1 Introduction

Due to its myriad potential applications in catalytic processes, detecting, gadgets, imaging, and medicine, scientists have recently been increasingly interested in creating NPs. An innate capacity of living things to decrease metallic components has been acknowledged by scientists since the nineteenth century, but the method is still a mystery. Researchers are increasingly focusing on biological methods as a result of the efficacy of generating NPs using biological suppression, capping, and strengthening factors while eliminating hazardous substances and a surplus of energy [1].

NPs with dimensions that fluctuate between one to one hundred nanometre can provide the connection between massive substances and nuclear or complex molecules [2]. NPs are being developed all over the world as a result of a variety of intriguing and unique characteristics that enable their use in a variety of logically unrelated fields, including luminescence photocatalytic potential and photodiode response on the one hand and nano-diagnostics, nanomedicine, and antimicrobials on the other [3].

The most versatile of them, dating back to the Bronze Age, are ZnO nanoparticles. They have attracted the interest of researchers due to their unusual visual and chemical-based actions, and their ability to be readily impacted by altering the shape, and they garnered considerably greater attention in the scientific sector [4].

Zinc oxide, an inorganic powder that is durable and resistant to severe procedures compared to organic materials, offers a possible substitute for chemical preservatives with microbicidal capabilities. ZnO is regarded as one of the GRAS (generally acknowledged as safe) elements for use in humans [5]. The potential biological applications of ZnO NPs are increased by their ease of production, non-toxicity, environmental friendliness, biocompatibility, and biosafety [6]. Due to its unique optical and chemical behavior, which may be readily improved by modifying their size and shape, ZnO NPs have been considerably garnering the attention of researchers among other NPs. In addition, the ZnO NPs are renowned for their photo-catalytic and photo-oxidizing abilities for chemical and biological species. In the fields of medicine and environmental science, ZnO NPs are used as antimicrobial, anti-inflammatory, anti-diabetic and as a photocatalytic agent for the degradation of organic pollutants responsible for water pollution due to their distinctive catalytic and oxidizing abilities [7]. ZnO NPs are essential for several biological applications, including their anti-angiogenic, anti-tumor, wound-healing, UV scattering, and wound-healing capabilities. In commercial products like paints and cosmetics, ZnO NPs play a crucial role [8].

Agriculture is the backbone of the economies of developing countries, this sector is facing numerous global challenges like climate change, urbanization, sustainable resource use, and environmental problems like runoff, and accumulation of fertilizers and pesticides. Food demand is expected to increase with population increase from 6 billion people to 9 billion people by the year 2050. Consequently, we need to use efficient methods to improve the sustainability of agriculture [9]. Agriculture and food production are being revolutionized by nanotechnology. Nanotechnology’s use in agriculture is attracting interest due to its effectiveness in the exact control and release of fertilizers, insecticides, and herbicides. The development of nano-sensors can aid in calculating the necessary dosage of agricultural inputs like fertilizers and insecticides [10]. High sensitivity, minimal detection limits, extreme selectivity, quick reactions, and compact diameters are all features of nano-sensors used to detect pesticide residue. They can also measure the amount of soil moisture and nutrients. Nano-fertilizers can be quickly absorbed by the plants. Slow-release fertilizers that are nano-encapsulated can reduce environmental pollution and fertilizer usage [11].

In the past, leaf extracts of Salvia officinalis, Parthenium hysterophorus, and Solanum torvum, as well as others, have been utilized to create ZnO NPs using a green synthesis process [12,13,14]. Since the extracts aid in creating well-organized ZnO NPs and increase their antibacterial activity while also serving as reducing and stabilizing agents, using green methods has several advantages [15]. Due to its uniqueness and well-known therapeutic characteristics, Fioria vitifolia was taken into consideration for developing ZnO NPs.

The plant Fioria vitifolia Linn., a native of India and a member of the Malvaceae family, proceeds by the name Hibiscus vitifolius. Pain relieving, inflammatory-fighting properties, reducing fever, urinary tract infection, unpleasant, cerebral depressant, antibacterial, and anti-fertility effects are present in the herb in its traditional use. In herbal therapy, plant extracts have been reported as a remedy for alleviating pain, fever, and inflammation. The pharmacological effect of plant (rat studies) showed very effective than aspirin drug [16].

