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Biochemistry > Experiment 9: Phytochemical Screening > Flashcards

Experiment 9: Phytochemical Screening Flashcards

1
Q

Phytochemicals

A

-Plant chemicals
-Natural bioactive compounds (activities in the biological system once consumed) found on different parts of a plant (leaves, roots, stems, flowers)

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2
Q

Secondary Metabolites

A

-Organic compounds that are not directly involved in a plant’s growth, reproduction, and development, basically provide other needs of a plant

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3
Q

Secondary Metabolites Major Classes

A
  1. Terpenes
  2. Phenolics
  3. Polyketides
  4. Alkaloids
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4
Q

Terpenes

A

-Unsaturated
-Based on isoprene molecule (2-methyl,1-3-butadiene)
-Essential oils, spices, flavorings (e.g. citronella, camphor, eucalyptus)

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5
Q

Terpenoids

A

-Oxygenated derivatives of terpenes
-Contains -OH, -C=O
-Unsaturated

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6
Q

Flavonoids

A

-Derived from Phe and acetate metabolism
-Contain flavan (C6-C3-C6) skeleton

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7
Q

Alkaloids

A

-Basic nitrogenated compounds
-Largest class of secondary metabolites
-Analgesics, narcotics, CNS stimulants, antimicrobial
*e.g. morphine

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8
Q

Glycosides

A

-Sugar (glycone) + non-sugar (aglycone) molecule via a glycosidic bond
-Sugar derivatives

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9
Q

Saponins

A

-Kind of glycoside
-Steroid/tritepenoid glycosides
-Used as detergents
-Forms froth when agitated in an aqueous solution

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9
Q

Tannins

A

-Polyphenols
-Can react with and precipitate proteins
-Tanning agent

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10
Q

Types of Tannins

A

-Hydrolyzable
-Condensed

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11
Q

Hydrolyzable Tannins

A

Can be hydrolyzed by enzymes
-phenolic acid + glc via ester linkage

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12
Q

Condensed Tannins

A

-Derivatives of flavonoids

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12
Q

Sample Preparation

A

(1) Sun dried (60-80% moisture removed).
(2) Grind into fine particles (increase surface area)
(3) Immersion of sample to 95% ethanol for several days (Increase phytochemicals yield)
(4) Increase of extract concentration via rotary evaporator

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13
Q

Drying Methods of Sample

A

-Natural Drying
-Artificial
*Cold-air drying
*Warm-air drying

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14
Q

Natural Drying

A

-Sun drying
-Sample can be damaged by the weather

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15
Q

Cold-air drying

A

Use of fans that blow unheated air

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16
Q

Is oven drying recommended for this experiment?

A

No, phytochemicals may detoriate at high temperatures

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17
Q

Dragendorff’s Test

A

Test for alkaloids (nitrogenated)

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18
Q

Dragendorff’s Test Positive and Negative Results

A

-Positive Result: Colored precipitate (red, orange, brown, or yellow)
-Negative: No precipitate

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19
Q

Dragendorff’s Test Procedure

A

(1) +Concentrated extract
(2) +5mL of 2 M HCl
(3) Heat with stirring for 5 minutes
(4) Filter residue
(5) +2M HCl for washing
(6) Discard residue
(7) +1 mL of filtrate
(8) +5 drops of Dragendorff’s reagent
(9) Note of the color of precipitate and the amount of precipitation observed
+ slight turbidity
++ definite turbidity
+++ heavy precipitation

20
Q

Keller Killani Test

A

Test for glycosides with deoxysugars (no 2’ OH)

21
Q

Keller Killani Test Reaction

A

Acid hydrolysis of sugar-aglycone (destroy glycoside bonds)

