Green synthesis and biomedicinal applications of silver and gold nanoparticles functionalized with methanolic extract of Mentha longifolia

Figures & data

TABLE 1. Effect of phytochemical tests of MLE.

Chemical components	Methanolic extract
Alkaloids	_
Tannins	+
Anthraquinone	_
Glycosides	_
Reducing sugar	+
Saponins	+
Flavonoids	+
Phlobatanins	_
Steroids	+
Terpenoids	+
Cardiac glycosides	+
Coumarins	+
Emodins	_
Anthocyanins	+
Carbohydrates	+
Monosaccharide’s	_
Free Reducing Sugar	_
Combined reducing sugars	_
Soluble starch	+

Figure 1. Image of (A) MLE have green colour due to the presence of UV active natural product, (B) Silver Solution are colourless due to the UV inactive ions (C) AgNPs having brown colour due to the surface plasmon resonance (D) Gold solution having no colour due the UV inactive ions of gold and (E) AuNPs having pink colour due to the surface plasmon resonance.

Figure 2. UV-Visible spectrum of (A) AgNPs and (B) AuNPs of MLE.

Figure 3. FTIR spectrum recorded for (A) MLE, (B) AgNPs and (C) AuNPs.

Table 2. FTIR spectral analysis of MLE, and AuNPs and AgNPs.

MLE	AgNPs	AuNPs	Assignment	Ref
3600–3100 cm^−1	3600–3100 cm^−1	3600–3100 cm^−1	–OH (H-bondong)	[13]
2900 cm^−1	---	---	–NH2	[59]
1700 cm^−1	1650 cm^−1	1650 cm^−1	–C = O	[60]
1500 cm^−1	---	---	COO of protein side chain	[61]
1000 cm^−1	---	---	C–H and –OH deformation	[59]

Figure 4. Atomic force microscopy images of (A) AgNPs) and (B) AuNPs of MLE.

Figure 5. TEM images of (A) showing particles size distribution of AgNPs (B) Average particles size and size distribution of AgNPs.

Figure 6. TEM images of (A) showing particles size distribution of AuNPs (B) Average particles size and size distribution of AuNPs.

Figure 7. DPPH radical scavenging activity of MLE and NPs with 20–150 µg/mL. The results are presented as mean ± SEM of three different readings SEM: standard error mean.

Table 3. Antibacterial activity of MLE and AuNPs and AgNPs.

Microorganisms		Zone of inhibition (mm at 3 mg/mL) ± S.E.M.
	Gram	MLE	AgNP’s	AuNP’s	Streptomycin
K. pneumoniae	–	0	0	0	26 ± 0.02
S. aureus	+	0	12 ± 0.03	10 ± 0.01	28 ± 0.02
B. subtilis	+	0	10 ± 0.01	0	28 ± 0.05

The results are presented as mean ± SEM of three different readings, Streptomycin: Standard drug used.

Figure 8. Effect of intraperitoneal administration of AuNPs and AgNPs in acetic acid induced test. Values are expressed as mean ± SEM *p<.05, **p<.01, ***p<.001 as compared to control. n = 6.

Table 4. Sedative effect of MLE and NPs in open field test (Locomotive activity).

Treatment	Dose (mg/Kg)	No of line crossed in 10 min
Distilled water	10 (mL/Kg)	126 ± 1.23
Diazepam	0.5	6 ± 0.12***
MLE	50	123.38 ± 2.99
	100	115.84 ± 2.22*
AgNPs	5	100.34 ± 0.87***
	10	88.56 ± 1.88***
AuNPs	5	98.89 ± 1.22***
	10	89.44 ± 1.99***

Values represent the number of lines crossed by an animal in a box, 30 min after treatment with distilled water (10 ml/kg, control), MLE (50 and 100 mg/Kg), AgNPs and AuNPs (5 and 10 mg/kg) or diazepam (0.5 mg/kg). Data presented as mean ± SEM, (n = 6). *p<.05, **p<.01, ***p<.001, all compared with control.

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