Hybridisation of in silico and in vitro bioassays for studying the activation of Nrf2 by natural compounds

Oxidative stress, characterized by the damaging accumulation of free radicals, is associated with various diseases, including cardiovascular, neurodegenerative, and metabolic disorders. The transcription factor Nrf2 is pivotal in cellular defense against oxidative stress by regulating genes that detoxify free radicals, thus maintaining redox homeostasis and preventing cellular aging. Keap1 plays a regulatory role through its interaction with Nrf2, ensuring Nrf2 degradation under homeostatic conditions and facilitating its stabilization and nuclear translocation during oxidative stress. In the initial stage of our study, we conducted in vitro assays on HaCaT cells, a human keratinocyte cell line, to measure the expression levels of Nrf2 to reveal the activity of promising medicinal plants, which were then selected for further evaluation. Subsequently, this study leverages in silico techniques, integrating machine learning with molecular docking and dynamics, to screen natural compounds that potentially activate Nrf2. Data from the ChEMBL database were categorized into active and inactive compounds and used for training different machine-learning models to predict potential Nrf2 activators. The best-performing model was used to select compounds for further evaluation via molecular docking and dynamics, assessing their interactions with Keap1/Nrf2. The LC-MS/MS-based chemical profiles also validated the presence of these chemical compounds. This approach underscores the synergy between in vitro bioassays and in silico approaches in identifying Nrf2 activators, offering a cost-effective strategy for drug development.

In-silico evaluation of Oroxylum indicum vent compounds in the plausible treatment and prevention of nasopharyngeal cancer

BACKGROUND

Shyonaka (Oroxylum indicum Vent) is widely used in Ayurveda and in ethnomedical practice for the treatment of inflammation, pain, diarrhea, non-healing ulcers, and cancer. Owing to the high prevalence of Epstein-Barr virus (EBV) infection in Nasopharyngeal carcinoma (NPC) patients, simultaneous targeting of proteins involved in both EBV replication and NPC proliferation might help to manage the disease effectively.

OBJECTIVES

This study is designed to identify potential dual targeting inhibitors from Oroxylum indicum having the potential to inhibit both EBV and NPC. This study also attempted quantitative analysis of Shyonaka Bark Decoction (SBD) to confirm the presence of Baicalein and Chrysin which are predominant marker compounds of Shyonaka.

METHODOLOGY

The HPLC analysis of stem bark and root bark of Oroxylum indicum was done to estimate the presence of marker compounds Baicalein and Chrysalin. The in-silico analysis included ADMET analysis followed by molecular docking of known compounds from Oroxylum indicum (retrieved from IMPPAT database) onto the target proteins of EBV (BHRF1, NEC1, dUTPase, Uracil DNA glycosylase) and NPC (COX-2, EGFR, and MDM2) using DOCK6 tool. Further validations were done using the molecular dynamics simulations of top screened molecules onto the selected target proteins using AMBER20 package and their corresponding MMGBSA binding free-energy values were calculated.

RESULTS

The molecular docking revealed that the key molecules from the plant, scutellarein 7-rutinoside (S7R), scutellarin (SCU) and 6-hydroxyluteolin, Baicalein and 5,7-Dihydroxy-2-phenyl-6-[3,4,5-trihydroxy-6-(hydroxymethyl)oxan-2-yl]oxychromen-4-one (57D) are effectively intervening with the target proteins of EBV, one of the key causative factors of NPC and the NPC specific targets which have the potential to reduce tumor size and other consequences of NPC. The molecular dynamics simulations of S7R, Baicalein and 57D, Baicalein with MDM-2 protein and dUTPase protein, respectively, showed stable interactions between them which were further assessed by the binding energy calculations.

CONCLUSION

Overall, the in-silico evaluation of these phytochemicals with target proteins indicates their potential to inhibit both EBV and NPC which needs further in-vitro and in-vivo validations.

Evaluation and molecular docking study of two flavonoids from Oroxylum indicum (L.) Kurz and their semi-synthetic derivatives as histone deacetylase inhibitors

Chrysin (5,7-dihydroxyflavone, 6) and galangin 3-methyl ether (5,7-dihydroxy-3-methoxy flavone, 7) were obtained from the leaves of Oroxylum indicum (L.) Kurz in 4% and 6% yields, respectively. Both compounds could act as pan-histone deacetylase (HDAC) inhibitors. Structural modification of these lead compounds provided thirty-eight derivatives which were further tested as HDAC inhibitors. Compounds 6b, 6c, and 6q were the most potent derivatives with the IC50 values of 97.29 ± 0.63 μM, 91.71 ± 0.27 μM, and 96.87 ± 0.45 µM, respectively. Molecular docking study indicated the selectivity of these three compounds toward HDAC8 and the test against HDAC8 showed IC50 values in the same micromolar range. All three compounds were further evaluated for the anti-proliferative activity against HeLa and A549 cell lines. Compound 6q exhibited the best activity against HeLa cell line with the IC50 value of 13.91 ± 0.34 μM. Moreover, 6q was able to increase the acetylation level of histone H3. These promising HDAC inhibitors deserve investigation as chemotherapeutic agents for treating cancer.

