Structural with different biological activity

Lin L, Lee KH. Structure-activity relationships of curcumin and its analogs with different biological activities. In Studies in Natural Products Chemistry, Volume 33. Ur-Rahman A, ed. Elsevier, New York, pp. 785-812. 

Figure 9.5 Structural analogs with different biological activity.

The antagonism of diclofop-methyl(DM) by 2,4-D is reciprocaf and has been demonstrated in coleoptiles or whole plants of wild oat as well as in corn and soybean tissue culture. DM and 2,4-D are structural analogues with different biological activities. DM is phytotoxic to grasses but inactive against broadleaf weeds, whereas the activity of 2,4-D is just the opposite. While the effects of DM on wild oat are much reduced by... 

Since the value of H depends on the choice of , modifications of this procedure have been proposed (Fernandez Piema and Massart 2000). Another modification of the Hopkins statistic—published in the chemometrics literature—concern the distributions of the values of the used variables (Hodes 1992 Jurs and Lawson 1991 Lawson and Jurs 1990). The Hopkins statistic has been suggested for an evaluation of variable selection methods with the aim to find a variable set (for instance, molecular descriptors) that gives distinct clustering of the objects (for instance, chemical structures)—hoping that the clusters reflect, for instance, different biological activities (Lawson and Jurs 1990). 

Natural compounds offer a vast array of chemical structural diversity associated with evolved biological activities attacking many different molecular... 

Kosan Biosciences was formed almost 6 years ago, founded on an interest in polyketides, microbial metabolite-based drugs. Polyketides have many diverse chemical structures including erythromycin, which will be mentioned again later. These chemicals include fused-ring aromatic compounds, compounds decorated with sugars, and compounds with large stretches of double bonds. Each of these compounds has different biological activities and utilities, but they are all made in nature by very similar biochemistry. 

The retrospective analysis of the chemical structures of the various drags used in medicine led medicinal chemists to identify some molecular motifs that are associated with high biological activity more frequently than other structures. Such molecular motifs were called privileged structures by Evans et al. [2], to represent substructures that confer activity to two or more different receptors. The implication was that the privileged structure provides the scaffold and that the substitutions on it provide the specificity for a particular receptor. Two monographs deal with the privileged structure concept [3, 4]. 

The cathodic process (reduction) has been studied in different experimental conditions being the potential of the one-electron reaction correlated with other structural parameters, i.e., with the reduced-product lowest vacant orbital energy [86], with the substituent Hammett a parameter [87], or with the biological activity (see below). Table 4 shows reduction potentials for some QDO and PDO derivatives in different experimental conditions [88,89]. 

Because of their large amount of chemically different functionalization, trans-CHD are promising precursors especially for the synthesis of, e.g., carbasugars and their analogs with potential biological activity. The simple, but highly functionalized structure of trans-CHD also has a high potential for diversity-oriented syntheses that could lead to a vast variety of different structures in short chemical reaction sequences. 

The two diuretic hormones with unambiguous biological activity are both strongly homologous to known peptide hormone families represented in vertebrates, fish, and birds, yet they are of different peptide families. Members of both peptide families have antidiuretic effects in mammals The complexity of diuresis in insects suggests that a diversity of structures remain to be discovered. 

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