A Standardized Comparative Index (Effect Factor) for Antioxidant Referencing and Database-Level Benchmarking of Complex Herbal Extracts

Comparative interpretation of antioxidant activity across complex natural-product extracts and multi-component formulations is often limited by heterogeneous endpoints, assay-specific reporting, and incompatible units. In this study, we establish a dimensionless Effect Factor (EF) framework as a standardized comparative indexing system for matched-condition comparison of antioxidant-related readouts. EF maps four widely used antioxidant-related readouts—ABTS, DPPH, total phenolic content (TPC), and total flavonoid content (TFC)—into a common dimensionless index space while preserving endpoint meaning through two complementary tracks: potency-type EF and content-type EF. Using a standardized extraction and assay pipeline, we generated EF indices for 586 extracts prepared under water and 30% ethanol conditions and organized them into EF-indexed databases. EF is not intended as a predictive or biologically validated efficacy metric, but as a standardized comparative indexing framework that enables reproducible benchmarking, database-level referencing, and structured interpretation of heterogeneous antioxidant-related data under harmonized experimental conditions. These results establish the EF-indexed resource as a scalable and expandable comparative infrastructure for natural-product research.