Rapid green synthesis of silver nanoparticles from Chrysanthemum indicum L and its antibacterial and cytotoxic effects: an in vitro study

Figures & data

Figure 1 Schematic illustration of the green synthesis of silver nanoparticles using an aqueous extract of the Chrysanthemum indicum (flower).

Table 1 Phytochemical screening of the flower extract of Chrysanthemum indicum

Phytochemicals	C. indicum
Tannins	+
Saponins	−
Flavonoids	+
Terpenoids	−
Steroids
Alkaloids	−
Glycosides	+

Notes: + Presence; − absence.

Figure 2 Ultraviolet–visible spectroscopy analysis of synthesized silver nanoparticles, and the peak noted around 435 nm.

Figure 3 X-ray diffraction pattern of synthesized silver nanoparticles from the floral extract of Chrysanthemum indicum.

Figure 4 Transmission electron microscopy micrograph of the green synthesized silver nanoparticles.

Notes: Scale bars: (A) 200 nm and (B) 500 nm. The arrows indicate the particle size in nm.

Figure 5 Energy-dispersive X-ray spectrum of green synthesized silver nanoparticles.

Table 2 Antibacterial activity of AgNPs synthesized by the aqueous flower extract of Chrysanthemum indicum

Indicator bacteria	Inhibitory activity (mm)a
	C. indicum (25 μg/disc)	Silver nitrate (25 μg/disc)	AgNPs (25 μg/disc)	Streptomycin (25 μg/disc)
Gram-positive
Bacillus subtilis (MTCC 121)	–	–	–	13.16±0.28
Staphylococcus aureus (MTCC 96)	–	–	8.33±0.57	08.12±0.57
Staphylococcus epidermidis (MTCC 435)	–	–	–	10.12±0.76
Gram-negative
Escherichia coli (MTCC 433)	–	–	13.00±0.90	10.00±0.90
Klebsiella pneumoniae (MTCC 109)	–	07.00±0.50	19.10±0.50	08.00±0.50
Pseudomonas aeruginosa (MTCC 1934)	–	–	09.60±0.51	14.12±0.76

Notes:

a Each value is the mean of three replicates of the diameter (mm) of the inhibition zone in the bacterial layer. Values are the means of three independent experiments. The zone of inhibition was measured after incubating the strains for 17 hours at 37°C in Muller Hinton Agar medium.

Abbreviations: AgNPs, silver nanoparticles; MTCC, Microbial Type Culture Collection and Gene Bank.

Figure 6 The antimicrobial efficacy of the aqueous extracts of Chrysanthemum indicum, AgNO₃, and AgNPs were examined against three selected Gram-positive bacterial strains (D, E, and F) and three selected Gram-negative bacterial strains (A, B, and C).

Notes: The Gram-positive bacterial strains included BS (MTCC 121), SE (MTCC 435), and SA (MTCC 96), and the three Gram-negative bacterial strains included KP (MTCC 109), EC (MTCC 433), and PA (MTCC 1934). The arrows indicate the zone of inhibition.

Abbreviations: PE, plant extract; C, control (streptomycin); KP, Klebsiella pneumoniae; AgNP, silver nanoparticle; EC, Escherichia coli; PA, Pseudomonas aeruginosa; BS, Bacillus subtilis; SE, Staphylococcus epidermidis; SA, Staphylococcus aureus; MTCC, Microbial Type Culture Collection and Gene Bank.

Table 3 Minimum inhibitory concentration of AgNPs synthesized by aqueous flower extract of Chrysanthemum indicum

Indicator bacteria	Minimum inhibitory concentration (μg/mL)
	AgNPs	Streptomycin
Gram-positive
Bacillus subtilis (MTCC 121)	>25	25
Staphylococcus aureus (MTCC 96)	>25	12.5
Staphylococcus epidermidis (MTCC 435)	25	>25
Gram-negative
Escherichia coli (MTCC 433)	12.5	12.5
Klebsiella pneumoniae (MTCC 109)	6.25	25
Pseudomonas aeruginosa (MTCC 1934)	37.5	25

Note: Streptomycin was the control antibiotic used for the bacteria.

Abbreviations: AgNPs, silver nanoparticles; MTCC, Microbial Type Culture Collection and Gene Bank.

Table 4 Cell viability and LDH leakage in control- and AgNP-treated 3T3 cells after 24 hours of exposure

Concentration (μg/mL)	Percentage of viability	LDH activity (μmol/NADH/well/minute)
25	93.33±1.45*	0.12±0.007*
50	45.14±1.38*	0.42±0.003*
Control	97.70±1.49	0.11±0.005

Notes: The values represent the mean ± standard deviation of two independent experiments.

* P<0.001 versus control.

Abbreviations: LDH, lactate dehydrogenase; AgNP, silver nanoparticle; NADH, nicotinamide adenine dinucleotide.

Figure 7 Cytotoxicity of synthesized silver nanoparticles on 3T3 mouse embryo fibroblast cells.

Notes: (A) Control (cell + phosphate buffered saline); (B) cell +25 μg/mL of silver nanoparticles; (C) cell +50 μg/mL of silver nanoparticles. The arrows indicate the cell nucleus.