1. Pharmacognosy 2
PHG 203 Week (4)
Dr Heba

2. Bark
The Bark

3. Intended Learning Outcomes (ILOs)
a1- The basic concepts of Pharmacognosy through principles of the morphological, histological and taxonomical features of medicinally important plant organs including fruits, herbs, barks, woods and subterraneans. a2- The natural drugs characteristics (belonging to fruits, herbs, barks, woods and subterraneans) as sources for pharmaceutical active ingredients. a3- The different medicinal applications of the selected drugs in the alternative and complementary therapy in relation to their active constituents. c1- Select the most appropriate methods for identification and purification of the selected drugs based on macroscopical, microscopical and/or chemical criteria. c2- Suggest the most suitable natural drugs (from the selected ones) as remedies for treatment of several diseases and disorders. d1- Express well all studied information with their clear special terminological principles. d2- Draw skillfully all scientific drawings related to the studied course.

4. Definition:
Barks consists of all the tissues outside the cambium layer of the stems or the roots of the medicinal plant.
Collection and Preparation:
Barks are collected either from
stems or roots by making transverse
and longitudinal incisions and
peeling the outer layers
(layers outside the cambium).

5. Shape of Barks : B) Flat. C) Curved D) Channelled E) Single quill
F) Double quill
G) Compound quill

6. Surface of the Bark:
Presence or absence of epiphytes (unicellular plants such as lichens) they are in form of grayish patches.
Presence or absence of lenticels.
Lenticels: Special pores, formed in the stem by the cork cambium for the exchange of gases.
Cracks and fissures

7. Cambium
The cambium consists of thin-walled meristematic cells, dividing rapidly.
Types of Cambium:
1- Cork Cambium:(Phellogen): originates from cortex or pericycle. It gives cork to the outside and secondary cortex (phelloderm) to the inside.
2- Vascular Cambium:(Fasicular cambium): It exists in the vascular bundles between the xylem and phloem. It gives secondary phloem to the outside and secondary xylem to the inside.

8. Typical structure of the bark:
Rhytidoma.
Cork cells.
Phellogen "cork cambium".
Phelloderm "secondary cortex".
Primary cortex.
Endodermis.
Pericycle.
Primary phloem.
Inner bark " secondary phloem .

10. 2 ry thickening

11. Typical structure of the bark:
Rhytidoma: It is the outer most tissues of the bark formed of ruptured tissues including the epidermis and some of the cortex.
Cork cell: It is the protective tissue of secondary origin developed in stems or roots from secondary meristimatic tissue kn. as phellogen (cork cambium). Cork cells are polygonal rectangular cells regularly arranged in radial rows having no intercellular spaces except for lenticels, the walls of the cork cells are cellulosic and rich in suberin which is a waxy materials

12. Cork cells:
polygonal rectangular cells regularly arranged in radial rows having no intercellular spaces.

13. Typical structure of the bark:
Phellogen: It is the secondary meristematic tissue developed by the activation of parenchymatous cells and divide to produce cork cells to outside (suberised cells) and phelloderm to the inside formed of un-suberised cells ).
Phelloderm "secondary cortex": It is formed of several layers of un-suberised cells regularly arranged in radial rows.

14. Typical structure of the bark:
Cortex.
Endodermis.
Pericycle: May be parenchymatous or sclermchymatous formed of sclereids and fibers).
Primary phloem: formed of highly compressed or reduced tissue.
Secondary phloem: constitutes the major part of the bark and known as inner bark. The secondary phloem consist of sieve tubes, companion cells, Phloem parenchyma, sclerenchyma (phloem fiber and sclereides).
All these elements are traversed by medullary rays

15. Try to remember: What is the bark of the trees consist of?
What is the peridem of the trees consist of?
Label cross section of a bark?
What are the differences between stem and root bark?

16. Complete:
Cork is a tissue of secondary origin developed in stems and roots.
Cork is formed of polygonal cells, which are either slightly radially elongated or radially flattened.
In barks, the phloem is usually collapsed,
or totally absorbed, thus the phloem is composed of phloem.

17. Cinchona bark قشر الكينا

18. .
Origin: the dried stem and root bark of Cinchona succirubra and its hybrids known as red Cinchona, C. Ledgeriana and C. calisaya and their hybrids known as yellow Cinchona, C. officinalis and its hybrids known as pale Cinchona, F. Rubiaceae

19. Cinchona bark:
Morphology: flat, curved and quill, with Lichens (white grayish spots).
rough outer surface
longitudinally striated inner surface.

20. How can you differentiate between Root bark & Stem bark?
Item
Stem bark
Root bark
l-Shape
Single or double quill.
Curved or channeled
2-Size
Larger in size
Smaller in size
3-Colour
The outer and inner surfaces have different color.
The outer and inner surfaces have one and the same color.
4-Lenticels
Present
5-Epiphytes
absent
Microscopically differences:
Phloem Fibers
Having blunt tapered ends.
Having forked ends.

21. Active constituents & Uses:
1-Alkaloids:
quinine, quinidine, cinchonine and cinchonidine
2-Tannins.
Uses:
Quinine is antimalyrial.
Quinine is used externally as hair tonic.
Quinidine is antiarrythmic.
Cinchonine and cinchonidine are antirehumatic.
Bitter Stomachic [Due to presence of Alkaloid].

