EFFECT OF SAMPLE PREPARATION ON PHYTOCHEMICAL CONTENT, SILVER NANOPARTICLES SYNTHESIS, ANTIMICROBIAL AND ANTIOXIDANT PROPERTIES OF ZINGIBER OFFICINALE AND CURCUMA LONGA SYNERGISTIC COMBINATION

This work compared the effect of hot aqueous extraction and blending on phytochemical content, AgNPs synthesis, antibacterial and antioxidant properties of ginger and turmeric. Qualitative and quantitative phytochemical screening was conducted on a hot aqueous extract of ginger and turmeric combination (CHAE) and blended ginger & turmeric combination (CBLE). An attempt was then made to synthesize silver nanoparticles by reducing 1mM AgNO₃ solution with CHAE & CBLE, respectively. The biosynthesized AgNPs were characterized using UV-Visible spectroscopy, FTIR, and SEM. Using existing protocols, the antioxidant and antibacterial properties of CHAE, CBLE, and biosynthesized AgNPs were evaluated. The result of the phytochemical screening revealed the presence of phytochemicals required for synthesizing silver nanoparticles, such as flavonoids and phenols in CBLE but absented in CHAE. The UV-Visible spectrum confirmed the synthesis of AgNPs using CBLE (AgNPs-CBLE), with the highest absorbance peak observed at 412 nm. The FTIR analysis revealed the involvement of phenolic compounds in the bioreduction of Ag⁺ as well as the capping/stabilization of the biosynthesized nanoparticles. AgNPs-CBLE were irregularly granulated and highly aggregated, as revealed by the SEM micrograph. The result of the antioxidant activity revealed that the test samples (CHAE, CBLE, and AgNPs-CBLE) possessed a concentration-dependent antioxidant power. Also, antibacterial result revealed that CHAE had no zone of inhibition against Salmonella typhi and Bacillus substilis. At the same time, CBLE exhibited antibacterial activity against Salmonella typhi with an inhibition zone diameter of 20 mm and none against Bacillus subtilis. However, AgNP-CBLE exhibited a greater antibacterial activity against Bacillus subtilis and a significant antibacterial activity against Salmonella typhi compared to Levofloxacin. These results indicate that the sample preparation method influenced the phytochemical levels, synthesis of silver nanoparticles, antibacterial and antioxidant capacities of the ginger and turmeric combination.