Antioxidant activity of  ZnO Nanoparticles synthesized using Luffa acutangula peel extract

 

R. Ananthalakshmi¹, S. R. Xavier Rajarathinam², A. Mohamed Sadiq³

¹Department of Biochemistry, Sacred Heart College, Tirupattur, Vellore District, Tamilnadu, India

²Department of Chemistry, Sacred Heart College, Tirupattur, Vellore District, Tamilnadu, India

³Department of Biochemistry, APCAS, Kalavai, Vellore District, Tamilnadu, India

 

ABSTRACT:

Zinc is well known for its physical and optical properties. Today, nanomedicine gain importance for their therapeutic purposes. Zinc oxide nanoparticles gained the attention of world for their excellent physical, chemical and biological properties. The main objective of the current study was to synthesis the zinc oxide nanoparticles (ZnO NPs) in a cost effective biological method. The aqueous extract of Luffa acutangula peel was used to synthesis Zinc oxide nanoparticles. The synthesized zinc oxide nanoparticles were confirmed   by ultra violet visible spectroscopy band obtained at 377 nm. The Fourier Transform Infra Red Spectroscopy was performed to identify the functional groups present. Also the scanning electron microscope (SEM) was used for the determination of shape of the zinc oxide nanoparticles and it was found to be spherical in shape. The characterized zinc oxide nanoparticles were used to evaluate their antioxidant activity by 2, 2-di phenyl picryl hydrazyl (DPPH) assay. It showed the significant antioxidant activity with IC₅₀ value of 134.12µg/ml. It could be seen that zinc oxide nanoparticles thus prepared had the antioxidant activity and was one of the best candidate for this effect. Further investigations are necessary for chemical characterization of the active compounds and more comprehensive biological assays for their activity.

 

 

 

1. INTRODUCTION:

Nanotechnology involves the use of materials that are having nanoscale dimensions in the range of 1–100 nm. Usage of nano materials has allowed the researchers to have a much better understanding of biology. The green synthesis of nanoparticles has helped to reduce the use of physical and chemical methods. Various chemical methods have been proposed for the synthesis of zinc oxide nanoparticles (ZnO NPs), such as reaction of zinc with hydrothermal synthesis, precipitation method etc^{[1], [2], [3], [4]}.

 

Recently, ZnO nanoparticles were prepared by various methods like ultrasound, co-precipitation, electrophoretic deposition and so on. Plants contain secondary metabolites and novel therapeutic compounds which enhance human health with controlled adverse effect. The importance of plant mediated biological synthesis of nanoparticles is mainly due to its ecofriendliness^[5,6]. Ridge (Luffa acutangula L.) gourd is a popular vegetable consumed as common vegetable in daily Indian diet and it is widely growing vegetative climber and traditionally used in folk medicines for many ailments. Ridge gourd has been recognized with a number of health benefits which current clinical research is supporting as well. These plants are used to safeguard from Jaundice when taken in the form of very fine powder through nose while the seeds possess emetic, expectorant and demulcent property^[7]. The present study was planned to synthesize the zinc oxide nanoparticles from Luffa acutangula peel aqueous extract. As green synthesis is an area of interest having significant focus in present scenario with important objectives like manufacture of nanotechnology based products ecofriendly and safer for all beings with sustainable commercial viability. In particular, we have established a captivating approach to study the invitro antioxidant activity of green synthesized ZnO NPs.

 

2. MATERIALS AND METHODS:

All the chemicals used in this study were procured from Hi Media, India and were of analytical grade and with high purity.

 

2.1 Collection of plant material:

The peel of Luffa acutangula (Ridge Gourd) used in this study was collected from the field of Tirupattur, Vellore district, Tamil Nadu, India.

 

2.2 Preparation of aqueous peel extract:

Following thorough washing, removed the peel from Luffa acutangula. Then peeled skin were kept in sun shade and dried to eliminate the residual moisture. After drying, the peel was ground into fine powder using electric mixer. The aqueous extract of Luffa acutangula was prepared by placing 10 g of dried peel powder with 100 ml of double distilled water and then boiled for 60 minutes at 100 °C. This extract was cooled to room temperature and filtered using Whatman filter paper No.1. The aqueous extract thus filtered was stored in a refrigerator at 4 °C for further experiments.

 

2.3 Preparation of Zinc oxide nanoparticles:

Zinc nitrate hexahydrate Zn(NO3)₂6H2O was used as precursor to synthesize ZnO nanoparticles using Luffa acutangula aqueous peel extract. For the synthesis of zinc oxide nanoparticles, 50 ml of peel aqueous extract of Luffa acutangula was taken in a clean conical flask and 5 g of zinc nitrate was added to the solution and mixed thoroughly and kept in hot plate magnetic stirrer till water empties at 100°C.The greenish white powder formed at the bottom was scaled up and transferred to crucible. Then it was annealed at 400°C for 2 hours. The light yellow colored ZnO nano powder was thus prepared and utilized for further studies by storing in an air tight container.

 

2.4 Characterization of Zinc oxide nanoparticles:

For analytical study UV–Vis spectra was recorded for the prepared zinc oxide nanoparticles using UV – Vis – Varian – Cary 50 Bi in the wavelength range of 200- 700nm. The FTIR spectrum was taken in the mid-IR region of 400 – 4000 cm^-1 to study the functional groups. The field emission scanning electron microscopy was performed to study the morphology of the synthesized ZnO nanoparticles.

