In the context of screening, which best describes hits?

• A. A compound with known clinical approval
• B. An inactive compound identified in a screen
• C. New active compounds
• D. A compound with poor potency

Answer: (C)

In screening, a hit is a compound that shows the desired biological activity in the assay and crosses a predefined threshold, signaling potential to modulate the target. This means the molecule is actively producing the effect being measured, making it a candidate for further investigation. Hits are typically newly identified active compounds that emerge from the screen, rather than compounds already known to have clinical approval or inactive ones. They are not chosen for poor potency; rather, they become starting points for optimization to improve potency, selectivity, and drug-like properties. After a hit is found, it’s usually validated with dose–response testing and counterscreens to confirm true activity and weed out false positives, with the goal of developing a lead compound.