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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_158_библиотеки_им_акад_М_И_Перельмана
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Squalene
epoxide
(2,3-oxidosqualene)
is
produced
by
the
и.
vine
squalene
epoxidase
which
use
NADPH
and
oxygen
to
wMilizc
squalene.
This
metabolic
step
is
the
first
in
sterol
I
ih
»
lynthesis
leading
to
the
formation
of
lanosterol
or
cycloartenol.
Squalane
is
a
completely
saturated
derivative
of
squalene.
I'lescnt
in
sebum,
it
is
largely
used
as
a
component
in
many
cosmetic
piodncts.
It
is
obtained
by
hydrogenation
of
squalene
extracted
from
>ilive
oil.
The
large
group
of
steroids,
including
sterolsare
present
in
very
1
1
in
11
amounts
in
bacteria
but
at
larger
amounts
in
plants
and
animals
Mule
the
hopanoids
are
very
abundant
in
prokaryotes
where
they
i
'place
cholesterol.
Triterpenoids
are
widely
distributed
in
edible
and
i
nr<
licinal
plants
and
are
an
integral
part
of
the
human
diet.
They
are
lining
evaluated
for
use
in
new
functional
foods,
drugs,
cosmetics
■ни
I
healthcare
products.
Screening
plant
material
has
identified
fruit
peel
and
especially
fruit
cuticular
waxes
as
promising
and
highly
Jivnilable
sources
[108].
Amyrin
isomers
are
the
predominant
■
i
impounds
in
tomato
fruit
wax,
with
quantities
that
vary
considerably
in
different
cultivars
and
during
the
subsequent
stages
nl
fruit
development.
A
methyl
ether
derivative
of
an
amyrin
isomer,
nnliacin,
has
been
proposed
as
a
sedimentary
molecular
tracer
of
I
lie
history
of
Panicum
(broomcorn
millet)
cultivation.
Among
the
liii
’
gc
number
of
triterpenoid
structures,
some
of
them
are
shown
below.
Serratane-type
compounds
constitute
an
important
group
of
pen
(acyclic
triterpenes
with
an
unusual
seven
carbons
ring.
They
-KI
-
https://t.me/med1917
are
synthesized
through
the
cyclisation
of
bis-epoxy-squalene
and
not
from
epoxy-squalene,
the
precursor
of
more
common
pentacycb.
triterpene.
More
than
100
different
serratenoids
(serratenes
and
derivatives
have
been
reported,
most
having
been
identified
in
club
mosses,
conifers,
and
in
few
angiosperms
(Primulaceae
and
Leguminosae).
Serratene
As
opposed
to
other
serratenoids,
methoxy-serratenes
appear
constrained
to
conifers,
and
more
specifically
to
Pinaceae
(mainly
Pinus,
Picea)
[109].
In
addition
to
diterpenoids,
they
potentially
constitute
a
new
powerful
tool
for
palaeoenvironmental
reconstruction.
Steroids
are
modified
triterpenes
which
derived
also
from
squalene
by
cyclization,
unsaturation
and
substitution.
The
nucleus
of
all
steroids
is
the
tetracyclic
C17
hydrocarbon
1,2-cyclo-
pentanoperhydrophenanthrene
(gonane
or
sterane)
substituted
by
methyl
groups
at
CIO
and
C13,
as
well
as
an
alkyl
side-chain
at
C17.
https://t.me/med1917
•J
loids
may
possess
a
nucleus
derived
from
the
former
one
by
one
и
more
C-C
bond
scissions
or
ring
expansions
or
contractions.
'
i
inline
and
three
examples
of
basic
unsubstituted
steroids
are
shown
in
low:
Unsaturated
steroids
with
most
of
the
skeleton
of
cholestane
1
1
inlaining
a
3/?-hydroxyl
group
and
an
aliphatic
side
chain
of
8
or
пин
е
carbon
atoms
attached
to
position
17
forms
the
group
of
sterols.
I
lie
hopanoids
are
pentacyclic
triterpenoids
based
on
the
hopane
I
dclon
(with
a
five-membered
ring
E)
are
widely
distributed
in
luokaryotes
but
were
not
detected
in
Archaea[\
10].
In
most
cases,
I
In-
liopanoid
content
of
the
cell
is
comparable
with
the
cholesterol
i
ontent
of
eukaryotic
cells.
They
are
considered
as
membrane
i
igidifiers.
Furthermore,
they
are
the
precursors
of
several
derived
compounds
(homohopanoids)
in
sediments
and
oils
and
thus
could
be
considered
as
the
most
abundant
natural
products
on
earth
[111].
