Piyush More

Dual Drug Conjugated Nanoparticle for Simultaneous Targeting of Mitochondria and Nucleus in Cancer Cells

Effective targeting of mitochondria has emerged as an alternative strategy in cancer chemotherapy. However, considering mitochondrias crucial role in cellular energetics, metabolism and signaling, targeting mitochondria with small molecules would lead to severe side effects in cancer patients. Moreover, mitochondrial functions are highly dependent on other cellular organelles like nucleus. Hence, simultaneous targeting of mitochondria and nucleus could lead to more effective anticancer strategy. To achieve this goal, we have developed sub 200 nm particles from dual drug conjugates derived from direct tethering of mitochondria damaging drug (α- tocopheryl succinate) and nucleus damaging drugs (cisplatin, doxorubicin and paclitaxel). These dual drug conjugated nanoparticles were internalized into the acidic lysosomal compartments of the HeLa cervical cancer cells through endocytosis and induced apoptosis through cell cycle arrest. These nanoparticles damaged mitochondrial morphology and triggered the release of cytochrome c. Furthermore, these nanoparticles target nucleus to induce DNA damage, fragment the nuclear morphology and damage the cytoskeletal protein tubulin. Therefore, these dual drug conjugated nanoparticles can be successfully used as a platform technology for simultaneous targeting of multiple subcellular organelles in cancer cells to improve the therapeutic efficacy of the free drugs.

Diosgenin from Dioscorea bulbifera: Novel Hit for Treatment of Type II Diabetes Mellitus with Inhibitory Activity against α-Amylase and α-Glucosidase

Diabetes mellitus is a multifactorial metabolic disease characterized by post-prandial hyperglycemia (PPHG). α-amylase and α-glucosidase inhibitors aim to explore novel therapeutic agents. Herein we report the promises of Dioscorea bulbifera and its bioactive principle, diosgenin as novel α-amylase and α-glucosidase inhibitor. Among petroleum ether, ethyl acetate, methanol and 70% ethanol (v/v) extracts of bulbs of D. bulbifera, ethyl acetate extract showed highest inhibition upto 72.06 ± 0.51% and 82.64 ± 2.32% against α-amylase and α-glucosidase respectively. GC-TOF-MS analysis of ethyl acetate extract indicated presence of high diosgenin content. Diosgenin was isolated and identified by FTIR, 1H NMR and 13C NMR and confirmed by HPLC which showed an α-amylase and α-glucosidase inhibition upto 70.94 ± 1.24% and 81.71 ± 3.39%, respectively. Kinetic studies confirmed the uncompetitive mode of binding of diosgenin to α-amylase indicated by lowering of both Km and Vm. Interaction studies revealed the quenching of intrinsic fluorescence of α-amylase in presence of diosgenin. Similarly, circular dichroism spectrometry showed diminished negative humped peaks at 208 nm and 222 nm. Molecular docking indicated hydrogen bonding between carboxyl group of Asp300, while hydrophobic interactions between Tyr62, Trp58, Trp59, Val163, His305 and Gln63 residues of α-amylase. Diosgenin interacted with two catalytic residues (Asp352 and Glu411) from α-glucosidase. This is the first report of its kind that provides an intense scientific rationale for use of diosgenin as novel drug candidate for type II diabetes mellitus.

Phytochemical Analysis and Free Radical Scavenging Activity of Medicinal Plants Gnidia glauca and Dioscorea bulbifera

