PharmacognosyPharmacognosy IIII

Herbs

Lecture 1By

Dr. Rola Milad

Herbs

Content:Introduction to herbs.

Herbs containing Volatile oil e.g. Mentha & Thyme.Herbs containing Alkaloids e.g. Lobelia, Hyoscyamus & Catharanthus.

Herbs containing Resin e.g. Cannabis.Thallophytes.

Miscellaneous herbs.

Definition of Herb

In Botany: a plant with non-woody & non permanent stem, which dies after fruiting.

In Pharmacognosy: it is a drug formed of a tender part of the plant axis (stem) together with the leaves, flowers & fruits.

Examples:1. Upper part of the aerial shoot i.e. tops e.g. Cannabis.2. Whole aerial parts e.g. Lobelia.3. Whole undifferentiated plant body or thallus e.g. Carrageen &

Ergot.

HerbHerbs are collected from:

1. Annual plants [live for one season & die after production of seeds].

2. Biennial plants [live for 2 seasons before production of seeds & then die].

3. Perennial plants [live for more than 2 years, surviving e.g. trees].

Stem1. General characters.2. Shape.3. Kind.4. Branching.5. Surface.6. Fracture.7. Structure.8. Secondary thickening.

1- General Character of Stem

Main axis.Main axis.

Bearing leaves & flowers.Bearing leaves & flowers.

Nodes & internodes.Nodes & internodes.

Aerial or subterranean.Aerial or subterranean.

Conducting water & minerals Conducting water & minerals to the leaves & the elaborated to the leaves & the elaborated food from the leaves to the food from the leaves to the root.root.

2- Shape of Stem

1. Cylindrical.

2. Angular: with angles & sides; It may be:

A. Triangular.B. Quadrangular or

square.C. Pentagonal.

3. Ribbed: marked with alternate ridges & furrows e.g. Broom tops.

Cylindrical

stem

Ridged

stem

2- Shape of Stem (cont’d.)

2. Winged: marked with wings e.g. Lobelia.

3. Flattened or Collapsed:either normally or by compression or due to shrinkage during drying e.g. Belladonna.

4. Tortuous: Twisted, usually by winding e.g. Convolvulus. Winged stem

3- Kind of the Stem

1. Herbaceous:Soft, easily broken,usually green e.g. Mentha.

3- Kind of the Stem (cont’d.)

2. Succulent:Thick, Fleshy due to stored water e.g. Euphorbia.

3- Kind of the Stem (cont’d.)

3. Woody:In case of shrubs & trees with large amounts of secondary xylem e.g. Eucalyptus. It is usually covered with cork.

3- Kind of the Stem (cont’d.)

4. Suffruiticose or shrubby stem: When lower parts are woody & herbaceous in the upper part e.g. Thyme.

3- Kind of the Stem (cont’d.)

5. Culm:When having hollow internodes & enlarged nodes e.g. Maize.

3- Kind of the Stem (cont’d.)

6. Creeping:With the main axis of plant lies along the ground. At each node, roots & aerial shoots are given.

3- Kind of the Stem (cont’d.)

7. Runner:when it is a prostrate branch, where the end of the branch on coming in contact with the soil becomes rooted & turned upwards to give a new young shoot e.g. Strawberry.

3- Kind of the Stem (cont’d.)

8. Climbing:When it attaches itself to a support by means of tendrils or hooks due to its low content of supporting elements e.g. Piper.

3- Kind of the Stem (cont’d.)

9. Twining:Winding itself around a support e.g. Convolvulus.

4- Branching of the Stem1. Axillary or lateral:

a) Monopodial or Racemose or IndefiniteBranching; in which the main axis continues to grow, giving off lateral branches that don’t exceed length.

b) Sympodial or Cymose or Definite Branching; inwhich main axis stops growing because apical bud is destroyed or developed into flower ortransformed into tendrils.

2. Dichotomous or Apical: in Thallophytes e.g. Chondrus.

Dichotomusbranching

5- Surface of the Stem

1. Smooth or glossy.2. Rough.3. Glabrous.4. Hairy.5. Spiny.6. Striated or wrinkled.

6- Fracture of the Stem1. Short: when breaks quickly & straight across smooth fractured

surface.

2. Fibrous: when resist during breaking showing fibrous projections protruding from the broken surface.

3. Splintery: when breaking irregularly giving jagged projecting points in the broken surfaces.

4. Flexible: when readily bending & breaks only by twisting.

5. Horny: when it is hard to break.

6. Granular: when the broken surfaces show grain-like appearance.

T.S. in T.S. in DicotDicot stemstemT.S. in Monocot stemT.S. in Monocot stem

7- Structure of the Stem

7- Structure of Dicot Stem

1. An epidermis.2. A cortex.3. An endodermis. 4. A pericycle.5. Vascular bundle.6. Pith.

Stele

7- Structure of the Stem (cont’d.)

1. Epidermis:Outermost layer.Polygonal, axially elongated cells.Shows stomata & trichomes.

2. Cortex:Narrow in Dicotyledons & absent in monocot.It exhibits 3 regions:

Outer region: usually formed of collenchyma or parenchyma.Middle region: parenchyma but may show sclerenchyma e.g. Broom tops.Inner region (endodermis): with no intercellular spaces. The cells may be cutinised or lignified (Casparian strip) e.g. Lobelia, or numerous starch (Starch sheath) e.g. Solanaceous herbs.

