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Fairy rings resulting from a fungus-plant interaction appear worldwide. 2-Azahypoxanthine (AHX) and imidazole-4-carboxamide (ICA) were first isolated from the culture broth of one of the fairy ring-forming fungi, Lepista sordida. Afterward, a common metabolite of AHX in plants, 2-aza-8-oxohypoxanthine (AOH), was found in AHX-treated rice. The biosynthetic pathway of the three compounds that are named as fairy chemicals (FCs) in plants has been partially elucidated; however, that in mushrooms remains unknown. In this study, it was revealed that the carbon skeletons of AHX and ICA were constructed from Gly in L. TH-257 sordida mycelia and the fungus metabolized 5-aminoimidazole-4-carboxamide (AICA) to both of the compounds. These results indicated that FCs were biosynthesized by a diversion of the purine metabolic pathway in L. sordida mycelia, similar to that in plants. Furthermore, we showed that recombinant adenine phosphoribosyltransferase (APRT) catalyzed reversible interconversion not only between 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranosyl 5'-monophosphate (AICAR) and AICA but also between ICA-ribotide (ICAR) and ICA. Furthermore, the presence of ICAR in L. sordida mycelia was proven for the first time by LC-MS/MS detection, and this study provided the first report that there was a novel metabolic pathway of ICA in which its ribotide was an intermediate in the fungus.Extracts from Streptomyces sp. S4.7 isolated from the rhizosphere of edelweiss, an alpine medicinal plant, exhibited activity against Gram-positive bacteria. LC-HRMS analyses of the extracts resulted in the detection of two unknown, structurally related lipopeptides that were assumed to be responsible for the antibiotic activity. LC-MS guided isolation and structure elucidation of viennamycins A and B (1 and 2) by HR-MS/MS, 1D and 2D NMR, and Marfey's analyses revealed them to be novel compounds, with viennamycin A containing cysteic acid, a unique feature for lipopeptides. Tests for antibacterial, antifungal, and cytotoxic activities of purified viennamycins, both with and without divalent cations, did not reveal any bioactivity, suggesting that their biological function, which could not be determined in the tests used, is atypical for lipopeptides. The genome of Streptomyces sp. S4.7 was sequenced and analyzed, revealing the viennamycin biosynthetic gene cluster. Detailed bioinformatics-based analysis of the viennamycin gene cluster allowed elucidation of the biosynthetic pathway for these lipopeptides.Phytochemical investigation of extracts of the stems of Hypoestes aristata led to the isolation of nine lignans that included four known compounds, namely, hinokinin (1), savinin (2), medioresinol (3), and two cubebins (8a,b), three new butyrolactone lignans (4-6), and butyrolactol lignans 7a-c. The structures of the new compounds were established using 1D and 2D NMR and HRESIMS data. The absolute configurations of the new lignans were determined from their ECD data and the Mosher's ester method. This is the first unequivocal assignment of the absolute configuration at C-7 and C-7' of 7- and 7'-hydroxybutyrolactone lignans. The compounds were screened for inhibition of an HIV-1 protease enzyme, and compounds 1 and 6 exhibited moderate activity in this regard.An ethanol extract of the powdered twigs of Podocarpus imbricatus afforded 14 new diterpenoids (1-14), which all share an aromatized C ring. These isolates belong to five diterpenoid types that include abietanes (1-3), semperviranes (4-9), totaranes (10-12), a C-17 norabietane (13), and an icetexane (14). Their structures were assigned mainly by analysis of the spectroscopic data, and the absolute configuration of 1 was determined by X-ray crystallography. A biosynthetic pathway for five of the biogenetically related types of diterpenoids was proposed. Compound 7 showed moderate inhibitory activity against Zika virus with an IC50 value of 2.5 μM.Hypocrellins and hypomycins are naturally occurring fungal perylenequinones with potential photodynamic activity against cancer and microbial diseases. This project pursued three lines of research. First, the production of perylenequinones was enhanced by investigating the effect of culture medium and light exposure on their biosynthesis. Solid-fermentation cultures on rice medium allowed for enhanced production of hypocrellins as compared to Cheerios or oatmeal medium. Alternatively, increased production of hypomycins, which are structurally related to the hypocrellins, was observed on oatmeal medium. In both cases, light exposure was an essential factor for the enhanced biosynthesis. In addition, this led to the discovery of two new perylenequinones, ent-shiraiachrome A (5) and hypomycin E (8), which were elucidated based on spectroscopic data. Finally, the photocytotoxic effects of both classes of compounds were evaluated against human skin melanoma, with EC50 values at nanomolar levels for hypocrellins and micromolar levels for hypomycins. In contrast, both classes of compounds showed reduced dark toxicity (EC50 values >100 μM), demonstrating promising phototherapeutic indices.Phytochemical investigations of an extract of the aerial parts of Rydingia persica led to the isolation of 14 labdane-type diterpenoids, of which compounds 1-5, 8, and 12-14 turned out to be new natural products, while the remaining compounds were isolated for the first time from the genus Rydingia. Their structures were elucidated using 1D- and 2D-NMR and mass spectrometry, and their absolute configurations were determined by quantum chemical calculation methods. Furthermore, DP4+ NMR chemical shift probability calculations were performed for compounds 12-14, in order to elucidate the orientation of the ambiguous chiral center at C-15, prior to absolute configuration determination. The methanol extract of the aerial parts of R. persica along with subfractions obtained and selected isolated compounds were evaluated for their effects on inflammation-related factors such as nitrotyrosine formation, IL-6 release, and TNF-α release, along with tight-junction proteins claudin-1 and occludin expression in LPS-stimulated HaCaT cells.
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