Lithospermic acid B is chemically identical to salvianolic acid B (Sal B), which is a prominent bioactive compound derived from Salvia miltiorrhiza (Danshen). Here is its chemical characterization:

Key Chemical Features

Structural Class:

• Dimeric phenolic acid formed from rosmarinic acid and danshensu (salvianic acid A) units.

• Comprises four phenylpropanoid subunits (caffeic acid derivatives).

  Molecular Formula: C??H??O??

• Molecular Weight: 718.6 g/mol.

  Core Functional Groups:

• Two ester bonds: Linking danshensu and two caffeic acid residues.

• Four catechol groups (ortho-dihydroxyphenyl): Responsible for potent antioxidant activity.

• Carboxylic acid groups (–COOH): Enhancing water solubility.

• Labile lactone ring: Easily hydrolyzed under heat/alkaline conditions.

  Stereochemistry:

• Contains chiral centers (e.g., in danshensu unit), typically existing as a racemic mixture in natural extracts.

  Systematic Name:

• β-[[2-O-(3,4-Dihydroxybenzoyl)-3-(3,4-dihydroxyphenyl)-1-oxopropoxy]-3,4-dihydroxybenzenepropanoic acid.

Key Chemical Properties:

Distinction from Lithospermic Acid:

• Lithospermic acid (monomeric) is a precursor to lithospermic acid B (dimeric).

• Lithospermic acid formula: C??H??O??; lacks one caffeic acid unit compared to Sal B.

Note: In pharmacology and botany, "lithospermic acid B" and "salvianolic acid B" are used interchangeably. Its dimeric structure underpins its potent bioactivities (antioxidant, cardioprotective, etc.).