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The versatile methodology was developed for synthesizing kujigamberol B, a dinorlabdane diterpenoid isolated from the methanol extract of Kuji amber. A highly efficient intramolecular cyclization is followed by a Sonogashira-coupling reaction during the total synthesis. The synthesized compounds were evaluated for the growth-restoring activity against the mutant yeast (zds1Δ erg3Δ pdr1Δ pdr3Δ) and for the degranulation of RBL-2H3 cells. We found that in both activities, primary alcohol and secondary alcohol analogs are as active as kujigamberol B. [ABSTRACT FROM AUTHOR]

The enantioselective synthesis of violaceoid D, a cytotoxic phenolic compound isolated from the culture broth of Aspergillus violaceofuscus Gasperini, was achieved. The total synthesis involves stereoselective construction of the stereogenic center of violaceoid D via Sharpless asymmetric dihydroxylation, followed by Smiles rearrangement. The absolute configuration of natural violaceoid D was determined to be R from the specific rotation value. Synthesized violaceoid D and its analogs were evaluated for cytotoxicity against two human cancer cell lines, Jurkat and HCT116. Because the enantiomer of violaceoid D showed no cytotoxicity, it is plausible that violaceoid D binds selectively to specific target molecules, such as proteins in the cancer cells. [ABSTRACT FROM AUTHOR]

In response to environmental stressors such as blast fungal infections, rice produces phytoalexins, an antimicrobial diterpenoid compound. Together with momilactones, phytocassanes are among the major diterpenoid phytoalexins. The biosynthetic genes of diterpenoid phytoalexin are organized on the chromosome in functional gene clusters, comprising diterpene cyclase, dehydrogenase, and cytochrome P450 monooxygenase genes. Their functions have been studied extensively using in vitro enzyme assay systems. Specifically, P450 genes (CYP71Z6, Z7; CYP76M5, M6, M7, M8) on rice chromosome 2 have multifunctional activities associated with ent-copalyl diphosphate-related diterpene hydrocarbons, but the in planta contribution of these genes to diterpenoid phytoalexin production remains unknown. Here, we characterized cyp71z7 T-DNA mutant and CYP76M7/M8 RNAi lines to find that potential phytoalexin intermediates accumulated in these P450-suppressed rice plants. The results suggested that in planta, CYP71Z7 is responsible for C2-hydroxylation of phytocassanes and that CYP76M7/M8 is involved in C11α-hydroxylation of 3-hydroxy-cassadiene. Based on these results, we proposed potential routes of phytocassane biosynthesis in planta. [ABSTRACT FROM AUTHOR]