Volatile Oils: Limonene and Humulene

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Questions and Answers

What is the primary active component found in the volatile oil of lemon peel?

Limonene (correct)

Borneol

Menthol

Linalool

Which volatile oil constituent is known for its significant anti-inflammatory effects?

Humulene (correct)

Cineole

Eucalyptol

Kaurene

Which compound has demonstrated anti-tumor effects against pancreatic and breast cancer?

Limonene (correct)

Kaurene

Hesperidin

Myrcene

What type of alcohol is menthol classified as?

Monocyclic Alcohol Signup and view all the answers

What is the source plant for the volatile oil of turpentine?

Pinus palustris Signup and view all the answers

Which property of limonene contributes to its potential use in cancer therapy?

Antioxidant activity Signup and view all the answers

Which of the following volatile oils is derived from the Humulus lupulus plant?

Rectified turpentine oil Signup and view all the answers

What mechanism of action has been observed with limonene against cancer cells?

Induction of cell necrosis Signup and view all the answers

What is a primary use of zingiberol?

Antiemetic Signup and view all the answers

What mechanism contributes to the cardiovascular activity of zingiberol?

Inhibition of thromboxane synthesis Signup and view all the answers

Which side effect is associated with menthol?

Gallstones Signup and view all the answers

What is the first step in the biosynthesis process to produce camphor from geranyl pyrophosphate?

Cyclisation of linaloyl pyrophosphate Signup and view all the answers

How does menthol exert its cytotoxic effects on cancer cells?

By inhibiting expression of topoisomerase I and II Signup and view all the answers

What is a key step in the biosynthesis of menthol?

Dehydration of terpineol Signup and view all the answers

Which of the following properties does camphor NOT possess?

Stimulate appetite Signup and view all the answers

What type of compound is camphor classified as?

Bicyclic terpene ketone Signup and view all the answers

What effect does camphor have when applied to the skin?

Stimulates nerve endings Signup and view all the answers

Which component is a major constituent of cinnamon oil?

Cinnamaldehyde Signup and view all the answers

Which of the following is a common property of zingiberol?

Antifungal Signup and view all the answers

What is the natural source of camphor?

Cinnamomum camphora Signup and view all the answers

What is one of the uses of spearmint according to the content provided?

Calm the nervous system Signup and view all the answers

Thymol, an active ingredient in some mouthwashes, is extracted from which plant?

Thymus vulgaris Signup and view all the answers

What notable effect do aldehyde volatile oils, such as citral and cinnamaldehyde, have?

Promote relaxation Signup and view all the answers

What potential risk does applying camphor to broken skin present?

Higher absorption rate Signup and view all the answers

What are the primary uses of thymol?

Antiseptic and treatment for digestive issues Signup and view all the answers

Which constituent is found in clove oil?

Eugenol Signup and view all the answers

What is one of the uses of anethole?

Flavoring and carminative Signup and view all the answers

Which of the following statements about nutmeg is true?

Nutmeg contains psychoactive properties when ingested excessively. Signup and view all the answers

Which constituents are found in eucalyptus oil?

1,4-Cineole and 1,8-Cineole Signup and view all the answers

What is a notable sensory characteristic of eucalyptus oil?

It has a fresh camphor-like smell. Signup and view all the answers

Why should anethole be preserved in light-resistant containers?

It degrades when exposed to light. Signup and view all the answers

What are the effects of ingesting large amounts of nutmeg?

