Green Synthesis of Terminalia Arjuna-mediated Hydroxyapatite Nanoparticles, Its Morphological Assessment and Evaluation of Cytotoxic and Antioxidant Properties: An In-vitro Study

Introduction: Terminalia Arjuna (TA) has been used in the field of ayurvedic and unani medicine for quite some time now. It has been shown to possess several medicinal properties. Literature has highlighted the osteoinductive properties of TA and has been extensively been used for its fracture healing and bone forming potential. This would have a positive impact in the field of periodontics and orthodontics, which require bone grafts to maintain ideal periodontal conditions.

Aim: To synthesise TA-mediated Hydroxyapatite Nanoparticles (TA-HApNPs) and subject it to morphological assessment and evaluate its cytotoxic and antioxidant properties.

Materials and Methods: This in-vitro study was done under a laboratory setting within the city of Chennai, Tamil Nadu, India, extending for a period of one month from April 2022 to May 2022. A 1 g of TA plant bark was mixed with 100 mL distilled water and heated to derive the plant extract. A 20 mL of distilled water was mixed with 0.502 g of Hydroxyapatite (HAp). An 80 mL of TA extract was mixed with 20 mL of HAp solution. The mixture was placed in a magnetic stirrer and was subjected to an Ultraviolet Visible (UV-Vis) double beam spectrophotometer. The solution was dried and was subjected to Transmission Electron Microscope (TEM) analysis for morphological characterisation, 2,2-Diphenylpicrylhydrazyl (DPPH) assay for the assessment of
antioxidant properties and brine shrimp lethality test to evaluate its cytotoxic properties. The results were obtained electronically, tabulated in a spreadsheet and were subjected to descriptive statistics using Microsoft excel 2019 Management Services Organisation (MSO) (Version 2202; Build 16.0.14931.20118).
Results: The UV-Spectroscopy revealed a sharp peak at 375 nm wavelength suggesting Nanoparticle (NPs) formation. Spherical shaped NPs with size ranging from 5-25 nm were seen under the TEM. At concentration of 48 μL also TA-HApNPs elicited good cytotoxicity as seven out of 10 brine shrimps were alive at the end of 24 hours. Good antioxidant properties at 50 μL concentration with a DPPH assay reading of 1.044 was noted.

Conclusion: The TA-HApNPs can be synthesised using simple and routinely used laboratory armamentarium in the size range of 5-25 nm. TA-HApNPs have minimal cytotoxic effect and a good antioxidant activity.