D296 Nucleic Acids Research, 2009, Vol. 37, Database issue from Scorpiones or DNA and protein sequence analysis. Admittedly, these databases are restrictively applicable for complete consideration of the structural and chemical properties of toxic compounds, within science and industry. To solve this problem, we established the database SuperToxic, which provides a comprehensive collection of toxins from diﬀerent sources (animals, plants, syn- thetic, etc.), combined with chemical features, as well as information about commercial availability. This dataset enables a detailed investigation of the correlations between chemical, functional and structural properties of toxins. Furthermore, these data can be used to evaluate the risk of use for compounds within medicine or industry, and give valuable insight into the mechanisms of toxicity. While certain toxins aﬀect many types of cell lines, some toxic compounds only interfere with deﬁned cell types leading to a speciﬁc toxicity. Cytostatic drugs, which are often used in chemotherapy, aﬀect the cell cycle or the DNA replication mechanisms (6) and are therefore toxic to all living cells, although tumorigenic cells are more inﬂuenced due to their high rate of cell proliferation. In contrast, omeprazole, a drug for the treatment of gastric or duodenal ulcer, only aﬀects cells in the stomach, as it needs an acidic environment to become active (7). Since it is of great interest to ﬁgure out, whether a compound interacts speciﬁcally with particular cells, SuperToxic is a distinguished tool for the search of such information. Additionally, the toxicity of an unknown substance can be estimated by comparison with structurally similar compounds with known toxicity. Another application of this database is the estimation of health hazards for a variety of chemicals, especially with respect to the new European chemical management system REACH (regis- tration, evaluation, authorization of chemicals) (8), a reg- ulation for the registration, evaluation and conﬁnement of chemicals. This regulation is necessary, as in many chemical production processes, for example, fabrication of colors, varnishes or leather, the usage of toxic com- pounds is almost inevitable. Therefore, it is essential to assess potential hazardous eﬀects, to safeguard such sub- stances during transportation, usage and storage. The vast usage of chemicals and new chemical registration pro- grams, like REACH, demands alternatives to experimen- tal validation. All producers or importers, who introduce more than one ton per annum of a substance to the European Union, must evaluate the chemical regarding its toxicity, according to REACH. In order to reduce cost-intensive animal testing of toxic compounds, the pro- motion of data exchange (9–11) and predictive toxi- cology gains importance and acceptance (12). There are several theoretical approaches, besides QSAR (quantita- tive structure–activity relationship) (13), which describe the relationship between toxicity and physicochemical properties of compounds. For such predictions, high qual- ity, comprehensive and well-structured databases are essential. The toxicity values and chemical information given by SuperToxic provide such basis for hazard assessment. THE DATABASE SuperToxic comprises data from publicly available databases and scientiﬁc literature, assembling a vast amount of toxic compounds. Currently, there are about 60 000 structures with corresponding properties stored in the database. Additionally, properties like the number of hydrogen bond (H-bond) donors and acceptors, mole- cular weight or the octanol–water partition coeﬃcient logP, which allow the evaluation of the Lipinski’s Rule of Five (14), can be found within the database. The web interface (available at http://bioinformatics.charite. de/supertoxic) provides diﬀerent options to access the data: Within the ‘Toxin Search’ option (Figure 1, I-A), it is possible to perform a distinct search, given the name of the compound, the Chemical Abstracts Services Registry Number (CASRN) or NSC number, an iden- tiﬁer of the National Cancer Institute database. A search for a certain pathway lists all compounds asso- ciated with this pathway. The ‘Structure Search’ option (Figure 1, I-B) allows a structure upload via InChI (IUPAC International Chemical Identiﬁer), SMILES (Simpliﬁed Molecular Input Line Entry System) or MOL ﬁle. Additionally, the structure can be drawn, using a built-in molecule editor. The provided structure can either be used as input for a similarity screening or a substructure search. Another way to search the database is imple- mented in the ‘Property Search’ (Figure 1, I-C). Here, the deﬁnition of value ranges for certain attributes (e.g. the molecular weight, the logP, the number of rings, H-bond donors or acceptors) pro- vides a list of all database entries fulﬁlling the conditions. To browse the whole database, the user can choose an alphabetic character or numbers, to display all data- base entries starting with the selection. Alternatively, all CASRN or NSC numbers, which are available in the database, can be listed. To demonstrate the functionality of the database, the toxicity and the chemical characterization of a new potential drug candidate (Hit1) is exemplarily evaluated: the structure can either be uploaded as MOL ﬁle or be drawn, using the molecule editor. The similarity search results in a list of matches to the query compound ordered by similarity (Figure 1 II, column 1–6). The following information are given: links to resources, external to SuperToxic: order information for more than 60 diﬀerent sup- pliers (Figure 1, II-C) pathway information (Figure 1, II-D) ligand information target information synonyms including CASRN and NSC number the empirical formula