,Question 1
A research team investigates a medicinal plant traditionally used to
relieve pain. An extract reduces pain-related behavior in an
experimental model. Which is the most appropriate next step toward
identifying a potential therapeutic agent?
A. Market the plant extract because traditional use establishes clinical
efficacy.
B. Isolate and characterize candidate active constituents, then evaluate
their biological activity using appropriate assays.
C. Assume that all compounds in the extract contribute equally to its
analgesic effect.
D. Proceed directly to large-scale clinical trials without further
laboratory investigation.
Correct Answer: B. Isolate and characterize candidate active
constituents, then evaluate their biological activity using appropriate
assays.
Rationale:
• A is incorrect: Traditional use can provide a valuable starting point
for investigation, but it does not establish efficacy, safety,
reproducible composition, or an appropriate dose in humans.
• B is correct: Bioassay-guided fractionation can help identify
constituents responsible for the observed effect. Chemical
characterization and follow-up testing are necessary to investigate
activity, potency, and potential toxicity.
, • C is incorrect: Plant extracts contain multiple substances with
different biological activities. Some may be inactive, antagonistic,
toxic, or responsible for the observed effect only in combination.
• D is incorrect: Laboratory characterization and appropriate
preclinical evaluation are important before exposing human
participants to a candidate drug.
Question 2
A scientist identifies a purified plant-derived molecule that reproducibly
inhibits an enzyme implicated in a disease. What does this finding
establish most directly?
A. The molecule is already an effective treatment in humans.
B. The molecule has an established safety profile at therapeutic doses.
C. The molecule is a potential starting point for further drug discovery
and validation.
D. The molecule can be administered orally without additional testing.
Correct Answer: C. The molecule is a potential starting point for further
drug discovery and validation.
Rationale:
• A is incorrect: Enzyme inhibition in an experimental assay does
not establish clinical benefit. The molecule must undergo further
evaluation of its biological effects and therapeutic potential.
• B is incorrect: An enzyme assay does not determine systemic
toxicity, organ toxicity, or the safety of repeated exposure.