# Synergistic anti-inflammatory effects of the aqueous extract from Desmodium heterophyllum and photobiomodulation in a carrageenan-induced paw edema model

## TL;DR

This study shows that combining a plant extract with light therapy can reduce inflammation more effectively than either treatment alone, offering a promising new approach for treating inflammatory conditions.

## Contribution

First study to demonstrate the synergistic anti-inflammatory effects of Desmodium heterophyllum extract combined with photobiomodulation.

## Key findings

- The combination of Desmodium heterophyllum extract and photobiomodulation significantly reduced paw edema and pro-inflammatory cytokines comparable to dexamethasone.
- The extract showed no cytotoxicity to macrophage cell lines and reduced nitric oxide production in vitro.
- The synergistic treatment supports the development of safe integrative strategies for managing inflammation.

## Abstract

Inflammation is a complex biological response that, when uncontrolled, contributes to the development and worsening of several pathological conditions. Identifying safe and effective anti-inflammatory strategies remains an important therapeutic challenge. In this context, medicinal plants and photobiomodulation therapy (PBM) have emerged as promising approaches due to their immunomodulatory potential. This study aimed to investigate the anti-inflammatory properties of the aqueous extract from Desmodium heterophyllum (AEDh), alone and in combination with PBM, using a carrageenan-induced paw edema model. AEDh was obtained, chemically characterized through high-resolution mass spectrometry, and evaluated for cytotoxicity and nitric oxide (NO) production in J774A.1 and RAW 264.7 macrophages. In vivo anti-inflammatory activity was assessed in BALB/c mice subjected to carrageenan-induced paw edema and treated with AEDh (50–250 mg/kg), PBM (780 nm, 70 mW, 35 J/cm²), or their combination. Paw thickness was measured for up to 4 h post-induction, and cytokine levels (IL-1β, IL-6, TNF, IFN-γ) were quantified by enzyme-linked immunosorbent assay (ELISA). AEDh showed no cytotoxicity at the concentrations tested and significantly reduced NO production in vitro. In vivo, both AEDh and PBM reduced paw edema, with the combined treatment—especially AEDh at 250 mg/kg—producing a more pronounced effect, comparable to dexamethasone. The combination also markedly reduced pro-inflammatory cytokines, particularly IL-1β and IL-6, supporting a synergistic action. AEDh demonstrated relevant anti-inflammatory and immunomodulatory activity, which was further enhanced when combined with PBM. These findings highlight the therapeutic potential of integrating herbal medicine and photobiomodulation as a safe and effective strategy for managing inflammatory conditions. Keywords: Desmodium heterophyllum; Photobiomodulation; Cytokines; Synergistic effect; Low-level laser therapy.

First study to demonstrate the synergistic anti-inflammatory effects of Desmodium heterophyllum extract combined with photobiomodulation;Significant reduction in edema and pro-inflammatory cytokines comparable to dexamethasone;Extract exhibited excellent biocompatibility, with no cytotoxicity to macrophage cell lines;Findings support the development of safe and effective integrative therapeutic strategies for inflammatory conditions.

First study to demonstrate the synergistic anti-inflammatory effects of Desmodium heterophyllum extract combined with photobiomodulation;

Significant reduction in edema and pro-inflammatory cytokines comparable to dexamethasone;

Extract exhibited excellent biocompatibility, with no cytotoxicity to macrophage cell lines;

Findings support the development of safe and effective integrative therapeutic strategies for inflammatory conditions.