Prenyltransferases (PTs) are involved in the biosynthesis of a multitude of pharmaceutically and agriculturally important plant, bacterial, and fungal compounds. Although numerous prenylated compounds have been isolated from Basidiomycota (mushroom-forming fungi), knowledge of the PTs catalyzing the transfer reactions in this group of fungi is scarce. Here, we report the biochemical characterization of an O- and C-prenylating dimethylallyltryptophan synthase (DMATS)-like enzyme LpTyrPT from the scurfy deceiver Laccaria proxima. This PT transfers dimethylallyl moieties to l-tyrosine at the para-O position and to l-tryptophan at atom C-7 and represents the first basidiomycete l-tyrosine PT described so far. Phylogenetic analysis of PTs in fungi revealed that basidiomycete l-tyrosine PTs have evolved independently from their ascomycete counterparts and might represent the evolutionary origin of PTs acting on phenolic compounds in secondary metabolism.

In the past few decades, magnetic resonance spectroscopy (MRS) and MR imaging (MRI) have developed into a powerful non-invasive tool for medical diagnostic and therapy. Especially 19 F MR shows promising potential because of the properties of the fluorine atom and the negligible background signals in the MR spectra. The detection of temperature in a living organism is quite difficult, and usually external thermometers or fibers are used. Temperature determination via MRS needs temperature-sensitive contrast agents. This article reports first results of solvent and structural influences on the temperature sensitivity of 19 F NMR signals of chosen molecules. By using this chemical shift sensitivity, a local temperature can be determined with a high precision. Based on this preliminary study, we synthesized five metal complexes and compared the results of all variable temperature measurements. It is shown that the highest 19 F MR signal temperature dependence is detectable for a fluorine nucleus in a Tm3+ -complex.

19F-based magnetic resonance is a powerful tool to overcome several difficulties of standard 1H MR. We present the syntheses and characterization (including cell viability and stability tests) of two Tm3+ complexes. Both complexes allow the detection of temperature (ΔCT = -0.2319 ppm K-1 and -0.2122 ppm K-1) without a reference compound.

The Front Cover shows 19F-labeled molecules studied in two different liquids. By using 19F-MR signals (here the mountain), determination of the local temperature is possible. Signal intensities decrease with increasing temperature. The chemical shifts vary strongly depending on 19F position and solvent (here DMSO or D2O). Cover design by Mona Borggrefe and Felix Mysegaes and Dr. Markus Plaumann. More information can be found in the Research Article by Felix Mysegaes, Markus Plaumann and co-workers.

Discopodium penninervium is a medicinal plant endemic to Ethiopia. Its twigs extract led to the isolation of three new withanolides, discopodinolides A - C, and four known analogues. The structures of the compounds were elucidated using NMR, HRMS data analyses, and literature data. The relative configurations were defined by single-crystal X-ray crystallography and NOESY correlations. The antibacterial efficacy of the isolated compounds was evaluated against four commonly dispersed environmental strains of Escherichia coli, Bacillus subtilis, Bacillus pumilus, and Bacillus megaterium. Discopodinolides B and C exhibited moderate antibacterial activities against the pathogenic strains of E. coli, B. subtilis, and B. megaterium.

Here we report an efficient and short total synthesis of bulgarein (1), a natural compound from Bulgaria inquinans with cytotoxic activity. Key steps in the total synthesis are a SUZUKI-MIYAURA coupling reaction of two substituted naphthalene derivates followed by a polyphosphoric acid (PPA) mediated condensation reaction to form the benzo[j]fluoranthene skeleton. Bulgarein (1) was achieved over 4 steps with an overall yield of 25%.

Seven sesquiterpenoids, named nebucanes A-G (1-7), featuring a rare alliacane scaffold with unprecedented furan or pyrrole functions, were isolated from the fermentation broth of Clitocybe nebularis. Their structures were established on the basis of 1D/2D NMR spectroscopic analyses, HR-(+)-ESIMS spectra, and comparison of measured and calculated CD spectra for determination of the absolute configuration. Assessing the biological activities, nebucane D (4) exhibited antifungal effects against Rhodotorula glutinis, while nebucane G (7) displayed significant cytotoxicity against MCF-7 and A431 cell lines.

Bacteria and fungi have a high potential to produce compounds that display large structural change and diversity, thus displaying an extensive range of biological activities. Secondary metabolism or specialized metabolism is a term for pathways and small molecule products of metabolism that are not mandatory for the subsistence of the organism but improve and control their phenotype. Their interesting biological activities have occasioned their application in the fields of agriculture, food, and pharmaceuticals. Metabolic engineering is a powerful approach to improve access to these treasured molecules or to rationally engineer new ones. A thorough overview of engineering methods in secondary metabolism is presented, both in heterologous and epigenetic modification. Engineering methods to modify the structure of some secondary metabolite classes in their host are also intensively assessed.

