PubMed Health⌕ Search
Home/Archive/PubMed

PubMed · 11280050

Chemo-defence system.

A Rico
View original source ↗Export metadata ↓

Abstract

By analogy with the immune defence system, the existence is suggested of a chemo-defence system protecting living organisms against toxic substances, whether natural or man-made, that are present in the environment. This paper deals first with the various facets of such a system: mechanisms involving, among others, lipophilic compounds, hydrophilic compounds, oxidants, acidosis, genotoxics and metals; second, with the biological characteristics of the system and a comparison with the immune defence system: partial immaturity of the young, inducibility, non-specificity and specificity, and saturability; we will show that the two systems share many common features; third, with the evolution of the system, which demonstrates that the system is very old and suggesting that it came into existence before the immune defence system; and fourth, with some of its consequences: estimation of the 'toxic effects' of low doses, hormesis, impact of a vegetable diet on health. Finally, it could be emphasised that life is well protected against chemicals by its chemo-defence system, which appeared very early with the first living organisms on the earth.

Explore related subjects

BiotransformationCarcinogensDietEnvironmental PollutantsHumansImmunityImmunity, InnatePoisonsJournal ArticleReview

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

A Rico. 2001. Chemo-defence system.. https://doi.org/10.1016/s0764-4469(00)01281-6

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2026

Divergent PXR function in seals: Endocrine adaptation or functional loss?

Seals accumulate xenobiotics through dietary biomagnification and exposure to polluted marine environments, with contaminants concentrating in their blubber. Biotransformation mitigates xenobiotic toxicity by converting lipophilic compounds into excretable hydrophilic metabolites, a process coordinated by nuclear receptors including the Pregnane X Receptor (PXR), whose plastic ligand-binding domain enables broad xenobiotic sensing. By examining PXR in pinnipeds, we investigated the evolutionary conservation and functional characterization of PXR using genomic sequence analysis, protein structural prediction, and transactivation assays, revealing broadly conserved structural features alongside species-specific functional divergence in receptor responsiveness to environmental stressors. Specifically, the obtained results highlight divergent gene and functional landscapes with ORF-disrupting mutations identified in Monachus monachus and Neomonachus schauinslandi that abolish receptor activation toward known PXR ligands. In contrast, Leptonychotes weddelli retained an intact PXR ORF but showed reduced receptor activity, revealing functional divergence in PXR among pinnipeds.

Biotransformation↗
PubMed2003

High-performance liquid chromatography-mass spectrometry analysis of diltiazem and 11 of its phase I metabolites in human plasma.

The aim of the present work was to develop a high-performance liquid chromatography-mass spectrometry method for analysis of diltiazem (DTZ) and metabolites in human plasma after single dose administration (120 mg). Human plasma samples (1 ml) were cleaned up by a solid phase extraction procedure (C18 cartridges) using codeine as an internal standard. Reconstituted extracts were separated on a reversed-phase C8 column with a linear gradient mobile phase system. The run time per sample analysis was 11 min. Detection was performed using selected ion monitoring following atmospheric pressure chemical ionization. The lower limit of quantification was estimated to be 1 microg/l (in spiked plasma) for all available reference compounds (i.e. DTZ and five metabolites). Validation of the method showed good linearity, precision and accuracy for quantification of these six reference compounds. In addition, tandem MS analyses of human plasma sampled from healthy individuals after peroral intake of 120 mg DTZ revealed that the method enabled detection of six additional metabolites for which reference compounds were not available.

Biotransformation↗
PubMed2003

Microbial deracemization of alpha-substituted carboxylic acids: substrate specificity and mechanistic investigation.

A new enzymatic method for the preparation of optically active alpha-substituted carboxylic acids is reported. This technique is called deracemization reaction, which provides us with a route to obtain the enantiomerically pure compounds, theoretically in 100% yield starting from the racemic mixture. This means that the synthesis of a racemate is almost equal to the synthesis of the optically active compound, and this concept is entirely different from the commonly accepted one in the asymmetric synthesis. Using the growing cell system of Nocardia diaphanozonaria JCM3208, racemates of 2-aryl- and 2-aryloxypropanoic acid are deracemized smoothly and (R)-form-enriched products are recovered in high chemical yield (>50%). In addition, using optically active starting compounds and deuterated derivatives as well as inhibitors, we have disclosed the fact that a new type of enzyme takes part in this biotransformation, and that the reaction proceeds probably via the same mechanism as that in rat liver.

Biotransformation↗