Considering the above facts, in the present study, Fioria vitifolia leaf extracts were successfully used to synthesize zinc oxide NPs. To define and validate the green production of NPs, many spectroscopic and microscopic investigations, such as ultraviolet–visible spectroscopy, the FTIR technique, HR-TEM, XRD analysis, and scanning electron microscope with energy-dispersive X-ray spectroscopy, have been examined. The biological (antioxidant, antibacterial, anti-inflammatory, and anticancer) characteristics of ZnO NPs from Fioria vitifolia were also tested in vitro.

2 Experimental section

2.1 Chemicals and reagents

Zinc acetate dihydrate [Zn (CH3COO)2. 2H2O], sodium hydroxide pellets, ethanol, methanol, DPPH (2,2-diphenyl-1-picrylhydrazyl), and ABTS (2,2-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid) were acquired from HiMedia laboratories, Mumbai, India, and used as received. All other reagents were of an analytical grade.

2.2 The strategy of creating a water-based Fioria vitifolia extract from leaves

The foliage of Fioria vitifolia was washed under fresh water, regularly rinsed with distilled water, and then desiccated for ten days in a shaded environment to wring out any wet matter that could have remained [17]. The leaves were pulverized into a homogeneous, finely ground powder using an electric blender in a monitored laboratory setting [18]. To filter the mixture through Whatman No 1 filter paper, hundred milliliters of purified water and 10 g of powdered leaves were mixed, heated at 60 °C for a period of twenty minutes, and then allowed to cool to room temperature (Fig. 1).

Fig. 1
figure 1

Schematic diagram shows the preparation of leaf extract

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2.3 ZnO NPs made using a green method

Tiny particles of zinc oxide were synthesized with an altered version used by [19] using plant resources. NPs were created using Zinc acetate as an initial substance. 50 mL aqueous solution of 2 M Zinc acetate was prepared using deionized water. pH was then adjusted to 12 by adding extracts of foliage (5 mL) and two molar sodium hydroxide (50 mL) after 2 h of stirring. To get rid of contaminants, the white precipitate was washed multiple times with purified water and then ethanol (C2H5OH). The resulting product was then drenched at 60 °C in an oven, and the tiny particles were subsequently calcined for 3 h at 350 °C in a muffle furnace. These operations are shown in Fig. 2.

Fig. 2
figure 2

Schematic diagram shows the synthesis of zinc oxide nanoparticles using the leaf extract of Fioria vitifolia Linn

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3 Characterization techniques

3.1 UV–spectrum analysis

Using a UV–Vis spectroscopic analysis of tiny particles of zinc oxide, the spectral characteristics of the created nanomaterial were investigated. After only a small quantity of the nano-powder was reincorporated in around 10 mL of distilled water and read over 200 and 800 wavelength, the maximum absorbance was determined using a Shimadzu UV-1800 UV-Spectrophotometer [20].

3.2 FT-IR analysis

We employed powder XRD and FT-IR to investigate the molecular makeup, content, configuration, and dimension of the NPs. The sample’s Fourier-transform infrared spectroscopy adsorption spectrum was recorded on a Perkin Elmer’s (Model; 95,277) FT-IR imaging Spectrometer Rainbow Spectrum RX-1 in the wavelength range of 4000–400 cm−1 [21].

3.3 Analysis of X-ray powder diffraction (XRD)

The structure of the crystals and the high purity of naturally synthesized zinc oxide NPs have been investigated using an XRD (XRD 7000, Shimadzu, Japan) system with Copper K-alpha (1.541 A°) exposure and a Ni filter functioning at an input voltage of fifty kV and a current of thirty mA [22].

3.4 Analysis employing SEM alongside EDX and TEM

The surface characteristics and elemental makeup of the manufactured nanomaterial were examined using SEM alongside EDX (Make: EVO18, Carl Zeiss Microscopy, USA). Using a concentrated electron source from a charged particle cannon and a 15 kV acceleration voltage, the sample was scanned to provide a highly accurate planar picture [23]. The grain size of the ZnO NPs was assessed using a 200 keV electron source and an FEI Tecnai T20 transmission electron microscope [24].

4 Biological activity

4.1 Antibacterial properties

The synthesized NPs made of ZnO have been evaluated for their ability to kill bacteria by an agar disc diffusion technique that causes sickness in humans such as Bacillus subtilis, Staphylococcus aureus, Klebsiella pneumonia, and Escherichia coli. The overnight fresh culture of each strain was swabbed uniformly onto its plate. The impregnated ZnO NPs solution in volumes of 25, 50, and 75 µL was placed on the plates and heated to 37 °C for 24 h. As a benchmark, commercial antibiotic discs were employed. The extent of zonation’s development around the disc was evaluated after an appropriate incubation period [25].

