Download Sheet #24 (archive) Medicinal Plants

Medicinal Plants – Sheet #24
Tetraterpenes:
mixed class of the terpiniod substances .
Tetraterpenes are the second class of the terpinoid substances
obtained by tail-tail condensation of GGP units, the previously
observed condensation of 2 FPP pyrophosphate units was involved in
the formation of triterpenoid linked to a reduction step to obtain a
symmetric molecule.
tetraterpens : 2 GGP which means 8 isoprene unit we have in the
middle of the molecule a double bond > this indicate that this
conversion is non-reductive & the 1st intermediate is phytoene
obtained by phytoene synthase , other tetraterpenes are carotenoids
,they comprise a relatively widely distributed class of 2ndry
metabolites in the nature, imparting bright colors to different edible
fruits specially vegetables( characterized by their yellow /orange/red
color such as the orange color of carrots ,or the red color of tomatoes)
,and therefore they are widely used in the pharmaceutical industry as
coloring agents .
The primary classes of tetratepines ,we have:
carotene ,indicating already hydrocarbons
Xanthophylls, composed of carbon, hydrogen & oxygen, both of them
are C40 compounds
there is small group considered as degradation product of carotenes
& carotinoids are CAROTINOID ACID( the name indicates the
presence of carboxylic acid) . they are differing from their precursor in
that they are 20 C, so splitting will lower the chain of 40C carotene
& Xanthophylls to 20 C ,subsequent modification (oxidation) to
obtain the carotinoid acid .
so these are the 3 subclasses : 2 major and one small subclass of the
carotinoid substances which are exclusively of plant origin although
identified by different types of animals .
Astaxanthin ,they are detected in the shell-fish or other organisim ,if
you eat so much amount continuously you will have yellow points
1
Oxygenated derivative
2
Medicinal Plants lecture 22/4/2012
In the last lecture we started discussion about tetraterpenes and we mentioned it is
contain basic 40carbon units .And we mentioned the tetraterpenes have 4 major rxns
in there biosynthesis ( condensation of the 40carbon units then dehydrogenation
followed by cyclization and/or oxidation ) . So cyclic derivatives which are
comprising the formation of one cyclic structure at both of the molecules can
observed with the carotenes as well as xanthophylls(it is oxygenated derivative).
We need this cyclic derivatives because carotenoid especially β carotene classified as
Pro-Vitamin A.
β Carotene it is monocyclic structure in both ends of the molecule and this cyclic
structure has only one double bond , and these double bond either in agreement with
double bonds of side chain then we get β ionene ring( conjugated between double
bond of cycle and side chain [ ‫ [ ــــ = ـــــ = ــــ‬single bond , double bon ]]), or these
double bond occur in non conjugation then we get α ionene ring, and both β and α
ionene are considered as Pro vit A.
When possessing two β ionenes and theoretically when they are splitted centrally of
this molecule they can yield two molecules of the Vit A ( 1 molecule β carotene
gives 2 molecules of Vit A ) , but the cleavage in nature does not occur centrally but
they can be excentric cleavage .
But in the case of α carotene which it is consist of 1 molecule β ionene and 1
molecule α ionene ( 1 molecule of α carotene gives 1 molecule of Vit A).
The conversion from Pro vit A to vit A ( retinal
human bodies by enzymes .
Oxidized to
retinol )carried out in
General Information about Vit A
*In plant kingdom we don't have Vit A but we have only Pro Vit A.
*The Vit A itself is only found in animal.
*Vit A fat soluble vitamin .
*Have recommended diagnoses by ( 6000 IU ) .
*It is involved in many different physiological functions such as vision and
reproduction.
*Vision defects result from deficiency of Vit A.
3
*Not only the Vit A deficiency lead to defects but also overdose of Vit A can end up
of pathological condition , when Vit A dose exceed 10000 IU this make teratogenic
effects.
*Pro vit is rarely cause pathological condition.
*Major abnormal rxn of Vit A is observed by synthetic product of Vit A which used
for acne.
