Dendrimers as activity enhancers in plant chemotherapy

Dendrimers are macromolecules recently developed for medical application, able to enhancing activity of small chemicals. In fact, one of main limits of chemicals used in cancer or antiviral therapy relies in low efficacy of receptor/ligand binding, and an useful tool could be building high molecular weight clusters, characterized by functional chemicals linked to an inert scaffold. These dendrimeric structures show branches that are able to bind many receptor sites, increasing binding stability and local concentration. This feature could be useful for antiviral therapy in plant, considering few chemicals available, especially in cases of limited efficacy against plant viruses. Among available scaffolds usable as core of dendrimer, polyamidoamine (PAMAM) are simple to use, versatile and biologically compatible, and a protocol for binding 2 or 4 molecules of mycophenolic acid (MPA) was developed. That chemical eradicate Cucumber mosaic virus (CMV), but limited antiviral effects are showed against other woody plant viruses. Thus, MPA efficacy could be theoretically increased or extended as MPA-dendrimers. A preliminary study of these novel drugs in in vitro experimental system (Nicotiana tabacum L. cv. Xanthi / CMV) was performed, with the aim to investigate drugs toxicity, optimal dosage and potential antiviral efficacy. Results considering toxicity until 0.30 mM application are encouraging, and these novel drugs seem to be strongly effective against virus replication, suggesting this approach as potentially useful for enhancing antiviral chemicals.