4.2 In vitro antioxidant assay

4.2.1 Test for DPPH radical sequestration

The method used to quantify samples’ total capacity to eliminate free radicals (as evaluated by the DPPH radical test) was somewhat modified from that employed previously by [26]. Methanol was utilized to prepare 500 µM of DPPH. The reaction mixture for the DPPH scavenging test is made up of 1 mL of ethanol, 100 µL of DPPH solution, and different extract concentrations. For 5 h in complete darkness at 23 °C, the reaction product was left to sit. The preparations’ ability to capacity to neutralize harmful radicals is demonstrated by the disappearance of the original purple tint. The absorbance of the resultant substance was calculated at 517 nm.

$$\mathrm{Scavenging}\;\mathrm{activity}\;(\%)\:=\:\lbrack\mathrm{absorbance}\;(\mathrm{control})\:-\:\mathrm{absorbance}\;(\mathrm{sample})\;/\;\mathrm{absorbance}\;(\mathrm{control})\rbrack\:\times\:100.$$

4.2.2 Radical scavenging test for ABTS

The ABTS neutralizing experiment was conducted via a modification of [27] methodology. Water was used to dissolve 7 mM of ABTS. The ABTS radical cation (ABTS● +) was created by reacting the ABTS base suspension with 2.45 mM Potassium persulfate (K2S2O8) final concentration, which then remained undisturbed at ambient level for 12 to 16 h before usage. To achieve equilibrium at 30 °C and an absorption value of 0.70 at 734 nm, the resulting mixture was mixed with C2H5OH.

For the ABTS scavenging test, the reaction mixture consisted of 900 µl of ABTS solution, and various extract concentrations, and the solution was mixed with C2H5OH to 1 mL. Three hours were endured incubation, the reaction mixture at room temperature without any illumination. The extracts’ ability to scavenge free radicals was shown by the loss of the original blue hue. At a wavelength of 734 nm, the absorbing capacity of the reaction mixture was assessed.

$$\mathrm{Scavenging}\;\mathrm{activity}\;(\%)\:=\:\lbrack\mathrm{absorbance}\;(\mathrm{control})\:-\:\mathrm{absorbance}\;(\mathrm{sample})\;/\;\mathrm{absorbance}\;(\mathrm{control})\rbrack\:\times\:100.$$

4.3 An anti-inflammatory response

4.3.1 Method for stabilizing HRBC membrane

The effectiveness of the sample in laboratory anti-inflammatory properties was evaluated using the HRBC barrier stabilization technique [28]. Healthy participants who had avoided NSAIDS for 2 weeks before, to the study had their blood collected. The collected blood was combined with a comparable volume of sterile Alsever solution (2% glucose, 0.8% sodium citrate, 0.5% citric acid, and 0.42% sodium chloride in water). After packed cells were rinsed with 0.85% iso-saline (with a pH of 7.2), and the blood was centrifuged at 3000 revolutions per minute, an iso-saline solution of 10% (v/v) was produced. The test combination contains samples with a variety of sample concentrations, as well as 0.5 mL of HRBC solution, 1 mL of phosphate buffer (0.15 molar, pH 7.4), and 2 mL of hyposaline (0.36%). As a benchmark medication, diclofenac was employed. The hyposaline solution was replaced in the control with 2 mL of purified water (H2O). All of the test solutions were centrifuged after 30 min of 37° C incubation. At 560 nm, a spectrophotometer was used to quantify the amount of hemoglobin in the supernatant solution. To calculate the percentage of haemolysis, it was assumed that all haemolysis that occurs in the presence of purified H2O would be 100%.

$$\mathrm{Anti}-\mathrm{inflammatory}\;\mathrm{activity}\;(\%)\:=\:\lbrack\mathrm{absorbance}\;(\mathrm{control})\:-\:\mathrm{absorbance}\;(\mathrm{sample})\;/\;\mathrm{absorbance}\;(\mathrm{control})\rbrack\:\times\:100.$$