22. Specific test of A.C of Cinchona:
For Tannins:-
Dry heat test: - powder in test tube, Heat Reddish Violet Fumes , after addition of 50 % alc Blue Fluorescence
Specific test for Quinine:-
Quinine produces blue fluorescence with oxygenated acids e.g. H2S04
Thalleoquin test: - acidic solution of Quinine + 1ml of Br2 water followed by addition of 1 or 2 ml (NH40H) , Green col. is produced ( Due to formation of a compound known as Thalleoquin).

23. Powder: Color: reddish brown
Taste: astringent bitter (why), Showing fragments of:
Cork cells thin walled suberized with brown content.
Phloem fibre, long, fusiform, thick wall, lignified with narrow lumen, blunt or forked apex and showing funnel-shaped pits.

24. Cinnamon & Cassia bark Item Cinnamon Cassia Origin:
The dried bark of the shoots of coppiced trees of Cinnamomum zeylanicum , F.lauraceae .deprived of most of its cortex and known as Ceylon cinnamon
The dried stem bark of Cinnamon cassia F. lauraceae
Condition:
Dry decorticated bark
Dry entire bark
Thickness:
Thin
Thick
Shape:
Compound single and double quill
Flat curved or channeled
Color:
Pale brown
Grayish brown

25. Decortication: The absence of active constituents in the outer layers.
Is the removal of the outer layers of the bark (including cork & most of the cortex) and this done because of :
The absence of active constituents in the outer layers.
Presence of large amounts of coloring material in the outer layers.
Presence of undesirable bitter constituents as in Cinnamon.

26. The different methods for preparation of barks:
Felling method: the large tree is cut down at the surface of the ground and the barks are -prepared from the stems e.g. Cassia.
Uprooting: the large tree is cut down at surface of the ground and the roots removed from soils and the barks are prepared from stems and roots e.g. Cinchona.
Coppicing: the large tree is allowed to grow to an age about 8 years and then cut down to a short distant (about 1 meter) and the bark is removed from the stems and branches. The stumps remained in the soil are allowed to grow and produce new shoots or branches and then cut down again when grow to an age to 7-8 years and the barks are prepared from the new shoots and so on. e.g. Cinnamon.

27. Microscopically differences:
Cinnamon
Cassia
Microscopically differences: - Cork &cortex: - Fiber:
- Starch granules:
- Medullary rays:
Absent (decorticated)
- Long narrow fibers
- Small in diameter
- Uniseriate to triseriate
Present
- Short thick fiber - Large
- Uniseriate

28. A.C:
Cinnamon
Cassia
Volatile oil (the major components are cinnamic- aldehyde & eugenol).
Tannins.
Mucilage.
V. oil (the major component is cinnamic aldehyde representing 85% & no eugenol.)

29. Uses of cinnamon: Stomachic (due to V.O). Antiseptic (due to eugenol).
Flavoring agent in pharmaceutical preparation

30. Powder of cinnamon:

31. Barks containing anthraquinon glycoside
Cascara & Frangula

32. The collection of Cascara and frangula:
Comment:
Cascara and frangula barks are collected and used medicinally after 1 year at least of their collection.
Because of the following:
1. Fresh barks have disagreeable odour and taste.
2. Fresh bark has an emetic effect.
3.Fresh barks contain small amounts of anthraquinon gly.(after at least 1 year of collection due to anthrone glycoside are completely convened into anthraquinon glycoside

33. Item
Cascara
Frangula
Origin:
The dried stem bark of Rhamnus Purshiana , F. Rhamnaceae, collected at least 1 year before being used medicinally**.
The dried stem bark of Rhamnus frangula, F. Rhamnaceae.
Shape:
Single quill curved or channeled
Double quill.
Outer surface:
Showing grayish white patches of *epiphytes (lichens).
Absent.

34. Cascara bark:
epiphytes

35. Item Cascara Frangula Color: Reddish brown Dark purple in color
Lenticels:
Present
Microscopically:
Sclerides
Absent
A.C
Anthraquinon glycosides, Known as Cascarasides A,B,C and D.
Anthraquinon glycosides, Known as Frangulin A and B.

36. Item Cascara Frangula Uses :
Purgative in treatment of: constipation & hemorrhoids and rectal fissure
-Purgative in treatment of constipation &hemorrhoids and rectal fissure
Chemical test:
Borntrager's test In details.
Borntrager's test In details

37. Pomegranate bark:
Origin : The dried stems and root barks of Punica granatum, F.Punicaceae
A.C:
Liquid alkaloids of pipieridine group [pelliterin, isopelliterin, methyl pelliterien].
Chemical test:
Mayer’s test: yellowish white ppt.
Uses : Anthelmintic [against tape warm].

38. Quillai bark or [Soap bark]:
Origin: The dried inner part (secondary phloem) of the bark of Quillai saponaria F. Rosaceae .
A.C:
Saponin glycosides
Chemical tests:
1- Formation of persistent froth on shaking with water.
2-Causing blood hemolysis.
Uses: Expectorant.