Glycosides 3

Question 1

Facts about Saponins

Plants containing saponins give __________ solutions in water – ___________ on shaking – and hence have been used as _______________

Saponins have a ______, ________ taste and are ______________.

If they come into contact with blood then can _______________

Answer 1

Plants containing saponins give colloidal solutions in water – foam on shaking – and hence have been used as detergents

Saponins have a bitter, acrid taste and are sternutatory.

If they come into contact with blood then can haemolyse red blood cells – can be toxic!

Question 2

Hydrolysis of saponin gives……

Answer 2

Hydrolysis gives ‘sapogenins’ (aglycones).

Question 3

List the two types of sapogenins known…

Answer 3

triterpenoids and steroidal

Question 4

An example of a Triterpenoid Saponin is…..

Answer 4

Liquorice (root) Glycyrrhiza glabra (Leguminosae

Question 5

State the traditional use of Liquorice

Answer 5

used as a flavouring agent and as a soothing agent for GI tract related problems

Question 6

What is the main constituent of liquorice?

Answer 6

glycyrrhizin – w. sol., sweet (50 x that of sugar), K+ and Ca2+ salt of glycyrrhiznic acid.

Question 7

Hydrolysis of glycyrrhizinic acid gives…….

Answer 7

Glycyrrhetinic acid and two molecules of glucuronic acid.

Question 8

Uses of Liquorice

Answer 8

As an expectorant in cough mixtures and in confectionery. Has a sweet taste and hence used in confectionery and to mask taste of bitter drugs.

Question 9

Use of Glycyrrhizic acid

Glycyrrhizic acid ameliorates ___________ by the regulation of inflammation and ______________.

These observations indicated that GA has ______________ effects against ___________, and these effects might be related to the ___________and __________________ in the myocardium.

Answer 9

Glycyrrhizic acid ameliorates myocardial ischemic injury by the regulation of inflammation and oxidative state.
These observations indicated that GA has cardioprotective effects against MI, and these effects might be related to the activation of Nrf-2/HO-1 and inhibition of NF-κB signaling pathway in the myocardium.

Question 10

What is the use of Betulinic acid?

Betulinic acid, a __________- from _____________ species

Answer 10

Betulinic acid, a triterpenoid from Betula species, has been found to reduce hyperglycemia by interaction with a G-protein bile acid receptor 1

Question 11

Why are Saponins/Sapogenins pharmaceutically important?

Answer 11

Saponins/Sapogenins are pharmaceutically important due to their structural similarity to physiological steroids, e.g. progesterone, oestrogen, and hydrocortisone.

Question 12

What steroid is used to treat patients seriously ill with Covid 19?

Answer 12

‘An anti-inflammatory drug called dexamethasone

Question 13

State how to prepare bioactive different steroids or any of the steroid hormones…..

WHICH IS THE BEST AND WORST AND WHY?

_____________:

Technically possible, but has to be cost-effective and overcome problems of ___________________. Steroids have a number of _______________.

_________:
Require suitable __________ to start synthesis from. It has to be conveniently ___________________.

Answer 13

I     Isolate from the source

Not usually practical because they are present in very low concentrations (e.g. oestrogens from pregnant horses’ urine).

II    Total synthesis

Technically possible, but has to be cost-effective and overcome problems of racemisation. Steroids have a number of chiral centres.

III Partial synthesis

Require suitable raw material to start synthesis from. It has to be conveniently available and easy to extract from the raw material. This is the preferred method and a variety of raw materials are utilised

Question 14

List two industrially important plant sterols obtained from soya beans oil

Answer 14

Stigmasterol and Sitosterol

Question 15

…….is chemically converted to progesterone with some ease

Answer 15

Stigmasterol

Question 16

Facts about side chain of Sitosterol

The side chain of sitosterol, not possible to manipulate chemically, but can be degraded by microbial means to _____________ and _________________ which are versatile and can be synthetically converted to different ______________ such as _________, ______________, and ______________ and also ( _________, ______________, _______________)
see slide 8 for structures

Answer 16

The side chain of sitosterol, not possible to manipulate chemically, but can be degraded by microbial means to androst-4-ene-3,17-dione and androsta-1,4-diene-3,17-dione which are versatile and can be synthetically converted to different steroids such as Diuretics (spironolactone), Androgen, and Oestrogens and also ( Progestogens, anabolic steriods, anticancer steriods)
see slide 8 for structures

Question 17

State the two most important commercially steroidal sapogenin….