4.3.2 Albumin denaturation assay suppression

The soothing effect of the nanomaterial was investigated by using the prevention of denaturation of bovine serum albumin, the same as in the prior approach described by [29]. After adding different test chemical concentrations to 450 µL of 0.5% bovine serum albumin, purified H2O was used to prepare the solution up to 1 mL. The resultant solution was raised to 37 °C for a period of 20 min. Albumin-denatured state was achieved after incubation by holding the product at 72 °C over 15 min. After freezing the reaction liquid, 2.5 mL of a 0.2 M buffer solution of trisodium phosphate (pH 6.3) was added. The turbidity was measured at 660 nm using an Epoch 2 UV–visible multi-well plate reader (Biotek, USA). The lone buffer was used to set a blank. In the absence of bovine albumin, true blanks were established using test chemicals at the same concentration utilized in the experiment. The percentage inhibition of protein denaturation obtained by:

$$\mathrm{Anti}-\mathrm{inflammatory}\;\mathrm{activity}\;(\%)\:=\:\lbrack\mathrm{absorbance}\;(\mathrm{control})\:-\:\mathrm{absorbance}\;(\mathrm{sample})\;/\;\mathrm{absorbance}\;(\mathrm{control})\rbrack\:\times\:100.$$

4.4 Action against cancer

4.4.1 The preservation of a cancerous cell line

National Centre for Cell Science, Pune, supplied several carcinoma cell lines (colon tumor (HT 29), malignancy of the liver (HepG2), and prostate cancer (MCF 7)), which were cultured in α-MEM (Minimum Essential Medium Eagle, alpha modification) containing 10% fetal bovine serum. The cells were maintained at 370 °C, 5% CO2, 95% air, and 100% relative humidity. Every week, maintenance cultures were passed, and the growth media was switched out two times weekly.

4.4.2 Method of cell therapy

The single-walled cells were divided into individual cell suspensions using Ethylenediaminetetraacetic acid (EDTA), and alive cells were measured by a haemocytometer. Each of the cell suspensions was reduced to a final density of 1 × 105 cells per mL using a medium containing 5% fetal bovine serum (FBS). Using a hundred microliters of cell solution per well, 10,000 cells were seeded onto plates with 96 wells. The cells were then given time to adhere over an incubation period at 37C, 5% of carbon dioxide, 95% of air, and a humidity level of 100%. After 24 h, the test samples were subjected to increasing doses of the cells. They were first dissolved in Dimethyl sulfoxide, and a sample preparation was then mixed with seraless solution to double the required final highest assay dosage. Four further consecutive dilutions were carried out to produce an overall 5 sample dosage. The requisite final material concentrations were achieved by adding these varied sample dilutions in aliquots of 100 µl to the relevant wells that already had 100 µl of the medium. The plates were then incubated for a further 48 h at 37 °C, 5% of carbon dioxide, 95% of air, and a humidity level of 100% after the sample had been added. Every dosage was maintained in triplicate, and the media without any samples served as the control [30].

4.4.3 MTT assay

The yellow tetrazolium salt MTT is hydrophilic. The mitochondrial enzyme succinate-dehydrogenase breaks the tetrazolium ring of the MTT and transforms the formazan into an insoluble purple material. As a result, the number of cells that are alive closely relates to the amount of Formazon generated. Each well received 15 µL of MTT (5 mg/mL) in PBS (phosphate buffered saline) 48 h after the first incubation, and then underwent a 4-h incubation at 37 °C. After removing the MTT medium, 100 µL of Dimethyl sulfoxide was added for dissolving the Formazon crystals that had formed. A microplate reader was then used to determine the absorbance of the material at 570 nm [31].

4.5 Analytical statistics

The data was examined by employing the one-path ANOVA method using the data analysis program Statistical Package for the Social Sciences (SPSS version 21, IBM Corporation, Armonk, New York, America). At p < 0.05, the variance was deemed significant.

5 Results and discussion

5.1 Characterization of ZnO NPs

5.1.1 Evaluation of the ultraviolet spectrum and band gap energy

The primary tool for assessing the confirmation of the synthesized nanomaterial is the UV–visible absorption spectrum. The white precipitate that forms when Zinc acetate is added to the extract is one of the most important signs of the production of ZnO NPs. Between 200 and 800 wavelength, the ZnO NPs frequently exhibit a broad peak. [32] claim that ZnO NPs with a prominent absorbance peak at 371 nm were produced using Fioria vitifolia leaf extract (Fig. 3a). Previous research has indicated that ZnO NPs exist because the ultraviolet–visible spectrum exhibits a significant absorbance peak at 371 nm [33]. Similar to this, [34] pointed out that the identification of an absorption peak at 371 nm in the ultraviolet spectrum offered unmistakable proof for the production of ZnO NPs.

