Abstract

Amyloidosis encompasses a spectrum of diseases in which insoluble protein aggregates are deposited in various parts of the body, including the brain, giving rise to Alzheimer’s disease, prion disease, and Parkinson’s disease, and also being a manifestation of Type II diabetes. The soluble protein gets aggregated as insoluble plaques by an unknown phenomenon, leading to the disease. If an agent is developed that can dissociate or disintegrate these plaques, it can be proposed as a lead molecule for amyloid dissociation. In the present study, we have taken the aqueous extract of a herb, Shankhapushpi (Convolvulus pluricaulis), and synthesized zinc oxide nanoflowers (ZnO-NFs-Skp). The plant extract was characterized using phytochemical analysis, and the ZnO-NFs-Skp were characterized using various photophysical tools like dynamic light scattering, zeta potential, XRD, FTIR, and scanning electron microscopy (SEM). The in vitro cytotoxicity of the ZnO-NFs-Skp was assessed in the PC12 cell line using an MTT assay and a fluorescent dual-staining assay. The effect of ZnO-NFs-Skp on zebrafish embryos was evaluated for in vivo biocompatibility. Finally, the amyloid degradation of the ZnO-NFs, after incubation with preformed insulin amyloids, the model amyloid protein used for the amyloid study, was evaluated at different time intervals using the Thioflavin T fluorescence assay. The results indicated that the Shankhapushpi extract had alkaloids, coumarins, and glycosides. The hydrodynamic diameter of ZnO-NF-Skp was found to be 181 nm, and the zeta potential was −17.7 mV. SEM imaging showed a carnation flower-like morphology with a petal thickness of 30 ± 5 nm. The ZnO-NFs-Skp did not induce any toxicity up to a dose of 160 μg/mL, both in vitro and in vivo. The amyloid degradation study revealed 38% degradation of the IA, 24 h after incubation at 37 °C. SEM analysis also evidenced the degradation of IA. Compared to ZnO nanoparticles (18%), ZnO-NFs-Skp could degrade almost double (35%) the amount of IA after 12 h incubation, as shown by the ThT assay. Overall, the data suggested that Shankhapushpi-mediated ZnO-NFs (ZnO-NFs-Skp) are biocompatible and have a good capacity to degrade amyloids. In the future, amyloid degradation using Aβ-42 and the prion protein needs to be investigated.

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