Instructions: Given some example of real abstract, a title, list of keywords and main findings, create an abstract for a scientific article. Sequence of molecules like "molecule A, molecule B, molecule C" must be writen in the contracted form as a range "molecules A-C" or "molecules A to C". For instance "amathaspiramide A, amathaspiramide B, amathaspiramide C, amathaspiramide D" is preferentially written as "amathaspiramides A-D" or "amathaspiramides A to D". Or, "placidene D, placidene E, placidene F, placidene G" can be written "placidene D-G" or "placidene D to G".
Title: Configurational assignment of cyclic peroxy metabolites provides an insight into their biosynthesis: isolation of plakortolides, seco-plakortolides, and plakortones from the Australian marine sponge Plakinastrella clathrat and root parasite Kitagawia praeruptora. 
Keywords: Australian sponge, root of Peucedanum praeruptorum, relative configurational assignment, spectroscopic analysis, absolute configurations, (1)H NMR analysis, polyketide-derived precursor. 
Main findings: Plakinastrella clathrata produces plakortolide C, plakortolide D, plakortolide E, 6-hydroperoxydienoic acid. Plakinastrella produces 4 seco-plakortolides. Kitagawia praeruptora produces Praeroside VI, Isofraxidin, Scopoletin. Kitagawia praeruptora produces 12 coumarins.
Abstract: Use some words in all caps in your response, but those all-caps words should appear at most 15 times.
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