Flushing of the skin and tachycardia. Signup and view all the answers

Study Notes

Volatile Oils

Hydrocarbon Volatile Oils
- Lemon peel (Synonym: limon)
  - Origin: outer rind of fresh ripe Citrus limon fruit (Rutaceae).
  - Constituents: terpene (limonene), aldehyde, volatile oil, coumarins, flavonoids (rutin, hesperidin)
  - Research shows limonene has significant antioxidant and cytotoxic activity in mouse leukemia cells, impacting cells via necrosis and apoptosis.
- Types of Hydrocarbons:
  - Monocyclic (e.g., limonene in citrus)
  - Dicyclic (e.g., Pinene)
  - Acyclic (e.g., Myrcene)
  - Sesquiterpene (e.g., Cadinene)
- Limonene: Further studies show anti-tumorigenic effects against pancreatic and breast cancer. Limonene exhibits antioxidant, radical scavenging, and cytotoxic activity in several model systems for those cancers. It has strong anti-inflammatory, antiproliferative, and anti-invasive activities along with potential anti-angiogenic effects.
Humulene:
- A naturally occurring monocyclic sesquiterpene from Humulus lupulus Cannabinaceae.
- Shown to produce anti-inflammatory effects, potentially valuable in managing inflammatory diseases.
- Similar effects to dexamethasone; reduces edema formation caused by histamine injections.
- Inhibits tumor necrosis factor-α (TNF-α) and interleukin-1β.
Kaurene:
- A diterpene found in Agathis plants.
- Exhibits potent anti-tumor activity by inhibiting cell proliferation.
Oil of Turpentine (Synonym: spirit of turpentine, rectified oil of turpentine)
- Origin: rectified volatile oil distilled from the oleoresin of Pinus palustris (Pinaceae).
- Constituents: α- and β-pinene, camphene
- Primarily used as an external counterirritant, rubifacient, fragrance, and flavoring agent.
- Rectified turpentine oil:
  - Derived from Humulus lupulus (Cannabinaceae)
  - Consists of β-myrcene
  - Used as a local irritant, expectorant, diuretic, and urinary antiseptic
Alcoholic Volatile Oils
- Acyclic Alcohols:
  - Methyl, ethyl, isobutyl, isoamyl, hexyl, and higher aliphatic alcohols are present, typically removed during steam distillation due to water solubility.
- Monocyclic Alcohols:
  - Menthol, a key example
- Bicyclic Alcohols:
  - Borneol, a bicyclic terpene
Sesquiterpene Alcohols:
- Includes zingiberol, found in Zingiber officinale.
- Used as an antiemetic, carminative, and in treating hyperemesis gravidarum as well as postoperative nausea and vomiting
- Possesses cardio vascular properties mainly due to the inhibition of prostaglandin synthetase; also inhibits thromboxane synthesis, and lowers cholesterol levels. It has antifungal, antibacterial and anthelmintic properties.
Peppermint Oil
- Origin: dried leaves of Mentha piperita (Labiatae)
- Constituents: menthol, pinene, limonene, resin, tannin
- Uses: pharmaceutical aid (flavor enhancer), carminative, stimulant, counterirritant, antibacterial, antiviral, antispasmodic, and anti-flatulence.
- Menthol has cytotoxic effects on murine leukemia cells in a concentration-dependent manner. Menthol inhibits topoisomerase I and II, impacting prostate and bladder cancer cells and reducing their invasive potential.
Adverse Effects (Menthol):
- Gallstones, obstructed bile ducts, gall bladder inflammation and severe liver damage.
- Skin irritation in burns and sunburns
- Internal use can be a depressant to the heart.
Biosynthesis of Menthol Pathway: Neryl p.p. → Terpineol → Terpinolene → Piperitone → Menthone → Menthol
Key step in menthol biosynthesis: Dehydration of Terpineol to Terpinolene, a reaction where NADPH2 is an essential cofactor in the reduction reaction.
Menthol exists as levo(-) (from natural sources) and racemic (+) (synthetic) forms.
Ketone Volatile Oils
- Monocyclic: Menthone, Carvone, Pulegone
- Di/Bicyclic: Camphor
- Non-Terpenic:
- Important drugs are Camphor, Spearmint, and Caraway
Camphor:
- Origin: Cinnamomum camphora (Lauraceae), occurs as crystalline product in clefts of the wood of the plant.
- Biosynthesis: Geranyl pyrophosphate → Linaloyl pyrophosphate→ Bornyl pyrophosphate → Borneol → Camphor
