What percentage of hits are of mineral origin?

• A. 6%
• B. 25%
• C. 50%
• D. 12%

Answer: (A)

In screening data, the origin of hits matters: mineral-origin hits are a small minority. Minerals and metal ions often cause nonspecific inhibition or readout interference, so many apparent mineral-related hits don’t reflect true, target-directed activity and are weeded out in follow-up tests. Because screening libraries are mostly organic compounds with drug-like properties, the share of mineral-origin hits stays in the single digits, around six percent. That’s why this option best matches the expected distribution. Larger percentages would imply an unrealistically large contribution from minerals, which isn’t supported by how these libraries typically behave. If you encounter a mineral-associated hit, use orthogonal, metal-free assays to confirm true activity.