7- Structure of the Stem (cont’d.)

3. The Stele:A. Pericycle:• Outer sheath of the vascular bundles.• vary in thickness from a single layer to

generally several layers.• It may be:

Parenchymatous.Isolated groups of fibres e.g. Solanum.Occasionally sclerenchyma e.g Cinnamon.

7- Structure of the Stem (cont’d.)B. Vascular Bundle:

Collateral.Bicollateral.Concentric {vasocentric or amphivasal).

Remember: Phloem: sieve tubes + phloem parenchyma+ phloem fibres.Cambium: intra-fascicular or inter-fascicular.Xylem:

Lignified, formed either of 1ry xylem only or it may show a little amount of 2ry tissues. In stems, xylem is always endarch.Xylem consists of vessels of various types of thickening + wood fibres + wood parenchyma + tracheids.

7- Structure of the Stem (cont’d.)

C- Pith:Parenchyma in the young stems.

contain starch, calcium oxalate crystals, mucilage or tannins, scattered isolated or grouped sclerenchymatous cells.

The pith may be solid or hollow.

88-- Secondary Secondary

ThickeningThickening

Herbs containing Volatile Oil

Mentha.Thyme.

Thyme Mentha

Syn.:Herba Thymi; CommonThyme

Origin:Dried aerial parts of Thymus vulgaris & other Thymusspecies, Family Labiatae(Lamiaceae)

Syn.: Herba Menthae Piperitae;Peppermint.

Origin:Dried leaves & flowering topsof Mentha piperitaFamily Labiatae (Lamiaceae)

Mentha

Thyme

Thyme Mentha

Stem: quadrangular, grayish-brown or purplish & hairy.

*suffruiticoseLeaves : opposite decussate,

*sessile or shortly petiolate.

Inflorescence: verticillaster.

Fruit: nutlet.

Morphology: Stem: quadrangular, green to dark purple, nearly glabrous; HerbaceousLeaves: opposite decussate, petiolate; ovate lanceolate, light or dark green with purplish tinge, acute apex; sharply serrate margin.

Inflorescence: verticillaster.

Fruit: nutlet.

Thyme Mentha

Quadrangular or circular.Collenchyma is one continuous layer.Narrow pith & wide xylem.Hairy; As in Mentha

Non-glandular hair (Unicellularconical & bent hair)***.

Diacytic stomata.Odor: aromatic.Taste: aromatic, spicy.

Histology: Outline: quadrangular.Cortex: collenchyma in the

corners only.Narrow xylem & wide pith.Less hairy; Glandular hair: (Labiaceous & Capitate).Non- glandular hair: (multicellularuniserriate).*****Diacytic stomataOdor: aromaticTaste: aromatic followed by a cold sensation

Mentha

Diacytic stomata

Labiaceous hair

Capitate hair

Non gl. Hair

Spherical Pollen grain

Thyme

Diacytic stomata, covered with striated cuticle

Bent hair

Labiaceous hair

Spherical Pollen grain

Thyme Mentha

1% volatile oil (containingphenolic compounds, mainly thymol & carvacrol).

TanninsFlavonoids*****.Saponin.

Active constituent:

Volatile oil (0.7 to 1.5%), which contains up to 78% of free menthol & up to 20% of menthol combined as esters.

6 to 12 % tannin (higher).Flavonoid.

Thyme Mentha

1- Respiratory tract:****Expectorant (secretolytic, secretomotor, disinfectant & antispasmodic) in cases of whooping cough, bronchitis.Disinfectant in inhalations.

2-G.I.T:Carminative.Digestive.Antispasmodic (Flavonoids)Anthelmintic (vermifuge).Antimicrobial.

The oil should be administered in the form of enteric-coated capsules.

Uses & actions:G.I.T:-1

Spasmolytic.Carminative.Digestive.Anti-emetic.Promotion of liver & gall bladder function (choleretic & cholagogue).

2- Externally:Locally anesthetic***.Antiparasitic.Antipruritic.

3- Respiratory tract:Decongestant.

Thyme Mentha

1. Cough syrups.2. Dental preparations as

Antiseptic.3. Anthelmentic.

Pharmaceutical preparation:1. Tooth paste.2. mouth washes & gargles.3. Soft gelatin capsules.4. Aromatherapy****.Aromatherapy is now a significant Complementary therapy involving the use of volatile oils to heal or improve well being

Pharmaceutical Preparation

Thyme Mentha

1. Positive microchemicaltests with Sudan lll.

2. Special chemical test:Thymol crystals + 1ml ofglacial acetic acid + fewdrops conc. H2SO4 + 1 drop ofHNO3 → a deep bluish greencolor is developed.

Chemical Tests:1. Positive microchemical tests

with Sudan lll.

2. Special chemical test:Menthol crystals + few dropsConc. H2SO4 + few drops Of vanillin / H2SO4 → orange-yellow color + H2O → violet color