abstraction:
a chemical process by which an atom or group of atoms is
removed from a molecule. For example, a hydrogen atom [H],
which is taken away by a strong oxidant or by a
dehydrogenating enzyme, is said to be abstracted.
acetyl-L-carnitine:
a molecule which carries acetyl groups (CH3-CO-) into the
mitochondria where these are fed into the Kreb's cycle
(tricarboxylic acid cycle) and metabolized to produce NADH.
activation:
causing an enzyme to function or causing an enzyme to increase
its rate of function; altering conditions to become more
conducive to enzyme function. For example, an enzyme which
requires a certain cofactor becomes active only when that
cofactor is present. Digestive enzymes of the intestinal lumen
are only active in a solution of alkaline pH. Many dehydrogenases
require an abundance of the electron acceptor NAD+ or NADP+
to enable them to function. Many kinases require magnesium.
active center:
that part of an enzyme which is utilized to perform the
catalytic function of that enzyme.
acyl radical (R-CO*):
a carbonyl group with an unpaired electron at one of the
binding sites of the carbon atom and a hydrocarbon group
at the other. Acyl radicals can be generated by oxidative
removal of the terminal hydrogen atom of an anhydrous aldehyde.
adduct:
a contraction of the phrase "addition product"; the product
of the covalent attachment of one molecule to another.
Some adducts cause the permanent blocking or inhibition of
an enzyme. Adducts to DNA can be mutagenic and/or carcinogenic.
Many adducts are allergenic and known as haptens. Mechanisms
of adduct formation can vary. Some occur by simple trapping
of a free radical, others by combining with a nucleophile
or an electrophile.
adenosine triphosphate (ATP):
a three part molecule consisting of the nitrogenous
heterocyclic base adenine covalently attached to a sugar
molecule which is covalently attached to three colinear
phosphoryl groups. ATP functions as a source of highly
reactive phosphoryl groups which energize numerous biochemical
reactions or which modify certain substrates for specific use.
adrenochrome:
a quinone imine produced by the exposure of a catecholamine
to fairly harsh oxidizing conditions.
aerobic:
able to survive in and utilize atmospheric oxygen;
the characteristic of utilizing metabolic pathways in
which diatomic oxygen is the final electron acceptor.
aglycone:
the nonsugar part of a glycoside or the nonsugar product
of hydrolysis of a glycoside.
agmatine (NH2-CNH-NH-CH2-CH2-CH2-CH2-NH2):
1-amino-4-guanido-n-butane; the amine produced by the
decarboxylation of arginine.
alcohol (R-OH):
any organic molecule with a hydroxyl group attached to one
of its a carbon atoms.
alcohol dehydrogenase:
an enzyme which abstracts two atoms of hydrogen from primary
alcohols producing aldehydes. It requires zinc and NAD+
as cofactors.
aldehyde (R-CH=O):
a molecule possessing a carbonyl group bound to a hydrogen
atom on one side and any organic radical on the other.
Aldehydes can be hydrogenated to become alcohols or oxidized
to become carboxylic acids. They readily form adducts with
alcohols, with thiols, and with amines by nucleophilic
addition at the carbon atom. In aqueous solution, aldehydes
are mostly hydrated by the acceptance of one molecule of water
(another nucleophile) to become 1,1-dihydroxy compounds.
aldehyde dehydrogenase:
an enzyme which abstracts two atoms of hydrogen from a
hydrated aldehyde (R-CH=O) to produce a carboxylic acid
(R-COOH). It requires molybdenum (Mo), FAD, and iron (Fe)
as cofactors. It donates electrons one at a time to diatomic
oxygen (O2) producing superoxide radical (*OO-).
alkoxyl radical (RO*):
a free radical with the unpaired electron is localized to
an oxygen atom and a bound organic radical attached to the
other valence of the oxygen atom. Alkoxyl radicals are able
to abstract hydrogen atoms from numerous donors or to attach
themselves to the pi bonds of other molecules.
alkylation:
the addition of an alkyl radical to another molecule.
alkyl radical (R*):
a free radical with the unpaired electron localized to one
of the carbon atoms of the radical; a carbon centered free
radical.
alkylperoxyl radical (ROO*):
a free radical with the unpaired electron localized to the
terminal oxygen atom, which itself is also attached to another
oxygen atom, which is in turn bound to an alkyl group.
