Immunostimulatory 6/6/6/6 Tetracyclic Triterpenoid Saponins with the Methyl-30 Incorporated Cyclization from the Root of Colquhounia elegans

Astracondensatol D: A 6/6/5/6 Cycloartane Triterpenoid from Astragalus condensatus

Astracondensatol D (1), a pentacyclic triterpenoid featuring an uncommon 6/6/5/6-fused ring system, along with its precursor astracondensatol E (2), and two simplified 20(27)-octanorcycloastragenol derivatives (3 and 4) were isolated from Astragalus condensatus for the first time. Classical NMR spectroscopic data, integrated with NMR and DP4+ calculations, unambiguously determined their absolute stereostructures. X-ray crystallography provided independent confirmation of the structure of compound 3. The plausible biosynthetic pathway, encompassing the Wagner-Meerwein rearrangement and retro-aldol reaction, was proposed for their formation and supported by computational analysis.

Masterpenoids A-D, Four Unprecedented Nortriterpenoids from the Mastic (Pistacia lentiscus) and Their Anti-inflammatory Activity

Four unprecedented nortriterpenoids, masterpenoids A-D, were isolated and fully elucidated from the resin of the mastic tree (Pistacia lentiscus). Masterpenoids A-C are the first norterpenoids featuring an unprecedented 6/6/6/10 ring system, while masterpenoid D possesses a novel 6/6/6/7/5 ring system. The anti-inflammatory potential of the compounds was meticulously assessed through the establishment of an in vitro model of lipopolysaccharide-induced inflammation in RAW264.7 macrophage cells. Among them, Masterpenoids A and D showed potent inhibition of NO production, with IC50 values of 10.6 ± 0.8 and 8.2 ± 0.9 μM, respectively, compared to positive control dexamethasone (IC50 = 23.2 ± 1.2 μM).

Four New Furofuran Lignans from Phryma leptostachya Inhibit the Accumulation of Molting Hormones in Armyworm

Furofuran lignans have been identified as the main substances responsible for the biological activities of the plant genus Phryma. Here, four new phrymarolin-type leptolignans A-D (7-10) and eight previously known lignans were isolated from P. leptostachya. Of these, nine exhibited significant antifeedant activity against armyworm (Mythimna separata) through a dual-choice bioassay, with the EC50 values ranging from 0.58 to 10.08 μg/cm2. In particular, the newly identified lignan leptolignan A (7) showed strong antifeedant activity, with an EC50 value of 0.58 ± 0.34 μg/cm2. Further investigation found that leptolignan A can inhibit the growth and nutritional indicators in the armyworm M. separata. The concentrations of two molting hormones, 20-hydroxyecdysone and ecdysone, were also found to decrease significantly following the treatment of the armyworms with the lignan, implying that the target of the P. leptostachya lignan may be involved in 20-hydroxyecdysone and ecdysone synthesis. These results enrich our knowledge of P. leptostachya metabolite structural diversity, and provide a theoretical basis for the control of armyworm using lignans.

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A personal selection of 32 recent papers is presented covering various aspects of current developments in bioorganic chemistry and novel natural products such as asporychalasin from Aspergillus oryzae.