Facile synthesis of silver nanoparticles using Tribulus longipetalus extract and their antioxidant and antibacterial activities

Figures & data

Figure 1. UV-Vis absorption spectra of the silver nanoparticles prepared via green synthesis method recorded after 10, 30, 60, and 120 min.

Table 1. Antioxidant activities of Tribulus longipetalus extracts.

Sample	DPPH IC50(μg mL^−1)	Total phenol contents GAE^a (µg/mg)
Methanol extract	212.4 ± 4.8	nd
Polar subfraction	70.3 ± 2.1	175.8 ± 5.8
Nonpolar subfraction	312.5 ± 6.17	87.4 ± 2.3
Ascorbic acid	5.8 ± 0.3	nd
BHT	25.4 ± 1.5	Nd

^aGAE: gallic acid equivalents.

^bnd: not determined.

Figure 2. Reducing power of different concentrations of essential oil and methanol extract of T. longipetalus compared to ascorbic acid (spectrophotometric detection of the Fe⁺³–Fe⁺² transformations). PS: polar subfraction, NS: non-polar subfraction, AA: ascorbic acid.

Table 2. Antibacterial activity of aqueous and methanol extract of T. longipetalus.

	PS			Methanol			NS			Gentamicin
Test bacteria	DD^a	MIC^b		DD	MIC		DD	MIC		DD	MIC
S. aureus	8.3	1000 ± 50		10.7	500 ± 20		8.1	1000 ± 40		17.1	10.0 ± 1.0
E. coli	7.5	1000 ± 45		10.3	500 ± 25		10.0	500 ± 10		10.2	17.0 ± 1.2
B. subtilis	9.6	500 ± 30		12.1	256 ± 15		11.9	256 ± 10		14.0	20.0 ± 1.7
B. cereus	7.3	1000 ± 55		9.8	500 ± 22		9.5	500 ± 15		14.1	20.0 ± 1.5
S. typhimurium	7.0	1000 ± 40		9.5	500 ± 25	–	7.4	1000 ± 45	–	10.1	12.0 ± 0.7
K. pneumoniae	—	—	—	—	—	—	—	—	—	10.0	25.0 ± 0.9

^aDiameter of inhibition zone including disc diameter of 6 (mm).

^bMIC: minimum inhibitory concentration (as µg mL⁻¹).

A dash (—) indicates no antibacterial activity.

Figure 3. DLS analysis of silver nanoparticles prepared under optimum conditions.

Figure 4. XRD pattern of the synthesized silver nanoparticles by green synthesis method.

Figure 5. TEM image of Ag NPs synthesized using T. longipetalus extract via green synthesis method.