Soils contaminated with low levels of heavy metals and other trace elements are now frequently used for vegetable growing. In this situation, heavy metals and trace elements from these polluted soils may accumulate in the agricultural plants being grown in them and thereby enter the human food chain. The objectives of this study are to elucidate the effects of growth conditions, manipulated by ...

and comprises six species. One of these is Amberboa ramosa JAFRI, which is an annual herbaceous plant found in India and Pakistan. The plant has tonic, aperient, febrifuge, deobstruent, cytotoxic, and antibacterial activities. Previously triterpenoids, flavanoids, steroids, and steroidal glycosides have been reported from this species. Here we report the isolation and structure elucidation of l...

Olive-mill wastewater (OMW), an effluent of olive oil extraction process, is annually produced in huge amounts in olive growing areas. An interesting option for its disposal is the spreading on agricultural land, provided that phytotoxic effects are neutralized. The objective of the present investigation was to evaluate the potential of an enzyme-based treatment in removing OMW phytotoxicity. T...

This paper describes the preparation of a biomimetic Langmuir-Blodgett film of tyrosinase incorporated in a lipidic layer and the use of lutetium bisphthalocyanine as an electron mediator for the voltammetric detection of phenol derivatives, which include one monophenol (vanillic acid), two diphenols (catechol and caffeic acid) and two triphenols (gallic acid and pyrogallol). The first redox pr...

Tyrosinases, bifunctional metalloenzymes, catalyze the oxidation of monophenols and o-diphenols to o-quinones, the precursor compounds of the brown-coloured pigment melanin. In eukaryotic organisms, tyrosinases are expressed as latent zymogens that have to be proteolytically cleaved in order to form highly active enzymes. This activation mechanism, known as the tyrosinase maturation process, ha...

The inhibition of the type-3 copper enzyme tyrosinase by halide ions was studied by kinetic and paramagnetic (1)H NMR methods. All halides are inhibitors in the conversion of l-3,4-dihydroxyphenylalanine (l-DOPA) with apparent inhibition constants that follow the order I(-) < F(-) << Cl(-) < Br(-) at pH 6.80. The results show that the inhibition arises from the interaction of halide with both t...

In fruits and vegetables, browning occurs due to the oxidation of polyphenols. Oxidative browning is catalysed by polyphenol oxidase (PPO; monophenol, dihydroxyphenyl alanine:oxygen oxidoreductase; EC.1.14.18.1). When fresh products are damaged oxidative browning occurs, and this is an economic problem for producers and consumers. Polyphenoloxidase, which is a copper-containing enzyme, catalyse...

The dinuclear copper enzyme tyrosinase (Ty) from genetically engineered Streptomyces antibioticus has been investigated in its paramagnetic half-met form [Cu(I)-Cu(II)]. The cw EPR, pulsed EPR, and hyperfine sublevel correlation spectroscopy (HYSCORE) experiments on the half-met-Ty and on its complexes with three different types of competitive inhibitor are reported. The first type includes p-n...

Soaps have been extensively used, often with added alkali, to emulsify or make soluble phenolic compounds of limited solubility (Klarmann, Shternov and Von Wowern, 1929; McCulloch, 1936). There is, however, a good deal of controversial information in the literature dealing with the effect of soaps on the germicidal action of phenolic compounds. Frobisher (1927) reported that small amounts of so...

Laccases are blue multicopper oxidases, which catalyze the monoelectronic oxidation of a broad spectrum of substrates, for example, ortho- and para-diphenols, polyphenols, aminophenols, and aromatic or aliphatic amines, coupled with a full, four-electron reduction of O2 to H2O. Hence, they are capable of degrading lignin and are present abundantly in many white-rot fungi. Laccases decolorize an...