Most estrogen receptor α (ERα) ligands target the ligand binding domain (LBD). Agonist 17β-estradiol (E₂) and tamoxifen (TM, known SERM), bind to the same site within the LBD. However, structures of ligand-bound complexes show that E₂ and TM induce different conformations of helix 12 (H12). During the molecular modelling studies of some naturally occurring flavonoids such as quercetin, luteolin, myricetin, kaempferol, naringin, hesperidin, galangin, baicalein and epicatechin with human ERα (3ERT and 1GWR), we observed that most of the ligands bound to the active site pocket of both 3ERT and 1GWR. The docking scores, interaction analyses, and conformation of H12 provided the data to support for the estrogenic or antiestrogenic potential of these flavonoids to a limited degree. Explicit molecular dynamics for 50 ns was performed to identify the stability and compatibility pattern of protein-ligand complex and RMSD were obtained. Baicalein, epicatechin, and kaempferol with 1GWR complex showed similar RMSD trend with minor deviations in the protein backbone RMSD against 1GWR-E₂ complex that provided clear indications that ligands were stable throughout the explicit molecular simulations in the protein and outcome of naringin-3ERT complex had an upward trend but stable throughout the simulations and all molecular dynamics showed stability with less than overall 1 Å deviation throughout the simulations. To examine their estrogenic or antiestrogenic potential, we studied the effect of the flavonoids on viability, progesterone receptor expression and 3xERE/3XERRE-driven reporter gene expression in ERα positive and estrogen responsive MCF-7 breast cancer cells. Epicatechin, myricetin, and kaempferol showed estrogenic potential at 5 µM concentration.

Antiviral therapy is crucial for the circumvention of viral epidemics. The unavailability of a specific antiviral drug against the chikungunya virus (CHIKV) disease has created an alarming situation to identify or develop potent chemical molecules for remedial management of CHIKV. In the present investigation, in silico studies of dihydrorugosaflavonoid derivatives (5a–f) with non-structural protein-3 (nsP3) were carried out. nsP3 replication protein has recently been considered as a possible antiviral target in which crucial inhibitors fit into the adenosine-binding pocket of the macrodomain. The 4′-halogenated dihydrorugosaflavonoids displayed intrinsic binding with the nsp3 macrodomain (PDB ID: 3GPO) of CHIKV. Compounds 5c and 5d showed docking scores of −7.54 and −6.86 kcal mol^–1, respectively. Various in vitro assays were performed to confirm their (5a–f) antiviral potential against CHIKV. The non-cytotoxic dose was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and was found to be <100 μM. The compounds 5c and 5d showed their inhibitory potential for CHIKV, which was determined through cytopathic effect assay and plaque reduction assay, which show inhibition up to 95 and 92% for 70 μM concentration of the compounds, respectively. The quantitative real-time polymerase chain reaction assay result confirmed the ability of 5c and 5d to reduce the viral RNA level at 70 μM concentration of compounds to nearly 95 and 93% concentration, respectively, in cells with CHIKV infection. Further, the CHIKV-inhibitory capacity of these compounds was corroborated by execution of immunofluorescence assay. The executed work will be meaningful for the future research of studied dihydrorugosaflavonoids against prime antiviral entrants, leading to remedial management to preclude CHIKV infection.