*Retinoic acid and it's isomer ( 5-cis retinoic acid or iso retinoic acid which are
marketed as tretinoin and iso tretinoin )can be involved in the occurrence of
misformation in the fetuses and it is recommend for six months after discontinuation
by the fertile aged not to get pregnant .(‫)يعني بالعربي الزم المرأة الحامل تقطع استخدام الدواء‬
* retinoic acid and iso retinoic acid are used for treatment of acne vulgaris .
* Vit D is sun shine vitamin.
4
*When we said Vit A we mean Vit A1.
*3,4 dehydro Vit A1 (The source of Vit A2)
*New Vit A has cis double bond at the carbon 5.
 There are subgroup of carotenoids which is a Carotenoic Acids and a
very well known example is Crocetin.
*Crocetin is a dicarboxylic acid and it is obtained by saffron stigmas .
*Crocetin has one carboxylic acid at each end so it is found in plant in the form of
glycoside (Crocein).
*Crocein is made by forming ester linkage between crocetin and
disaccharide(gentiobiose sugare).
*In plant Crocus sativus we found crocetin and crocein and it is contain colored
stigmas and also Crocus sativus used as expensive spice .
*Stigmas in flowers is orange color and it is responsible of this spice characteristic.
*And may be use as coloring agent depend on crocein .
*And use as aroma(‫ )تعطي نكهة‬which it is originating from aldehyde Safranal.
*So crocien and crocetin responsible of yellow/orange coloring of this spice and
safranal responsible of flavoring .
*To obtain 1 kg of this stigmas you will need 100 thousand flower heads of these
plant so it is most expensive spices .
*In the past Saffron are not used because abortifiacient effect , but recently based on
guinea pig discovered no abortifiacient effect unless we have high dose .
* Recently based on superoxide scavenger activity, Saffron use as preservation of
sperms.
5
 There are 2 groups of secondary metabolite obtained by tail to tail
condensation which are tri and tetra terpene . know we wil start with last
chapter of terpenoid which is known as polyterpenes and are product of head
to tail condensation , by using up to million IPP units can be attached by head
to tail and produce this huge molecular wight of terpenoids.
 And there are 2 diff subgroups of polyterpenes either all cis polyterpenes or
all trans polyterpenes, and the most common in the nature are the all cis
polyterpenes. And about 2000species of higher plants produce
polyterpenes.(So it is widely distributed in diff plant species)
 Achras sapota most presentative use of polyterpenes.
 Achras sapota gives elasticity of chewing gum .
 These substances not found in nature as it is ,but we make chemical
modification on it to improve elasticity and strength of the substance in nature.
 Polyterpenes have diff. uses .
* we talked about diff pathways (AMP , MAP , SAP ) and know we will to talk
about nitrogenous compounds because there are no single certain pathway of the
previous chapters talked about nitrogenous compounds. And the alkaloid includes
biggest group of these nitrogen substances.
 Terpenes , glucosydolase and biogen deaminase these small chapters are
contain nitrogen substances.
 1819 first discovered of alkaloids by pharmacist.
6
 Alkaloid it is heterogenic compounds.
 Alkaloid it is from plant origin and has basicity characteristic and contain
nitrogen in heterocyclic ring .
 Alkaloid has biological , pharmacological, physiological and toxilogical
activity.
 Definition of alkaloid by basicity, nitrogen in heterocyclic ,plant origin and
biological activity , but there are deviation from this definition , so we use
new definition.










 There are many classification of alkaloids.
5
Aromatic a . a
Origin from shikimic
acid pathway
Aliphatic a .a
7








Pharmacological effects according to physiological action.
True alkaloids (Typical , classical , real alkaloids) it is have different
pharmacological and physiological rxn.
Proto-alkaloids : contain amine group from amino acids
(a.a).
N in the side chain .
Proto-alkaloids : it is known as Biogenic amine
a.a decarboxylation
biogenic amine … then there are several rxns
(oxidation, methylation , ethylation and cylization).
