Trace heavy metals, such as arsenic, cadmium, lead, chromium, nickel, and mercury, are important environmental pollutants, particularly in areas with high anthropogenic pressure. In addition to these metals, copper, manganese, iron, and zinc are also important trace micronutrients. The presence of trace heavy metals in the atmosphere, soil, and water can cause serious problems to all organisms, and the ubiquitous bioavailability of these heavy metal can result in bioaccumulation in the food chain which especially can be highly dangerous to human health. This study reviews the heavy metal contamination in several areas of Pakistan over the past few years, particularly to assess the heavy metal contamination in water (ground water, surface water, and waste water), soil, sediments, particulate matter, and vegetables. The listed contaminations affect the drinking water quality, ecological environment, and food chain. Moreover, the toxicity induced by contaminated water, soil, and vegetables poses serious threat to human health.

Starting from ibuprofen, a non-steroidal anti-inflammatory drug, N,N’-disubstituted thiourea derivatives were synthesized by refluxing the acid chloride of ibuprofen with potassium thiocyanate followed by substituted anilines to get N-2-(4-(2-methylpropyl)phenyl)propionoyl-N’-(2’-bromophenyl) thiourea (1), N-2- (4-(2-methylpropyl)phenyl)propionoyl-N’-(2’-chlorophenyl) thiourea (2) and N-2-(4-(2-methylpropyl)phenyl)propionoyl-N’-(3’,4’-dichlorophenyl) thiourea (3). Metal complexes (4-15) of (1-3) were synthesized by refluxing it with one equivalence salts of Co (ΙΙ), Ni(II), Pb(II) and Cu(I). Structures of all the synthesized thiourea ligands and their metal complexes were determined by FTIR and ¹HNMR spectroscopy. Shift in stretching frequency in FTIR and resonance frequency in ¹HNMR spectroscopic data suggested that the ligands and metal are coordinated to afford respective metal complexes M[L]_n. The synthesized compounds were tested against urease enzyme and the results were compared with standard thiourea, as positive control. Most of the investigated compounds showed potential inhibitory activity against Jack bean urease. Compound 5 was found to be the most potent urease inhibitor with IC₅₀ of 14.6 μΜ, whereas compounds 8, 11 and 12 possessed potent urease inhibition. The tested compounds can be taken as lead molecules for gastrointestinal ulcer therapy.

Ru^II(cym)Cl (cym = η⁶-p-cymene) complexes of pyridinecarbothioamides have shown potential for development as orally active anticancer metallodrugs, underlined by their high selectivity towards plectin as the molecular target. In order to investigate the impact of the metal center on the anticancer activity and their physicochemical properties, the Os(cym), Rh- and Ir(Cp*) (Cp* = pentamethylcyclopentadienyl) analogues of the most promising and orally active compound plecstatin 2 were prepared and characterized by spectroscopic techniques and X-ray diffraction analysis. Dissolution in aqueous medium results in quick ligand exchange reactions; however, over time no further changes in the ¹H NMR spectra were observed. The Rh- and Ir(Cp*) complexes were investigated for their reactions with amino acids, and while they reacted with Cys, no reaction with His was observed. Studies on the in vitro anticancer activity identified the Ru derivatives as the most potent, independent of their halido leaving group, while the Rh derivative was more active than the Ir analogue. This demonstrates that the metal center has a significant impact on the anticancer activity of the compound class.