Phenylphenalenones and related natural products from Wachendorfia thyrsiflora L.

4‐Phenylphenalenones as a template for new photodynamic compounds against Mycosphaerella fijiensis

“…Interestingly, comparing compounds 1 to 3 with compounds 4 to 6 points to the relevance of the α ‐hydroxyenone moiety for the activity of these compounds. This is intriguing, considering that natural 4‐phenylphenalenones ubiquitously contain this substitution . Pyrazole derivative 7 displays an extreme difference between IC 50 values of 72 ± 8 ppm in the dark and 20 ± 1 ppm under the photoperiod.…”

“…Phenylphenalenones are natural products isolated mainly from the Haemodoraceae and Musaceae families . In Musa plants, these compounds are clearly involved in the defence mechanism against nematodes, and their accumulation is elicited by Colletotrichum musae , Fusarium oxysporum , Mycosphaerella fijiensis , Radopholus similis and Sporobolomyces salmonicolor , meeting the definition of phytoalexins .…”

“…In Musa plants, these compounds are clearly involved in the defence mechanism against nematodes, and their accumulation is elicited by Colletotrichum musae , Fusarium oxysporum , Mycosphaerella fijiensis , Radopholus similis and Sporobolomyces salmonicolor , meeting the definition of phytoalexins . The phenyl group can be found attached to phenalenone positions C‐9 or C‐4, and some identical 9‐phenylphenalenones have been reported in both families . However, 4‐phenylphenalenones remain exclusive to Musaceae.…”

Publisher's Note

“…In vitro root cultures of A. preissii and W. thyrsiflora are rich sources of phenylphenalenones (Hölscher and Schneider, 1997;Opitz et al, 2002;Opitz and Schneider, 2003;Fang et al, 2011) and therefore were selected for the present study. However, only one compound of that type, 2-hydroxy-9-(4 0 -hydroxy-3 0 -methoxyphenyl)-1H-phenalen-1-one (musanolone F (3)), which has a methoxylated lateral phenyl ring D, was reported from A. preissii (Schmitt et al, 2000).…”

“…Musanolone F (3) is biosynthetically derived from ferulic acid (1), which is an abundant phenylpropanoic acid in A. preissii (Schmitt and Schneider, 2001). Most of the phenylphenalenones occurring in W. thyrsiflora have an unsubstituted ring D (Fang et al, 2011(Fang et al, , 2012, and no compound with a methoxy substituent in ring D has yet been reported from this plant. Also no data about the occurrence of phenylpropanoic acids in W. thyrsiflora are available.…”