A
11
hough
oxygen
is
not
required
for
hopanoid
biosynthesis,
the
vast
majority
of
known
hopanoid
producers
are
aerobic
or
micro-
iierophilic
bacteria
[112].
Thus,
hopanoids
are
found
predominantly
in
aerobic
methanotrophs,
heterotrophs
and
cyanobacteria,
but
have
also
been
found
in
some
anaerobic
bacteria.
The
simplest
C30
hopanoid
is
diploptene.
https://t.me/med1917
Cyanobacteria
are
presently
the
only
known
bacteria
(o
synthesize
abundant
2-methylhopanoids
with
an
extended
polyhj
droxylated
side
chain.
The
most
abundant
hopanoids
are
C35
bacteriohopanepolyols
in
which
the
side-chain
of
the
parent
structure
contains
a
variable
number
of
vicinal
hydroxyl
groups
The
hopanoids
are
widely
distributed
in
bacteria
and
blue-green
algae
where
they
are
important
cell
membrane
constituents.
It
is
often
said
that
hopanoids
are
the
«most
abundant
natural
products
on
Earth».
As
hopanoids
are
very
stable
and
are
not
easily
degraded,
they
are
receiving
an
intense
attention
as
biological
markers
with
applications
for
geochemical
studies
of
petroleum
source
rocks
and
oils.
These
biomarkers
are
mainly
derived
from
bacterial
bac
teriohopanepolyols
(biohopanoids).
The
2-methylhopane
derivatives
are
abundant
in
organic-rich
sediments
as
old
as
2,500Myr.
These
lipids
may
help
constrain
the
age
of
the
oldest
cyanobacteria
and
the
advent
of
oxygenic
photosynthesis.
They
could
also
be
used
to
quantify
the
ecological
importance
of
cyanobacteria
through
geological
time.
More
recent
investigations
have
shown
that
the
production
of
substantial
quantities
of
polyhydroxylated
2-methyl-
hopanoids
may
occur
in
phototrophs
other
than
cyanobacteria
and
that
their
biosynthesis
does
not
require
molecular
oxygen
[113].
Aminohopanoids
not
very
different
from
the
previous
one
have
been
identified
in
several
methylotrophic
bacteria
[114].
One
of
the
most
abundant
is
a
aminohopane
pentol,
mixed
with
other
parent
compounds
(triol
and
tetrol).
This
C30
aminopentol
is
a
possible
precursor
of
the
widespread
C29
hopanoid
chemical
fossils.
https://t.me/med1917
Different
bacterial
groups
possess
recognizable
biohopanoid
ili'.lributions,
giving
hopanoids
marker
potential
for
specific
bacterial
populations
and
environmental
conditions.
More
than
150
individual
liopane
derivatives
have
been
isolated
from
various
types
of
u'llimentary
organic
matter.
Other
pentacyclic
triterpenoids
based
on
the
lupane
skeleton
include
a
very
large
number
of
naturally
ix
i
luring
members
with
different
functional
groups
which
are
found
in
vegetables
and
fruit.
Among
them,
lupeol
is
one
of
the
most
ubiquitous
compounds.
Lupeol
was
shown
to
have
various
pharmacological
properties,
inducing
anti-inflammatory
and
anti-arthritic
responses
and
inhibition
of
tumor
growthin
animal
cells.
Long-chain
fatty
acid
esters
(C20,
C22
and
C26)
of
lupeol
extracted
from
an
African
plant,
llolarrhena
floribunda
(Apocynaceae),
were
shown
to
have
strong
n
nti
malarial
activity,
especially
against
drug-resistant
strains
of
Plasmodium
falciparum
[115-116].
Fatty
acid
esters
(palmitic
or
stearic
acid)
of
lupeol
have
been
isolated
from
green
propolis
produced
by
honeybees
from
vegetative
apices
of
the
Asteraceae
llaccharis
dracunculifolia
from
Brazil
[117].
These
compounds
were
named
procrim
a
and
b.
https://t.me/med1917
Palmitic
acid
ester
of
lupeol
(Procrim
a)
Ursolic
acid
is
present
in
numerous
plants
and
is
the
best
known
triterpene
from
the
ursane
group.
It
amounts
at
more
than
1
g
per
100
g
dry
weight
in
Thymus,
Rosmarinus,
Salvia,
Lavandula,
and
Eucalyptus.
It
is
found
at
high
concentration
in
coffee
seeds
and
in
apple
fruit
(mainly
in
apple
peels).
It
is
used
in
cosmetics
as
an
anti
inflammatory,
antibacterial
and
antifungal
drug.