 

2.5 Antioxidant Activity by DPPH free radical scavenging assay:

The Zinc oxide nanoparticles were subjected to DPPH assay to study their antioxidant activity. DPPH dissolved in methanol solution was added to different concentrations of sample. The tubes were incubated at 25ºC for 20minutes and the absorbance value was recorded at 510 nm using Shimadzu UV 1800 spectrophotometer. The concentration (µg /ml) of the fractions that was required to scavenge 50% of the radicals was calculated by using the percentage scavenging activities.

 

Percentage inhibition (I %) was calculated using the formula,

 

                       (A_c-A_s)

I % = --------------------------   x 100

                           A_c                                                          

 

Where

A_c is the absorbance of the control and

A_s is the absorbance of the sample.

 

3. RESULTS AND DISCUSSION:

3.1 Characterization of ZnO Nanoparticles:

3.1.1 UV Visible spectroscopy studies:

 

 

Fig-1 UV Visible spectra of ZnO NPs synthesized using Luffa  acutangula peel extract

 

The optical property of the ZnO nanoparticles synthesized by biological approach was revealed by UV visible spectrum data. Fig -1 shows UV visible spectrum obtained between 200-700 nm and the maximum absorption wavelength was observed at 377 nm. The similar result was reported by the ZnO nanoparticles synthesized by precipitation method. ^[8]

 

 

 

3.1.2 FTIR Analysis:

 

Fig-2 FTIR spectra of ZnO NPs synthesized using Luffa acutangula peel extract

 

The bands were observed at 3425 cm^-1, 2427 cm^-1, 2341 cm^-1, 1765 cm^-1, 1631 cm^-1, 1384 cm^-1, 1117 cm^-1, 1042 cm^-1, 826 cm^-1, 620 cm^-1 and 458 cm^-1.The FTIR spectrum of ZnO nanoparticles consists of a band around 1631 cm^-1 due to O-H bending of absorbed water. 1384 cm^-1 attributed to the C-O-H bending of carboxylic group, 1117 cm^-1 attributed to S=O bond  and a lower frequency band at 826 cm^-1 which could be assigned to S-C absorption of organo sulfur compounds present in the peel extract .The peak at 3425 cm^-1 was characteristic of alcohol group. The band found at 1042 cm^-1 corresponds to saturated primary alcohol C–O stretching. An absorption peak observed at 2341 cm^-1 and 2427 cm^-1 reveal the presence of C –H stretching vibrations of an aromatic aldehyde.^[9] The ZnO nanoparticles observe FTIR spectrum between 450 - 650 cm^-1. The peak at 1765 cm^-1 and 1631 cm^-1 was well established with the C=O, carbonyls groups.

 

3.1.3 SEM Analysis:

Fig -3 SEM image of ZnO NPs synthesized using Luffa  acutangula peel extract

 

 

The SEM image in Fig 3 shows the morphology of the ZnO nanoparticles. It is evident that ZnONPs were spherical and cuboid in shape, with a size less than 100 nm. It was poly dispersed and aggregated. Most of the nanoparticles formed show tendency to congregate. Similar results were reported by Singh et al ^[10].

 

3.2 Antioxidant Activity:

DPPH Free Radical Scavenging activity Assay

 

Table -1 Free radical scavenging activities of ZnO Nanoparticles determined by DPPH assay                      

S. No	Sample   marking	Nanoparticle Concentration (µg/ml)	DPPH  Antioxidant Activity
			% Inhibition	IC50
1	ZnO Nanoparticles	100	47.96	134.12
2		200	53.96
3		400	59.85
4		600	63.71
5		800	72.35
6		1000	80.99

Fig – 4 DPPH Scavenging activity of ZnO NPs synthesized using Luffa  acutangula peel extract

 

 

The antioxidant Property of ZnO NPs could be attributed by functional groups present in the peel extract. Fig.-4 and Table-1 shows the DPPH radical scavenging activity of ZnO nanoparticles. An IC₅₀ value refers to the concentration of the sample required to scavenge 50% of the free radicals present. IC ₅₀ value obtained for ZnO nanoparticles was found to be 134µg/ml.

 

4. CONCLUSION:

From our study we conclude that Luffa acutangula peel extract is an effective agent for the synthesis of ZnO nanoparticles of nanosize. SEM analysis was done to elucidate the shape of the ZnO nanoparticles formed. The presence of Zn-O bonding and other bondings like C-O, O-H were confirmed by FTIR spectral analysis. The biosynthesized ZnO nanoparticles were proved to have an antioxidant property by DPPH analysis. Thus in further investigations, we can accelerate to study their pharmacological applications.

 

5. ACKNOWLEDGEMENT:

This work was supported by Sacred Heart College, Vellore District, Tamilnadu, India, through Don Bosco Research Grant. We would like to show our gratitude to the Management of Sacred Heart College, Vellore District, Tamilnadu, India for supporting the research by granting Don Bosco Research Grant.

 

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Received on 22.10.2018         Modified on 21.11.2018

Accepted on 18.12.2018         © RJPT All right reserved