Fig. 3
figure 3

a UV- vis absorption spectrum. b Tauc plot of ZnO NPs synthesized using Fioria vitifolia

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The band gap energy value of synthesized ZnO NPs from Fioria vitifolia was found with the help of the Tauc plot equation.

$${(\mathrm{\alpha h\upsilon })}^{2}= A (\mathrm{h\upsilon }-\mathrm{ Eg})$$

whereas hυ is the energy of the incident photon, αA is the absorption coefficient, Eg is the optical band gap energy, and the exponent n depends on the type of transition between bands. Since a direct transition is considered for ZnO, n = 2 for our estimations [35]. The plot of (αhυ) 2 versus (hυ) is shown in Fig. 3b. The band gap energy value for ZnO NPs was estimated to be 3.31 eV.

5.1.2 Analysis of Fourier transform infrared spectrum

By FTIR research, the potential functional groups involved in the formation of NPs made of ZnO were found. Figure 4 displays the FT-IR spectrum of ZnO NPs between 500 and 4000 cm−1. The -OH stretching vibrations were detected due to the significant peak at 3442 cm−1. The existence of C-H stretching was suggested by the medium peak, which was located in the vicinity of 2949 cm−1. The peak at 1452 cm−1 is caused by a bend in the C–H bend [36]. The height of the peak at 1049 cm−1 is attributed by [37] to the C–N stretching vibration of the amine functional group. According to [38], the presence of the C–H bends in the alkane group causes a significant rise at 878 cm−1. C–Cl stretching may be seen at the signal at 624 cm−1 [39]. The signal between 400 and 600 cm−1 is produced by bonding vibrations between zinc and oxygen. The strong bond is seen at 552 cm−1, which is corroborated by the results of [40]. The current study displayed in Table 1, confirmed the formation of ZnO NPs. Xanthomonas oryzae pv. [41] and Coleus aromaticus [42] leaf extract were used in past studies on synthesized ZnO NPs to compare the current result to those findings.

Fig. 4
figure 4

FTIR spectrum of ZnO NPs synthesized by Fioria vitifolia

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Table 1 FTIR functional groups analysis for Fioria vitifolia ZnO NPs
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5.1.3 Analysis of X-ray powder diffraction (XRD)

ZnO NPs that have been synthesized are examined using the XRD method to determine their crystal phases and crystallinity. Several Bragg reflections in ZnO NPs at 2θ values = 31.75°, 34.4°, 36.23°, 47.5°, 56.56°, 62.83°, 66.33°, 67.91°, 69.06°, 72.55°, and 76.93° indicate crystallographic axes of (100), (002), (101), (102), (110), (103), (200), (112), (201), (004), and (202) accordingly and other peaks (32.02°, 33.5°, 38.12°, 39.5°, 40.49°, 43.31°, and 45.49°) indicating * which are the impurities of Pure ZnO. Comparably, [43] published the XRD pattern of nanomaterial, and the current work demonstrates that all of the diffraction peaks (in Fig. 5) were accurately matched to the phase of hexagons (wurtzite pattern) of zinc oxide and are quite near to the approved values (Joint Committee on Powder Diffraction Standards (JCPDS) number. 36–1451). The average crystalline size of ZnO NPs was determined using Scherrer’s Equation to be 26.1 nm.

Fig. 5
figure 5

X-ray diffraction spectrum of ZnO NPs synthesized using Fioria vitifolia

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5.1.4 Analysis of SEM (scanning electron microscopy) analysis employed with EDX (energy-dispersive X-ray spectroscopy)

SEM has been employed to look at the physical characteristics of nanoparticles. The agglomerated morphology of ZnO NPs which are produced from Fioria vitifolia leaf extract are depicted in Fig. 6A and B, a SEM image. This SEM result coincides with earlier observations that plant extracts from Cochlospermum religiosa [44] and Papaver somniferum [45] developed ZnO NPs. SEM result is in support of previous work noticed that agglomerated morphology of ZnO NPs [46].