Pseudo – alkaloids: have nitrogen in heterocyclic structure so we need
to what is the nitrogen donor.
Pseudo-alkaloids produce by subsequent transamination rxn , using
nitrogen either from glutamate or aspartate or ammonia.
Pseudo alkaloid produced from other precursor ( from other a.a )
False – alkaloids : Not alkaloid ! .. No nitrogen in there structure
..Nothing to do.. but gives false positive rxn with alkaloidal reagents in
classical identification rxn .. like furanocoumarine, percabtane react with
alkaloidal substances but it is not alkaloid, may called as new alkaloid.
*Distribution and Occurance of Alkaloid:
* Primarily, Alkaloids are produced by vascular plants (Higher plants)which are
consist of mono- and di- cotyledons, but the dicotyledons are more rich in
alkaloids than monocotyledons.
*Ergometrine : it is alkaloid originate from fungi and it is potent and still used .
*plant families you not to need to memorize it.
(‫ليست للحفظ‬
alkaloids
‫)يعني بالعربي اسماء العائالت التي تحتوي على‬
8
*Alkaloids are distributed in any organ of plant like roots, leaves, seeds, fruits…etc
*In Solanaceae family we cannot find final decision about the part of plant
which contains alkaloids . there are diff parts contain alkaloids according to the
species of plant.
Solanaceae
alkaloids ‫يعني كل اجزاء النبات فيها تحتوي‬
Solanaceae
(Nicotiana tobacco)
*(Tomato) lycopericon is free from alkaloids.
*(Potato) Folam tuberusea
when exposed tubers to sun it will form
sprout which is rich in solanine glycosidic alkaloids.
*Atropa belladonna contains alkaloids in seeds and leaves.
Solanaceae family
*You should to know which forms of alkaloids are found in the plant because
this help in isolation of the alkaloids .
(It is easily extracted by pure organic solvents like chloroform.)
[Salts can be extracted by 70%
alcoholic solvents(methanol ,ethanol)]
Addictive agent
9
Free bases with sugar
*alkaloids in the form of salts with acids we can be split the acids by bases(such as
nitrate,ammonia) so then we will take the alkaloids as free bases .
*always alkaloids are found as combination with acids , sugars .. then we make
certain rxn to get alkaloids as free bases .
*It is easily identification of meconic acid by FeCl3.
Few drops of FeCl3 + Opium powder( contain Meconic acid)
Intensive Red color
*when we talked about the functions of alkaloids (about 5000 compounds) there are
diff cological important.
*alkaloids are very toxic and bitter so the animals and insects avoid plants which
contain alkaloids.
10
‫‪*There are major and minor alkaloids.‬‬
‫‪*closely related alkaloids are determined by prefix and suffix(which are depend on‬‬
‫)‪organic chemistry‬‬
‫‪* prefix and suffix : they are depend on organic chemistry.‬‬
‫حسـبـنـا هللا ‪ ..‬سيؤتـيـنـا هللا من فضله ‪ ..‬إنـّـا إلى هللا راغبون ‪....‬‬
‫هللا يبارك بأوقاتكم ‪ ..‬موفقين في كل امتحاناتكم ‪ ..‬وياااارب اللي كان مزبط بالميد يرجع يزبط‬
‫‪ ..‬واللي ما زبط يارب يزبط بالفاينل‪‬‬
‫وما تنسوا الدعاء لألسرى الذين يخوضون معركة مفتوحة مع الصهاينة في االضراب عن‬
‫الطعام لليوم ‪ .. )2012/5/11( 25‬اللهم فرج عنهم وفك أسرهم وحقق أمانيهم وفرّح أهاليهم‬
‫بعودتهم إلى ديارهم ‪..‬‬
‫تذكير ‪ :‬يوم ‪ 2012/5/15‬يصادف الذكرى ال ‪ 64‬للنكبة الفلسطينية ‪ ..‬‬
‫فما تنسوا الدعاء ألرض فلسطين بالتحرير والنصر ‪...‬‬
‫‪Done By : Lijan 2009 ‬‬
‫‪11‬‬