Ursolic
acid
is
also
able
to
inhibit
some
form
of
cancer,
particularly
multiple
myeloma
[118].
Oleanolic
acid
J
fC
0H
О
A
compound
very
similar
to
ursolic
acid,
oleanolic
acid,
is
widely
distributed
in
food
and
medicinal
plants.
It
is
hepatoprotective
and
exhibits
antitumor
and
antiviral
properties.
It
is
the
main
constituent
of
grape
berry
cuticular
waxes
[119].
Its
presence
could
be
at
the
origin
of
the
numerous
health
benefits,
including
protection
against
heart
disease,
ascribed
to
the
moderate
consumption
of
wine.
Oleanolic
acid
and
another
parent
compounds,
maslinic
acid,
are
concentrated
in
olive
cuticular
waxes,
representing
31^14
%
and
55
68
%
of
total
wax
extract,
respectively.
These
compounds
could
be
related
to
the
numerous
health-promoting
properties,
such
as
https://t.me/med1917
uni
icancer,
antihyperglycemic
and
antiparasitic
activities,
reported
lor
olive
consumption.
As
ursolic
acid
but
in
contrast
with
the
hopane
series,
which
possesses
a
f
ive-membered
ring
E,
the
gammacerane
skeleton
is
i
bnracterized
by
a
six-membered
ring
(see
below).
Tetrahymanol
(gammaceran-21a-ol),
a
typical
representative
of
I
lie
series,
was
first
isolated
from
the
ciliate
protozoan
Tetrahymena
lyriformis.
Later,
it
was
detected
in
a
number
of
other
eukaryotes,
c.g.
in
ferns,
fungi
and
some
other
ciliates.
Its
occurrence
was
long
l
bought
to
be
restricted
to
eukaryotes
but
its
presence
in
sediments
pointed
out
a
much
more
widespread
distribution
in
living
orga
nisms.
The
finding
of
tetrahymanol
in
the
purple
nonsulfur
bacterium
IViodopseudomonas
palustris
opened
new
insights
into
the
biochemistry
of
these
molecules
in
bacteria.
Tetrahymanol
and
novel
methylated
homologues
were
discovered
in
nitrogen-fixing
Ilacterium
Bradyrhizobium
japonicum
[120-121].
Gammacerane
structures
were
shown
to
be
reliable
geochemical
indicators
for
water
column
stratification
in
marine
or
in
lacustrine
deposits
[122].
Tetrahymanol
https://t.me/med1917
Celastrol
is
a
hopanoid
tri
terpene
extracted
from
a
plant
used
in
the
Chinese
medicine,
Tripterygium
wilfordii.
That
plant
is
useful
h
treat
inflammatory
and
autoimmune
diseases.
New
research
l|r.
demonstrated
that
it
is
a
potent
proteasome
inhibitor
and
can
help
и
the
treatment
of
prostate
cancer
[123].
Several
biochemknl
properties
bring
about
several
investigations
in
the
field
of
cancel
treatment
or
prevention.
Its
antioxidant
and
anti-inflammatory
properties
has
been
the
basis
of
research
on
diseases
induced
by
monocytes
and
macrophages
activation,
including
neurodegenerativi
process
[124].
4.6.
Carotenoids
The
nature
of
these
compounds
was
discovered
during
the
19111
century.
In
1831,
Wachen
roder
H.
proposed
the
term
«carotene»
for
the
hydrocarbon
pigment
he
had
cristallized
from
carrot
roots
Berzelius
J.
called
the
more
polar
yellow
pigments
extracted
from
autumn
leaves
«xanthophylls»
and
Tswett
M.,
who
separated
many
pigments
by
column
chromatography,
called
the
whole
group
«carotenoids».
Among
this
important
group,
the
numerous
compounds
consist
of
C40
chains
(tetraterpenes)
with
conjugated
double
bonds,
they
show
strong
light
absorption
and
often
are
brightly
colored
(red,
orange).
They
occur
as
pigments
in
bacteria,
algae
and
higher
plants.
Carotenoids
perform
three
major
functions
in
plants:
accessory
pigments
for
light
harvesting,
prevention
of
photooxidative
damage
and
pigmentation
attracting
insects.
The
hydrocarbon
carotenoids
are
known
as
carotenes,
while
oxygenated
derivatives
of
these
hydrocarbons
are
known
as
xanthophylls.
To
date,
700
carotenoids
have
been
identified,
of
which
only
50
are
regularly
consumed
in
the
human
diet
and
24
have
so
far
been
detected
in
human
plasma.
