Constituents of the higher fungi. IX. Bovinone, 2,5-dihydroxy-3-geranylgeranyl-1,4-benzoquinone from Boletus (Suillus) bovinus (linn. ex Fr.) Kuntze

Chemical Compounds, Bioactivities, and Potential Applications of the Mushroom Species of Genus Suillus (Agaricomycetes): A Review

The genus Suillus, also known as "Song mo," falls under the order Boletales and consists of various higher fungi. It establishes mycorrhizae primarily with pine trees and has a good taste and medicinal values. Herein, we reviewed the chemical compounds present in the genus Suillus, including polysaccharides, steroids, phenols, polyprenyl phenol derivatives, fatty acids, organic acids, and amino acids, and their reported bioactivities and potential applications. This review aims to promote the utilization of the resources belonging to the genus Suillus and serves as a theoretical basis for their future studies and clinical applications.

Potential of small-molecule fungal metabolites in antiviral chemotherapy

Various viral diseases, such as acquired immunodeficiency syndrome, influenza, and hepatitis, have emerged as leading causes of human death worldwide. Scientific endeavor since invention of DNA-dependent RNA polymerase of pox virus in 1967 resulted in better understanding of virus replication and development of various novel therapeutic strategies. Despite considerable advancement in every facet of drug discovery process, development of commercially viable, safe, and effective drugs for these viruses still remains a big challenge. Decades of intense research yielded a handful of natural and synthetic therapeutic options. But emergence of new viruses and drug-resistant viral strains had made new drug development process a never-ending battle. Small-molecule fungal metabolites due to their vast diversity, stereochemical complexity, and preapproved biocompatibility always remain an attractive source for new drug discovery. Though, exploration of therapeutic importance of fungal metabolites has started early with discovery of penicillin, recent prediction asserted that only a small percentage (5-10%) of fungal species have been identified and much less have been scientifically investigated. Therefore, exploration of new fungal metabolites, their bioassay, and subsequent mechanistic study bears huge importance in new drug discovery endeavors. Though no fungal metabolites so far approved for antiviral treatment, many of these exhibited high potential against various viral diseases. This review comprehensively discussed about antiviral activities of fungal metabolites of diverse origin against some important viral diseases. This also highlighted the mechanistic details of inhibition of viral replication along with structure-activity relationship of some common and important classes of fungal metabolites.

Metabolite profiling and fingerprinting of Suillus species (Basidiomycetes) by electrospray mass spectrometry

The genus Suillus is known for the occurrence of a series of prenylated phenols and boviquinones. The extracts of four different Suillus species [S. bovinus, S. granulatus, S. tridentinus and S.variegatus) were investigated by using rapid ultra-performance Liquid chromatography/electrospray ionization mass spectrometry (UPLC/ESI-MS) and direct infusion electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FT-ICR-MS). While direct infusion ESI-FT-ICR mass spectra give a fast overview concerning the elemental compositions of the compounds and, therefore, hints to the main metabolites, UPLC/ESI-tandem mass spectrometry is shown to be a useful tool for their identification. A principal component analysis (PCA) and hierarchical cluster analysis (HCA) based on the UPLC/ESI-MS clearly showed that the metabolite profiles can be used not only for the identification and classification of such fungi but also as a sophisticated and powerful tool for the chemotaxonomy of fungi. Furthermore, a clear discrimination of various types of biological samples (fruiting bodies versus mycelial cultures) is also possible. The orthogonal partial least squares (OPLS) two-class models of both UPLC/ESI-MS and ESI-FT-ICR-MS possess a clear differentiation of two compared Suillus species representing the between class variation and the within class variation. Based on generated S-plots and Loading plots, statistically significant metabolites could be identified as potential biomarker for one species.

Sorgoleone

Sorgoleone, a major component of the hydrophobic root exudate of sorghum [Sorghum bicolor (L.) Moench], is one of the most studied allelochemicals. The exudate also contains an equivalent amount of a lipid resorcinol analog as well as a number of minor sorgoleone congeners. Synthesis of sorgoleone is constitutive and compartmentalized within root hairs, which can accumulate up to 20 microg of exudate/mg root dry weight. The biosynthesis pathway involves unique fatty acid desaturases which produce an atypical 16:3 fatty acyl-CoA starter unit for an alkylresorcinol synthase that catalyzes the formation of a pentadecatrienylresorcinol intermediate. This intermediate is then methylated by SAM-dependent O-methyltransferases and dihydroxylated by cytochrome P450 monooxygenases. An EST data set derived from a S. bicolor root hair-specific cDNA library contained all the candidate sequences potentially encoding enzymes involved in the sorgoleone biosynthetic pathway. Sorgoleone interferes with several molecular target sites, including inhibition of photosynthesis in germinating seedlings. Sorgoleone is not translocated acropetally in older plants, but can be absorbed through the hypocotyl and cotyledonary tissues. Therefore, the mode of action of sorgoleone may be the result of inhibition of photosynthesis in young seedlings in concert with inhibition of its other molecular target sites in older plants. Due to its hydrophobic nature, sorgoleone is strongly sorbed in soil which increases its persistence, but experiments show that it is mineralized by microorganisms over time.

Structure and absolute configuration of the fungal ansabenzoquinone rhizopogone

The main pigment of the basidiomycete Rhizopogon pumilionus is the [13]paracyclophane derivative rhizopogone (1). The structures of 1 and the accompanying 2-acetoxyrhizopogone (5) were determined by spectroscopic studies, including 1D and 2D NMR measurements. The absolute configuration of 1 was assigned by comparison of its CD spectrum with that of secotridentoquinone (4). The structures of 1 and tridentoquinone (3) suggest a common biosynthesis originating from 2-geranylgeranyl-6-hydroxy-1,4-benzoquinone (9). This supports the close taxonomic relationship of the genera Rhizopogon and Suillus (Boletales).

Boletunones A and B, highly functionalized novel sesquiterpenes from Boletus calopus

Highly functionalized novel sesquiterpenes, named boletunones A and B, were isolated from the methanolic extract of the fruiting body of the mushroom Boletus calopus. Their structures and relative stereochemistry were established by various spectral analyses. [structure: see text]