In addition, the Pirouette program was used to perform the Principal Component Analysis (PCA) and Hierarchical Clustering Analysis (HCA). RG7420 The chemometric

methods are particularly appropriate to provide insight into the Structure–Activity Relationships (SAR) when one is dealing with systems depending on many variables (Beebe and Pell, 1988). (PCA) and (HCA) are statistical methods used in the recognition of standards in multivaried studies (Da Silva et al., 2004, Weber et al., 2005 and Calgarotto et al., 2007). The properties calculated by DFT were auto-scaled using the Fisher weight (Costa and Takahata, 2003). The differences in the calculated properties are able to better discriminate the relationship between the structures of the sesquiterpene lactone derivative compounds and their biological activities. Results are presented

as the mean values ± S.D., obtained from the indicated number of tested animals. The statistical significance of differences between groups was evaluated using Student’s unpaired t-test. A P-value < 0.05 was considered to indicate significance. Myonecrosis, muscle tissue damage, is a common consequence of envenoming by snakes of the Bothrops genus and selleck chemicals this effect is, partially, caused by PLA2 (Gutiérrez, 2002 and Soares et al., 2004). Compounds Lac01 and Lac02 reduced myotoxicity by approximately 70%, when compared to the PLA2 control assay (Fig. 2). Compounds Lac03 and Lac04 reduced the myotoxic activity by approximately 56%, while compounds Lac05–Lac08 did not demonstrate any activity against myotoxic effects. Edema-inducing activity is a pharmacological activity that depends upon the combined action

of various toxins, including PLA2 (Soares and Giglio, 2003 and Soares et al., 2004). Fig. 3 shows that, after a 2 h period, Lac01–Lac04 reduces the levels of edema-inducing activity of PLA2 to 40–50%, Dichloromethane dehalogenase when compared to the PLA2 control experiment. In this same period, the compounds Lac05–Lac08 reduced edema levels to only 90%. The action of PLA2 from B. jararacussu on the micellar substrate, HPGP, reflects the classical behavior of a Michaelian enzyme, not only in the presence of small concentrations of the lactone compounds (1–4 μM), but also in their absence (graphics not show) ( Souza et al., 2008 and Da Silva et al., 2008a). The kinetic parameters obtained in this study are shown in Table 1 and Fig. 4. Fig. 4 demonstrates that, in all the tests, the maximum velocity of the enzyme (Vmax) varied in function of the presence of growing concentrations of inhibitor compounds. Lac01 and Lac02 were the more efficient inhibitors and reduce the enzymatic activity around 80–90% ( Fig. 4A).