,
,Question 1
A research team investigates a plant traditionally used to relieve pain.
An extract produces a reproducible analgesic-related effect in a
laboratory assay. The team wants to identify the chemical constituent
responsible for this activity. Which approach is most appropriate?
A. Administer the uncharacterized extract to human volunteers to
determine its therapeutic efficacy.
B. Use bioassay-guided fractionation to separate the extract into
fractions and test each fraction for biological activity.
C. Discard the extract because compounds derived from plants cannot
be developed into modern medicines.
D. Identify the most abundant chemical in the extract and assume it is
responsible for the observed activity.
Correct Answer: B. Use bioassay-guided fractionation to separate the
extract into fractions and test each fraction for biological activity.
Rationale:
Bioassay-guided fractionation combines chemical separation with
repeated biological testing. Researchers separate a complex natural-
product extract, test the resulting fractions, and continue isolating the
constituents associated with the desired activity. The active compound
can then be chemically characterized and evaluated further.
• A is incorrect: An uncharacterized extract has uncertain
composition, potency, and toxicity. Laboratory activity alone does
not justify immediate testing in humans.
, • B is correct: This approach links biological activity to specific
fractions and ultimately helps identify the active chemical
constituent.
• C is incorrect: Natural products have historically contributed
important therapeutic agents and remain valuable starting points
for drug discovery.
• D is incorrect: Abundance does not establish biological activity. A
less abundant constituent may account for most or all of the
observed effect.
Question 2
During an initial screening campaign, researchers identify a synthetic
compound that inhibits a disease-associated enzyme in a laboratory
assay. The compound has modest potency, and its pharmacokinetic and
safety properties have not yet been characterized. How should this
compound initially be classified?
A. An approved therapeutic agent.
B. A validated clinical treatment.
C. A screening hit that may warrant further investigation.
D. A development candidate ready for routine clinical use.
Correct Answer: C. A screening hit that may warrant further
investigation.
Rationale:
A screening hit is a compound that produces a measurable effect in an
initial assay and meets the criteria for further investigation. A hit may
,Question 1
A research team investigates a plant traditionally used to relieve pain.
An extract produces a reproducible analgesic-related effect in a
laboratory assay. The team wants to identify the chemical constituent
responsible for this activity. Which approach is most appropriate?
A. Administer the uncharacterized extract to human volunteers to
determine its therapeutic efficacy.
B. Use bioassay-guided fractionation to separate the extract into
fractions and test each fraction for biological activity.
C. Discard the extract because compounds derived from plants cannot
be developed into modern medicines.
D. Identify the most abundant chemical in the extract and assume it is
responsible for the observed activity.
Correct Answer: B. Use bioassay-guided fractionation to separate the
extract into fractions and test each fraction for biological activity.
Rationale:
Bioassay-guided fractionation combines chemical separation with
repeated biological testing. Researchers separate a complex natural-
product extract, test the resulting fractions, and continue isolating the
constituents associated with the desired activity. The active compound
can then be chemically characterized and evaluated further.
• A is incorrect: An uncharacterized extract has uncertain
composition, potency, and toxicity. Laboratory activity alone does
not justify immediate testing in humans.
, • B is correct: This approach links biological activity to specific
fractions and ultimately helps identify the active chemical
constituent.
• C is incorrect: Natural products have historically contributed
important therapeutic agents and remain valuable starting points
for drug discovery.
• D is incorrect: Abundance does not establish biological activity. A
less abundant constituent may account for most or all of the
observed effect.
Question 2
During an initial screening campaign, researchers identify a synthetic
compound that inhibits a disease-associated enzyme in a laboratory
assay. The compound has modest potency, and its pharmacokinetic and
safety properties have not yet been characterized. How should this
compound initially be classified?
A. An approved therapeutic agent.
B. A validated clinical treatment.
C. A screening hit that may warrant further investigation.
D. A development candidate ready for routine clinical use.
Correct Answer: C. A screening hit that may warrant further
investigation.
Rationale:
A screening hit is a compound that produces a measurable effect in an
initial assay and meets the criteria for further investigation. A hit may
