The preparation of cocrystals from active pharmaceutical ingredients (APIs) and biologically relevant coformers offers the opportunity of obtaining compounds with more desirable physicochemical and biological properties. This work focuses on theophylline–­trimesic acid, caffeine–­isophthalic acid, and caffeine–­trimesic acid cocrystals. All the cocrystals were produced via slow evaporation and were characterized using Fourier transform infrared, differential scanning calorimetry, thermogravimetric analysis, and single-crystal X-ray diffraction. Structural characterization revealed that interactions such as CO···H, N···H···O, π–π, and C–H···π between the APIs and coformers significantly contribute to crystal packing. Density functional theory studies further revealed the electronic properties of cocrystals, as well as the functional groups that enhance their solubility. Drug activity through the weak groove-binding mode was realized through docking studies of the cocrystals with the DNA structure (Protein Data Bank identifier 1ZEW). Similarly, major interactions, including hydrogen bonding and π-π bonding, were observed between cocrystals and 4HL2, a New Delhi metallo-β-lactamase-1 produced by resistant clinical strains of K. pneumoniae. Biological studies revealed cocrystals with antimicrobial properties, particularly against clinically relevant gram-negative bacterial pathogens (Acinetobacter baumannii, Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa). So, these compounds represent a novel promising group of anti-infective agents.

Mixed-ligand Cu(ii) complexes of the type [Cu(doxycycline)(L)(H2O)2](NO3)2, where doxycycline = [4-(dimethylamino)-3,5,10,12,12a-pentahydroxy-6-methyl-1,11-dioxo-1,4,4a,5,5a,6,11,12a-octahydrotetracene-2-carboxamide] and L = 2,2'-bipyridine (bpy, 1), 1,10-phenanthroline (phen, 2), dipyrido[3,2-d:2',3'-f]quinoxaline (dpq, 3) and dipyrido[3,2-a:2',3'-c]phenazine (dppz, 4) have been synthesised and characterised by structural, analytical, and spectral methods. The single-crystal X-ray structures of 1 and 2 exhibited two different geometries, distorted square-pyramidal and octahedral respectively as well as different coordination modes of doxycycline. Complexes 2-4 exhibit prominent plasmid DNA cleavage at significantly low concentrations probably by an oxidative mechanism. Matrix Metalloproteinase (MMP-2) inhibition studies revealed that all complexes inhibit MMP-2 similar to doxycycline which is a well-known MMP inhibitor with 3 being the most potent. IC50 values of doxycycline and 1-4 against MCF-7 (human breast cancer) and HeLa cell lines were almost equal in which 3 showed the highest efficiency (IC50 = 0.46 ± 0.05 μM), being consistent with its increased MMP inhibition potency. The antimalarial activities of these complexes against the chloroquine-sensitive Plasmodium falciparum NF54 and chloroquine-resistant Plasmodium falciparum Dd2 strains reveal that complex 3 exhibited a higher activity than artesunate drug against the chloroquine-resistant Dd2 strain.

Silver nanoparticles (AgNPs) were synthesized using Azadirachta indica and Vernonia amygdalina leaves extracts. Current nanotechnology research uses a lot of chemicals which are quite often toxic and flammable. In this research article, a simple and eco-friendly synthetic method for silver nanoparticles preparation was reported using the leaves extracts of Azadirachta indica (commonly called neem) and Vernonia amygdalina (commonly called bitter leaf) as reducing agents. The synthesis of AgNPs was monitored and confirmed with the use of UV-Visible spectrophotometer, Fourier Transform Infrared (FTIR) spectroscopy and Powder X-ray Diffraction (PXRD). The reduction process of Ag + to Ag 0 was observed by the change of color from yellow to brown for both leaves. The UV-Vis Spectra of AgNPs in aqueous solution showed absorbance peaks around 455 nm for Azadirachta indica and 460 nm for Vernonia amygdalina due to silver surface plasmon resonance. Crystallinity of the AgNPs was confirmed with PXRD. In addition, FTIR spectra showed that the AgNPs were capped with phytochemicals from the leaves extracts.

No abstract