Fig. 6
figure 6

A, B, C, D, E, and F SEM and EDX spectrum of synthesized ZnO nanoparticles from Fioria vitifolia

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The stereochemical makeup and mineral content of the NPs made of zinc oxide were analyzed by EDX (Fig. 6C, D, E, F); zinc and oxygen signals show that the synthesized nanocrystals were in their purest chemical state. O (37%), and Zn (63%), were the predominant elements in the obtained peaks [47]. While the previous study reported that zinc and oxygen were composed of 25% oxygen and 65% zinc, respectively, the EDX analysis in the current study shows similar results for synthesized NPs [48]. The present findings were matched with those made by zinc, which makes up more than 66.33% of the total constituents, and oxygen, which accounts for 25.48% and the results demonstrate that the high purity of the mediated ZnO NPs [49].

5.1.5 Analysis of TEM (transmission electron microscopy)

Transmission electron microscopy was employed to characterize the morphology of ZnO NPs, such as distribution of size, grain size, and nanoparticle dimensions. The spherical-shaped ZnO NPs made from Fioria vitifolia are described in SAED and TEM monographs. The average size of the ZnO NPs was found to be 88 nm. After TEM analysis of the NPs, Fig. 7A, B, C, D, and E shows the SAED pattern that was found. SAED determined that (100), (002), and (101) were consistent and matched the XRD findings of [50]. Before this, [51] and [52] used TEM imaging examination of green-generated nanomaterials to show the random distribution of spherical-shaped nanomaterials.

Fig. 7
figure 7

A, B, C, D, and E TEM images and SAED pattern of ZnO NPs using Fioria vitifolia

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5.2 Biological activity

5.2.1 Anti-bacterial resistance

The prepared particles made from ZnO demonstrated a substantial level of antibacterial capacity against common bacterial infections. Figures 8 and 9 display the disc-based diffusion approach for evaluating the antibacterial activity of various dosages of ZnO NPs (25, 50, and 75 μL), along with positive and negative controls made of Streptomycin discs (25 mcg) and DMSO (25 μL) respectively. Bacillus subtilis (11 ± 0.57 mm) had the most significant antibacterial zone of inhibition, followed by Staphylococcus aureus (10 ± 0.88 mm), Klebsiella pneumonia (10 ± 0.57 mm), and Escherichia coli (9 ± 0.33 mm). Table 2 displays the antibacterial zone of inhibition. The chosen infections don't exhibit a DMSO inhibition zone. Additionally, compared to the synthesized ZnO NPs Streptomycin had higher antibacterial activity. The current study found that Gram + ve bacteria had greater resistance to the bactericidal effects of synthesized ZnO NPs [53]. The findings demonstrated that Bacillus subtilis is the bacterial strain that is most sensitive to ZnO NPs inhibitory action, having the largest inhibition zone [54, 55].

Fig. 8
figure 8

Antibacterial activity of ZnO NPs against Gram-positive and Gram negative pathogens: ( +) Positive control—Streptomycin (25 mcg). ( −) Negative control—DMSO (25 μl)

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Fig. 9
figure 9

Histogram of antibacterial activity of synthesized ZnO nanoparticles

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Table 2 Antibacterial activity: zone of inhibition (ZOI) against Gram-positive and Gram-negative bacterial pathogens
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5.2.2 In vitro antioxidant assay

Assay for scavenging DPPH radicals

Using the DPPH technique, the antioxidant strength of synthetic NPs made of zinc oxide (purple hue changed to yellow) was evaluated. At 517 nm, this reduction was examined spectrophotometrically. The produced ZnO NPs of Fioria vitifolia leaves extract showed 16.5% inhibitory at a therapeutic level of 40 µg/ mL, and 85.2% at a dosage of 200 µg/ mL. The antioxidant activity of ZnO NPs, ascorbic acid, a standard compound, was found to have a value of 14.2% at 2 µg/ mL and 94.2% at 10 µg/ mL. The outcomes demonstrate ZnO NPs have the capacity to scavenge free radicals influenced by dose way. Figure 10 shows that NPs composed of ZnO have lower activity in neutralizing radicals than usual. To gauge the efficacy of an antioxidant activity, look at its IC50 value. The sample volume necessary to scavenge the free radicals by 50% is known as the IC50 value. The percent inhibition vs. concentration sigmoidal curve was used to calculate the IC50 values of ZnO NPs using a linear regression analysis. Compared to the benchmark value of 5.47 µg/ mL, the sample extract’s IC50 value was much higher at 122.37 µg/ mL. As per the current study report the ZnO NPs have lesser antioxidant effectiveness than ascorbic acid and the outcome has been supported by [56]. The IC50 value of ZnO NPs is 134 µg/ mL, and prior findings of [57] were the complement of the present findings. Similar to this, [58] reported the free radical scavenging activity of DPPH using Coccinia abyssinica (Lam.) Cong. tuber extracts had an IC50 value of 127.74 µg/ mL.

