biostudies-literatureLi WNatural Science Foundation of Shandong ProvinceNational Natural Science Foundation of China29684-29689https://www.ebi.ac.uk/biostudies/studies/S-EPMC9040924biostudies-literatureUnknown11(47)Two unique trinorlabdane diterpenoid alkaloids, forsyqinlingines A (1) and B (2), were isolated from the ripe fruits of <i>Forsythia suspensa</i>. Their structures, including absolute stereochemical configurations, were fully elucidated from extensive spectroscopy experiments, single-crystal X-ray diffraction, and electronic circular dichroism (ECD). In addition, a plausible biosynthetic pathway for the formation of compounds 1 and 2 in <i>Forsythia suspensa</i> was also proposed. <i>In vitro</i>, the two C₁₇-labdane diterpenoid alkaloids exhibited anti-inflammatory activities by inhibiting the release of β-glucuronidase in rat polymorphonuclear leukocytes (PMNs), and antiviral activities against influenza A (H1N1) virus and respiratory syncytial virus (RSV).RSC advancesTrinorlabdane diterpenoid alkaloids featuring an unprecedented skeleton with anti-inflammatory and anti-viral activities from <i>Forsythia suspensa</i>.PMC904092421372189ZR2019HM091Li WXie ZPZhao LSun LTZhang SMDai SJYue XDfalseTrinorlabdane diterpenoid alkaloids featuring an unprecedented skeleton with anti-inflammatory and anti-viral activities from <i>Forsythia suspensa</i>.Two unique trinorlabdane diterpenoid alkaloids, forsyqinlingines A (1) and B (2), were isolated from the ripe fruits of <i>Forsythia suspensa</i>. Their structures, including absolute stereochemical configurations, were fully elucidated from extensive spectroscopy experiments, single-crystal X-ray diffraction, and electronic circular dichroism (ECD). In addition, a plausible biosynthetic pathway for the formation of compounds 1 and 2 in <i>Forsythia suspensa</i> was also proposed. <i>In vitro</i>, the two C₁₇-labdane diterpenoid alkaloids exhibited anti-inflammatory activities by inhibiting the release of β-glucuronidase in rat polymorphonuclear leukocytes (PMNs), and antiviral activities against influenza A (H1N1) virus and respiratory syncytial virus (RSV).2021-01-01T00:00:00Z2021 Sep2025-04-04T07:44:07.065Z2025-04-04T07:44:07.065ZS-EPMC90409243547956210.1039/d1ra05760j