Two new pairs of corresponding isomers of flavonoids in star anise lotus
The medicinal herb Dysosma versipellis is derived from the dried rhizomes of the Berberidaceae plant Dysosma versipellis. It is a unique medicinal herb in China, mainly distributed in Zhejiang, Guangxi, Hubei, Hunan, Sichuan, Guizhou and other places. This medicinal herb was first recorded in the “Shennong Bencao Jing”. It has a cool nature, a bitter taste, and a small toxicity. It has the effects of clearing heat and detoxifying, resolving phlegm and nodules, and relieving pain and swelling. Clinically, it is often used to treat traumatic injuries, hemiplegia, arthralgia, snakebite, sore, swollen, condyloma acuminatum, epidemic hemorrhagic fever, breast cancer, esophageal cancer, Japanese encephalitis, lymphadenitis, mumps, and other inflammatory diseases. The medicinal herb of star anise mainly contains aromatic naphthalene lignans and flavonoids. As of now, 40 flavonoids have been isolated, including 14 flavonoids. The flavonoids in star anise lotus are mostly polymers of flavonols and dihydroflavonols, which have strong cytotoxic, antioxidant, acetylcholinesterase, and neuraminidase inhibitory activities. This study aims to search for novel natural antioxidants and elucidate the pharmacological substance basis of star anise lotus. The flavonoids in star anise lotus were studied and their ability to scavenge DPPH free radicals was tested.

This experiment studied the flavonoids in the 95% ethanol and 50% ethanol extracts of star anise lotus. Two new isomers of flavonoids and one flavonoid compound were isolated and identified, namely (+) – star anise lotus flavonoids H (1a), (-) – star anise lotus flavonoids H (1b), (+) – star anise lotus flavonoids I (2a), (-) – star anise lotus flavonoids I (2b), and podoverine F (3). Using DPPH radical scavenging assay, the antioxidant activity of compounds 1, 1a, 1b, 2, 2a, and 2b was tested. The results showed that compounds 2, 2a, and 2b had strong scavenging ability against DPPH radicals and were stronger than the positive drug trolox. Studies on structure-activity relationships have shown that the ortho dihydroxy group on the B ring is an essential structural group for flavonoids to exhibit DPPH radical scavenging activity. This experiment discovered novel flavonoids with strong scavenging effects on DPPH free radicals from star anise lotus, providing a reference for the rational development and utilization of star anise lotus medicinal resources.