Fig. 10
figure 10

Antioxidant activity of ZnO NPs at different concentrations by DDPH and ascorbic acid was used as a standard

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ABTS radical scavenging assay

Body cells and tissues produce free radicals, which are molecules or unpaired electrons. Additionally, called reactive oxygen species. In addition to internal variables like autoimmune disorders, external causes like inhaling nicotine, radiation, hazardous substances, and pollution, stress caused by oxidation may also occur from external sources like pollution, radiation, poisonous chemicals, and smoking. Numerous diseases are intimately related, including Parkinson’s disease, arthritis, cancer, heart disease, and oxidative stress. By removing free radicals from our systems, antioxidants improve our bodies’ levels of ROS. It halts tissue and cellular degeneration, including the degradation of proteins and DNA. Calculating the total antioxidant activity is done using a decolorization method known as the ABTS test. By decolorizing the response of a composed of persistent blue/green ABTS radical cations at 734 nm with various doses of ZnO NPs, the antioxidant capacity in the ABTS experiment was evaluated. To assess the relative antioxidant potential, standard ascorbic acid has been employed. In a dose-responsive way, the spherical-like ZnO NPs significantly acquired the radicals (30 to 150 µg/ mL); the highest extent of neutralizing capacity (79.2%) was reported at 150 µg/ mL dosage; the IC50 value for ZnO NPs is 95.52 µg/ mL. The dose of the standard (ascorbic acid) varied from 1 µg/ mL to 5 µg/ mL, and the concentration at which the highest percentage of scavenging potential (86.2%) was observed in Fig. 11 the IC50 value was 3.07 µg/ mL [59]. The results of this investigation agreed with a prior study by [60], and the highest free radical acts of scavenging of ABTS is 82.12%. Similarly, [61] reported the extreme scavenger behavior using the ZnO NPs as 89%.

Fig. 11
figure 11

Antioxidant activity of ZnO NPs at different concentrations by ABTS and ascorbic acid was used as a standard

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5.2.3 In vitro anti-inflammatory activity of ZnO NPs

HRBC membrane stabilization test

Inflammation is the living tissue’s defense system against microbes, substances, bodily harm, toxins, destruction of tissue, etc. Lysosomal enzymes contribute to the development of many diseases (cancer, neurological disorders, etc.) during inflammation by harming essential macromolecules, which creates a variety of pathological conditions. The anti-inflammatory mechanism prevents the release of lysosomal components that would otherwise harm the tissue and trigger the release of extracellular components, including neutrophils, bactericidal, and fungicidal enzymes.

In the current investigation, ZnO NPs demonstrated impressive, dose-dependent membrane stabilization of HRBCs (Fig. 12). It has been noted that the effect of stabilizing the membrane was enhanced by the increasing concentration of NPs. The stabilizing effects with the standard Diclofenac 85% (20 µg/ mL) and ZnO NPs 84% (100 µg/ mL). The present study observed the ZnO NPs from Fioria vitifolia have the greatest inflammatory-reduction action with an IC50 value of 60.97 µg/ mL. Thus, green synthesis of zinc oxide nanoparticles from Fioria vitifolia has been used as an alternative substitute for the treatment of autoimmune illnesses in the near future and it was supported by [62]. Similarly, [63] reported maximum percentage of anti-inflammatory inhibition (73.01%) was shown in ZnO NPs, and 89.31% inhibition was recorded in Mussaenda frondosa-mediated ZnO NPs by [64].

Fig. 12
figure 12

Anti-inflammatory activity of ZnO NPs at different concentrations by HRBC membrane stabilization activity and diclofenac was used as a standard

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Inhibition of albumin denaturation assay

It is generally known that the cause of inflammation resulted in protein denaturation. As part of the inquiry into the biological basis of the inhibiting inflammation, the protein denaturation capability of diluted in series, ZnO NPs was investigated. It was as effective in preventing albumin denaturation brought on by heat. The standard diclofenac drug had an ideal reduction in inhibition of 90% at an average concentration of 15 µg/ mL, whereas ZnO NPs expressed the greatest inhibition of 76% at 400 µg/ mL (Fig. 13). The IC50 value of the protein albumin-denatured state for both drugs is 275 µg/ mL and 8.70 µg/ mL, respectively [65]. When [66] examined the beneficial effect on inflammation of ZnO NPs from Cnidoscolus aconitifolius, they discovered that 0.35 mg/ mL provided the highest (82.81%) percentage of inhibition [67] revealed that at a concentration of 500 µL, the inflammatory-fighting properties of plant-mediated NPs were 94.62% inhibited.

