-Puc et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Very few studies have been performed to evaluate the effect of culture conditions on the production or activity of active metabolites in algae. Previous studies suggest that the synthesis of bioactive compounds is strongly influenced by irradiance level. To investigate whether the antiproliferative activity of Udotea flabellum extracts is modified after cultivation, this green alga was cultured under four photon flux densities (PFD) for 30 days. After 10, 20, and 30 days, algae were extracted with dichloromethane: methanol and screened for antiproliferative activity against four human cancer cell lines (laryngeal—Hep-2, cervix—HeLa, cervix squamous— SiHa and nasopharynx—KB) by SRB assay. Lipid and phenol content were evaluated by standardized methods on algae organic extracts. After 10 days of cultivation, organic U. flabellum extracts showed a significant increase in antiproliferative activity on Hela and SiHa cells when compared to noncultured algae extracts. Extracts obtained after 10 and 20 days of culture were active on KB and Hep-2 cells. Total phenol and polyunsaturated fatty acid content in organic extracts changed with cultivation time but not by irradiance treatment. Extracts from U. flabellum obtained after 10 and 20 days of culture have been selected for fractionation and isolation of active compounds. 1. Introduction Natural products and related drugs are used to treat 87% of all categorized human diseases including bacterial infection, cancer, and immunological disorders [1]. Approximately 25% of prescribed drugs in the world originate from plants [2] and over 3000 species of plants have been reported to have anticancer properties [3]. Recent trends in drug research on natural sources suggest that algae are a promising source of novel biochemical active substances [4]. To survive in a competitive environment, marine algae have developed defense strategies that result in a significant level of structural chemical diversity that is derived from different metabolic pathways [5]. The effect of culture conditions on the production or activity of active metabolites in algae has scarcely been studied and consequently remains poorly understood. In other alga models, such as the cyanophyte Scytonema, increasing irradiance gradually increased antibi- otic production [6]. Similarly, Spyridia filamentosa, a red alga cultured at different light irradiances, had contrasting antibi- otic activities that were strongly influenced by irradiance level [7]. Most recently, extracts obtained from Penicillus dumetosus cultured at different light irradiances displayed varying antiproliferative activity against diverse cancer cell lines [8]. The feasibility of algal cultivation can help to induce adaptations that can be measured through metabolite synthesis or biological activity. Fully controlled greenhouse- based cultivation systems have been developed for high- quality year-round vegetable production for the botanical drug market [9]. Therefore, a better understanding of the potential manipulation of algal culture conditions to modify metabolite synthesis and activity is required. Tropical green algae in the order Bryopsidales, including those of the genera Avranvillaea, Caulerpa, Halimeda, Peni- cillus, and Udotea, are noted for the production of sesqui and diterpenoids, compounds that have also shown antifungal and antiproliferative activity [5, 10]. Recent studies have shown that both aqueous and organic extracts of Udotea flabellum exhibit in vitro antiprotozoal [11, 12] as well as cytotoxic and antiproliferative activities on cancer cell lines [13]. In some cases, the antiproliferative activity of marine algae extracts has been positively correlated with