Drug Leads from Endophytic Fungi: Lessons Learned via Scaled Production.

Recently, the isolation and elucidation of a series of polyhydroxyanthraquinones were reported from an organic extract of a solid phase culture of an endophytic fungus, Penicillium restrictum (strain G85). One of these compounds, ω-hydroxyemodin (1: ), showed promising quorum-sensing inhibition against clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA) in both in vitro and in vivo models. The initial supply of 1: was 19 mg, and this amount needed to be scaled by a factor of 30 to 50 times, in order to generate material for further in vivo studies. To do so, improvements were implemented to enhance both the fermentation of the fungal culture and the isolation of this compound, with the target of generating > 800 mg of study materials in a period of 13 wk. Valuable insights, both regarding chemistry and mycology, were gained during the targeted production of 1: on the laboratory-scale. In addition, methods were modified to make the process more environmentally friendly by judicious choice of solvents, implementing procedures for solvent recycling, and minimizing the use of halogenated solvents.

Delitpyrones: α-Pyrone Derivatives from a Freshwater Delitschia sp.

In research focused on the discovery of new chemical diversity from freshwater fungi, a peak library was built and evaluated against a prostate cancer cell line, E006AA-hT, which was derived from an African American, as this population is disproportionately affected by prostate cancer. The chemical study of the bioactive sample accessioned as G858 (Delitschia sp.) led to the isolation of eight new α-pyrone derivatives (1:  - 7: , and 11: ), as well as the new 3S*,4S*-7-ethyl-4,8-dihydroxy-3,6-dimethoxy-3,4-dihydronaphthalen-1(2H)-one (15: ). In addition, the known compounds 5-(3-S-hydroxybutyl)-4-methoxy-6-methyl-2H-pyran-2-one (8: ), 5-(3-oxobutyl)-4-methoxy-6-methyl-2H-pyran-2-one (9: ), pyrenocine I (10: ), 5-butyl-6-(hydroxymethyl)-4-methoxy-2H-pyran-2-one (12: ), sporidesmin A (13: ), 6-ethyl-2,7-dimethoxyjuglone (14: ), artrichitin (16: ), and lipopeptide 15G256ε (17: ) were also obtained. The structures of the new compounds were elucidated using a set of spectroscopic (NMR) and spectrometric (HRMS) methods. The absolute configuration of the most abundant member of each subclass of compounds was assigned through a modified Mosher's ester method. For 15: , the relative configuration was assigned based on analysis of 3 J values. Compounds 1, 2, 5:  - 14, 16: , and 17: were evaluated against the cancer cell line E006AA-hT under hypoxic conditions, where compound 13: inhibited cell proliferation at a concentration of 2.5 µM.

Prealamethicin F50 and related peptaibols from Trichoderma arundinaceum: Validation of their authenticity via in situ chemical analysis.

In the field of natural products chemistry, a common question pertains to the authenticity of an isolated compound, i.e. are the interesting side chains biosynthesized naturally or an artefact of the isolation/purification processes? The droplet-liquid microjunction-surface sampling probe (droplet-LMJ-SSP) coupled to a hyphenated system (UPLC-UV-HRESIMS) empowers the analysis of natural product sources in situ, providing data on the biosynthetic timing and spatial distribution of secondary metabolites. In this study the droplet-LMJ-SSP was utilized to validate the authenticity of two new peptaibols (2 and 3) as biosynthesized secondary metabolites, even though both them had structural features that could be perceived as artefacts. Compounds 2 and 3 were isolated from the scaled up fermentation of Trichoderma arundinaceum (strain MSX70741), along with a new member of the trichobrevin BIII complex (1), and four known compounds (4-7). The structures of the isolates were established using a set of spectroscopic and spectrometric methods, and their absolute configurations were determined by Marfey's analysis. The cytotoxic activity of compounds 1, 3, 4 and 6 was evaluated against a panel of cancer cell lines, where cytotoxic activity in the single digit µM range was observed.