New p-terphenyl and benzoquinone metabolites from the bioluminescent mushroom Neonothopanus nambi

New benzoquinone pigments from the hydnoid fungus Sarcodontia setosa and their biosynthetic relationship

Chemical investigation of the hydnoid fungus Sarcodontia setosa resulted in the isolation of five compounds, including two new sarcodontic acid derivatives - setosic acid (1) and 7,8-dehydrohomosarcodontic acid (2) along with three known benzoquinone pigments - sarcodontic acid (3), 4,5-dehydrosarcodontic acid (4) and dihydrosarcodontic acid (5). The structures were elucidated using spectroscopic methods (UV, NMR and HR-ESIMS). The biosynthetic relationship of the isolated compounds is proposed and discussed. Antibacterial activity screening of compounds 1-5 against ESKAPE bacterial strains in vitro with zones of inhibition was performed and MIC values were established for the most active compounds (3 and 5).

Antiphytopathogenic activity of the bioluminescent mushroom Neonothopanus nambi against root-rot disease

Aurisin A (1) and the culture medium of the luminescent mushroom Neonothopanus nambi showed antifungal activity against Phytophthora palmivora, which causes the root-rot disease of Monthong durian, in a preliminary greenhouse experiment. Moreover, a new natural product, neonambiquinone B (2), was isolated. Their structures were elucidated by mass, IR and extensive analysis of their 1D and 2D NMR spectroscopic data. The results demonstrated that the culture medium of N. nambi is a promising potential for their agricultural applications.

Activity of aurisin A isolated from Neonothopanus nambi against methicillin-resistant Staphylococcus aureus strains

Mycopharmaceuticals from basidiomycetes represent a promising source of new antimicrobials to overcome the challenges of multidrug-resistant bacteria. Here we report for the first time the in vitro activity of aurisin A, a dimeric sesquiterpenoid isolated from wild bioluminescent basidiomycetes Neonothopanus nambi DSM 24013, against methicillin-resistant Staphylococcus aureus (MRSA). Aurisin A revealed strong anti-MRSA activity with minimum inhibitory concentration 7.81 μg/mL against ATCC 33591 and ATCC 43300 reference strains, and BD 16876 and BD 15358 clinical strains. Activity against the clinical strains is 10- to 40-fold higher than that of the antibiotic fusidic acid. Furthermore, aurisin A proved to be more potent (MIC 3.91 μg/mL) in inhibiting growth of vancomycin-intermediate S. aureus (VISA) ATCC 700699 and displayed a rapid time-dependent bactericidal activity against MRSA (complete killing within 1 h). Additionally, aurisin A and oxacillin combination displayed synergy with notable decrease in the MICs of both compounds against MRSA. Notable synergism was also observed in combinations with linezolid and fusidic acid. Our findings indicate that aurisin A is a promising candidate for developing therapeutic agents against multidrug-resistant S. aureus and warrants further investigation.

Anti-inflammatory and anticancer p-terphenyl derivatives from fungi of the genus Thelephora

Fungi from the genus Thelephora have been exploited to identify bioactive compounds. The main natural products characterized are para-terphenyl derivatives, chiefly represented by the lead anti-inflammatory compound vialinin A isolated from species T. vialis and T. terrestris. Different series of p-terphenyls have been identified, including vialinins, ganbajunins, terrestrins, telephantins and other products. Their mechanism of action is not always clearly identified, and different potential molecule targets have been proposed. The lead vialinin A functions as a protease inhibitor, efficiently targeting ubiquitin-specific peptidases USP4/5 and sentrin-specific protease SENP1 which are prominent anti-inflammatory and anticancer targets. Protease inhibition is coupled with a powerful inhibition of the cellular production of tumor necrosis factor TNFα. Other mechanisms contributing to the anti-inflammatory or anti-proliferative action of these p-terphenyl compounds have been invoked, including the formation of cytotoxic copper complexes for derivatives bearing a catechol central unit such vialinin A, terrestrin B and telephantin O. These p-terphenyl compounds could be further exploited to design novel anticancer agents, as evidenced with the parent compound terphenyllin (essentially found in Aspergillus species) which has revealed marked antitumor and anti-metastatic effects in xenograft models of gastric and pancreatic cancer. This review shed light on the structural and functional diversity of p-terphenyls compounds isolated from Thelephora species, their molecular targets and pharmacological properties.