Determination of Phytochemical Contents in Extracts from Different Growth Stages of Oroxylum indicum Fruits Using HPLC-DAD and QAMS Methods

Flavones are major compounds found in several parts of Oroxylum indicum (O. indicum). The quantification of multiple components by one marker (QAMS) method and the high-performance liquid chromatography (HPLC) method were developed for the quantitative analysis of extracts from the young fruits, green mature fruits, dry pod coats and seeds of O. indicum. Oroxin A, oroxin B and chrysin-7-O-glucuronide were identified in the O. indicum extracts. Oroxylin A and 5-hydroxymethylfurfural were isolated and structurally identified from the pod coat and young fruit extracts, respectively. From the HPLC analysis of the seven major flavones in the extracts, baicalin was the major compound in all extracts investigated (0.4-11% w/w of the extract). All flavone contents were low in the young fruit extract (<1% w/w of the extract). The green mature fruit and dry pod coat extracts showed similar constituent compositions. They contained small amounts of baicalin and oroxylin A, which were found only in these two extracts. Oroxylin A could be used as a marker to indicate the maturity of O. indicum fruits, while 5-hydroxymethylfurfural could be used as a marker for the young fruits. Baicalin was found to be a suitable single marker to calculate the contents of all flavones in the O. indicum extracts.

Ethyl Acetate Extract of Colletotrichum gloeosporioides Promotes Cytotoxicity and Apoptosis in Human Breast Cancer Cells

Fungal endophytes are known to be a paragon for producing bioactive compounds with a variety of pharmacological importance. The current study aims to elucidate the molecular alterations induced by the bioactive compounds produced by the fungal endophyte Colletotrichum gloeosporioides in the tumor microenvironment of human breast cancer cells. GC/MS analysis of the ethyl acetate (EA) extract of C. gloeosporioides revealed the presence of bioactive compounds with anticancer activity. The EA extract of C. gloeosporioides exerted potential plasmid DNA protective activity against hydroxyl radicals of Fenton's reagent. The cytotoxic activity further revealed that MDA-MB-231 cells exhibit more sensitivity toward the EA extract of C. gloeosporioides as compared to MCF-7 cells, whereas non-toxic to non-cancerous HEK293T cells. Furthermore, the anticancer activity demonstrated by the EA extract of C. gloeosporioides was studied by assessing nuclear morphometric analysis and induction of apoptosis in MDA-MB-231 and MCF-7 cells. The EA extract of C. gloeosporioides causes the alteration in cellular and nuclear morphologies, chromatin condensation, long-term colony inhibition, and inhibition of cell migration and proliferation ability of MDA-MB-231 and MCF-7 cells. The study also revealed that the EA extract of C. gloeosporioides treated cells undergoes apoptosis by increased production of reactive oxygen species and significant deficit in mitochondrial membrane potential. Our study also showed that the EA extract of C. gloeosporioides causes upregulation of pro-apoptotic (BAX, PARP, CASPASE-8, and FADD), cell cycle arrest (P21), and tumor suppressor (P53) related genes. Additionally, the downregulation of antiapoptotic genes (BCL-2 and SURVIVIN) and increased Caspase-3 activity suggest the induction of apoptosis in the EA extract of C. gloeosporioides treated MDA-MB-231 and MCF-7 cells. Overall, our findings suggest that the bioactive compounds present in the EA extract of C. gloeosporioides promotes apoptosis by altering the genes related to the extrinsic as well as the intrinsic pathway. Further in vivo study in breast cancer models is required to validate the in vitro observations.

