Pharmacology of Menstrual Induction and Phenols

Lecture 7: Volatile Oils - Part 3

• Oxygenated Compounds:
  • Essential oils contain various oxygenated terpenoid compounds.
  • These compounds include phenols, phenol ethers, aldehydes, ketones, esters, oxides, sulfur compounds, and nitrogenous compounds.
  • Phenols and phenol ethers are mentioned as important antiseptic and germicidal agents.
  • Classification and examples of these types are detailed in the notes.

Phenols and Phenolic Ethers

• Importance: Phenols are crucial antiseptic and germicidal agents (e.g., thymol, eugenol).
• Isolation:
  • Formation of phenolates (phenates) with alkali (water-soluble).
  • Fractional distillation
  • GC/MS and HPLC
• Note: Phenolic ethers are neutral and do not react with alkalis but form phenols upon heating.

Separation of Phenols

• Acidic Property: Phenols are weak acids and form water-soluble salts with dilute alkali.
• Separation Method: This property allows separation of phenols from other non-phenolic constituents in volatile oils.

Estimation of Phenols

• Principle: Phenols form water-soluble salts with alkalis.
• Method:
  • Add a known volume of oil to a Cassia flask.
  • Add aqueous potassium hydroxide solution (KOH) and mix well.
  • The non-phenolic portion separates into an oily layer.
  • The amount of the phenolic layer can be measured.
• Note: Use of KOH is preferred over NaOH because potassium salts of many phenols are more soluble than the corresponding sodium salts.
• Other methods include GC-MS and HPLC.

Uses of Phenols

• General uses: antiseptic, antioxidant, free radical scavenger, hypocholesterolemic, insect repellant.

Phenols & Phenol Ethers -Specific Examples

• Specific types: Thymol, Thymoquinone, 2-Eugenol, Anethole, 3-Apiole, 4-Dillapiole.
• Identification: Chemical tests (e.g., color tests with FeCl3).
• Occurrence: Specific plants or oils.
• Uses: Vary based on the specific phenol (e.g., local anesthetic, antiseptic, toothache remedies, flavoring agent, synthesis intermediates...).

1-Thymol

• Source: Oil of Thymus vulgaris (thyme).
• Isolation: Cooling the oil for crystallization.
• Identification: Thymol does not react with FeCl3, unlike carvacrol (green color).
• Synthesis: Conversion from menthol via oxidation.
• Uses: Antiseptic, disinfectant, antifungal, gargles, G.I.T. disinfectant, antioxidant, free radical scavenger, immune stimulant, cough treatment.

2-Eugenol

• Source: Clove oil (Eugenia aromatica).
• Isolation: Using 5% KOH.
• Properties: Oily liquid with clove-like odor and burning spicy taste.
• Identification: Color test with 2% alcoholic FeCl3 produces blue color.
• Uses: Local anesthetic, antiseptic, toothache remedies, restorative in dentistry, spice and flavouring agent.

1-Anethole

• Source: Oil of anise and fennel.
• Isolation: Cooling the oil to crystallize anethole.
• Properties: Has sweet odor and taste.
• Properties: Is oxidized by light and air to give products like photoanethole
• Uses: Flavoring agent in many pharmaceuticals, antioxidant, estrogenic and prolactin activity, precursor for illicit drugs.

3-Apiole and 4-Dillapiole

• Source: Parsley seed oil and dill oil respectively.
• Uses: Anti-hyperlipidemic, mild CNS activity, insect repellent, diuretic effect (kidney stones), stimulating uterine contractions (menstrual disorders), gallstones prevention.

Aldehydes and Ketones

• General: Include various chemical structures found in essential oils.
• Estimation: Condensation reactions with hydroxylamine HCl which provides quantitative estimations (oxime formation).
• This process is useful as it requires only a small sample size (1-5 ml of oil), is generally complete in 20 minutes for the reagents.
• While specific identification of all aldehydes and ketones in a mixture is not possible, it allows for the quantitatative determination of the total amount of carbonyl compounds in a sample.

Aldehyde and Ketone Examples

• 1-Citronellal:
  • Source: Eucalyptus oil and citronella oil.
  • Uses: Perfumes, soaps (lemon-like odor), citronellol (rose-like odor), insect repellent.
• 2-Citral:
  • Source: Lemongrass oil (mixture of isomers).
  • Properties: Lemon-like odor.
  • Uses: Industry, perfuming, flavoring and insect repellants.

3-Vanillin

• Source: Vanilla pods (glycoside).
• Isolation: Hydrolyzed by enzymatic action and purified using sodium bisulfite.
• Properties: Considered a phenol, and can be estimated as aldehyde using bisulfite method or as a phenol using alkali hydroxide.
• Identification: Turns blue with FeCl3.
• Uses: Flavoring agent in food, candies, perfumes and cosmetics. Also a TLC reagent.

3-Vanillin Synthesis

• Synthetic methods:
  • Oxidation of lignin (used commercially) and guaiacol
  • From eugenol

Other Compounds (Sulfur, Resins, Turpentine)

• Sulfur Containing Compounds (Allicin):
  • Source: Garlic
  • Properties: Immunostimulant, bacteriostatic, antiviral, antioxidant
• Resins:
  • General: Group of solid/semisolid substances with variable composition.
  • Properties: brittle, heavy than water, soften and melt on heating.
  • Classification (oleoresins, gum-resins, oleo-gum resins).
• Turpentine Oil:
  • Constituents: α-pinene and β-pinene.
  • Uses: pharmaceutical (mild antiseptic, insecticide), and non-pharmaceutical (solvent).

4- Cannabis Resin

• Source: Cannabis sativa (dried flowering tops).
• Constituents: Resin alcohol (Tetrahydrocannabinol and Cannabidiol)

Mastic

• Source: Mastic tree.
• Properties: A resin with Resin phenol composition.
• Uses: Anti-inflammatory, antioxidant, antibacterial, extends beyond H. Pylori eradication actions.

1-Myrrh

• Source: Commiphora species (Oleo-gum resin).
• Constituents: Volatile oil, resin, gum.
• Uses: Recent studies show potential schistosomicidal properties.

Olibanum

• Source: Boswellia carterii (Oleo-gum resin).
• Constituents: Boswellic acid, volatile oil, and bitter principal.
• Uses: Immunostimulant, expectorant, cough sedative, incense production.

This quiz focuses on pharmacological substances related to menstruation and phenolic compounds. It explores their functions, natural sources, and applications in commercial products. Test your knowledge on these vital topics in health and pharmaceutical science.