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After cellulose, lignin is the most abundant plant-derived polymer in nature. It provides mechanical support to plants, but it has also a defense role against pests and diseases, thanks to antioxidant, bactericidal, and antifungal properties, deriving from its polyphenolic nature. Huge quantities of technical lignins are obtained during several industrial processes and they actually represent a waste of paper pulp and bioethanol industry. Although in the last decades many efforts have been directed to obtain lignin valorization in several fields and for diverse applications, this biobased polymer is still largely underutilized. In particular, very little is known about the possibility to exploit its antioxidant, antifungal, and antibacterial properties in the agronomical field. On the other hand, pest control is often achieved by using copper-based pesticides, but environmental and health issues urge for novel solutions implying reduced copper content. We here describe novel hybrid organic-inorganic materials obtained by combining copper(II) salts with two types of technical lignins. Cu-containing materials (lignin@Cu) have been characterized by different techniques, including X-ray powder diffraction and transmission electron spectroscopy analyses, revealing nanocrystals of brochantite (Cu4SO4(OH)(6)) grown in the lignin matrix. Lignin@Cu was tested for its antifungal and antibacterial profile against a vast panel of pathogens of agronomical interest. Furthermore, preliminary tests on crops in a greenhouse were performed: lignin@Cu had better performances than a commercial pesticide based on copper(II) hydroxide on tomato plants against Rhizoctonia solani, indicating a great potential of these materials as plant protection products.

Tri-3,4-dimethoxycinnamoyl-1,5-γ-quinide was synthesized and fully characterized by a direct synthesis from quinic acid and a large excess of 3,4-dimethoxycinnamoyl chloride. Mono- and di-3,4-dimethoxycinnamoyl-1,5-γ-quinides were also obtained from the direct coupling of 1,5-γ-quinide and 3,4-dimethoxycinnamoyl chloride in different molar ratios. Moreover, a hypothetical mechanism of the direct lactonization is proposed.

Chlorogenic acids are secondary metabolites in diverse plants. Some chlorogenic acids extracted from traditional medicinal plants are known for their healing properties, e.g., against viral infections. Also, green coffee beans are a rich source of chlorogenic acids, with 5-O-caffeoylquinic acid being the most abundant chlorogenic acid in coffee. We previously reported the synthesis of the regioisomers of lactones, bearing different substituents on the quinidic core. Here, 3,4-O-dicaffeoyl-1,5-γ-quinide and three dimethoxycinnamoyl-γ-quinides were investigated for in vitro antiviral activities against a panel of 14 human viruses. Whereas the dimethoxycinnamoyl-γ-quinides did not show any antiviral potency in cytopathogenic effect reduction assays, 3,4-O-dicaffeoyl-1,5-γ-quinide exerted mild antiviral activity against herpes simplex viruses, adenovirus, and influenza virus. Interestingly, when the compounds were evaluated against respiratory syncytial virus, a potent antiviral effect of 3,4-O-dicaffeoyl-1,5-γ-quinide was observed against both subtypes of respiratory syncytial virus, with EC50 values in the submicromolar range. Time-of-addition experiments revealed that this compound acts on an intracellular post-entry replication step. Our data show that 3,4-O-dicaffeoyl-1,5-γ-quinide is a relevant candidate for lead optimization and further mechanistic studies, and warrants clinical development as a potential anti-respiratory syncytial virus drug.

Chlorogenic acids and their derivatives are abundant in coffee and their composition changes between coffee species. Human serum albumin (HSA) interacts with this family of compounds with high affinity. We have studied by fluorescence spectroscopy the specific binding of HSA with eight compounds that belong to the coffee polyphenols family, four acids (caffeic acid, ferulic acid, 5-O-caffeoyl quinic acid, and 3,4-dimethoxycinnamic acid) and four lactones (3,4-O-dicaffeoyl-1,5-c-quinide, 3-O-[3,4- (dimethoxy)cinnamoyl]-1,5-c-quinide, 3,4-O-bis[3,4-(dimethoxy)cinnamoyl]-1,5-c-quinide, and 1,3, 4-O-tris[3,4-(dimethoxy)cinnamoyl]-1,5-c-quinide), finding dissociation constants of the albumin–chlorogenic acids and albumin–quinides complexes in the micromolar range, between 2 and 30 lM. Such values are comparable with those of the most powerful binders of albumin, and more favourable than the values obtained for the majority of drugs. Interestingly in the case of 3,4-O-dicaffeoyl-1,5-c-quinide, we have observed the entrance of two ligand molecules in the same binding site, leading up to a first dissociation constant even in the hundred nanomolar range, which is to our knowledge the highest affinity ever observed for HSA and its ligands. The displacement of warfarin, a reference drug binding to HSA, by the quinide has also been demonstrated.

HIV-1 integrase (IN) has been validated as an attractive target for the treatment of HIV/AIDS. Several studies have confirmed that the metal binding function is a crucial feature in many of the reported IN inhibitors. To provide new insights on the metal chelating mechanism of IN inhibitors, we prepared a series of metal complexes of two ligands (HL1 and HL2), designed as representative models of the clinically used compounds raltegravir and elvitegravir. Potentiometric measurements were conducted for HL2 in the presence of Mg(II), Mn(II), Co(II), and Zn(II) in order to delineate a metal speciation model. We also determined the X-ray structures of both of the ligands and of three representative metal complexes. Our results support the hypothesis that several selective strand transfer inhibitors preferentially chelate one cation in solution and that the metal complexes can interact with the active site of the enzyme.