Amelioration of cognition by hesperidin-conjugated cobalt oxide nanoparticles

Abstract

Diabetes mellitus is one of the metabolic syndromes that is associated with cognitive deficit, dementia, and Alzheimer's disease (AD) like pathology due to impaired insulin-signalling in the brain, oxidative stress and mitochondrial dysfunction. Nanotechnology is one of the most promising techniques for targeting the brain. However, the toxicity of metal nanoparticles is one of the biggest challenges to be studied. In this study, cobalt oxide nanoparticles are conjugated to a bioflavonoid, hesperidin, a natural antioxidant. The study is designed to assess the efficacy and safety of the cobalt oxide conjugated hesperidin in the diabetes-induced cognitive deficit rat model. The neuropharmacological behaviour, in-vivo antioxidant status and level of acetylcholinesterase, nitrite, amyloid β, and pro-inflammatory cytokines were determined for cobalt oxide conjugated hesperidin and compared with bare cobalt oxide nanoparticles and hesperidin. The cobalt oxide conjugated hesperidin significantly improved learning and memory in the streptozotocin rat model. However, further studies are required to establish a cellular and molecular mechanism involved in the neuroprotective activity of cobalt oxide-conjugated hesperidin.

Keywords: Acetylcholinesterase; Amyloid β; Cognitive deficit; Cytokines; Oxidative stress.

Fig. 1

(A) Absorption maxima of pure hesperidin, (B) LSPR band of HSP - Co₃O₄ NPs.

Fig. 2

(A) FTIR spectrum of pure hesperidin, (B, C) FTIR spectra of HSP - Co₃O₄ NPs.

Fig. 3

(A) Hydrodynamic diameter of HSP - Co₃O₄ NPs of 201.7 nm, (B) Zeta potential of HSP - Co₃O₄ NPs at – 32.69mV.

Fig. 4

(A-C) HRTEM images and (D) SAED pattern of HSP - Co₃O₄ NPs.

Fig. 5

Effect of HSP and HSP-Co₃O₄ NPs on the spontaneous alternation behaviour activity in STZ-induced cognitive impaired rats. [Values are represented as mean ± SD (n = 6), one-way ANOVA followed by Tukey’s t-test, where *p < 0.05 STZ Vs All; ^#p < 0.05 Co₃O₄ NPs Vs HSP- Co₃O₄ NPs; ^δp < 0.05 HSP Vs HSP- Co₃O₄ NPs].

Fig. 6

Effect of HSP and HSP- Co₃O₄ NPs on the transfer latency in STZ-induced cognitive impaired rats. [Values are represented as mean ± SD (n = 6), one-way ANOVA followed by Tukey’s t-test, where *p < 0.05 STZ Vs All; ^#p < 0.05 Co₃O₄ NPs Vs HSP- Co₃O₄ NPs; ^δp < 0.05 HSP Vs HSP- Co₃O₄ NPs].

Fig. 7

Effect of HSP and HSP- Co₃O₄ NPs on the number of correct responses in STZ-induced cognitive impaired rats. [Values are represented as mean ± SD (n = 6), one-way ANOVA followed by Tukey’s t-test, where *p < 0.05 STZ Vs All; ^#p < 0.05 Co₃O₄ NPs Vs HSP- Co₃O₄ NPs; ^δp < 0.05 HSP Vs HSP- Co₃O₄ NPs].

Fig. 8

Effect of HSP and HSP - Co₃O₄ NPs on (A) SOD, (B) MDA, (C) GSH, and (D) CAT content of STZ-treated rat model [The values are expressed as mean ± SD with n = 3. One-way ANOVA followed by Tukey’s t-test, where *p < 0.05 STZ Vs All; ^#p < 0.05 Co₃O₄ NPs Vs HSP- Co₃O₄ NPs; ^δp < 0.05 HSP Vs HSP- Co₃O₄ NPs].

Fig. 9

Effect of HSP and HSP - Co₃O₄ NPs on AChE content of STZ-treated rat model [The values are expressed as mean ± SD with n = 3. One-way ANOVA followed by Tukey’s t-test, where *p < 0.05 STZ Vs All; ^#p < 0.05 Co₃O₄ NPs Vs HSP- Co₃O₄ NPs; ^δp < 0.05 HSP Vs HSP- Co₃O₄ NPs].

Fig. 10

Effect of HSP and HSP - Co₃O₄ NPs on Nitrite content of STZ-treated rat model [The values are expressed as mean ± SD with n = 3. One-way ANOVA followed by Tukey’s t-test, where *p < 0.05 STZ Vs All; ^#p < 0.05 Co₃O₄ NPs Vs HSP- Co₃O₄ NPs; ^δp < 0.05 HSP Vs HSP- Co₃O₄ NPs].

Fig. 11

Effect of HSP and HSP - Co₃O₄ NPs on pro-inflammatory cytokines in STZ-treated rat model [The values are expressed as mean ± SD with n = 3. One-way ANOVA followed by Tukey’s t-test, where *p < 0.05 STZ Vs All; ^#p < 0.05 Co₃O₄ NPs Vs HSP- Co₃O₄ NPs; ^δp < 0.05 HSP Vs HSP- Co₃O₄ NPs].

Fig. 12

Effect of HSP and HSP - Co₃O₄ NPs on amyloid – β levels in STZ-treated rat model [The values are expressed as mean ± SD with n = 3. One-way ANOVA followed by Tukey’s t-test, where *p < 0.05 STZ Vs All; ^#p < 0.05 Co₃O₄ NPs Vs HSP- Co₃O₄ NPs; ^δp < 0.05 HSP Vs HSP- Co₃O₄ NPs].

Fig. 13

Histopathological representation showing the brain of Group I-V at a magnification of 10x; (A) control group showing normal cell line structure of neuroglial cell; (B) streptozotocin group showing neuroglial cell degeneration and significant necrosis (black coloured arrow) and pyknosis (yellow coloured arrow) in the hippocampal region; (C)Co3O4 NPs group showing neurodegeneration with prominent necrosis and pyknosis depicts (D, E) HSP and HSP-Co3O4 NPs groups with less neurodegeneration and showing limited necrosis and pyknosis.

Fig. 14

Histopathological representation of Kidney of Group I-V; (A) control group-glomeruli having normal tubular structure without any vascular damage; (B) streptozotocin group-severe degeneration of the glomerulus followed by prominent inflammation and haemorrhage; (C) Co₃O₄ NPs - noticeable inflammation in the glomerulus followed by haemorrhage (D & E) HSP and HSP-Co₃O₄NPs - normal appearance of glomerulus as well as tubules indicating no degeneration.

Fig. 15

Histopathological representation of pancreas of Group I-V at a magnification of 10x; (A) control group-normal distribution of the pancreatic tissue surrounded by islets of Langerhans; (B) streptozotocin group-shrunken islets of Langerhans with cells having inflammation and degeneration; (C) Co₃O₄ NPs -islets of Langerhans having shrunken cells showing degeneration; (D & E) HSP and Co₃O₄-HSP NPs showing normal cells of islets of Langerhans with less degeneration.