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

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.