22
Q

Keller Killani Test Positive Results

A

Red-brown ring

23
Keller Killani Test Procedure
(1) +3 spoons of concentrated extract (2) +10 mL of 2:1 v/v hexane-water mixture for defatting (3) Get aqueous layer (4) Heat over water bath (5) Cool mixture (6) Divide into three portions (7) Portion 1: +3 mL Keller-Killani reagent and stir + 1 mL of concentrated sulfuric acid (8) Let test tube be and observe color at interface
24
Liebermann-Burchard Test
Test for steroids
25
Liebermann-Burchard Test Positive Result
Purple blue or blue-green solution
26
Liebermann-Burchard Test Procedure
(1) Portion 2 in Keller-Killani: +5mL dichloromethane (2) Stir mixture and stand for 10 mins (3) Get funnel with filter paper (4) +anhydrous sodium sulfate on filter paper (5) Filter dichloromethane layer on filter paper with anhydrous sodium sulfate (6) Divide filtrate into two portions (7) Portion 1: +3 drops of acetic anhydride and +1 drop of concentrated sulfuric acid (8) Observe for any immediate color change (9) Stand for 1 hour then compare with untreated portion
26
Kedde Test
Test for glycosides with lactone ring (non-sugar)
27
Kedde Test Positive Result
Purple color fading gradually to red-brown and white precipitate
28
Kedde Test Procedure
(1) +5mL of dichloromethane to portion in Keller-KIllani (2) Stir mixture and allow to stand for 10 minutues (3) Collect dichloromethane layer using a dropper (4) +4 drops of Kedde reagent (5) Record observed color
29
Bornträger’s Test
Test for glycosides with anthracene (3 benzene ring)
30
Bornträger’s Test Positive Result
Pink color in lower layer
31
Bornträger’s Test Procedure
(1) Spoonful of concentrated extract (2)+10 mL distilled water (3) Filter solution (4) +5mL benzene to filtrate (5) Collect benzene layer (6) Divide into two portions (7) Portion 1: +5mL of ammonia solution (8) Compare the results with the untreated portion
32
Bate-Smith and Metcalf Test
Test for flavonoids, leucoanthocyanins
33
Bate-Smith and Metcalf Test Positive Result
Red purple color
34
Bate-Smith and Metcalf Test Procedure
(1) +Concentrated extract (2) +5 mL 2:1 v/v hexane-water mixture for defatting (3) Collect aqueous layer (4) Heat over a water bath (5) Cool mixture (6) +10 mL methanol (7) Divide into two portions (8) Portion 1: +0.5 mL concentrated HCl (9) Note for any color changes (10) Warm solution for 15 minutes (11) Note color changes within an hour (12) Compare with untreated portion
35
Froth Test
Test for saponins
36
Froth Test Positive Result
-2cm layer of forth -Hydrophobic (fat-soluble) sapogenin + Hydrophilic (water souble) sugar
37
Froth Test Procedure
(1) +Concentrated extract (2) +10mL distilled water (3) Shake mixture for 30 seconds (4) Allow to stand for 10 minutes (5) Wait for formation of "honeycomb froth" and measure the height
38
Ferric Chloride Test
Test for tannins, phenolics
39
Ferric Chloride Test Positive and Negative Result
Positive: Dark blue/black color Negative: Colorless solution
40
Ferric Chloride Test Procedure
(1) +Concentrated extract (2) +10 mL hot distilled water (3) +5 drops of 10% sodium chloride solution (4) Filter (5) Divide filtrate into two portions (6) Portion 1: Control Portion 2: +3 drops of ferric chloride reagent (7) Compare results with control
41
Parts of an Rotary Evaporator
1. Rotary motor 2. Vacuum source 3. Glass tube 4. Heating bath 5. Condenser 6. Receiving flask 7. Rotary flask 8. Feeder valve
42
Rotary Motor
-Electrically powered motor that rotates evaporation flask at a continuous and constant speed to increase surface area for evaporation and even mixing.
43
Glass Tube
-Protect and support sample during rotation -Help in creating a vacuum
43
Heating Bath
Heat sample and aid in temperature regulation
44
Receiving flask
Distilled sample goes here
44
Vacuum source
System for creating a vacuum within the airtight set-up and reduce the pressure within the system.
45
Condenser
Condensate the evaporated sample and enhance convenient sample collection
46
Feeder valve
Ensures safe, efficient, and controlled evaporation process in a rotavap by gradual introduction of the sample and maintain vacuum.
46
Rotary Flask
Where the mixture is placed to be rotated and heated.

Biochemistry (6 decks)

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