ROO*'s are usually produced by the addition of diatomic oxygen
to an alkyl radical.
allicin (CH2=CH-CH2-SO-S-CH2-CH=CH2):
diallyl-disulfide monoxide; the odiferous component of Allium
sativum (garlic). Allicin is a weak oxidant and is able to
accept four hydrogen atoms from thiol group donors.
It has significant antibacterial properties.
allyl group (-CH2-CH=CH2):
a bound hydrocarbon radical composed of three carbon atoms,
the middle bond being single and the outer bond double.
It is found in compounds as diverse as allicin and lapachol.
aloe-emodin:
a bitter tasting anthroquinone found in the rind of aloe vera
having antiinfective and immunostimulating effects.
alpha-keto-aldehyde (R-CO-CHO):
an aldehyde with an adjacent carbonyl group.
The two carbonyl groups usually rotate to opposing positions.
This tends to orient the pi bonds in a parallel configuration
allowing them to conjugate, which facilitates redox cycling.
Growth inhibiting properties have been observed for many
of these compounds. They are enzymatically eliminated
by glyoxalase.
alpha-keto-carboxylic acid (R-CO-COOH):
a carboxylic acid with an adjacent carbonyl group.
alpha-keto-ketone (R-CO-CO-R):
an organic molecule with two adjacent keto groups. The keto
groups usually orient in opposing positions, which allows
them to conjugate, which facilitates redox cycling.
amine (R-NH2, R-NH-R', R-NR'-R"):
an organic molecule containing nitrogen connected to carbon
or hydrogen by single bonds. Primary amines contain nitrogen
attached to one carbon and two hydrogens. In secondary amines
the nitrogen is attached to two carbons and one hydrogen.
In tertiary amines nitrogen is attached to three carbons only.
In quaternary ammonium compounds there are no hydrogen atoms
attached to the nitrogen only carbon atoms. The nitrogen atom
bares a positive charge and covalently binds four alkyl groups.
amine oxidase (AO):
any of a family of enzymes which dehydrogenate amines. They
function by abstracting two hydrogen atoms, one from the
nitrogen atom, and one from the adjacent carbon atom. The
resultant imine then hydrolyses. Usually this produces an
aldehyde and ammonia. AO's utilize various redox active
cofactors such as copper, FAD, TPQ, or TTQ.
amino group (-NH2):
a nitrogen atom covalently bound to two hydrogen atoms and
also bound to the rest of the molecule. Amino groups can be
removed by oxidation. Amino groups can add to carbonyl
compounds as nucleophiles, and then a subsequent dehydration
yeilds an imine. Amino groups are alkalinizing by the
acceptance of protons from the solvent.
anaerobic:
not able to survive in an atmosphere of oxygen; not
utilizing diatomic oxygen as the final electron acceptor.
anhydrous:
devoid of water; completely without water. Anhydrous compounds
are the products of the removal off water, which was normally
part of their makeup before drying. Drying can be accomplished
by contact with heat, special salts, or strong mineral acid.
anion (X-):
a molecular species baring a negative electric charge;
the molecular species which is attracted towards the anode
or positively charged plate.
anode:
the positively charged plate in electrochemistry or in vacuum
tubes; the electron removing or oxidizing plate.
anthroquinone (AQ):
a molecule having a quinone nucleus and conjugated with two
aromatic rings. The ethylene bridges connecting the carbonyl
groups are part of these aromatic rings making AQ's tricyclic
compounds. These aromatic side rings protect the 2,3,5 and 6
carbon positions of the quinone nucleus against free radical
addition reactions. The rings also provide enhanced
delocalization of the unpaired electron of the semireduced
species. This makes the semianthroquinone radical (*AQH)
extraordinarily stable and facilitates the ability of AQ's
to redox cycle.
antioxidant:
any of several types of compounds able to prevent or
neutralize the effects of oxyradicals and other oxidants.
