A Close View of the Production of Bioactive Fungal Metabolites Mediated by Chromatin Modifiers.

Secondary metabolites produced by fungi are well known for their biological properties, which play important roles in medicine. These metabolites aid in managing infections and treating chronic illnesses, thereby contributing substantially to human health improvement. Despite this extensive knowledge, the vast biodiversity and biosynthetic potential of fungi is still largely unexplored, highlighting the need for further research in natural products. In this review, several secondary metabolites of fungal origin are described, emphasizing novel structures and skeletons. The detection and characterization of these metabolites have been significantly facilitated by advancements in analytical systems, particularly modern hyphenated liquid chromatography/mass spectrometry. These improvements have primarily enhanced sensitivity, resolution, and analysis flow velocity. Since the in vitro production of novel metabolites is often lower than the re-isolation of known metabolites, understanding chromatin-based alterations in fungal gene expression can elucidate potential pathways for discovering new metabolites. Several protocols for inducing metabolite production from different strains are discussed, demonstrating the need for uniformity in experimental procedures to achieve consistent biosynthetic activation.

Isolation and In Vitro Biological Evaluation of Triterpenes from Salacia grandifolia Leaves.

Salacia grandifolia is naturally found in the Atlantic Forest regions of Brazil. Despite the pharmacological potential of plants from the Salacia genus, phytochemical studies on this species have not been reported in literature. A new triterpene, 28-hydroxyfriedelane-3,15-dione (1), and seven known compounds (friedelan-3-one (2), friedelan-3ß-ol (3), friedelane-3,15-dione (4), 15α-hydroxyfriedelan-3-one (5), 28-hydroxyfriedelan-3-one (6), 30-hydroxyfriedelan-3-one (7), and 29-hydroxyfriedelan-3-one (8)) were obtained from the hexane extract of Salacia grandifolia leaves. These isolated compounds and three extracts, hexane (EH), chloroform (EC), and ethyl acetate (EAE), were assessed for their potential biological activities, which consisted in the evaluation of antiviral activity against a murine coronavirus, mouse hepatitis virus 3 (MHV-3), antibacterial activity against the susceptible and methicillin-resistant Staphylococcus aureus (MRSA), and antileukemia activity against the THP-1 and K-562 cell lines. The extracts EH and EAE along with the triterpenes 1 and 6 exhibited moderate to high antiviral activity, with emphasis on 6, which presented an EC50 value of 2.9 ± 0.3 µM. None of the compounds presented antibacterial activity against the tested strains. The evaluated compounds 1, 4, 6 and 7 exhibited low cytotoxic activity against the tested leukemia cell lines. Taken together, this study comprises an overview for the potential of the Salacia grandifolia biological activities, including a new isolated triterpene.

Pentacyclic Triterpenoids Isolated from Celastraceae: A Focus in the 13C-NMR Data.

The Celastraceae family comprises about 96 genera and more than 1.350 species, occurring mainly in tropical and subtropical regions of the world. The species of this family stand out as important plant sources of triterpenes, both in terms of abundance and structural diversity. Triterpenoids found in Celastraceae species display mainly lupane, ursane, oleanane, and friedelane skeletons, exhibiting a wide range of biological activities such as antiviral, antimicrobial, analgesic, anti-inflammatory, and cytotoxic against various tumor cell lines. This review aimed to document all triterpenes isolated from different botanical parts of species of the Celastraceae family covering 2001 to 2021. Furthermore, a compilation of their 13C-NMR data was carried out to help characterize compounds in future investigations. A total of 504 pentacyclic triterpenes were compiled and distinguished as 29 aromatic, 50 dimers, 103 friedelanes, 89 lupanes, 102 oleananes, 22 quinonemethides, 88 ursanes and 21 classified as others.

Isophorone derivatives as a new structural motif of aggregation pheromones in Curculionidae.

The beetle Homalinotus depressus (Coleoptera: Curculionidae) is a major pest of coconuts in the Northern region of Brazil, for which environmentally friendly methods of control are desired. Behavioral responses of H. depressus to airborne volatile extracts from conspecifics suggested the presence of a male-produced aggregation pheromone. GC analyses of these extracts showed the presence of four male-specific compounds. Analytical data in combination with the synthesis of standards led to the identification of the male-released semiochemicals as epoxyisophorone (1), isophorone (2), homalinol (3), and 2-hydroxyisophorone (4), of which (3) was the major constituent. The configuration of homalinol was determined to be cis on the basis of retention times of synthetic cis and trans synthetic standards. Enantiomers of cis-homalinol were obtained in high enantiomeric excess by using biocatalysis. Their separation on a GC enantioselective column (ß-Dex325®), allowed us to unambiguously determine that the absolute configuration of natural homalinol was (1R,2R,6S). Field bioassays demonstrated that both the synthetic major compound per se and mixtures of all four male-specific compounds were attractive to H. depressus.