Gnidia glauca and Dioscorea bulbifera are traditional medicinal plants that can be considered as sources of natural antioxidants. Herein we report the phytochemical analysis and free radical scavenging activity of their sequential extracts. Phenolic and flavonoid content were determined. Scavenging activity was checked against pulse radiolysis generated ABTS•+ and OH radical, in addition to DPPH, superoxide and hydroxyl radicals by biochemical methods followed by principal component analysis. G. glauca leaf extracts were rich in phenolic and flavonoid content. Ethyl acetate extract of D. bulbifera bulbs and methanol extract of G. glauca stem exhibited excellent scavenging of pulse radiolysis generated ABTS•+ radical with a second order rate constant of 2.33×106 and 1.72×106, respectively. Similarly, methanol extract of G. glauca flower and ethyl acetate extract of D. bulbifera bulb with second order rate constants of 4.48×106 and 4.46×106 were found to be potent scavengers of pulse radiolysis generated OH radical. G. glauca leaf and stem showed excellent reducing activity and free radical scavenging activity. HPTLC fingerprinting, carried out in mobile phase, chloroform: toluene: ethanol (4: 4: 1, v/v) showed presence of florescent compound at 366 nm as well as UV active compound at 254 nm. GC-TOF-MS analysis revealed the predominance of diphenyl sulfone as major compound in G. glauca. Significant levels of n-hexadecanoic acid and octadecanoic acid were also present. Diosgenin (C27H42O3) and diosgenin (3á,25R) acetate were present as major phytoconstituents in the extracts of D. bulbifera. G. glauca and D. bulbifera contain significant amounts of phytochemicals with antioxidative properties that can be exploited as a potential source for herbal remedy for oxidative stress induced diseases. These results rationalize further investigation in the potential discovery of new natural bioactive principles from these two important medicinal plants.

Dioscorea bulbifera mediated synthesis of novel Au core Ag shell nanoparticles with potent antibiofilm and antileishmanial activity

Dioscorea bulbifera is a potent medicinal plant used in both Indian and Chinese traditional medicine owing to its rich phytochemical diversity. Herein, we report the rapid synthesis of novel AucoreAgshell nanoparticles by D. bulbifera tuber extract (DBTE). AucoreAgshell NPs synthesis was completed within 5 h showing a prominent peak at 540 nm. HRTEM analysis revealed 9 nm inner core of elemental gold covered by a silver shell giving a total particle diameter upto 15 nm. AucoreAgshellNPs were comprised of 57.34 ± 1.01% gold and 42.66 ± 0.97% silver of the total mass. AucoreAgshellNPs showed highest biofilm inhibition upto 83.68 ± 0.09% against A. baumannii. Biofilms of P. aeruginosa, E. coli, and S. aureus were inhibited up to 18.93 ± 1.94%, 22.33 ± 0.56%, and 30.70 ± 1.33%, respectively. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) confirmed unregulated cellular efflux through pore formation leading to cell death. Potent antileishmanial activity of AucoreAgshellNPs (MIC = 32 µg/mL) was confirmed by MTT assay. Further SEM micrographs showed pronounced deformity in the spindle shaped cellular morphology changing to spherical. This is the first report of synthesis, characterization, antibiofilm, and antileishmanial activity of AucoreAgshellNPs synthesized by D. bulbifera.

Novel platinum-palladium bimetallic nanoparticles synthesized by Dioscorea bulbifera: anticancer and antioxidant activities

Medicinal plants serve as rich sources of diverse bioactive phytochemicals that might even take part in bioreduction and stabilization of phytogenic nanoparticles with immense therapeutic properties. Herein, we report for the first time the rapid efficient synthesis of novel platinum–palladium bimetallic nanoparticles (Pt–PdNPs) along with individual platinum (PtNPs) and palladium (PdNPs) nanoparticles using a medicinal plant, Dioscorea bulbifera tuber extract (DBTE). High-resolution transmission electron microscopy revealed monodispersed PtNPs of size 2–5 nm, while PdNPs and Pt–PdNPs between 10 and 25 nm. Energy dispersive spectroscopy analysis confirmed 30.88%±1.73% elemental Pt and 68.96%±1.48% elemental Pd in the bimetallic nanoparticles. Fourier transform infrared spectra indicated strong peaks at 3,373 cm−1, attributed to hydroxyl group of polyphenolic compounds in DBTE that might play a key role in bioreduction in addition to the sharp peaks at 2,937, 1,647, 1,518, and 1,024 cm−1, associated with C–H stretching, N–H bending in primary amines, N–O stretching in nitro group, and C–C stretch, respectively. Anticancer activity against HeLa cells showed that Pt–PdNPs exhibited more pronounced cell death of 74.25% compared to individual PtNPs (12.6%) or PdNPs (33.15%). Further, Pt–PdNPs showed an enhanced scavenging activity against 2,2-diphenyl-1-picrylhydrazyl, superoxide, nitric oxide, and hydroxyl radicals.

