# Halimeda gracilis as a bioactive resource: exploring its antioxidant, antibiofilm, anti-inflammatory, and antibacterial potential for dental applications

## TL;DR

This study explores the potential of Halimeda gracilis as a natural resource with antibacterial, antioxidant, and anti-inflammatory properties useful for dental applications.

## Contribution

The study demonstrates the multifunctional bioactive properties of Halimeda gracilis extracts for potential use in dentistry.

## Key findings

- Halimeda gracilis extract inhibited biofilm formation and showed increased antimicrobial activity with higher concentrations.
- The extract exhibited antioxidant activity up to 40 µg/mL and anti-inflammatory effects by inhibiting BSA denaturation.
- Maximum zone of inhibition reached 17 mm against tested bacterial strains at 100 µg/mL concentration.

## Abstract

This study aimed to evaluate the antibacterial, antibiofilm, antioxidant and anti-inflammatory properties and of Halimeda gracilis extracts.

The H. gracilis sample was washed and extracted using methanol. The mixture was homogenized using a blender and centrifuged at high speed (10,000 × g) for 2 min, then stirred at room temperature for 30 min using magnetic stirrer, to ensure thorough extraction. Afterward, it was centrifuged at 5,000 × g for 10 min to separate the dissolved components from undissolved debris. Following this antioxidant activity was assessed using DPHH assay, the antimicrobial effects were tested against Streptococcus mutans, Escherichia coli, Enterococcus faecalis and Shigella sonnei using Kirby-Bauer disk diffusion, biofilm inhibition assay was done to assess biofilm inhibition against S. mutans, E. coli, E. faecalis and S. sonnei. Finally, the anti-inflammatory activities of the H. gracilis were determined using a modified version of the BSA assay.

When tested against S. mutans, E. coli, E. faecalis, and S. sonnei strains, the antimicrobial evaluation revealed that the extract successfully inhibited biofilm formation when tested against the same organism, and it also demonstrated increased activity with increasing concentration. The zone of inhibition progressively expanded with increasing concentration, reaching a maximum of 17 mm ± 0.1 for 100 µg/mL. In terms of antioxidant activity, the H. gracilis metholic extract gradually increased from 10 µg/mL to a higher activity at 40 µg/mL in comparison to the control and blank, and then decreased at a dose of 50 µg/mL. At different doses, the anti-inflammatory action of H. gracilis extracts successfully inhibited BSA denaturation, which causes inflammation; the maximum activity has been observed.

This comprehensive analysis highlights H. gracilis as a valuable natural resource with multifaceted biological activities, supporting its further investigation for therapeutic applications in dentistry.