Cationic carbosilane dendrimers of generations 1-3 have been synthesized employing thiol-ene click chemistry. The obtained dendrimers present three different types of ammonium functions, two of them with the charge at the surface, -NH 3 + and -NMe 3 + , and other with the charge internalized by the presence of ethylalcohol moieties, -[NMe 2 (CH 2 CH 2 OH)] + . The influence of -NMe 3 + and -[NMe 2 (CH 2 CH 2 OH)] + in dendrimer structure have been studied by molecular dynamics. The antibacterial properties of these families of dendrimers have been evaluated against Gram-positive (Staphylococcus aureus CECT 240) and Gramnegative (Escherichia coli CECT 515) bacterial strains, and the results have been compared with those obtained for related cationic carbosilane dendrimers functionalized by hydrosilylation reactions. These data show the relevance of the sulfur atom versus the silicon atom close to the dendrimer surface and the outer charge versus the inner charge.Finally, the stability of the most active first generation dendrimers vs. pH and temperature has also been studied.

A new family of amine- and ammonium-terminated carbosilane dendrimers of the type Gn-[Si(CH2)3N(Et)CH2CH2NMe2]x and Gn-{[Si(CH2)(3)N+R(Et)CH2CH2N+RMe2]x(X-)y} (where n = 1, 2 and 3; R = H, X = Cl; R = Me, X = I) respectively has been synthesized by hydrosilylation of N,N-dimethyl-N'-allyl-N'-ethyl-ethylenediamine, [(CH2=CH-CH2)(Et)N(CH2)2NMe2] with the corresponding hydride-terminated dendrimers and subsequent quaternization with HCl or MeI. Quaternized dendrimers are soluble and stable in water or other protic solvents for long time periods. The antibacterial properties of the quaternary ammonium functionalized dendrimers have been evaluated showing that they act as potent biocides in which the multivalency along with the biopermeability of the carbosilane dendritic skeleton play an important role in the antibactericidal activity of these compounds.

A new family of amine- and ammonium-terminated hyperbranched polycarbosilanes (PCS) and dendrimers has been synthesized. The functionalization of a polycarbosilane matrix was carried out with peripheral allyl groups by two strategies in the case of PCS: 1) hydrosilylation of allyl amines with PCS containing terminal Si-H bonds, or 2) hydrosilylation of PCS-allyl with an aminosilane. Dendrimers with terminal amine groups were synthesized by hydrosilylation of allydimethylamine. Quaternized systems with MeI are soluble and stable in water or other protic solvent. The antibacterial properties of the ammonium-terminated hyperbranched polycarbosilanes and dendrimers have been evaluated showing that they act as potent biocides against Gram-positive and Gram-negative bacterial strains.

The bactericidal activity of a library of cationic dendritic systems depends on the hydrophilic/hydrophobic structural balance, being the presence of a sulfur atom proximal to the peripheral ammonium functions of relevance.

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Strategies to synthesize a cationic carbosilane dendron containing the antibiotic penicillin V potassium salt (PenVK) at the focal point are discussed. The preparation of such a compound requires the use of systems with no donor atoms such as N or S in their framework, because their presence favours the rupture of the penicillin β-lactam ring. The antibacterial activity of the new dendron containing ammonium groups, at the periphery, and the PenV moiety, at the focal point, against gram-positive Staphylococcus aureus strains was evaluated. These results were compared with those obtained for free PenVK, a related cationic dendron without a penicillin moiety at the focal point, and also compared with an equimolar mixture of this last dendron with free PenV. The data obtained indicate that, on one hand, the conjugation or interaction of PenV with cationic dendrons reduces its activity in comparison with free PenVK. On the other hand, the penicillin dendron is able to release the antibiotic in the presence of esterease, due to the breaking of the ester bond in this derivative.

Abstract. Natural substances such as elicitors of plant defense response, has become a promising option for effective management of plant diseases and are a prerequisite for sustainable and ecological agriculture. Recognition of diverse elicitors, effectors and modulators by specific and nonspecific plant receptors activates signalling cascades eventually leading to gene expression and defense responses. Elicited plants or "primed plants" display either faster, stronger, or both activation of the various cellular defense responses that are induced following attack by either pathogens or insects or in response to abiotic stress.The aim of this work has been to develop new elicitor compounds from natural vegetal substrates, and predict its effectiveness in the field by using robust molecular techniques and appropriate biomarkers of plant defense. Thus, Fragaria x ananassa Duch. cv. Chandler cell suspension cultures, and real-time, quantitative PCR analysis (RTqPCR) were utilized to test the elicitor capability of new natural elicitors. This experimental approach was applied to analyze the pattern of gene expression of specific strawberry genes already known to be good markers of SA-and JA-dependent signalling pathways, which were used as defense induced biomarkers in plants. In addition, determination of total phenols and antioxidant activity, and HPLC-DAD-MS analysis of polyphenolic compounds was performed in these cell suspension samples. Susceptibility to C. acutatum of strawberry plants treated with the new elicitor was performed in greenhouse under controlled conditions.In collaboration with AGROMETODOS, S.A., we have produced new natural compounds that can act as elicitors. We have compared the elicitor activity of a new compound (EH) with the commercial product BROTOMAX ® . The new product EH and BROTOMAX ® activate plant defense related genes in cell suspension cultures. Also, both products induce polyphenol production in this assay. The new product EH and BROTOMAX ® increased the strawberry (Fragaria x ananassa Duch. cv. Camarosa) and olive (Olea europaea L. cv. Picual) resistance against Colletotrichum acutatum and Fusicladium oleaginum plant infections, respectively.We can conclude that new natural bioelicitors can be produced by low-cost procedures based on fermentation of natural substrates derived from plants. The use of suitable, sensitive, appropriate and robust molecular biomarkers also provide an excellent molecular tool to predict the effectiveness in the field of natural compounds with potential eliciting ability, which may be conveniently exploited as ecological bioinducers of plant defense response in strawberry and in many other important crops.