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Chemical investigation of two Irciniidae sponges collected by hand (SCUBA) from Australian near shore waters, afforded six new examples of a rare class of sesterterpene lactam; ircinialactams B ( 1 ), G ( 2 ), H ( 5 ), and I ( 6 ), and 8-hydroxyircinialactams C ( 3 ) and G ( 4 ); together with the new biosynthetically related lactone, ircinialactone A ( 7 ). Also isolated were seven biosynthetically related known Irciniidae metabolites; ircinialactams A ( 8 ) and C ( 9 ), (7 E ,12 E ,20 Z ,18 S )-variabilin ( 10 ), (7 Z ,12 Z ,20 Z ,18 S )-variabilin ( 11 ), (7 E ,12 Z ,20 Z ,18 S )-variabilin ( 12 ), (7 Z ,12 E ,20 Z ,18 S )-variabilin ( 13 ) and irciniafuran A ( 14 ). The structure elucidation of 1 – 14 was achieved by detailed spectroscopic analysis, and consideration of a plausible biosynthetic relationship linking Irciniidae sesterterpene β-furans, lactams and lactones. [ABSTRACT FROM AUTHOR]

Abstract: Propolis of Australian stingless bees (Tetragonula carbonaria, Meliponini) originating from Corymbia torelliana (Myrtaceae) fruit resins was tested for its antimicrobial activities as well as its flavonoid contents. This study aimed at the isolation, structural elucidation and antibacterial testing of flavanones of C. torelliana fruit resins that are incorporated into stingless bee propolis. Flavanones of this study were elucidated by spectroscopic and spectrometric methods including UV, 1D and 2D NMR, EI-MS, ESI-MS and HR-MS. The results indicated known C-methylated flavanones namely, 1 (2S)-cryptostrobin, its regioisomer 2 (2S)- stroboponin, 3 (2S)- cryptostrobin 7-methyl ether, and 6 (2S)- desmethoxymatteucinol, and known flavanones 4 (2S)- pinostrobin and 5 (2S)- pinocembrin as markers for C. torelliana fruit resins and one propolis type. Ethanolic preparations of propolis were shown to be active against Staphylococcus aureus (ATCC 25923) and to a lesser extent against Pseudomonas aeruginosa (ATCC 27853). C. torelliana flavanones inhibited the growth of S. aureus therefore contributing to the antibacterial effects observed for Australian stingless bee propolis extracts. [Copyright &y& Elsevier]