Anticancer potential of phytochemicals from Oroxylum indicum targeting Lactate Dehydrogenase A through bioinformatic approach

In recent years, small molecule inhibition of LDHA (Lactate Dehydrogenase A) has evolved as an appealing option for anticancer therapy. LDHA catalyzes the interconversion of pyruvate and lactate in the glycolysis pathway to play a crucial role in aerobic glycolysis. Therefore, in the current investigation LDHA was targeted with bioactive phytochemicals of an ethnomedicinally important plant species Oroxylum indicum (L.) Kurz. A total of 52 phytochemicals were screened against LDHA protein through molecular docking, ADMET (Absorption, Distribution, Metabolism, Excretion and Toxicity) assay and molecular dynamics simulation to reveal three potential lead compounds such as Chrysin-7-O-glucuronide (-8.2 kcal/mol), Oroxindin (-8.1 kcal/mol) and Oroxin A (-8.0 kcal/mol). ADMET assay unveiled favorable pharmacokinetic, pharmacodynamic and toxicity properties for all the lead compounds. Molecular dynamics simulation exhibited significant conformational stability and compactness. MM/GBSA free binding energy calculations further corroborated the selection of top candidates where Oroxindin (-46.47 kcal/mol) was found to be better than Chrysin-7-O-glucuronide (-45.72 kcal/mol) and Oroxin A (-37.25 kcal/mol). Aldolase reductase and Xanthine dehydrogenase enzymes were found as potential drug targets and Esculin, the FDA approved drug was identified as structurally analogous to Oroxindin. These results could drive in establishing novel medications targeting LDHA to fight cancer.

Oroxylum indicum Stem Bark Extract Reduces Tumor Progression by Inhibiting the EGFR-PI3K-AKT Pathway in an In Vivo 4NQO-Induced Oral Cancer Model

OBJECTIVES

Oral squamous cell carcinoma (OSCC) is the predominant type of oral cancer. Its incidence is high in certain geographic regions, and it is correlated with chewing tobacco. Epidermal growth factor receptor (EGFR), induced by tobacco carcinogens, is overexpressed in OSCC, leading to poor prognosis. Thus, EGFR inhibitors are promising agents against OSCC. High cost and toxicity of existing EGFR inhibitors necessitate alternative EGFR-targeted therapy. Here, we tested the antitumor potential of ethyl acetate fraction of an ethnomedicinal tree, Oroxylum indicum stem bark extract (OIEA) in a 4-nitroquinoline-1-oxide (4NQO)-induced oral carcinogenesis model.

METHODS

OIEA was prepared by solvent extraction method, and subsequently its in vitro radical scavenging activities were measured. High-performance liquid chromatography (HPLC) analysis of OIEA was done to identify the constituent active compounds. Hemolytic, trypan blue exclusion, and MTT [3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide] assays were performed in normal and cancer cells to select an optimum dose of OIEA for antitumor activity study in 4NQO-induced oral cancer in F344 rats. Measurement of tumor volume, weight, and cell count was followed by tumor cell cycle analysis and comet and annexin V/Propidium Iodide (PI) assay. Pro-apoptotic markers were detected by western blot testing. Molecular docking was done to predict the interaction between OIEA active component and EGFR or phosphatidylinositol-3-kinase (PI3K), which was further validated biologically. Finally, hepatic and renal function testing and histopathology were performed.

RESULTS

OIEA reduced tumor burden and increased survivability of the tumor-bearing rats significantly as compared to untreated tumor bearers. HPLC revealed oroxylin A as the predominant bioactive component in OIEA. Molecular docking predicted significant binding between oroxylin A and EGFR as well as PI3K, which was confirmed by western blot analysis of in vivo samples. OIEA also ameliorated hepato-, renal- and myelotoxicity induced by 4NQO.

CONCLUSION

OIEA reduces 4NQO-induced OSCC by modulating the EGFR/PI3K/AKT signaling cascade and also ameliorated toxicity in tumor bearers.

A developed high-performance thin-layer chromatography method for the determination of baicalin in Oroxylum indicum L. and its antioxidant activity

Abstract

A simple, accurate, precise, and specific high-performance thin-layer chromatography (HPTLC) method for the quantitative determination and validation of baicalin in different extracts of Oroxylum indicum has been developed for the first time. The mobile phase of acetone‒ethyl acetate‒water‒formic acid (2:10:0.5:0.5, V/V) was used for achieving good separation. Densitometric determination was carried out at 318 nm. The calibration curves were found to be linear in the range between 200 and 1000 ng per spot. During the analysis, the ethanolic extract of O. indicum showed higher content of baicalin than acetone, DMSO, and DMF extracts. Further, the antioxidant potential of different extracts of O. indicum were assessed with the 2,2-diphenyl-1-picrylhydrazyl (DPPH) method. The developed method of HPTLC was validated for specificity, accuracy, precision and linearity. The ethanolic extract has unveiled significant antioxidant activity with a percentage inhibition of 67.34%.

