Saponins test, Tannins & Polyphenols test, Cyanogenic Glycosides test

froth test

formation of persistent honeycomb upon shaking

2 cm
10 minutes

froth test positive result:
the honeycomb is greater than _ height from the surface of the liquid persists after __

5% Na₂CO₃

for plant extracts with poor frothing effects, add a little __ to basify the extract

free fatty acids

the formation of a stable and dense froth indicates presence of __

blood agar plate

• 100 mL 0.9% NaCl sol’n + 1.8 g agar powder, let it stand for 30 mins.

• heat to 80C on a water bath with stirring, then cool to 40 C

• add 1 mL defibrinated cow’s blood & stir then pour 10 Ml in each Petri dish and allow to set

• Bore cleanly three equidistant cups of 10 mm diameter into the agar

• Fill one agar cup with the extract, one with the gugo extract (positive control) and one with distilled water (negative control)

clear zones of hemolysis (hemolytic halos)

Agar cup hemolytic test positive result

tannins and polyphenols

• first applied to plant constituents capable of transforming raw animal skin to leather

• precipitates proteins, alkaloids and glycosides

• acidic, sharp-puckering taste

tannic acid

antidote for alkaloid poisoning

condensed

other name of non-hydrolyzable

related to catechol

structure of non-hydrolyzable

related to pyrogallol

structure of hydrolyzable

phlobaphenes (red dye)

+HCl on non-hydrolyzable

phenolic acid + sugars

+HCl on hydrolyzable

brownish green

+FeCl₃ on non-hydrolyzable

bluish black

+FeCl₃ on hydrolyzable

tanner’s red

leather of non-hydrolyzable

bloom

leather of hydrolyzable

tannins industry

treatment of burns, potential value as cytotoxic and/or antineoplastic agents, astringent properties

polyphenols

used as additives in tanning agent in the leather industry

FeCl₃

polyphenols do not yield a positive result with the gelatin test but yield positive results with __

gelatin-salt reagent

• gelatin test reagent

• equal amount of 1% gelatin soln & 10% NaCl soln

formation of jelly precipitate

gelatin test positive result

iron (III) chloride
FeCl₃

• ferric chloride test reagent

• 3mL 1% FeCl₃ soln in 100mL d. H₂O

bluish black

ferric chloride test positive result for hydrolysable tannins

brownish green

ferric chloride test positive result for condensed tannins

cyanogenic glycosides

often found in legumes, root crops, and grasses

hydrolytic enzymes

cyanogenic glycosides usually found in plants together with __

spontaneous hydrolysis

most cyanogenic glycosides are lost after plant harvest due to __

Manihot esculenta (cassava)

the roots of ____________ Crantz, causes poisoning when eaten if tubers are half-cooked or cooked with intact root peelings

hydrogen cyanide

due to _______ released by enzymatic hydrolysis of cyanogenic glycosides

Prunus amydalus (almonds)

__ are also known to contain cyanogenic glycosides

emulsin

___ hydrolyses glycosides

Guignard’s test

• picrate paper

• dip strips of filter paper into freshly prepared sodium picrate sol’n

• drip dry and then finally dry between sheets of newsprints

various shades of red
yellow to brick red

Guignard’s test positive result within 15 mins when the tube is warmed