- Properties: readily absorbed through skin, creates cooling sensation (similar to menthol), local anesthetic and antimicrobial, anti-itch. Used topically to increase blood flow and as a counter-irritant, reducing pain and swelling by causing irritation. It is important to avoid broken skin because camphor can quickly absorb into the body and potentially cause poisoning due to high concentration.
Spearmint:
- Origin: Mentha spicata (Labiatae)
- Constituents: (-) carvone, (-) limonene, phellandrene
- Use: carminative, stimulant, flavoring agent.
Dill:
- Origin: Anethum graveolens (Apiaceae)
- Constituents: carvone, limonene
- Use: carminative, flavoring agent, infant's gripe water, antispasmodic, bacteriostatic, calming effect, menstrual cycle regulation.
Aldehyde Volatile Oils:
- Acyclic: Citral (cinnamal)
- Cyclic: Aromatic (cinnamon oil)
- Aldehyde oils have a calming effect on the nervous system, reducing stress.
Cinnamon:
- Origin: Dried bark of Cinnamomum verum (Lauraceae)
- Constituents: Cinnamaldehyde (major compound)
- Benefits: regulates blood sugar levels, reduces cholesterol levels, aids digestion, relieves sinus congestion, joint pain, muscle stiffness, reduces inflammation and arthritis pain, prevents tooth decay, improves circulation, relieves menstruation cramps.
Phenolic Volatile Oils (Thyme)
- Origin: Dried leaves and flower tops of Thymus vulgaris (Labiatae)
- Constituents: Thymol, carvacrol
- Thymol is a powerful antibacterial and antiseptic agent, effective against various bacteria (E. coli, Pseudomonas aerogenosa, Staphyllococcus aureus, and Bacillus), and also has significant antifungal activity across different fungi. Thymol benefits in reducing bloating spasms, boosting appetite and treating candidiasis, gastroenteritis and digestive tract issues.
Clove Oil:
- Origin: Dried flower buds of Eugenia caryophyllus (Myrtaceae)
- Constituents: Eugenol, gallotannic acid, oleanolic acid, vanillin, chromone, eugenin
- Use: flavoring, stimulant, aromatic, antiseptic, dental analgesic, and antibacterial agent.
Phenolic Ether Volatile Oils (Anise)
- Origin: Dried ripe fruits of Pimpinella anisum (Apiaceae)
- Constituents: Anethole, methyl chavicol, pinene, linalool, anisaldehyde
- Use: flavoring, aromatic stimulant, carminative. Anethole is a colorless or pale yellow liquid that solidifies to a crystalline mass at lower temperatures. It has a sweet taste and aroma of anise..
Nutmeg:
- Origin: Dried kernels of Myristica fragrans (Myristicaceae)
- Constituents: Myristicin, safrole, eugenol
- Use: flavoring agent, carminative, condiment, traditional medicine (infantile diarrhea). Nutmeg has psychoactive and hallucinogenic properties; however, excessive consumption can lead to adverse effects like skin flushing, tachycardia, and reduced saliva production.
Oxide Volatile Oils (Eucalyptus)
- Origin: Dried leaves of Eucalyptus globulus (Myrtaceae)
- Constituents: 1,4-Cineole, 1,8-Cineole, resins, tannic acid
- Properties: Fresh camphor-like smell, spicy and cooling taste; insoluble in water but miscible with ether and ethanol, boiling point reaches 176°C. Eucalyptol forms crystalline adducts with hydrohalic acids and phosphoric acid which aids in purification processes.
- Use: Pleasant aroma and taste, used in flavorings, fragrances and certain cosmetics. It can also be a flavoring agent at low levels, used for mouthwash and cough suppressants.
Ester Volatile Oils (Wintergreen Oil)
- Origin: Gaultheria procumbens (Ericaceae)
- Constituents: Methyl salicylate
- Use: Topical treatment (diluted) for muscle aches, arthritis, edema, poor circulation, headaches, inflammation, eczema, psoraisis, gout, ulcers; aroma therapeutic uses; added to toothpaste, chewing gum, and soft drinks.
- Risks of excessive consumption are similar to aspirin.

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Description

Explore the fascinating world of volatile oils with a focus on hydrocarbon compounds such as limonene and humulene. This quiz covers their origins, constituents, and significant biological activities, including anti-tumorigenic and antioxidant effects. Test your understanding of these essential oils and their potential health benefits.