Graphic Abstract

Bioprospecting of fungal endophytes from Oroxylum indicum (L.) Kurz with antioxidant and cytotoxic activity

Oroxylum indicum (L.) Kurz, a medicinal plant, shows numerous pharmacological properties which may be attributed to the bioactive compounds produced by O. indicum or due to associated endophytes. In the present study, leaf of O. indicum was evaluated for the presence of associated fungal endophytes, and antioxidant and cytotoxic activities of bioactive compounds produced from them. Using culture-dependent approach, eight fungal endophytes belonging to five different genera were identified. Two endophytes Daldinia eschscholtzii and Ectophoma multirostrata have been reported for the first time from the leaf of O. indicum plant. High-performance thin-layer chromatography (HPTLC) of ethyl acetate (EA) extract of isolated fungal endophytes showed a distinct fingerprinting profile in EA extract of Colletotrichum gloeosporioides. Among identified endophytes, EA extract of C. gloeosporioides showed significant antioxidant activity against DPPH free radical, superoxide anion radical, nitric oxide radical and hydroxyl radical with EC50 values of 22.24±1.302 μg/mL, 67.46±0.576 μg/mL, 80.10±0.706 μg/mL and 61.55±1.360 μg/mL, respectively. EA extract of C. gloeosporioides exhibited potential cytotoxicity against HCT116, HeLa and HepG2 cancer cell lines with IC50 values of 76.59 μg/mL, 176.20 μg/mL and 1750.70 μg/mL, respectively. A comparative HPTLC fingerprinting and the antioxidant activity of C. gloeosporioides associated with two different hosts (leaf of O. indicum and dead twigs of other plant) showed that C. gloeosporioides produces bioactive compounds in a host-dependent manner.

In vitro immuno-stimulatory and anticancer activities of Oroxylum indicum (L.) Kurz.: An evidence for substitution of aerial parts for conservation

BACKGROUND

In Ayurveda, "Dashamoolarishta" is one of the important composite herbal formulations. Mainly, the root and root bark of Oroxylum indicum are used as one of the ingredients in its preparation. This leads to over exploitation of medicinal plants owing, to excessive demand due to population expansion and its perceived importance in traditional herbal remedies.

OBJECTIVE

For the conservation of biodiversity, the present investigation had an objective to prepare the extracts of different parts of O. indicum plant and to, compare the chemo-profiles as well as to study the biological activities of the prepared extracts.

MATERIALS AND METHODS

Hydro-alcoholic (HA) and aqueous (Aq) extracts of various plant parts were prepared and chemical investigation was done with the help of (LC-MS/MS). Further, in vitro biological activities such as immuno-stimulation (IS) using a cytokine bioassay in RAW264.7 and in vitro anticancer in TNF-α ELISA in THP-1 cells were studied.

RESULTS

The mass spectral profile of the plant revealed the presence of markers such as oroxylin A and chrysin in HA and Aq extracts of stem, leaf, bark and root. Cytokine release and TNF-α secretion was observed in both hydro-alcoholic and aqueous extracts.

CONCLUSION

Based on the results from the present study, it can be concluded that it is possible to replace the roots and the bark of O. indicum with the stem of young plants and leaves. It paves a way for the conserving the medicinal plants without uprooting and extinguishing the whole plant.

Sonapatha (Oroxylum indicum) mediates cytotoxicity in cultured HeLa cells by inducing apoptosis and suppressing NF-κB, COX-2, RASSF7 and NRF2

Oroxylum indicum (Sonapatha) is traditionally used to cure several human ailments. Therefore, the cell killing effect of chloroform, ethanol, and water extracts of Sonapatha was studied in cultured HeLa cells treated with 0-100 µg/mL of these extracts/doxorubicin by MTT assay. Since ethanol extract was most cytotoxic its effect was further investigated by clonogenic, apoptosis, necrosis, and lactate dehydrogenase assays. The mechanism of cytotoxicity of Sonapatha was determined at the molecular level by estimation of caspase 8 and 3 activities and Western blot analysis of NF-κB, COX-2, Nrf2, and RASSF7 which are overexpressed in neoplastic cells. HeLa cells treated with Sonapatha extract exhibited a concentration and time-dependent rise in the cytotoxicity as indicated by the MTT assay. Ethanol extract of Sonapatha (0, 20, 40, and 80 μg/mL) reduced clonogenicity, increased DNA fragmentation, apoptotic and necrotic indices, lactate dehydrogenase release, caspase 8 and 3 activities and inhibited the overexpression of NF-κB, COX-2, Nrf2, and RASSF7 in HeLa cells concentration-dependently.