Brosimine B and the biphasic dose-response: insights into hormesis and retinal neuroprotection

Abstract

Introduction: The biphasic dose-response behavior, also known as hormesis, is a characteristic feature of numerous natural products. It is defined by beneficial effects at low concentrations and toxicity at higher doses. This study investigates the hormetic effects of Brosimine B, a flavonoid derived from Brosimum acutifolium, on retinal cell viability under oxidative stress.

Methods: To simulate ischemic conditions, we used an oxygen-glucose deprivation (OGD) model. Retinal cells were treated with varying concentrations of Brosimine B, and analyses of cell viability, reactive oxygen species (ROS) production, and antioxidant enzyme activity were performed.

Results: Brosimine B at 10 µM significantly enhanced cell viability and reduced ROS production, likely through modulation of oxidative stress-protective enzymes such as catalase. However, higher concentrations (>10 µM) induced cytotoxic effects. A computational modeling approach using a hormetic (inverted U-shaped) model revealed biologically interpretable parameters, including a peak response at 10.2 µM and a hormetic zone width (σ = 6.5 µM) (R² = 0.984).

Discussion: These results confirm that Brosimine B exhibits hormetic neuroprotective effects within a well-defined concentration window, supporting its potential as a therapeutic agent for oxidative stress-related retinal damage. The study highlights the value of computational modeling in optimizing dose-response analyses, offering a framework for refining natural product therapies and predicting toxicological thresholds in pharmacological applications.

Keywords: Brosimine b; antioxidant; hormesis; natural products; neuroprotection; oxidative stress; retinal cell.

FIGURE 1

Chemical structure of Brosimine B.

FIGURE 2

Effect of Brosimine B on cell viability after 24 h in culture. Retinal cells in normal culture were treated with different concentrations of Brosimine B (1, 5, 10, 25, 50, and 100 µM) for 24 h. Cell viability was analyzed with the MTT assay. All values are normalized to control and expressed in percentage. ^***p < 0.0001.

FIGURE 3

Hormetic Model Fit of Brosimine B Dose-Response Curve. Cell viability is expressed as a percentage relative to the control. Observed data points (blue dots) represent measured cell viability at various Brosimine B concentrations. The fitted parameters were baseline = 0.715, amplitude = 0.217, x₀ (peak concentration) = 10.2 µM, and σ (spread) = 6.5 µM.

FIGURE 4

Protective effect of Brosimine B on embryonic retinal cells subjected to OGD. OGD condition reduces cell viability at 3, 6, and 24 hours (A). Brosimine B exerts a protective effect on embryonic retinal cells exposed to OGD for 3 (B), 6 (C), and 24 hours (D). Results are expressed as percentage relative to control. Statistical significance: ***p < 0.0001 compared to the control; **p < 0.0001 compared to the OGD group.

FIGURE 5

Effect of Brosimine B on ROS Production in Cells Subjected to OGD. Brosimine B (10 μM) reduces ROS production in cell cultures exposed to OGD for 3 h (A), 6 h (B), and 24 h (C). Results are expressed relative to the control. Statistical significance: ***p < 0.0001 compared to control and ^###p < 0.0001 compared to the OGD group.

FIGURE 6

Effect of 10 μM Brosimine B on the activity of the enzyme catalase in retinal cell cultures during OGD for 3, 6 or 24 h in vitro (A–C), respectively). The catalase activity was analyzed using an assay de catalase. **p < 0,01, in comparison with a control group and OGD. Error bars represent Mean ± SD; *p < 0.005, comparing with control groups and OGD; ***p < 0.0001 comparing with OGD by one-way analysis of variance (ANOVA), post-test Tukey.