Structure elucidation and NMR assignments for two amide alkaloids from a Mangrove endophytic Fungus (No. ZZF‐22)

Abstract

The structure elucidations and complete (1)H and (13)C NMR assignments are reported for two new natural products: 3-benzylidene-8,8a-dihydroxy-2-methyl-hexahydro-pyrrolo[1,2-a]pyrazine-1,4-dione(1) and 4-hydroxy-6-(hydroxy-phenyl-methyl)-N-(3-methyl-butyryl)-nicotinamide (2). Both of these secondary metabolites were isolated from the fermentation medium of a Mangrove endophytic fungus. High resolution electron impact mass spectrometry (HREIMS), FT-IR Spectroscopy and NMR experiments including gCOSY, gHMQC, gHMBC and NOE were used for determination of the structures and assignments of the amide alkaloids.

Marine natural products

“…142 The amide alkaloids 131 and 132 were characterised from an unidentified endophytic fungus [mangrove, Acanthus ilicifolius, (South China Sea)]. 143 The alkaloid cottoquinazoline A 133 and the cyclopentapeptides, cotteslosin A 134 and B 135 were isolated from Aspergillus versicolor [sand, (Cottesloe, Western Australia)]. 144 Culture of Aspergillus sp.…”

Trametramide A, a new pyridone alkaloid from the fungus Trametes trogii TGC‐P‐3

“…According to the 1 H‐ and 13 C‐NMR spectral data, compound 2 was identified as 4‐hydroxy‐6‐(hydroxy‐phenylmethyl)‐ N ‐(3‐methyl‐butyryl)‐nicotinamide, a tautomer derivative of compound 1 . According to the CD spectrum of compound 2 (Figure S10), the cotton effect at 228 nm (Δ∆ ε ‐24.6) was negative which reversed to that of compound 1 ; as a result, the configuration of compound 2 was elucidated as 7 R .…”

An Update on 2,5-Diketopiperazines from Marine Organisms

“…The amide alkaloid ( 54 ) was isolated from an unidentified endophytic fungus (mangrove, Acanthus ilicifolius , South China Sea) [ 31 ]. The spirocyclic DKP alkaloid, 7- O -methylvariecoloride A ( 55 ) was sourced from the Eurotium rubrum (stem of the mangrove Hibiscus tiliaceus , Hainan Is., China) [ 32 ].…”