PCOG LAB FINAL EXAM

Steam bath evaporation

concentrates the plant extract without degrading thermolabile

compounds.

Benzene extraction

is employed due to anthraquinones’ non-polar nature, allowing

separation from aqueous components

Ammonia addition

deprotonates anthraquinones, forming water-soluble salts that

exhibit a red or pink color in the alkaline phase

Modified Borntrager’s

includes oxidation (with H₂O₂) and alkaline hydrolysis (KOH)

to cleave stable C-glycosidic bonds, making otherwise undetectable anthraquinones visible.

Anthraquinone glycosides

are glycosylated forms of anthraquinones, often inactive in

glycoside form but become purgative upon hydrolysis in the colon

diluted alcohol

Facilitates partial dissolution of anthraquinones due to amphipathic nature

Hot water

Poor solubility with anthraquinone unless hydrolyzed or aglycone is free

Modified Borntrager’s test

is needed because C-glycosides are more stable and require oxidative cleavage to release the anthraquinone moiety

stimulant laxative

Anthraquinones acts as a _____, increasing peristalsis and fluid secretion in the large intestine by irritating mucosal cells.

Anthranol and anthrone

are reduced intermediates of anthraquinones that irritate the colon more than anthraquinones themselves, making them pharmacologically more potent.

Anthraquinones (Borntrager’s & Modified Borntrager’s Test)

What is experiment 10

Acid hydrolysis and heat

____ and ____ in the Bate-Smith test cleaves sugar moieties from

leucoanthocyanins to yield colored anthocyanidins

Magnesium and acid

in the Wilstatter test reduce flavonoids to colored forms and

extract them into octyl alcohol, separating based on polarity and pH sensitivity.

Flavonoids

are plant polyphenolic compounds with diverse structures based on the flavone backbone, often contributing color and biological activity.

γ-benzopyrone (chromone) nucleus

Flavonoids are characterized by the _____ —a fused aromatic ring with a ketone and oxygen heterocycle

• Bate-smith and metcalf

• Wilstatter

Flavonoids involve what methods

Bate-Smith & MetcalF

Flavonoid methods that detects leucoanthocyanins via acid hydrolysis

Wilstatter

Identifies flavonols via reduction and extraction.

Anthocyanins

when hydrolyzed and heated, change color depending on

pH—indicating presence in plant extract through visible red-blue shades

Flavonoids (Bate-Smith & Metcalf and Wilstatter Test)

What is expt 11

Saponins

being natural surfactants, reduce surface tension, explaining froth formation and capillary behavior

Froth test

visualizes the saponins amphiphilic structure by persistent foam

Capillary Test

measures the effect of saponins on liquid rise/drop due to surface tension reduction

Saponins

are glycosides that contain hydrophobic aglycones and hydrophilic sugar units, allowing them to form micelles and foam

Saponins

Their most distinct trait is forming persistent honeycomb froth

• Froth test

• Capillary test

• Blood hemolysis

Three screening methods of saponins

Froth test

This screening test of saponins observes foam stability and height

Capillary test

This screening test of saponin detects lowered surface tension

Blood hemolysis

This screening test of saponins detects ability to lyse RBCs

Sapogenin

is the aglycone component of saponin released upon hydrolysis; responsible for

biological activity.

• triterpenoid

• steroidal

Triterpenoid and steroidal saponins differ in ring structure and source— _____ is more plant-based, ____ more common in monocots.

Saponins (Froth & Capillary Tube Test)

What is expt 12

Picrate paper

reacts with liberated hydrogen cyanide (HCN), forming red-colored

complexes.

Chloroform

inhibits microbial activity to prevent premature hydrolysis

Warming (35–45°C)

accelerates enzymatic breakdown of glycosides without denaturing

the enzyme.

Chloroform

prevents bacterial enzymes from degrading glycosides prematurely,

preserving accurate test conditions

physiologic to slightly elevated temperatures

Warming at ____ optimizes enzymatic hydrolysis of cyanogenic glycosides

Reducing substances

____ substances like H₂S, SO₂, and aldehydes may react with picrate to cause false positives

Cyanogenic glycosides

are plant compounds that liberate toxic HCN when enzymatically hydrolyzed, posing toxicity risks upon ingestion.

Cyanogenic Glycosides (Guignard Test)

What is expt 13

Gelatin-salt reagent

reacts with polyphenols to precipitate tannin-protein complexes

Ferric chloride test

exploits metal-chelation, producing colorimetric changes: blue-black

(hydrolysable) or greenish-brown (condensed)

Are large polyphenols that can precipitate proteins, giving them astringent and antimicrobial effect

• hydrolysable tannins

• Condensed tannins

Two groups of tannins

Hydrolysable

Tannin group that is easily broken down into gallic/ellagic acids.