Fig. 13
figure 13

Anti-inflammatory activity of ZnO NPs at different concentrations by albumin denaturation assay and Diclofenac was used as a standard

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5.2.4 Using the MTT cytotoxicity test, ZnO NPs in vitro anti-cancer efficacy against hepatic malignant cells (HepG2) was assessed

One of the major causes of death globally, cancer is a deadly disease that will probably take the lives of approximately 21 million individuals by the year 2030. Among the various types of cancer, malignancy of the liver currently causes 745, 517 deaths, ranking second among male cancer deaths and sixth among female cancer deaths. The associated risk factors include viral illness, heavy alcohol consumption, and toxin exposure (aflatoxin). The MTT cytotoxicity test was used to assess the synthesized Zinc oxide NPs’ capacity to prevent the proliferation of cells associated with liver cancer (HepG2). The major results of the 48-h ZnO NPs treatment of HepG2 cells using a range of doses between 6.5 and 100 µg / mL (Fig. 13) MTT cytotoxicity testing. Data from the current experiment revealed that HepG2 cancer cells’ metabolic activity had significantly decreased. The greatest inhibitory potential (57.74% mortality) was noted at 100 µg /mL. As the concentration was lowered, the strength of the cytotoxicity increased. ZnO NPs may have a potential anticancer effect, as evidenced by the decrease in metabolic activity and the result expressed to have an IC50 of 52.60 µg/ mL against HepG2 cell lines (Figs. 14 and 15). The harmful effects produced by ZnO NPs at lower concentrations may be due to botanical elements bound to the ZnO NPs, according to [68]. Another study reported the ZnO NPs synthesized from Pandanus odorifer extracts from leaves have observed better cytotoxicity effect against the HepG2 cell line, with a 62% inhibition [69]. Recently, [70] investigated ZnO NPs from Aquilegia pubiflora leaf extract showed significant cytotoxic potential properties against cancerous cell lines.

Fig. 14
figure 14

Anticancer observed at the different concentrations (6.5 µg/ mL, 12.5 µg/ mL, 25 µg/ mL, 50 µg/ mL, 100 µg/ mL, control) of ZnO NPs using Fioria vitifolia

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Fig. 15
figure 15

MTT Assay confirming the anticancer effects of synthesized ZnO NPs by Fioria vitifolia against liver cancer cell line (HepG2)

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6 Conclusion

To create NPs using green method that protect the environment rather than using hazardous chemical reduction agents and organic solvents, one should make use of recent advancements in nanotechnology. Analyzing, ZnO NPs made from Fioria vitifolia leaf extract was the goal of the current work. The biosynthesized ZnO NPs UV–Vis absorbance peak was discernible at 371 nm. The XRD pattern showed the pure hexagonal wurtzite structure. The creation of deep peaks was confirmed by FTIR to be the product of many functional groups. SEM coupled with EDX, and HR-TEM analysis exhibited the spherical structure of synthesized NPs. ZnO NPs have antioxidant properties, as demonstrated by the DPPH and ABTS tests, with an IC50 value of 122.37 µg/ mL and 3.07 µg/ mL, respectively, at various dosages. In addition, ZnO NPs showed outstanding curative properties against both Gram-positive (Bacillus subtilis and Staphylococcus aureus) and Gram-negative (Klebsiella pneumonia and Pseudomonas aeruginosa) bacterial strains. Similarly, balancing the in vitro tests for albumin denaturation and HRBC membrane stabilization, which both had IC50 values of 275 µg/ mL and 60.97 µg/ mL, respectively, revealed ZnO NPs to be more effective as a medication for inflammation. The results of anti-proliferative experiments employing the HepG2 cell line demonstrated a better IC50 value of 52.60 µg/ mL for liver cancer. The outcomes of this study show that manufactured ZnO NPs have potent anti-inflammatory, antibacterial, antioxidant, and anticancer effects, making them a suitable replacement for artificial medications in the fields of pharmacological and biological studies.