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Clinical pharmacy PharmD program Third level Phytochemistry-1 (PG-504)

Isolation: The cooling of the peppermint oil afforded menthol crystals after
fraction crystallized at different low temperatures.

Detection:

1- Colour test:

Crystals of menthol + Conc H 2SO 4 + vanillin/H 2SO 4 reagent → orange yellow
colour → add 1 ml water gives violet colour

Uses

* Local antipruritic (relieves itching).

* Topical analgesic, it is used to relieve minor aches and pains, such as muscle

cramps, headaches and similar conditions, alone or combined with chemicals
such as camphor, eucalyptus oil

* Counter irritant.

* Antiseptic

* Carminative, gastric sedative

* In oral hygiene products, flavouring agent in tooth paste, mouth wash,
candies, gums….etc.

Pharmacological Actions

Menthol can trigger the cold-sensitive TRPM8 receptors in the skin causing the
well-known cooling sensation produced when inhaled, eaten, or applied to the

skin

-Menthol activates κ-opioid receptors causing analgesic effect.

-Menthol affects GABA A receptor causing anaesthetic effect.

- Menthol is widely used in dental care as a topical antibacterial agent,
effective against several types of streptococci and lactobacilli

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