Most antioxidants are reductants, while others function by
trapping oxyradicals. Some antioxidants deactivate certain
precursors which would otherwise promote oxidation. Some
absorb the energy of a strong oxidant or alter its composition
causing it to become less active. Still others surround or
protect the substrate which is at risk of oxidation.
AP-1:
a transcription factor complex containing subunits Jun and Fos
which binds to DNA. Upon association with other transcription
factors promotes mRNA production in the cell nucleus. AP-1 and
its subunits contain redox sensitive cysteine residues which
are readily inhibited by oxidants and reactivated by reductants
(usually thiols). Substitution of certain cysteine residues
of AP-1 to serine results in an irreversibly active factor.
apoptosis:
programed cell death; a natural physiologic process whereby
cells self destruct; autolysis of living cells. Apoptosis
eliminates certain cells which are no longer of benefit to
the organism as a whole. One of the physiologic triggers
within many types of cells to initiate apoptosis is activated
by oxidants. Apoptosis is observable in embroyology and
immunology. It's failure to occur in certain clones of tumor
cells makes these more resistant to therapy.
arbutin:
the beta-D-glucoside of hydroquinone; a combination of glucose
and hydroquinone. Arbutin naturally occurs in the leaves
of cranberry, blueberry, and pear. Arbutin has been found useful
as a urinary antiseptic. It can be hydrolyzed to release
the free hydroquinone by dilute acid or by the enzyme emulsin.
arginine (NH2-CNH-NH-CH2-CH2-CH2-HCNH2-COOH):
an essential amino acid and precursor to numerous proteins,
including highly alkaline proteins such as histones and
protamines; precursor to nitric oxide by action of nitric oxide
synthase; precursor to urea and ornithine by action of arginase.
aromatic compounds:
organic compounds containing a benzene ring. A benzene ring
is a coplanar six carbon ring connected by six sigma bonds
and three conjugated pi bonds.
arsenic cation (Ar+++):
a toxic element which forms adducts with thiol groups
particularly dithiols such as thioctic acid (lipoic acid).
Arsenic specifically inhibits the pyruvate dehydrogenase
enzyme complex preventing the admission of new acetyl
groups into the Kreb's cycle from pyruvate. Arsenic is a
recognized cause of fatigue, arteriosclerosis, and cancer.
arsenite (AsO3---):
the anionic component of the salts of arsenic acid (H3AsO3).
Arsenite can be reduced in vivo to produce the highly toxic
arsenic cation (Ar+++).
artemisinin:
an endoperoxide naturally occuring in the wormwood species
Artemisia annua. It becomes active as an oxidant in vivo
and has been found effective to treat numerous parasitoses and
some cancers. A related compound is artemether.
aryl group:
phenyl group; a benzene ring bound by one of its six carbons
and maintaining its conjugated triple pi bond structure.
ascorbic acid (AA or AAH2):
vitamin C in its reduced form; hexuronic acid. Ascorbic acid
is a highly water soluble reductant with an enediol reactive
group. In the presence of both oxidants and reductants it
can redox cycle. In vivo it serves as a rechargeable reductive
antioxidant and as a physiologic reducing agent for some
synthetic functions.
ascorbyl radical (*AAH):
the semioxidized form of ascorbic acid having only one
of its hydrogen atoms removed.
autohemotherapy:
removing a patients blood, treating it, and reinfusing it.
autooxidation:
the spontaneous oxidation of certain substances upon exposure
to atmospheric oxygen (O2) at ambient temperature and pressure.
azide anion (NN-):
a negatively charged molecular species composed of two
nitrogen atoms and one electron. Azide binds as a ligand
to copper cations. It is used in research as an inhibitor
of enzymes which utilize copper.
