Chemical characterization of procyanidins from Spatholobus suberectus and their antioxidative and anticancer activities

• For the first time, the chemical characteristics of the procyanidins in Spatholobus suberectus (SS) were clearly described, including the mean degree of polymerization (mDP), the elementary units, the mass distribution of fractions with different mDP values, and the types of linkages. The SS procyanidins have unique chemical profiles and are beneficial sources of antioxidants and potential inhibitors of LDH-A and breast cancer.
• Procyanidins with mDP values of 2–6 were likely to be the substances responsible for its bioactivity.
• The graded precipitations method was applied effectively to separate the SS procyanidins with different mDP values.

Spatholobus suberectus (SS) is an excellent functional and medicinal food source of dietary procyanidins, which have numerous health benefits. Ten procyanidin fractions with different polymerization degrees were prepared from SS. For the first time, trimers to 11-mers were detected in SS extracts, and their compositions were elucidated through thiolysis, ESI-MS and MALDI-TOF-MS analyses. The results determined that the mean polymerization degree (mDP) of the crude SS procyanidins was 5.2 and that the mass distribution of the monomer and the oligomers (mDP of 1.0–5.7) was 70.4%, whereas that of the polymers (mDP of 6.2–11.8) was 25.6%. Catechin and epicatechin were the main monomeric units with minor quantities of epigallocatechin and gallocatechin. The observed interflavan linkages were both A-type (minor type) and B-type (major type). The fractions enriched in the monomer and oligomers showed the highest activities, including antioxidant activity and inhibitory activities on both the proliferation of MCF-7 breast cancer cells and lactate dehydrogenase A (LDH-A). These results suggested that the monomer- and oligomer-enriched procyanidin fractions from SS could undergo further development to become a beneficial source of antioxidants, LDH-A inhibitors, and potential inhibitors of breast cancer.

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