Alpha t model

FTIR, the spectrum of brown pigment was recorded on alpha ATR-FTIR spectrometer (ALPHA T model, Bruker Optics, Germany) Dried sample was loaded on diamond crystal and the spectrum was recorded from the range of 400–4000 cm⁻¹ at resolution 4 cm⁻¹ with 20–30 scans in transmittance mode. ESR and XRD analysis of purified pigment was done according to Prasuna et al.^{18 (link)}. Briefly, dried pigment (20 mg) was loaded into the ESR quartz tube and spectra were recorded on JEOL X-band ESR spectrometer at room temperature. X-ray Diffraction spectrum of purified pigment was recorded using Bruker D8 Advance, Germany X-Ray Diffractometer. Spectrum was recorded by scanning the pigment using the CuKα radiation at wavelength 1.5406 A° with a step size of 0.04°, voltage 40 kV, current 40 mA and 2θ range 10–90°.

Synthesis of ZnO NPs and extraction of secondary metabolites were performed in UWave - 1000 multifunction microwave workstation. Schimazu UV-Vis Spectroscopy (UV-1800) was used to record UV - Vis spectrum. FTIR was recorded in Bruker Alpha T model whereas XRD has been analyzed with the help of Bruker D8 instrument. SEM/EDAX (JEOL JSM-6390LV) and TEM (Philips; CM 200) were used to find the morphological and size of the ZnO NPs. Horiba nanoparticle analyzer was utilized for Zeta potential result.