An in-silico pharmacophore-based molecular docking study to evaluate the inhibitory potentials of novel fungal triterpenoid Astrakurkurone analogues against a hypothetical mutated main protease of SARS-CoV-2 virus.

BACKGROUND: The main protease is an important structural protein of SARS-CoV-2, essential for its survivability inside a human host. Considering current vaccines' limitations and the absence of approved therapeutic targets, Mpro may be regarded as the potential candidate drug target. Novel fungal phytocompound Astrakurkurone may be studied as the potential Mpro inhibitor, considering its medicinal properties reported elsewhere. METHODS: In silico molecular docking was performed with Astrakurkurone and its twenty pharmacophore-based analogues against the native Mpro protein. A hypothetical Mpro was also constructed with seven mutations and targeted by Astrakurkurone and its analogues. Furthermore, multiple parameters such as statistical analysis (Principal Component Analysis), pharmacophore alignment, and drug likeness evaluation were performed to understand the mechanism of protein-ligand molecular interaction. Finally, molecular dynamic simulation was done for the top-ranking ligands to validate the result. RESULT: We identified twenty Astrakurkurone analogues through pharmacophore screening methodology. Among these twenty compounds, two analogues namely, ZINC89341287 and ZINC12128321 showed the highest inhibitory potentials against native and our hypothetical mutant Mpro, respectively (-7.7 and -7.3 kcal mol-1) when compared with the control drug Telaprevir (-5.9 and -6.0 kcal mol-1). Finally, we observed that functional groups of ligands namely two aromatic and one acceptor groups were responsible for the residual interaction with the target proteins. The molecular dynamic simulation further revealed that these compounds could make a stable complex with their respective protein targets in the near-native physiological condition. CONCLUSION: To conclude, Astrakurkurone analogues ZINC89341287 and ZINC12128321 can be potential therapeutic agents against the highly infectious SARS-CoV-2 virus.

Structural elucidation and antimicrobial activity of a diketopiperazine isolated from a Bacillus sp. associated with the marine sponge Spongia officinalis.

A diketopiperazine (3S, 6S)-3,6-diisobutylpiperazine-2,5-dione was isolated from a sponge-associated microbe for the first time and characterized by FTIR, HRESI-MS, 1H, 13C NMR and 2D NMR. The source is novel for this compound. Single crystal XRD of this diketopiperazine obtained as a natural product was analysed for the first time and its melting point was determined to be 262 °C. MICs of this cyclic dipeptide against Escherichia coli and Staphylococcus aureus subsp. aureus were 16 µg mL-1 and 22 µg mL-1 respectively, the first report of antibacterial activity of this diketopiperazine.Supplemental data for this article can be accessed at https://doi.org/10.1080/14786419.2019.1672684.

Characterization and Inception of a Triterpenoid Astrakurkurol, as a Cytotoxic Molecule on Human Hepatocellular Carcinoma Cells, Hep3B.

Mushrooms are customary influential sources of pharmaceutically active metabolites. Usually lanostane-type triterpenoids from mushrooms had prospective for cancer disease treatments. Recently, a triterpenoid, astrakurkurol obtained from the fresh basidiocarps of the edible mushroom Astraeus hygrometricus, drew attention as a new cytotoxic therapeutic. The structural stability of this triterpenoid had been established with the amalgamation of density functional theory (DFT) calculations and study of single-crystal X-ray diffraction. To successfully manifest astrakurkurol as a potent cytotoxic therapeutics, a wide apprehension on the molecular and cellular mechanisms underlying their action is prerequisite. On this account, our study was directed to scrutinize the influence of this triterpenoid on human hepatocellular cancer cell model Hep3B. Encapsulating all experimental facts revealed that astrakurkurol had significantly decreased cell viability in a concentration-dependent manner. This effect was unveiled to be apoptosis, documented by DNA fragmentation, chromatin condensation, nuclear shrinkage, membrane blebing, and imbalance of cell cycle distribution. Astrakurkurol persuaded the expression of death receptor associated proteins (Fas), which triggered caspase-8 activation following tBid cleavage. Moreover, tBid mediated ROS generation, which triggered mitochondrial dysfunction and activated the mitochondrial apoptotic events. Astrakurkurol cytotoxicity was based on caspase-8-mediated intrinsic apoptotic pathway and was associated with inhibition at Akt and NF-κB pathway. Astrakurkurol had also inhibited the migration of Hep3B cells, indicating its antimigratory potential. These findings led us to introduce astrakurkurol as a feasible and natural source for a safer cytotoxic drug against hepatocellular carcinoma.

