pharmacognosy for pharmacy

1. ISOLATION IDENTIFICATION AND
ANALYSIS OF MENTHOL
By: Dr Vineet Mittal 14-09-2020

2. BIOLOGICAL SOURCE
 Herb (Peppermint)
 It is obtained from the dried leaves and flowering
tops of different species of Mentha (Family-
Labiatae)
- Mentha piperita Linn. (Peppermint)
- M. spicata ( spearmint)
- M. aquatica (water mint),
- M. longifolia (Horse mint)
- M. rotundifolia (Apple mint)
- M. arvensis (Japanese peppermint)

3. MORPHOLOGICAL CHARACTERS
 Odour: aromatic characteristic
 Taste: aromatic followed by cooling sensation
 Stem: - Herbaceous, perennial,Quadrangular,Green to
dark purple, Nearly glabrous, with scattered deflected
hairs.
 Leaves: - opposite decussate, petiolate
 Shape - ovate and lanceolate
 Color- Light or dark green with purplish tinge
upper surface: dark green nearly glabrous
lower surface: light green, hairy on the veins
 Apex: acute
 Base: acute or rounded
 Margin: sharply serrate
 Petiole: long slightly hairy

4. MENTHA PIPERITA HERB

5. USES
 G.I.T. -Spasmolytic, Carminative, Digestive, Anti-
emetic, Promotion of liver & gall bladder function
(choleretic & cholagogue)
 Local anesthetic
 Anti-parasitic
 Anti-pruritic
 Respiratory tract- Decongestant.
 In Pharmaceutical preparations: Tooth paste, mouth
washes & gargles, Soft gelatin capsules,
Aromatherapy
 Also used in pharmaceutical preparations as local
antipruritic, counter-irritant and antiseptic

6. PROPERTIES
 Moleular formula- C10 H20 O
 White solid crystalline in nature
 M.Pt- 41-43˚C
 Soluble in organic solvents like alcohol, Chloroform,
Pet ether, slightly soluble in water

7. CHEMICAL CONSTITUENTS
 Volatile oil ( 0.7-1.5%) contains free Menthol
(78%) Menthol esters (20%)
 Tannins (6 to 12 %)
 Flavonoids
Menthol

8. EXTRACTION AND ISOLATION
 STEAM DISTILLATION
 SOLVENT EXTRACTION (when oil is in low
amount)
Solvents like hexane and ethanol is used
Plant material are treated with the solvent to
produces a waxy aromatic compound called a
“concrete”
mixed it with alcohol to release the oil particles
Pass it through a condenser to separate out oil

9. MACERATION
The plant material is powdered
solvent is added and the mixture is kept
for 1 week
liquid is strained and solid residue is pressed to
recover any remaining liquid
Strained and expressed liquids are mixed

10. ENFLEURAGE
The fat is warmed to 500˚C
Liquid fat is covered with flower petals and kept for
several days until it saturated with essential oils
Remove the saturated petals, and the fat is treated with
ethanol
The alcoholic distillate is then fractionally distilled under
reduced pressure to remove the solvent
Recently the fat is replaced by coconut charcoal, due to greater
stability and higher adsorptive capacity.

11. IDENTIFICATION
 M. Pt- 41-43˚C
 Chemical test:
 Positive microchemical test with Sudan III
 Special chemical test:
Menthol crystals + H2SO4 + vanillin
orange yellow color
violet color
Add water

12.  Mixed few drops with 5 ml nitric acid & heated on
water bath
Within 5 min. liquid develops blue color
further heating shows cooper color fluorescence
After sometime its become yellow.

13. ANALYSIS OF MENTHOL
 By Physical methods
 TLC
Sample preparation – Dissolved 1mg of menthol in 1ml of
methanol
Stationary phase - Silica gel G
Standard sample - Menthol
Mobile phase – Pure Chloroform
Detecting agent – 1% vanillin- Sulphuric acid reagent
heat the plate 110˚C for 10 minutes
RF Value – 0.48
 HPLC
 HPTLC
 UV-Visible spectrophotometer

14. IR SPECTRUM OF MENTHOL

15. HPLC ANALYSIS
Column:Luna® 5 µm C8 Column 150 x 4.6 mm,
 Dimensions:150 x 4.6 mm ID
 Elution Type:Isocratic
Elution A:Methanol
Elution B:Sodium phosphate buffer pH 2.5
 Flow Rate:0.6 mL/min
 Coloumn Temp: ambient
 Detection:UV-Vis Abs.@ 242 nm (22°C)
 HPTLC
 GC analysis