Antidiabetic and Antioxidant Properties of Copper Nanoparticles Synthesized by Medicinal Plant Dioscorea bulbifera

Background: Biological route for synthesis of copper nanoparticles (CuNPs) with therapeutic potential is a major challenge. In this study, CuNPs were synthesized by D. bulbifera tuber extract (DBTE) which were further evaluated for antidiabetic and free radical scavenging activity. Methods: CuNPs synthesized by DBTE were characterized by UV-visible spectroscopy, transmission electron microscopy, energy dispersive spectroscopy and dynamic light scattering. CuNPs were checked for α-amylase and α-glucosidase inhibition along with interaction studies employing fluroscence spectroscopy, circular dichroism spectroscopy and computational docking. DPPH, nitric oxide and superoxide radical scavenging activities of CuNPs were also checked. Results: Spherical monodispersed CuNPs were synthesized within 5 h that was indicated by a colour change from pale blue to brown. Majority of the nanoparticles synthesized were found to be between 12 to 16 nm as showed in DLS which grew till a final size of 86 to 126 nm as indicated in TEM. Bioreduced CuNPs showed 38.70 ± 1.45% and 34.72 ± 1.22% inhibition against porcine and murine pancreatic amylase, respectively with an uncompetitive mode that was further confirmed by docking studies. Fluorescence spectroscopy confirmed the interaction of CuNPs to the enzyme via Trp residues while CD spectra indicated the structural and conformational changes on binding of CuNPs to the enzyme. CuNPs exhibited 99.09 ± 0.15% inhibition against α-glucosidase while 90.67 ± 0.33% inhibition against murine intestinal glucosidase, respectively. CuNPs showed 40.81 ± 1.44%, 79.06 ± 1.02% and 48.39 ± 1.46% scavenging activity against DPPH, nitric oxide and superoxide radicals respectively. Conclusion: D.bulbifera tuber extract mediated bioreduction is most rapid route to synthesize novel CuNPs with promising antidiabetic and antioxidant properties. This is the first detailed report which provides intense scientific rationale for the use of CuNPs as nanomedicine for efficient control of T2DM and oxidative stress.

Nanoparticle-Mediated Mitochondrial Damage Induces Apoptosis in Cancer

Detouring of conventional DNA damaging anticancer drugs into mitochondria to damage mitochondrial DNA is evolving as a promising strategy in chemotherapy. Inhibiting single target in mitochondria would eventually lead to the emergence of drug resistance. Moreover, targeting mitochondria selectively in cancer cells, keeping them intact in healthy cells, remains a major challenge. Herein, triphenylphosphine (TPP)-coated positively charged 131.6 nm spherical nanoparticles (NPs) comprised of α-tocopheryl succinate (TOS, inhibitor of complex II in electron transport chain) and obatoclax (Obt, inhibitor of Bcl-2) were engineered. The TOS-TPP-Obt-NPs entered into acidic lysosomes via macropinocytosis, followed by lysosomal escape and finally homed into mitochondria over a period of 24 h. Subsequently, these TOS-TPP-Obt-NPs triggered mitochondrial outer membrane permeabilization (MOMP) by inhibiting antiapoptotic Bcl-2, leading to Cytochrome C release. These TOS-TPP-Obt-NPs mediated mitochondrial damage induced cellular apoptosis through caspase-9 and caspase-3 cleavage to show improved efficacy in HeLa cells. Moreover, TOS-TPP-Obt-NPs induced MOMP in drug-resistant triple negative breast cancer cells (MDA-MB-231), leading to remarkable efficacy, compared to the combination of free drugs in higher drug concentrations. Results presented here clearly stimulate the usage of multiple drugs to perturb simultaneously diverse targets, selectively in mitochondria, as next-generation cancer therapeutics.