In
Western
diets,
the
most
abundant
carotenoids
are
the
three
oxygenated
xanthophylls
lutein,
zeaxanthin
and
b-cryptoxanthin
and
the
three
major
carotenes,
a-
carotene
b-carotene
and
lycopene.
The
human
intake
of
carotenoids
may
be
appreciated
using
databases
such
as
that
established
for
Swiss
vegetables
[125].
https://t.me/med1917
(
arotenoids
are
important
components
of
the
light
harvesting
in
pLnils,
expanding
the
absorption
spectra
of
photosynthesis.
The
11
in
|or
carotenoids
in
this
context
are
lutein,
violaxanthin
and
iiioxanthin.
Additionally,
there
is
considerable
evidence
which
indicates
a
photoprotective
role
of
xanthophylls
preventing
damage
№
dissipating
excess
light.
In
mammals,
carotenoids
exhibit
mu
niiiiomodulatory
actions,
likely
related
to
their
anticarcinogenic
lli.
’
cts.
b-Carotene
was
thus
shown
to
enhance
cell-mediated
iiiiiiiune
responses.
The
decrease
in
prostate
cancer
risk
has
been
linked
to
the
consumption
of
tomatoes,
vegetable
rich
in
lycopene,
as
prostatic
tissues.
While
there
is
yet
limited
direct
evidence
linking
lycopene
and
prostate
cancer,
several
observations,
11
и'
I
tiding
the
ability
of
the
prostate
to
concentrate
lycopene,
aiggcst
a
special
protection
of
lycopene
against
that
pathology
11
.
’
6-128].
Carotenoids
consist
of
eight
isoprenoid
units
joined
in
such
a
manner
that
the
arrangement
of
isoprenoid
units
is
inversed
at
the
center
of
the
molecule
so
that
the
two
central
methyl
pinups
are
in
a
1,6-position
relationship
and
the
remaining
non
terminal
methyl
groups
are
in
a
1,5-position
relationship.
They
are,
by
far
the
predominant
class
of
tetraterpenes.
They
may
be
also
classified
in
the
terpenoids.
Carotenoids
can
be
considered
derivatives
of
lycopene,
found
in
tomatoes,
fruits
and
flowers.
Its
long
straight
chain
is
highly
unsaturated
and
composed
of
two
identical
units
joined
by
a
double
bond
between
carbon
15
and
15'.
I
nch
of
these
20
carbon
units
may
be
considered
to
be
derived
from
I
isoprene
units.
Lycopene
is
a
bioactive
red
colored
pigment
naturally
occurring
in
plants.
Interest
in
lycopene
is
increasing
due
to
increasing
evidence
proving
its
antioxidant
activities
and
its
preventive
properties
toward
numerous
diseases.
In
vitro,
in
vivo
and
ex
vivo
studies
have
demonstrated
that
lycopene-rich
foods
are
inversely
associated
to
diseases
such
as
cancers,
cardiovascular
diseases,
diabetes,
and
others.
A
review
of
all
these
aspects
may
be
consulted.
Carotenoids
may
be
acyclic
(seco-carotenoids)
or
cyclic
(mono-
or
bi-,
alicyclic
or
aryl).
Oxyfunctionalization
of
various
carotenoids
leads
to
a
large
number
of
xanthophylls
in
which
the
function
may
be
a
hydroxyl,
methoxyl,
carbonyl,
oxo,
f
ormyl
or
epoxy
group.
https://t.me/med1917
lycopene
red;
Л
щи
,
476
nm)
■/-carotene
(СфД1
м
;
orange;
460
nm)
a-carotene
(С^ЕЦ,;
orange;
4
456
nm)
fl-catotene
(CVHy,
orange;
Л
шал
,
463
nm)
Only
some
of
the
most
common
carotenes
and
xanthophylls
are
given
below:
Phytoene
is
one
of
the
first
intermediates
in
the
biosynthesis
of
carotenoids.
It
is
formed
by
coupling
of
two
molecules
of
geranylgeranyl
pyrophosphate
by
the
action
of
the
phytoene
synthase.
The
diphosphate
is
removed
and
proton
shift
leads
to
the
formation
of
phytoene.
It
is
a
colorless
product
and
absorbs
light
in
the
UV
range
only.
Dietary
phytoene
is
accumulated
in
human
skin
where
it
can
potentially
protect
the
skin
(UV
absorber,
antioxidant,
anti
inflammatory).
Among
the
represented
molecules,
https://t.me/med1917
Соседние файлы в папке Библиотека им академика М.И. Перельмана