Identification of potential edible mushroom as SARS-CoV-2 main protease inhibitor using rational drug designing approach

Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) is highly pathogenic to humans and has created health care threats worldwide. This urgent situation has focused the researchers worldwide towards the development of novel vaccine or small molecule therapeutics for SARS-CoV-2. Although several vaccines have already been discovered and are in use for the masses, no therapeutic medication has yet been approved by FDA for the treatment of COVID-19. Keeping this in view, in the present study, we have identified promising hits against the main protease (M^pro) of SARS-CoV-2 from edible mushrooms. Structure-based virtual screening (VS) of 2433 compounds derived from mushrooms was performed with M^pro protein (6LU7). Four promising hits, namely, Kynapcin-12 (M_78), Kynapcin-28 (M_82), Kynapcin-24 (M_83), and Neonambiterphenyls-A (M_366) were identified based on the result of docking, Lipinski's rule, 100 ns molecular dynamics (MD) simulation and MM/PBSA binding free energy calculations. Finally, the inhibitory properties of these hits were compared with three known inhibitors, baicalein (1), baicalin (2), and biflavonoid (3). Data indicated that M_78, M_82 and M_83 compounds present in edible mushroom Polyozellus multiplex were potent inhibitors of M^proprotein (6LU7). It could be concluded that edible mushroom Polyozellus multiplex has potential activity against SARS-CoV-2 infection and identified molecules could be further explored as therapeutic inhibitors against SARS-CoV-2.

Scalarane Sesterterpenoids with Antibacterial and Anti-Proliferative Activities from the Mushroom Neonothopanus nambi

Seven undescribed scalarane sesterterpenoids, nambiscalaranes B–H (1–7), together with two known compounds, nambiscalarane (8) and aurisin A (9) were isolated from the cultured mycelium of the luminescent mushroom Neonothopanus nambi. Their structures were elucidated by thorough analysis of their 1D and 2D NMR spectroscopic data. The absolute configurations of 1–8 were determined by electronic circular dichroism (ECD) calculations and optical rotation measurements. The isolated sesterterpenoids were evaluated against A549, HT29, HeLa, and HCT-116 cancer cell lines, and against five bacterial strains. Compounds 3, 5, and 7 showed strong cytotoxicity against HCT-116 cell line, with IC50 values ranging from 13.41 to 16.53 µM, and showed no cytotoxicity towards Vero cells. Moreover, compound 8 inhibited the growth of Bacillus subtilis with a MIC value of 8 µg/mL, which was equivalent to the MIC value of the standard kanamycin.

A new p-terphenyl derivative from the insect-derived fungus Aspergillus candidus Bdf-2 and the synergistic effects of terphenyllin

A new p-terphenyl derivative 4″-deoxy-2′-methoxyterphenyllin (1), along with six known p-terphenyl derivatives (2–7), a known flavonoid derivative dechlorochlorflavonin (8) and a known fellutanine A (9), were isolated from the insect-derived strain of the fungus Aspergillus candidus Bdf-2, associated with Blaptica dubia. The structure of 1 was established by the analysis of the 1D and 2D NMR and HR-ESI-MS spectra. Compounds 1–9 were evaluated for antibacterial activities against Staphylococcus aureus ATCC29213, Escherichia coli ATCC25922 and Ralstonia solanacearum, and for antioxidant activities. Synergistic effects of compound 2 with the other compounds were also investigated. As a result, compound 6 displayed the best antibacterial activities in all single compound with MIC value of 32 µg/mL against S. aureus ATCC29213 and R. solanacearum, respectively. However, no antibacterial effect against E. coli ATCC25922 was detected from any single compound. The combination of 2 + 6 exhibited obvious synergistic effect against S. aureus ATCC29213 and the MIC value was 4 µg/mL. Compound 6 also showed the best antioxidant activity as a single compound with an IC₅₀ value of 17.62 µg/mL. Combinations of 5 + 6, 2 + 4 + 5 and 2 + 4 + 5 + 6 displayed synergistic effect and their antioxidant activities were better than that of any single compound.