Filamentous fungi synthesize natural products as an ecological function. In this study, an interesting indigenous fungus producing orange pigment exogenously was investigated in detail as it possesses additional attributes along with colouring properties. An interesting fungus was isolated from a dicot plant, Maytenus rothiana. After a detailed study, the fungal isolate turned out to be a species of Gonatophragmium belonging to the family Acrospermaceae. Based on the morphological, cultural, and sequence-based phylogenetic analysis, the identity of this fungus was confirmed as Gonatophragmium triuniae. Although this fungus grows moderately, it produces good amounts of pigment on an agar medium. The fermented crude extract isolated from G. triuniae has shown antioxidant activity with an IC₅₀ value of 0.99 mg/mL and antibacterial activity against Gram-positive bacteria (with MIC of 3.91 μg/mL against Bacillus subtilis, and 15.6 μg/mL and 31.25 μg/mL for Staphylococcus aureus and Micrococcus luteus, respectively). Dyeing of cotton fabric mordanted with FeSO₄ using crude pigment was found to be satisfactory based on visual observation, suggesting its possible use in the textile industry. The orange pigment was purified from the crude extract by preparative HP-TLC. In addition, UV-Vis, FTIR, HRMS and NMR (¹H NMR, ¹³C NMR), COSY, and DEPT analyses revealed the orange pigment to be “1,2-dimethoxy-3H-phenoxazin-3-one” (C₁₄H₁₁NO₄, m/z 257). To our understanding, the present study is the first comprehensive report on Gonatophragmium triuniae as a potential pigment producer, reporting “1,2-dimethoxy-3H-phenoxazin-3-one” as the main pigment from the crude hexane extract. Moreover, this is the first study reporting antioxidant, antibacterial, and dyeing potential of crude extract of G. triuniae, suggesting possible potential applications of pigments and other bioactive secondary metabolites of the G. triuniae in textile and pharmaceutical industry.

Novel drug regimens against tuberculosis (TB) are urgently needed and may be developed by targeting essential enzymes of Mtb that sustain the pathogenicity of tuberculosis. In the present investigation, series of compounds (5a–f and 6a–f) based on a naturally occurring rugosaflavonoid moiety were evaluated by in silico molecular modeling studies against β-ketoacyl-ACP reductase (MabA) (PDB ID: IUZN) and pantothenate kinase (PanK) (PDB ID: 3AF3). Compounds 5a, 5c, 5d, and 6c, which had docking scores of −8.29, −8.36, −8.17 and −7.39 kcal mol⁻¹, respectively, displayed interactions with MabA that were better than those of isoniazid (−6.81 kcal mol⁻¹). Similarly, compounds 5a, 5c, 5d, and 6c, which had docking scores of −7.55, −7.64, −7.40 and −6.7 kcal mol⁻¹, respectively, displayed interactions with PanK that were comparable to those of isoniazid (−7.64 kcal mol⁻¹). Because of their docking scores, these compounds were screened in vitro against Mycobacterium tuberculosis H37Ra (Mtb) using an XRMA protocol. Among the screened compounds, the dihydrorugosaflavonoid derivatives 5a, 5c, and 5d had IC₅₀ values of 12.93, 8.43 and 11.3 μg mL⁻¹, respectively, and exhibited better inhibitory activity than the parent rugosaflavonoid derivatives. The rugosaflavonoid derivative 6c had an IC₅₀ value of 17.57 μg mL⁻¹. The synthesized compounds also displayed inhibitory activity against the Gram-positive bacteria Bacillus subtilis and Staphylococcus aureus. The present study will be helpful for the further development of these molecules into antitubercular lead candidates.

The first synthetic route developed for Podocarflavone A reported from Podocarpus macrophyllus and its analogs in 7 steps. Computational analysis for binding with the pantothenate kinase (3AVO) of Mycobacterium tuberculosis showed their docking score (ds) in the range of −8.9 to −9.3 Kcal/mol. MD simulations delineated the stability of the protein-ligand complexes in the TIP3P model. MMGBSA and MMPBSA values of 8d were −42.46 Kcal/mol and −14.58 Kcal/mol, respectively. Further in-vitro antitubercular screening of compounds 8a, 8d, and 8e against M. tuberculosis H37Ra using XRMA protocol exhibited promising antimycobacterial activity with IC₅₀ values 21.82 µg/mL, 15.55 µg/mL, and 16.56 µg/mL, respectively. Compounds 8a, 8d, and 8e showed antibacterial activity with IC₅₀ values 41.56 µg/mL, 24.72 µg/mL, and 72.45 µg/mL respectively against the Staphylococcus aureus. 8a and 8d showed inhibition with IC₅₀ values 39.6 µg/mL and 27.64 µg/mL, respectively, against Bacillus subtilis. The present study could help in the further development of lead molecules against tuberculosis. Graphical Abstract