Answer 17

Hecogenin and Diosgenin

Question 18

State one prominent characteristic of sapogenin

Answer 18

Spirostan ring structure

Question 19

Hecogenin is obtained from……

Answer 19

Agave sisalana

Question 20

State how hecogenin is obtained from sisal juice…..

Answer 20

The sisal juice, which is a waste product of sisal fibre production, is concentrated and fermented to hydrolyse the glycoside bond. The recovered hecogenin is then chemically modified.

Question 21

What group makes it useful for the production of corticosteroids?

Answer 21

The C-12 carbonyl group

This requires the transposition of this oxygen function to C-11 followed by degradation of the side-chain.

Question 22

Hecogenin and cancer

More recently, hecogenin has been converted to the ______________, an alkaloid with a complex structure which is potent at __________________

Answer 22

More recently, hecogenin has been converted to the cephalostatin 1 (isolated from a marine worm), an alkaloid with a complex structure which is potent at inhibiting cancer cell growth

Question 23

Diosgenin is extracted from…..

_____________species from places like Mexico, India and China

Answer 23

various Dioscorea species from places like Mexico, India and China

Question 24

Facts about Diosgenin…

Unlike hecogenin, diosgenin does not have _______________.
However, a simple method of side-chain degradation (_______________) has been employed for a long time to prepare _____________, which can then be converted to progestogens, androgens and oestrogens.

Answer 24

Unlike hecogenin, diosgenin does not have an oxygen function in the C-ring.
However, a simple method of side-chain degradation (Marker degradation method) has been employed for a long time to prepare pregnenolone acetate, which can then be converted to progestogens, androgens and oestrogens.

Question 25

Diosgenin and cancer….

Recently diosgenin has been shown to possess potent anticancer effect on diverse range of tumours including _____________ (CML) by inducing production of reactive _____________ species.

Answer 25

Recently diosgenin has been shown to possess potent anticancer effect on diverse range of tumours including chronic myeloid leukemia (CML) by inducing production of reactive oxygen species.

Question 26

Facts about Obeticholic acid ……

Obeticholic acid (abbreviated to OCA, trade name \_\_\_\_\_\_\_\_\_\_\_\_\_), is a \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ which has the chemical structure 6α-ethyl-chenodeoxycholic acid.
 It is used as a drug in combination with ursodeoxycholic acid to treat primary biliary \_\_\_\_\_\_\_\_\_\_\_\_, and has been approved for \_\_\_\_\_\_\_\_\_\_\_\_\_ and related disorders.

__________________ is one of the bile acids.

Answer 26

Obeticholic acid (abbreviated to OCA, trade name Ocaliva), is a semi-synthetic bile acid analogue which has the chemical structure 6α-ethyl-chenodeoxycholic acid.
 It is used as a drug in combination with ursodeoxycholic acid to treat primary biliary cholangitis, and has been approved for rare liver diseases and related disorders.

Ursodeoxycholic acid is one of the bile acids.

Question 27

What is Betulinic acid used for…

Answer 27

Betulinic acid, a triterpenoid from Betula species, has been found to reduce hyperglycemia by interaction with a G-protein bile acid receptor 1.

Question 28

Mechanism of action of Glycyrrhizic acid

Answer 28

Glycyrrhizic acid ameliorates myocardial ischemic injury by the regulation of inflammation and oxidative state. These observations indicated that GA has cardioprotective effects against MI, and these effects might be related to the activation of Nrf-2/HO-1 and inhibition of NF-κB signaling pathway in the myocardium.