Organic Chemistry: Essential Oils and Taxol

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Questions and Answers

What type of bond is formed in the reaction shown?

Carbon-phosphorous bond

Carbon-oxygen bond

Carbon-carbon bond (correct)

Carbon-hydrogen bond

What is the name of the compound depicted in the diagram?

Squalene monophosphate

Isopentenyl monophosphate

Geranyl pyrophosphate (correct)

Farnesyl diphosphate

What is the leaving group in the reaction shown?

-H^+

OPP^+

OPP- (correct)

-H

What charge is present on the carbon atom before the reaction?

Positive Signup and view all the answers

What is the significance of the 'OPP' group in this reaction?

It serves as a good leaving group Signup and view all the answers

Which method is predominantly used for extracting essential oils?

Steam distillation Signup and view all the answers

What is the primary purpose of steam in the steam distillation method?

To carry the volatile oils as a vapor. Signup and view all the answers

What characteristic of essential oils enables steam distillation to be effective?

Their volatility. Signup and view all the answers

Besides steam distillation, which of the following methods is also commonly employed for extracting essential oils?

The text does not mention other methods. Signup and view all the answers

What advantage does steam distillation offer over alternative methods?

It prevents chemical alteration of the oils. Signup and view all the answers

Which structural component is necessary for the biological activity of taxol?

A four-membered oxetane ring Signup and view all the answers

What is the fundamental classification of ginkgo biloba?

It is the only species in its family Signup and view all the answers

What is the core structure of Taxol (paclitaxel)?

Taxane diterpene nucleus Signup and view all the answers

Besides the oxetane ring, what other structural feature is crucial for taxol's activity?

A complex ester side chain Signup and view all the answers

What is the common name for the plant that belongs to the Ginkgoaceae family?

Ginkgo Signup and view all the answers

Valerian is believed to promote sleep through which of the following primary mechanisms?

Increasing GABA secretion and inhibiting reuptake. Signup and view all the answers

The action of valerian on GABA reuptake leads to which effect?

Increased GABA levels in the synaptic cleft. Signup and view all the answers

What is the role of GABA in the context of valerian's effect?

It is an inhibitory neurotransmitter that promotes relaxation. Signup and view all the answers

If a compound increased GABA secretion but also promoted its reuptake, how would its effect compare to valerian?

It would have a weaker effect on sleep and relaxation than valerian. Signup and view all the answers

Which of the following best describes the combined actions of increased GABA secretion and inhibited reuptake, as seen with valerian?

It increases the amount of GABA available to the receptors, prolonging its action. Signup and view all the answers

What dosage of licorice root during pregnancy has been linked to potential brain impairments in offspring?

250 mg Signup and view all the answers

Which group is most directly affected by the consumption of licorice root during pregnancy, according to the findings?

Children later in life Signup and view all the answers

What is the potential long term health concern associated with maternal licorice root intake?

Development of brain impairments Signup and view all the answers

What aspect of a child’s health is specifically noted as potentially being impacted?

Cognitive function Signup and view all the answers

Based on the findings, what is the most accurate conclusion that can be made regarding the impact of licorice root on pregnant women?

Its effects are primarily noted on the child rather than the mother Signup and view all the answers

According to the information, what primary function does ginseng serve as an 'adaptogen'?

To help the body manage and adjust to stress. Signup and view all the answers

Which of the following benefits is associated with ginseng?

Enhancing cognitive abilities and reducing fatigue. Signup and view all the answers

A person experiencing erectile dysfunction may find which benefit from ginseng consumption?

A reduction in the symptoms of the condition. Signup and view all the answers

What is the primary way in which ginseng helps strengthen the immune system?

By enhancing the body's overall natural defenses. Signup and view all the answers

If ginseng is taken as an adaptogen, what effect may this indicate?

An increased ability to handle stress. Signup and view all the answers

Study Notes

Introduction to Terpenes (Terpenoids)

A large, structurally diverse family of natural products (>35,000)
Formed from C₅ isoprene units joined together head-to-tail or tail-to-tail
Classification based on the number of isoprene units in the carbon skeleton

Isoprene Units

Five-carbon unit (C₅)
Basic building block of terpenes
Chemical formula: C₅H₈
Also known as 2-methyl-1,3-butadiene

Mevalonic Acid Pathway

Pathway producing isopentenyl pyrophosphate (IPP)
Precursor to isoprene units
Starts with acetyl-CoA and utilizes ATP
Key enzymes include: Mevalonate kinase, 5-phosphomevalonate kinase, 5-pyrophosphomevalonate decarboxylase, isopentenyl pyrophosphate isomerase

Classification of Terpenes

Based on the number of isoprene units
Hemiterpenes (C₅)
Monoterpenes (C₁₀)
Sesquiterpenes (C₁₅)
Diterpenes (C₂₀)
Sesterterpenes (C₂₅)
Triterpenes (C₃₀)
Tetraterpenes (C₄₀)
Polyterpenes (>C₄₀)

Representative Monoterpenes

α-Phellandrene (eucalyptus)
Menthol (peppermint)
Citral (lemon grass)

Representative Sesquiterpenes

α-Selinene (celery)

Representative Diterpenes

Vitamin A

Representative Triterpenes

Squalene (shark liver oil)

Biological Isoprene Unit

Isoprene units in terpenes come from isopentenyl pyrophosphate (IPP)
IPP is derived from acetate (2 carbons) via mevalonate (6 carbons)

Carbon-Carbon Bond Formation

The key process is the nucleophilic attack of the double bond of isopentenyl pyrophosphate on the allylic carbon of dimethylallyl pyrophosphate.
This forms a new carbon-carbon bond.

