It is well known that silver nanoparticles exhibit yellowish
brown color in aqueous solution due to excitation of surface
plasmon vibrations in silver nanoparticles (Krishnaraj et al.,
2010). As the mangosteen leaf extract was mixed with aqueous
solution of the silver nitrate, it started to change the color from
watery to brown due to reduction of silver ion; which indicated
the formation of silver nanoparticles. It is generally recognized
that UV–Vis spectroscopy could be used to examine size and
shape-controlled nanoparticles in aqueous suspensions (Shrivastava
and Dash, 2009). Fig. 1 shows the UV–Vis spectra recorded
from the reaction medium after heating the solution
at 75 C for 60 min. Absorption spectra of silver nanoparticles
formed in the reaction media has absorbance peak at 438 nm
and broadening of peak indicated that the particles are
polydispersed.