Condensed tannins

Tannin group that is resistant to hydrolysis; form polymers like phlobaphenes.

Proteins

The gelatin test shows that tannins bind to this, forming stable complexes

The gelatin test

shows that tannins bind to proteins, forming stable complexes

Phlobaphenes

are reddish precipitates from condensed tannins formed after

polymerization.

Polyphenols

share structural similarity but often do not precipitate gelatin, making

them distinguishable from tannins

• astringents

• Hemostatics

• Antioxidants

• Excipient in pharmaceuticals

Uses of tannins

Tannins (Gelatin and Ferric Chloride Tests)

expt 14

Acidic water

softens and hydrolyzes protopectin into pectin.

Boiling

aids extraction of water-soluble pectin

Alcohol precipitation

removes water and solidifies pectin due to insolubility.

Pectin

a partially methylated polysaccharide made of galacturonic acid; found in cell walls.

95% ethanol

precipitates pectin by reducing solubility, facilitating its separation from solution.

• Gelling agent (jellies)

• stabilizer (syrups)

• suspending agent (oral preparations)

Pharmaceutical or industrial uses of Pectin Preparation from Kalamansi

Kalamansi peel → Acid extraction → Heat → Filtration → Concentration → Ethanol addition → Precipitate → Dry → Powder.

Preparation step of pectin from kalamansi

expt 15

Pectin Preparation from Kalamansi

Microsublimation

exploits caffeine’s low sublimation point, allowing vapor to condense

on a slide.

Reagents (Dragendorff’s & Mayer’s)

confirm the presence of alkaloids via colored precipitates.

Sublimation

is a phase change from solid to gas without liquid—used for volatile solids.

Microsublimation

uses minute quantities and a microscopic setup for visual detection.

• benzoic acid

• Camphor

• Menthol

• Naphthalene

Other sublimable substances Of caffeine isolation via microsublimation

expt 16.

Caffeine isolation via microsublimation

Maceration in acetone

dissolves chlorophylls and carotenoids

Liquid-liquid extraction

____ using solvents of varying polarity separates pigments based on

solubility.

Hydrophobic

Chlorophyll is (hydrophillic or hydrophobic?) due to its phytol chain, hence not water-soluble.

methanol, acetone, and diethyl ether

Photosynthetic pigments are soluble in these due to polar organic structure.

Water

Photosynthetic pigments are most polar in

Petroleum ether

Photosynthetic pigments are least polar in

Methanol

Organic most miscible with water

Solubilty table show:

• Chlorophyll a: Methanol, ether

• Carotene: Petroleum ether

• Xanthophyll: More soluble in methanol

Solubilty table show:

• _____: Methanol, ether

• _____: Petroleum ether

• _____: More soluble in methanol

chlorophyll a & b to

Plants have ____ absorb broader light ranges.

Carotenoids

extend light capture and protect against photooxidation

Pigment separation:

○Top layer (nonpolar): Carotene

○Middle (intermediate): Chlorophylls

○Bottom (polar): Xanthophylls

Pigment separation:

○Top layer (nonpolar):

○Middle (intermediate):

○Bottom (polar):

expt 17

Separation of Photosynthetic Pigments

Soxhlet extraction

allows continuous solvent cycling, maximizing yield

Hexane

dissolves non-polar fixed oils efficiently

Evaporation

removes solvent to leave pure oil.

1. Peanut oil characteristics:

• Color: Pale yellow

• Odor: Mild/nutty

• Taste: bland

1. Peanut oil characteristics:

• Color:

• Odor:

• Taste:

Solubility of peanut oil

• Water → Insoluble

• Ethanol → Slightly soluble

• Ether, Chloroform → Highly soluble

• Acetone → Partially soluble

Solubility of peanut oil

• Water →

• Ethanol →

• Ether, Chloroform →

• Acetone →

Persistent translucent mark = positive for fixed oil.

Fixed Oil Extraction from Peanut

Stain test

Refractive index

Confirms purity and identity per USP standards

Acid value (free acids)

Saponification value (fatty acid MW)

Iodine value (degree of unsaturation)

Are the USP tests for fixed oil extraction from peanut

Fixed oils vs. fats: Oils = liquid at room temp; fats = solid. Based on fatty acid saturation.

Fixed oils vs. fats: ___ = liquid at room temp; ___ = solid. Based on fatty acid saturation.

Rancidity

results from oxidation, particularly in unsaturated oils exposed to air/light.

Emollient, IM injection solvent, carrier oil, base in ointments/lotions.

Pharmaceutical uses of peanut oil

Expt 18

Fixed Oil Extraction from Peanut