After C-C Bond Formation

The carbocation loses a proton to form a double bond.
This forms geranyl pyrophosphate, a precursor to monoterpenes

From 10 Carbons to 15

A chain elongation process that adds an isoprene unit to geranyl pyrophosphate
The resulting 15-carbon compound is farnesyl pyrophosphate

From 15 Carbons to 20

Another isoprene unit is added to farnesyl pyrophosphate to form geranylgeranyl pyrophosphate (a diterpene precursor)

Cyclization

Formation of rings through intramolecular carbon-carbon bond formation
Key examples including limonene and α-terpineol

Bicyclic Terpenes

Examples: α-pinene and β-pinene

Volatile Oils (Essential Oils)

Complex mixtures of volatile, aromatic compounds
Common uses include: antimicrobial, antispasmodic, flavoring, aromatherapy, and other therapeutic applications.
Typically found in glandular structures or cells of certain plants

Steam Distillation

Common method for extracting essential oils
Botanical material heated in a still with pressurized steam.
Heat forces oils from pockets within the plant material through a tube to a condensation chamber.

Cold Pressing

Method to extract oils from citrus fruits.
Fruits are rolled and pressed to extract essential oils from the skin pouches.
The oil rises to the top of the juice and is separated from pulp by centrifugation

Enfleurage

Method to extract essential oils from delicate flowers (e.g., jasmine)
Flower petals placed on trays into an odorless oil (like fat) which absorbs the essential oil. Trays are changed regularly until the oil is saturated.

Testing Essential Oil Purity

Simple test to check if essential oils are pure, or have base oils added
Apply 1-2 drops to a tissue, and observe if it completely evaporates leaving no oily residue.

Common Properties of Volatile Oils

Liquid at room temperature
Colourless or slightly yellowish
Low solubility in H₂O
Soluble in organic solvents
Optically active
Higher refractive index
Usually lighter than water
Oxidized by O2 from air (resinification)
Do not stain filter paper (fixed oils do)
Evaporate at room temperature.
Obtained by steam distillation, water distillation, expression (citrus oils), organic solv. extraction

Phenylpropane-rich Volatile Oils

Aromatic compounds
Formed via shikimic acid
Contain C₆ phenyl ring and C₃ propane side chain (examples: cinnamon, anise, fennel, clove, nutmeg)

Cinnamon Oil

Obtained from the dried bark of the Cinnamomum tree.
Main component: cinnamaldehyde
Uses: carminative, flavoring agent, and antiseptic.
Warning: Taking high doses of cinnamon oil is possibly unsafe.

Anise Oil

Obtained from the dried ripe seeds of Pimpinella anisum,
Main component: anethol
Uses: antispasmodic, carminative, parasiticidal, and flavoring agent

Star Anise

Similar in appearance to Japanese but smaller with milder scent.
Has toxic compounds and should never be ingested if Japanese.

Fennel Oil

Obtained from the seeds of Foeniculum vulgare
Main components: trans-anethole and fenchone
Uses: remedy for digestive complaints, such as flatulence, constipation, and colic

Wormwood (Artemisia annua)

Family: Asteraceae
Contains absinthin, anabsinthin, and artemisinin (volatile oil)
Artemisinin used to treat malaria and some cancers

Feverfew

Family: Asteraceae (Chrysanthemum parthenium)
Contains parthenolide (used to treat migraine)

Camphor Oil

Extracted from the wood of camphor trees using steam distillation
Main component: D-camphor

Terpene Derivatives

Include compounds derived from the Acetate-Mevalonate pathway

Polyterpenes

Composed of many isoprene units (>40)
Often large, complex molecules

Phytol

A 20 carbon diterpene
Found in chlorophyll

Taxanes

Pharmaceutically significant diterpenes
Including paclitaxel, used as an anticancer drug

Ginkolides

Produced from extensive modification of diterpenes
Found in Ginkgo biloba (e.g. ginkgolides A, B, C, J, M and bilobolide)
Used traditionally for memory loss and as a blood flow improver

Steroidal Saponins

Less widespread than pentacyclic triterpenoid saponins
Commonly used in synthesis of sex hormones (such as testosterone and oestrogen),

Cucurbitacins

Tetracyclic terpenes found in plants of the Cucurbitaceae family (e.g., pumpkins and cucumbers)
Possess steroidal structures

Saponin Glycosides

Organic compounds producing persistent froth in water
Cause haemolysis (destruction of red blood cells) when injected intravenously

Licorice

Dried, unpeeled root of the herb Glycyrrhiza glabra
Contains Glycyrrhizic acid (sweetener) and other bioactive compounds
Has anti-inflammatory and antiviral effects, but in high doses, can have negative effects.

Essential Oils: Uses and Precautions

Vary in properties, and must be used in mixtures
Different oils have different properties.
Some may be irritating or toxic if not used correctly.

Monoterpene-rich Volatile Oils

Examples: peppermint oil, lavender oil, lemon oil, camphor, thyme oil, turpentine oil, rosemary oil

Terpenoid Components of Volatile Oils

Most monoterpenes are flavoring agents.
Some are rubefacients, sedatives, or insecticides.
Classified by degree of oxidation (hydrocarbons, alcohols, aldehydes, ketones, phenols).

How to Dilute Essential Oils

Essential oils should not be used undiluted
Dilutions should use an odorless carrier oil
Common carriers include sweet almond oil and coconut oil Important: Dilute essential oils according to recommended proportions given in the provided presentations before use.

Other Compounds

Other important information regarding each compound/plant has been extracted where possible from the presentation pages.

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Description

Test your knowledge on organic chemistry, focusing on essential oils extraction methods and the structure and classification of Taxol. This quiz covers key concepts such as bond formation, reaction mechanisms, and the significance of different molecular components. Enhance your understanding of these crucial topics in organic chemistry.