Chemical defence and counter-defence: In warm weather, production of the defence agent formaldehyde protects the mushroom Mycena rosea against infestation with the mycoparasitic fungus Spinellus fusiger. In contrast, in cool and wet weather, which is favourable for the growth of S. fusiger, the mycoparasite is able to inactivate the chemical defence of M. rosea by producing large amounts of gallic acid, which reacts with amino acids and toxic formaldehyde to form nontoxic Mannich adducts, thus enabling S. fusiger to invade the fruiting bodies of M. rosea. More information can be found in the full paper by P. Spiteller et al.

Mycenarubin C, a previously unknown red pyrroloquinoline alkaloid, was isolated from fruiting bodies of the mushroom Mycena rosea and its structure was elucidated mainly by NMR spectroscopy and mass spectrometry. Unlike mycenarubin A, the major pyrroloquinoline alkaloid in fruiting bodies of M. rosea, mycenarubin C, contains an eight-membered ring with an additional C-1 unit that is hitherto unprecedented for pyrroloquinoline alkaloids known in nature. Incubation of mycenarubin A with an excess of formaldehyde revealed that mycenarubin C was generated nearly quantitatively from mycenarubin A. An investigation into the formaldehyde content of fresh fruiting bodies of M. rosea showed the presence of considerable amounts of formaldehyde, with values of 5 mu g per gram of fresh weight in fresh fruiting bodies. Although mycenarubin C did not show bioactivity against selected bacteria and fungi, formaldehyde inhibits the growth of the mycoparasite Spinellus fusiger at concentrations present in fruiting bodies of M. rosea. Therefore, formaldehyde might play an ecological role in the chemical defence of M. rosea against S. fusiger. In turn, S. fusiger produces gallic acid-presumably to detoxify formaldehyde by reaction of this aldehyde with amino acids and gallic acid to Mannich adducts.

(5S,6S)-Aminotenuazonic acid, a new 3-acyltetramic acid, related to the well-known mycotoxin tenuazonic acid has been isolated from fruiting bodies of Laccaria bicolor. Its structure was mostly established by analysis of its 2D NMR and HR-(+)-ESI-MS spectra. A total synthesis starting from N-Boc-l-isoleucine gave (5S,6S)-aminotenuazonic acid in 8 % yield over nine steps (67 % de). The key steps of the total synthesis are a light-initiated Hofmann-Loffler-Freytag radical chain reaction and a Dieckmann cyclisation. The relative and absolute configurations of the natural product were determined by comparison of its NMR and CD spectra with those of the corresponding enantiopure synthetic compounds. Metabolic profiling of crude extracts of different mushrooms showed that aminotenuazonic acid is present in all four of the investigated Laccaria species. Aminotenuazonic acid shows phytotoxic activities against the root and shoot growth of Lepidium sativum, Pinus sylvestris and Arabidopsis thaliana comparable to those of tenuazonic acid.

Fruiting bodies of Laccaria proxima were screened for the presence of new secondary metabolites by means of HPLC-UV and LC-HR-(+)-ESIMS. Thus, two isomeric alkaloids with a highly unusual core structure, E-proxamidine and its Z-isomer, were isolated from Laccaria proxima. The proxamidines consist of an eight-membered heterocyclic ring system with a formamidine unit. The structures were established by 2D NMR spectroscopic methods, HR-(+)-ESIMS, and HR-(+)-ESIMS/MS. The proxamidines are probably biosynthetically derived from tryptophan, dimethylallyl pyrophosphate, and S-adenosylmethionine and the eight-membered ring of the proxamidines is likely to be generated by a rearrangement of the tryptophan sceleton. Metabolic profiling of fruiting bodies of some other Laccaria species revealed that the proxamidines appear in significant amounts only in L. proxima making the compounds suitable as chemotaxonomic markers. E-Proxamidine exhibits herbicidal activity against Lepidium sativum.

Is it recommended to consume the fruiting bodies of Laccaria bicolor? On the cover picture, the experiments leading to the detection of the so far unknown mycotoxin (5S,6S)-aminotenuazonic acid–structurally closely related to the well-known tenuazonic acid–are shown in a cryptic way and some light is shed on the chemical secrets of Laccaria species. By a combination of analytical, chemical, and biological methods, the structure of aminotenuazonic acid was elucidated, a hypothetical biosynthesis was proposed, a total synthesis was developed, and its bioactivity was evaluated. More information can be found in the Full Paper by P. Spiteller, et al. on page 10333.

