general introduction about alkaloid .it contain definition, classification etc.

1. Alkaloids

2. Prepared by
Dr. N.GOPINATHAN
ASSISTANT PROFESSOR
DEPARTMENT OF PHARMACEUTICAL
CHEMISTRY
FACULTY OF PHARMACY
SRIHER [DU]
CHENNAI-116
TAMILNADU

3. Introduction
• Alkaloid the term is coined by pharmacist W.
Meissner in 1819 for the basic, nitrogen
containing compounds of plant origin.
• The basicity is due to presence of nitrogen
inside the ring.
• It is physiologically active basic compounds of
plant origin, in which at least one nitrogen
atom forms part of a cyclic system.

4. • The above definition is not fully satisfactory
because some compounds although alkaloid
do not confine to this definition.
• Adrenalin and ephedrine have nitrogen atom
in the side chain.
Ephedrine

5. • Other compounds although not alkaloids
confined to this definition .
• Only 10-15 % found in all vascular region.
• It is rarely found in lower plants like algae, fungi [
ergot alkaloid ].

6. Vascular tissue

7. History

8. Heterocyclic physiologically active nitrogen
but not regarded as alkaloids
Thiamine
Purine
caffeine
theobromine
xanthine

9. It exist as salt of plant acid such as acetic acid, oxalic
acid, citric acid, malic, lactic, tartaric , tannic and
aconiticacid.

10. Tartaric acid Aconitic acid

11. Cinchona alkaloid with quininic acid ,
and opium alkaoid with meconic acid.

13. Basicity of alkaloids

14. Distribution of alkaloid in plant

15. Other sources

16. Occurence

17. Occur in free form narceine and
nicotine.

18. As glycoside – Solanum and veratrum.

19. As amides – Piperine

20. Esters- Tropine and cocaine.

21. Colchinine is regarded as alkaloid
although it is not heterocyclic.

22. Thiamine is heterocyclic nitrogenous base
because it is universally distributed in living
matter so not included in alkaloid.

23. It is found in dicotyledons like
• Apocynaceae,
• Papaveraceae,
• Papilionaceae,
• Ranunculaceae,
• Rubiaceae,
• Rutacea,
• Solanaceae.

24. The purpose of existence of alkaloid in
plant
• It is regarded as bye product of plant
metabolism.
• It act as reservoir of protein synthesis.
• It act as protective substance against the
animal or insect attack.
• It function as plant stimulant like growth,
metabolism and reproduction.
• As detoxifying agent by methylation,
condensing and cyclize the compounds.

25. Nomenclature
• Due to complex structure and some historical
reason there was no systematic nomenclature of
alkaloids.
• It is named according to the plants from which
they are obtained.
• Papaverine – papaver somniferum.
• Berberine – berberis vulgaris.L

26. Few named after their physiological
action such as
• Morphine [ German morphin- God of dreams ]
• Narcotine [ Greek narkov – be numb]
• Emetine [ Greek emetikos – to vomit ]

27. Some of it has been named after their
discoveries pelletierine group
• P.J.Pelletier

28. Minor alkaloids named has been
derived by adding one prefix or suffix
to the name of principal alkaloid
• Cinchona series

29. Nomenclature
• Related bases have been named by
transposition as narcotine, cotarine and
tarconine.
• Prefix such as epi, iso,neo,pseudo etc.. Greek
letters have been used to designate isomeric
or slightly modified structure.
• The prefix nor denotes the structure which
does not have a methyl group attached to the
nitrogen atom.

30. Classification

34. Taxonomic
• It is done according to family.
• Alkaloids are described as solanaceous or
papilionaceous without reference to chemical
type.
• Both the families contain alkaloid of several type.
• Solanaxeae -tropane,pyridine steroidal
• Papilionaceae-Quinolizidine & pyrrolizidine.
• Disadvantage of the system is obvious.

35. Pharmacological classification
• It is based on their use or
physiological activity.
• Analgesic, cardio active alkaloids.
• Alkaloids within a group frequently
have chemical similarities.

36. Biosynthetic classification
• It is more fundamental method than chemical
classification.
• It depends on the type of precursor or
building block of compounds used by plants to
synthesis complex structure.
• Hundreds of indole alkaoids are derived from
the amino acid tryptophan and mevalonic acid
as ergot or cinchona alkaloid.

37. • Similarly morphine, papaverine , narcotine
tubocurarine and colchinine may be listed as
phenyl alanine tyrosine derived base.
• The disadvantage of this method is precursor
which is not always apparent.

38. Chemical classification

39. 1. Phenylethylamine alkaloidEphedrine,
adrenaline and nor adrenaline

40. 2.Pyrolidine alkaloid Hygrine,
cusohygrine

41. 3.Pyridine Alkaloid-Ricinine, conine

42. 4.Piperidine Alkaloid piperine
pelletierine

43. 5.Pyridine –pyrrolidine Alkaloid
Nicotine

44. 6.Tropane alkaloid Atropine Cocaine

45. 7.Quinoline alkaloid Quinine,
cinchonine

46. 8.Isoquinoline Alkaloid papaverine
narcotine emetine

47. 9.Phenanthrene Alkaloid morphine

48. 10.Indole Alkaloid ergotamine,
Reserpine Strychnine Brucine

49. 11.Tropolone alkaloid Colchioine

50. 12. Imidazole alkaloid

51. Isolation
• Isolation and purification of an alkaloid from a
plant is always not a simple process.
• Plants may contain complex several alkaloids.
Their isolation of an pure alkaloid may
become an extremely laborious procedure.
• First of all the presence of an alkaloids in a
plant is ascertained by employing various
reagent called alkaloidal reagent

53. • Chloroplatinic acid H2PtCl6, chloroauric acid
HAuCl4, Phosphotringstic and molybdic acid
are useful precipitating agent.
• The precipitate have characteristic colours and
are used for the detection of alkaloids in very
small amount.
• After detection seperation of alkaloids from
plant.
• Final step is purification.
• For isolation of small quantity of an alkaloid
chromatography is most satisfactory.

54. Other colouring reagents usedto
detect alkaloids are
• Formaldehyde [ Marquis reagent]
• Nitric acid [ Erdmann’s reagent ]
• Molybdic acid [ Frende’s reagent ]