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. 2015 Oct 1;10 Suppl 1(Suppl 1):77-86.
doi: 10.2147/IJN.S79983. eCollection 2015.

Antibacterial Activity of Neem Nanoemulsion and Its Toxicity Assessment on Human Lymphocytes in Vitro

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Free PMC article

Antibacterial Activity of Neem Nanoemulsion and Its Toxicity Assessment on Human Lymphocytes in Vitro

Jayakumar Jerobin et al. Int J Nanomedicine. .
Free PMC article

Abstract

Neem (Azadirachta indica) is recognized as a medicinal plant well known for its antibacterial, antimalarial, antiviral, and antifungal properties. Neem nanoemulsion (NE) (O/W) is formulated using neem oil, Tween 20, and water by high-energy ultrasonication. The formulated neem NE showed antibacterial activity against the bacterial pathogen Vibrio vulnificus by disrupting the integrity of the bacterial cell membrane. Despite the use of neem NE in various biomedical applications, the toxicity studies on human cells are still lacking. The neem NE showed a decrease in cellular viability in human lymphocytes after 24 hours of exposure. The neem NE at lower concentration (0.7-1 mg/mL) is found to be nontoxic while it is toxic at higher concentrations (1.2-2 mg/mL). The oxidative stress induced by the neem NE is evidenced by the depletion of catalase, SOD, and GSH levels in human lymphocytes. Neem NE showed a significant increase in DNA damage when compared to control in human lymphocytes (P<0.05). The NE is an effective antibacterial agent against the bacterial pathogen V. vulnificus, and it was found to be nontoxic at lower concentrations to human lymphocytes.

Keywords: antibacterial; cytotoxicity; genotoxicity; lymphocytes; nanoemulsion; neem.

Figures

Figure 1
Figure 1
Droplet size distribution of the 1:3 ratio of neem oil nanoemulsion.
Figure 2
Figure 2
Leakage of cytoplasmic contents from Vibrio vulnificus treated with 150 μg/mL neem nanoemulsion.
Figure 3
Figure 3
SEM images. Notes: (A) control-untreated bacteria; (B) neem nanoemulsion-treated bacteria. The arrow (B) indicates damage to bacteria. The small arrow in the figure inset represent cell wall damage and leakage of intracellular contents. Abbreviation: SEM, scanning electron microscopy.
Figure 4
Figure 4
Cytotoxicity determined by cellular viability in human lymphocytes after 24 hours exposure to neem nanoemulsion. Notes: (A) MTT; (B) LDH. Each value is represented in mean ± SD. The significance versus control: *P<0.05, **P<0.01, ***P<0.001. Abbreviations: MTT, 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide; LDH, lactate dehydrogenase.
Figure 5
Figure 5
Oxidative stress generated in human lymphocytes after 24 hours exposure to neem nanoemulsion. Notes: (A) ROS; (B) LPO. Each value is represented in mean ± SD. The significance versus control: *P<0.05, **P<0.01, ***P<0.001. Abbreviations: ROS, reactive oxygen species; LPO, lipid peroxidation; MDA, malondialdehyde.
Figure 6
Figure 6
Antioxidant level after 24 hours of exposure to neem nanoemulsion. Notes: (A) catalase; (B) GSH; (C) SOD. Each value is represented in mean ± SD. The significance versus control: *P<0.05, **P<0.01, ***P<0.001. Abbreviations: GSH, glutathione; SOD, superoxide dismutase; H2O2, hydrogen peroxide.
Figure 7
Figure 7
DNA damage in human lymphocytes assessed by comet assay. Notes: (A) control cells; (B) lymphocytes exposed to neem nanoemulsion; (C) % tail DNA. Each value is represented in mean ± SD. The significance versus control: *P<0.05, **P<0.01, ***P<0.001.

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