Astrakurkurone, a sesquiterpenoid from wild edible mushroom, targets liver cancer cells by modulating Bcl-2 family proteins.

Induction of apoptosis is the target of choice for modern chemotherapeutic treatment of cancer, where lack of potent "target-specific" drugs has led to extensive research on anticancer compounds from natural sources. In our study, we have used astrakurkurone, a triterpene isolated from wild edible mushroom, Astraeus hygrometricus. We have discussed the structure and stability of astrakurkurone employing single-crystal X-ray crystallography and studied its potential apoptogenicity in hepatocellular carcinoma (HCC) cells. Our experiments reveal that it is cytotoxic against the HCC cell lines (Hep 3B and Hep G2) at significantly low doses. Further investigations indicated that astrakurkurone acts by inducing apoptosis in the cells, disrupting mitochondrial membrane potential and inducing the expression of Bcl-2 family proteins, for example, Bax, and the downstream effector caspases 3 and 9. A molecular docking study also predicted direct interactions of the drug with antiapoptotic proteins Bcl-2 and Bcl-xL. Thus, astrakurkurone could become a valuable addition to the conventional repertoire of future anticancer drugs. © 2019 IUBMB Life, 1-11, 2019.

Successful Therapy of Murine Visceral Leishmaniasis with Astrakurkurone, a Triterpene Isolated from the Mushroom Astraeus hygrometricus, Involves the Induction of Protective Cell-Mediated Immunity and TLR9.

In our previous report, we showed that astrakurkurone, a triterpene isolated from the Indian mushroom Astraeus hygrometricus (Pers.) Morgan, induced reactive oxygen species, leading to apoptosis in Leishmania donovani promastigotes, and also was effective in inhibiting intracellular amastigotes at the 50% inhibitory concentration of 2.5 µg/ml. The aim of the present study is to characterize the associated immunomodulatory potentials and cellular activation provided by astrakurkurone, leading to effective antileishmanial activity in vitro and in vivo Astrakurkurone-mediated antileishmanial activity was evaluated by real-time PCR and flow cytometry. The involvement of Toll-like receptor 9 (TLR9) was studied by in vitro assay in the presence of a TLR9 agonist and antagonist and by in silico modeling of a three-dimensional structure of the ectodomain of TLR9 and its interaction with astrakurkurone. Astrakurkurone caused a significant increase in TLR9 expression of L. donovani-infected macrophages along with the activation of proinflammatory responses. The involvement of TLR9 in astrakurkurone-mediated amastigote killing has been evidenced from the fact that a TLR9 agonist (CpG, ODN 1826) in combination with astrakurkurone enhanced the amastigote killing, while a TLR9 antagonist (bafilomycin A1) alone or in combination with astrakurkurone curbed the amastigote killing, which could be further justified by in silico evidence of docking between mouse TLR9 and astrakurkurone. Astrakurkurone was found to reduce the parasite burden in vivo by inducing protective cytokines, gamma interferon and interleukin 17. Moreover, astrakurkurone was nontoxic toward peripheral blood mononuclear cells of immunocompromised patients with visceral leishmaniasis. Astrakurkurone, a nontoxic antileishmanial, enhances the immune efficiency of host cells, leading to parasite clearance in vitro and in vivo.

A novel triterpene from Astraeus hygrometricus induces reactive oxygen species leading to death in Leishmania donovani.

AIM: The effect of astrakurkurone, a novel triterpene, isolated from Indian mushroom Astraeus hygrometricus has been investigated to elucidate the mechanisms involved in selective cell death of Leishmania donovani. MATERIALS & METHODS: The hypotheses were investigated using flow-cytometry, scanning electron microscopy and confocal microscopy. RESULTS: The time dependent elevation of astrakurkurone-induced reactive oxygen species (ROS) was found intimately associated with apoptosis. The involvement of ROS in promastigote death was found confirmed as NAC and GSH could decrease the ROS level and restored the mitochondrial membrane potential (ΔΨ(m)). It also inhibited the intracellular amastigotes. CONCLUSION: We claim the present invention as substantial in depth evidences that mushroom derived active molecules can be exploited as target specific, comparatively nontoxic leads for antileishmanial therapy.