Natural product chemistry II

Question 1

What are terpenes sometimes referred to as?

Answer 1

Terpenes are sometimes referred to as isoprenes.

Question 2

What is the chemical structure of terpenes?

Answer 2

Chemically, terpenes have the isopentane skeleton.

Question 3

How do terpenes contribute to plants?

Answer 3

Terpenes contribute to many of the aromas associated with plants.

Question 4

How are terpenes derived?

Answer 4

Terpenes are derived from extensive reactions between two C5 units, namely dimethylallyl pyrophosphate (DMAPP) and isopentenyl pyrophosphate (IPP)

Question 5

What are the classifications of terpenes based on their carbon content?

Answer 5

Terpenes are classified into:

Monoterpenes (C10)
Sesquiterpenes (C15)
Diterpenes (C20)
Triterpenes and steroids (C30-derived)
Tetraterpenes (carotenoids, C40)

Question 6

What are major constituents of the volatile oils common in plants?

Answer 6

Monoterpenes are major constituents of the volatile oils that are common in plants.

Question 7

How are monoterpenes produced?

Answer 7

Monoterpenes are produced by the reaction between dimethylallyl pyrophosphate (DMAPP) and isopentenyl pyrophosphate (IPP) in the presence of the enzyme prenyltransferase.

Question 8

What is the first product in the reaction that produces monoterpenes?

Answer 8

The first product in the reaction is geranyl pyrophosphate (a C10 unit).

Question 9

Provide examples of monoterpenes.

Answer 9

Examples of monoterpenes include β-citronellol, thymol, and limonene.

Question 10

How are monoterpenes utilized in the food and cosmetic industries?

Answer 10

Monoterpenes, with highly characteristic odors and tastes, are widely used in the food and cosmetic industries in flavorings and perfumes

Question 11

What is the starting unit for compounds in the diterpene class?

Answer 11

The starting unit for compounds in the diterpene class is farnesyl pyrophosphate (FPP).

Question 12

What is the most important sesquiterpene from a pharmaceutical perspective?

Answer 12

The most important sesquiterpene from a pharmaceutical perspective is artemisinin, an antimalarial product from sweet wormwood (Artemisia annua, Asteraceae).

Question 13

How are members of the diterpene class formed?

Answer 13

Members of the diterpene class are formed by the reaction of farnesyl pyrophosphate (FPP) with isopentenyl pyrophosphate (IPP). An example is paclitaxel, used for the treatment of ovarian cancers

Question 14

What are examples of molecules included in the triterpenes category?

Answer 14

Examples of molecules in the triterpenes category include steroids (e.g., testosterone) and sterols (e.g., β-sitosterol). Triterpenes are also components of resins and resinous exudates from plants, such as frankincense and myrrh.

Question 15

What are C40 natural products derived from?

Answer 15

C40 natural products, known as tetraterpenes, are derived from the reaction of two molecules of geranyl pyrophosphate (C20).

Question 16

What is a characteristic feature of tetraterpenes?

Answer 16

Tetraterpenes are highly pigmented natural products and are responsible for the vibrant colors of certain plants.

Question 17

Provide examples of tetraterpenes and the plants associated with their colors.

Answer 17

Examples of tetraterpenes include:

The orange of carrots, due to β-carotene.
The brilliant red color of tomatoes (Lycopersicon esculentum) and peppers (Capsicum anuum), which is due to lycopene and capsanthin

Question 18

What are the two main components of glycosides?

Answer 18

Glycosides consist of two parts: the sugar and the aglycone.

Question 19

What can the aglycone of a glycoside be?

Answer 19

The aglycone of a glycoside may be a terpene, a flavonoid, a coumarin, or practically any other natural product.

Question 20

How are C-glycosides different from O-glycosides?

Answer 20

C-glycosides have the sugar attached to the aglycone through a carbon–carbon bond, while O-glycosides have the sugar connected to the aglycone through an oxygen–carbon bond.

Question 21

What is an example of a cyanide glycoside used by plants as a chemical defense?

Answer 21

Amygdalin is an example of a cyanide glycoside used by plants as a chemical defense.

Question 22

What family of plants produces glycosides known as glucosinolates?

Answer 22

The Brassicaceae family, which includes cabbages, sprouts, and mustards, produces a group of glycosides known as glucosinolates.

Question 23

Provide examples of glucosinolates.

Answer 23

Examples of glucosinolates include acrinylisothiocyanate and allylisothiocyanate.

Question 24

What is the primary effect of cardiac glycosides found in many plants?

Answer 24

have a profound effect on heart rhythm

Question 25

What is the most widely used cardiac glycoside?

Answer 25

Digoxin- in congestive heart faiure

Question 26

What are anthraquinone glycosides known for?

Answer 26

Anthraquinone glycosides have long been known for their laxative properties.

Question 27

Provide examples of plants containing anthraquinone glycosides used for their laxative properties.

Answer 27

Plants such as cascara (Rhamnus purshiana), aloe (Aloe vera), and senna (Cassia angustifolia, Cassia senna) contain anthraquinone glycosides and are used for their laxative properties.

Question 28

How is aloe used medicinally, and what is its major anthraquinone glycoside component?

Answer 28

Aloe is used as a laxative as well as a treatment for minor burns. Its major anthraquinone glycoside component is barbaloin.

Question 29

What is the main active principle in cascara, and how is it used?

Answer 29

The main active principle in cascara is the diglucoside cascaroside, and it is used as a laxative.

Question 30

What are the active constituents in senna, and for what purpose is it widely used?

Answer 30

The active constituents in senna are sennosides A and B. Senna is widely used in the treatment of constipation.

Question 31

Provide examples of alkaloids belonging to the Pyridine, piperidine, and pyrrolizidine class, and mention their uses

Answer 31

nicotine -used in smoking cessation
coniine -poison in traditional medicine
arecoline -used to alleviate fatigue in traditional medicine

Question 32

Name some alkaloids classified as Phenylalkylamine, and state their medical applications.

Answer 32

ephedrine -used in the treatment of severe asthma
mescaline -consumed in traditional medicine to induce dreams and hallucinations in religious ceremonies
colchicine -used in the treatment of gout

Question 33

What are some examples of Quinoline alkaloids, and how are they used medicinally?

Answer 33

quinine -used in the treatment of malaria
quinidine -used to treat type I cardiac arrhythmias

Question 34

What is the medical application of Reserpine, an Indole alkaloid?

Answer 34

Reserpine is used in the treatment of hypertension.

Question 35

How is Physostigmine, an Indole alkaloid, utilized in medicine?

Answer 35

Physostigmine is used as a lead molecule for the synthesis of neostigmine and pyridostigmine, which are used to treat myasthenia gravis, a rare disease characterized by severe muscle weakness.

Question 36

Provide examples of Tropane alkaloids and mention their medical uses.

Answer 36

hyoscyamine-used to treat acute arrhythmias and dilate the pupil of the eye for ophthalmic examinations
cocaine -used to control severe pain in patients with terminal cancer

Question 37

What are some examples of Xanthine alkaloids, and how are they used medicinally?

Answer 37

caffeine -used for its CNS stimulant properties
theophylline -used in the treatment of asthma

Question 38

How is Pilocarpine, an Imidazole alkaloid, employed in medicine?

Answer 38

Pilocarpine is used in the treatment of glaucoma.