Three undescribed natural products, the anthranilic acid derivatives laccanthrilic acids A, B, and C, as well as the known (3S)-1,2,3,4-tetrahydro-3-β-carboline-3-carboxylic acid were isolated from fruiting bodies of Laccaria laccata. The structures were established by 1D and 2D NMR spectroscopy, HR-(+)-ESIMS and chemical synthesis. The absolute configuration of laccanthrilic acids A and B was determined by GC-MS after hydrolytic cleavage and derivatisation of the resulting glutamic acid with methanol and Mosher's reagent and subsequent comparison with authentic synthetic samples of known absolute configuration. The absolute configuration of laccanthrilic acid C was determined by comparison of the CD spectra of laccanthrilic acids B and C with each other. Metabolic profiling of related species showed that the compounds are common in the genus Laccaria. Laccanthrilic acid B exhibited moderate nematicidal effects against Caenorhabditis elegans, which might explain to some degree the beneficial role of these fungi for the growth and survival of their host plants.

Here we report the first total synthesis of the fungal alkaloids mycenarubin A, sanguinolentaquinone and mycenaflavin B. The pyrroloquinoline alkaloid mycenarubin A was obtained in 10 steps (21 % total yield, 92 % ee) from the known key precursor 6,7‐bis(benzyloxy)indole by an asymmetric alkylation and a biomimetic ring closure as the key steps. The indolo‐6,7‐quinone sanguinolentaquinone was obtained in eight steps (28 % total yield). Mycenaflavin B was also obtained in eight steps starting from the same key precursor (total yield 15 %) by a biomimetic ring closure and an acid‐catalysed decarboxylation reaction as the key steps. The cytotoxic activities of mycenarubin A and mycenaflavin B were evaluated against mouse fibroblasts (L929) and human malignant melanoma cells (RPMI‐7951).

Rosellin A and B, two red diketopiperazine alkaloids with unprecedented structures, have been isolated from the fruiting bodies of the mushroom Mycena rosella. The structures of the rosellins were mainly deduced from their 2D NMR and HRMS (ESI) spectra. Their absolute configuration was determined by comparison of the CD spectra of the rosellins with the corresponding CD spectra obtained by quantum chemical calculations. Root exposure to rosellin A led to bleaching of the leaves of Lepidium sativum plants.

Four so far unknown pyrroloquinoline alkaloids, yellow mycenaflavinsA, B, and C, and the purple mycenaflavinD, have been isolated from the fruiting bodies of Mycena haematopus. The structures of these new alkaloids were elucidated by NMR spectroscopy and HRMS (ESI+). The mycenaflavins are structurally related to mycenarubins and haematopodins, which have been previously identified in M. haematopus. However, compared with other known fungal pyrroloquinoline alkaloids, the mycenaflavins contain an additional double bond within the pyrroloquinoline moiety that accounts for the yellow colour of the monomeric mycenaflavinsA, B, and C. The purple mycenaflavinD is the first known dimeric pyrroloquinoline alkaloid with a C-C bridge between the two pyrroloquinoline units. Although the minor pyrroloquinoline alkaloid constituent mycenaflavinA exhibits only moderate bioactivity against the soil bacterium Azoarcus tolulyticus, the major pyrroloquinoline alkaloid constituent haematopodinB is similarly active as the antibiotic gentamicin.

Three new and seven known calopins were isolated from Caloboletus radicans. The structures of the new cyclocalopins, 8-deacetylcyclocalopin B (1), cyclocalopin A-15-ol (2), and 12,15-dimethoxycyclocalopin A (3), were mainly elucidated by NMR and MS data analysis. The stereochemistry of 1-3 was assigned based on NOE correlations and coupling constants and by comparison of their CD spectra with those of similar known calopins. While 1-10 were inactive against two cancer cell lines, they displayed anti-staphylococcal activity against methicillin-resistant Staphylococcus aureus strains (MRSA) with MIC values of 16-256 μg/mL. Moreover, some calopins were active against the fish pathogen Enterococcus faecalis F1B1.

The first total synthesis of makaluvamine O and batzelline D, pyrroloquinoline alkaloids isolated from marine sponges, are described. Key steps in the biomimetic synthesis are an intramolecular Michael addition leading to the pyrrolo[4,3,2-de]quinoline core and the following selective halogenation at C-6 position with NBS/NCS. Moreover, the related marine alkaloids damirone C, makaluvone and batzelline C were synthesised via this approach.

Site-selectivity, differentiating members of the same functional group type on one substrate, is an emerging tactic for shortened advanced building block and biomolecule synthesis. Despite its potential, site-selectivity remains less studied and especially so for ketone-based substrates. During this work ketone site-selectivity has been coupled with the chiral amine-catalyzed aldol desymmetrization of 4-keto-substituted cyclohexanones, allowing three stereogenic centers to form in the aldol product while leaving the acyclic ketone unreacted. Unique here, compared to all previous 4-substituted cyclohexanone desymmetrizations, is the first access to synthetically useful quantities of an epimeric (remote stereogenic center) aldol product. To demonstrate the value of these aldol products, we show their elaboration into eight keto-acetonide and one keto-lactone products. All compounds were isolated as single diastereomers and in high ee (≥96%). These efforts represent the first full characterization of aldol products with type III, Figure 2, relative stereochemistry, regardless of the enantiomer formed.