Tanzawaic acid derivatives from freshwater sediment-derived fungus Penicillium sp.

A New Antioxidant Decalin Polyketide from Freshwater‐Sediment‐Derived Fungus Penicillium sp. Strain S1a1

“…Compound 1 was purified as a pale‐yellow powder whose molecular formula was determined to be C 20 H 28 O 4 by HRESIMS (see supporting information, Figure S3). The UV spectrum exhibited an absorption maxima (λ max ) at 266 nm resembling that of the tanzawaic acids . The 13 C NMR and HMQC spectra revealed a total of 20 peaks, which were classified as two quaternary carbonyl carbons (δ C 175.6 and 170.6), thirteen methine carbons (divided into six olefinic and seven aliphatic), one methylene carbon (δ C 43.0) together with three methyls (δ C 23.3, 22.9 and 16.9) and one oxygenated methyl (δ C 52.0).…”

“…In a previous study dealing with the fungus Penicillium sp. strain S1a1, many isochromans and tanzawaic acids were isolated from the solid rice culture, including several new ones . In the present study, we cultivated this fungal strain on solid rice medium supplemented with 3.5% salt and this showed a clear difference in the fungal metabolic profile when compared with the solid rice cultures (please see supporting information, Figure S1).…”

“…These changes include altering the composition of media or changing some factors such as light, temperature, aeration, culture vessels’ shape and even the type and contents of water which is used for culturing of these fungi . Tanzawaic acids belong to decalin polyketide class of compounds and their biosynthesis was extensively discussed in many reports in the literature . These decalin polyketides (tanzawaic acids) proved to possess several biological activities such as antibacterial, antioxidant, cytotoxic and antifungal activities as established by Tominaga and co‐workers .…”

“…To date, more than 600 fungal species inhabit freshwater including ascomycete and mitosporic fungi . Although this huge number of fungal species exist in the freshwater ecosystem, phytobiological studies of these fungi are few leaving this environment as a fertile area for further investigation . The genus Penicillium is considered as one of the famous fungal taxa and is considered an untapped source for many bioactive secondary metabolites .…”

“…Although this huge number of fungal species exist in the freshwater ecosystem, phytobiological studies of these fungi are few leaving this environment as a fertile area for further investigation . The genus Penicillium is considered as one of the famous fungal taxa and is considered an untapped source for many bioactive secondary metabolites . In 2002, Zeeck and co‐workers established an effective approach in order to widen the chemistry and biodiversity of fungi by making small changes to culture conditions which could produce a huge influence on the natural product chemistry and hence the appearance of the OSMAC approach (One Strain MAny Compounds) .…”