Food Byproducts as a New and Cheap Source of Bioactive Compounds: Lignans with Antioxidant and Anti-inflammatory Properties from Crataegus pinnatifida Seeds

Abstract

During the process of manufacturing hawthorn (Crataegus pinnatifida) juice and jam, a significant quantity of byproducts (leaves, seeds) is generated. The antioxidant and anti-inflammatory bioassay-guided fractionation of the extract of hawthorn seeds has led to the isolation of eight new lignans, hawthornnins A–H (<b>1</b>–<b>8</b>), and seven known analogues (<b>9</b>–<b>15</b>). Their structures were elucidated by spectroscopic techniques, including 1D and 2D NMR and CD spectra. The radical-scavenging effects of all isolated compounds were investigated. <b>1</b>–<b>6</b> and <b>8</b> showed moderate activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH), whereas <b>1</b>–<b>6</b> and <b>14</b> displayed good 2,2′-azinobis­(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) free radical-scavenging activities that were even more potent than that of trolox. In addition, all isolates were evaluated for their anti-inflammatory activities by detecting the nitric oxide (NO) and tumor necrosis factor α (TNF-α) production by the LPS-induced murine macrophage cell line RAW264.7, and compounds <b>1</b>–<b>7</b>, <b>13</b>, and <b>14</b> exhibited potent inhibition of NO and TNF-α production. The structure–activity relationships of isolated lignans were also examined, and the results obtained show that <i>C. pinnatifida</i> seeds can be regarded as a potential new and cheap source of antioxidants and inflammation inhibitors