Synthesis, DNA interaction and anticancer activity of 2-anthryl substituted benzimidazole derivatives

2-Anthryl benzimidazole derivatives (5–7) with hydrogen, carboxyl and benzoyl substituents at the 5th position have been synthesized using a silica supported periodic acid catalyst. The DNA cleavage activity of 5–7 was studied in the presence of light using pBR322 plasmid DNA and was shown to vary with substitution at the 5th position of benzimidazole derivatives. DNA binding studies using ethidium bromide displacement assay demonstrated the non-intercalative binding mode of 5–7. The anticancer activity of these target molecules was tested against MCF-7 and HL-60 cell lines, and they exhibited remarkable activity in the micromolar range. Cellular uptake and morphological changes were confirmed by fluorescence and confocal microscopy. A molecular docking study was carried out to explore the DNA binding mechanism of 5–7.

Surface defect rich ZnO quantum dots as antioxidants inhibiting α-amylase and α-glucosidase: a potential anti-diabetic nanomedicine

Preventing chronic hyperglycaemia and associated oxidative stress is utmost important for the treatment and management of Type 2 Diabetes Mellitus (T2DM). Here we report the role of different size surface defect rich ZnO quantum dots (D-QDs) for inhibiting metabolic enzymes and scavenging free radicals, which plays a key role in reducing hyperglycaemia and oxidative stress. Quantitative analysis of radical scavenging and metabolic enzyme inhibition activity of D-QDs demonstrates a size dependent behaviour, where D-QDs with a smaller diameter shows superior activity compared to larger size D-QDs. Considering the size dependence in surface defect formation, the increased surface defect density in smaller size D-QDs can be considered as the reason behind this enhancement. Detailed studies establishing the underlying mechanism behind potent free radical scavenging and enzyme inhibition provides an intense scientific rationale for considering D-QDs to design safe and effective nanomedicine for T2DM.

Chimeric Nanoparticle: A Platform for Simultaneous Targeting of Phosphatidylinositol-3-Kinase Signaling and Damaging DNA in Cancer Cells

Phosphatidylinositol-3-kinase (PI3K) signaling has been hijacked in different types of cancers. Hence, PI3K inhibitors have emerged as novel targeted therapeutics in cancer treatment as mono and combination therapy along with other DNA damaging drugs. However, targeting PI3K signaling with small molecules leads to the emergence of drug resistance and severe side effects to the cancer patients. To address these, we have developed a biocompatible, biodegradable cholesterol-based chimeric nanoparticle (CNP), which can simultaneously load PI103, doxorubicin, and cisplatin in a controlled ratiometric manner. Size, shape, and morphology of these CNPs were characterized by dynamic light scattering (DLS), field-emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), and transmission electron microscopy (TEM). Increased amounts of PI103, doxorubicin, and cisplatin were released from CNPs through controlled and continuous manner over 120 h at pH = 5.5 compared to neutral pH. The CNPs showed much enhanced in vitro cytotoxicity in HeLa, HL60, MCF7, and MDA-MB-231 cancer cells compared to a free drug cocktail at 24 and 48 h by inducing apoptosis. Confocal laser scanning microscopy (CLSM) imaging revealed that indeed these CNPs were internalized into subcellular lysosomes through endocytosis in a time dependent mode over 6 h and retained inside for 48 h in HeLa, MDA-MB-231, and MCF7 cells. These CNPs showed their efficacy by damaging DNA and inhibiting Akt as a downstream modulator of PI3K signaling in HeLa cervical cancer cells. These CNPs have the potential to open up new directions in next-generation nanomedicine by simultaneous targeting of multiple oncogenic signaling pathways and inducing DNA damage for augmented therapeutic outcome by reducing toxic side effects and overcoming drug resistance.