Physicochemical Characteristics of Phospholipid Vesicles for Spirulina-Based Dietary Supplement Delivery

Abstract

Spirulina (Arthrospira platensis) is a microalga widely used as a dietary supplement in sports nutrition and in treating metabolic diseases such as diabetes, obesity and metabolic syndrome. Spirulina's cell structure limits digestibility and reduces the availability of bioactive compounds. The extraction processes, coupled with encapsulation, can enhance the bioavailability of nutritional and antioxidant compounds, protecting them from degradation, preserving their functional activity, and supporting controlled release. The physicochemical properties of liposomes (Lps), bilosomes (Bls), and gelatin-enriched bilosomes (G-Bls) with incorporated Spirulina extracts were investigated. The delivery systems exhibited small particle size (101.8 ± 0.5 to 129.7 ± 1.2 nm), homogeneous distribution (polydispersity index (PDI) 0.17 ± 6.67 to 0.33 ± 9.06), negative surface charges (-31.9 ± 5.2 to 31.1 ± 6.4 mV), and high entrapment efficiency (>80%). G-Bls demonstrated effective retention of the extract, with a low release rate at pH 1.2 (41.8% ± 6.1) and controlled release at pH 7.0 (52.5% ± 3.0). Biocompatibility studies on Caco-2 cells showed that G-Bls maintained high cell viability at 200 μg·mL^-1 (87.89% ± 10.35) and significantly mitigated H₂O₂-induced oxidative stress at 20 and 200 μg·mL^-1, increasing cell viability by 23.47% and 19.28%. G-Bls are a promising delivery system for enhancing the stability, bioavailability, and protective effects of Spirulina extracts, supporting their potential application in dietary supplements aimed at promoting sports performance and recovery, mitigating exercise-induced oxidative stress, and managing metabolic disorders.

Keywords: bilosomes; gelatin-enriched bilosomes; liposomes; physicochemical properties; spirulina extract.

Figure 1

The physicochemical properties of the vesicles freshly prepared after 15 days of storage at 5 °C and with mannitol addition, followed by freeze-drying and rehydration. Data reported as mean values ±  standard deviations (n = 6). * p < 0.05, ** p < 0.01, *** p <0.001, and **** p < 0.0001 express the statistical difference between extract free dispersion (control) and other groups based on an ANOVA Tuckey comparison.

Figure 2

The release of the Spirulina extract from the dispersion and the vesicles at pH 1.20 for 2 h and at pH 7.00 for 6 h. * p < 0.05, ** p < 0.01, *** p <0.001, and **** p < 0.0001 express the statistical difference between extract free dispersion (control) and other groups based on the ANOVA Tuckey comparison.

Figure 3

The viability of Caco-2 cells after 48 h of incubation with Spirulina extract dispersion or vesicles at three concentrations (2, 20, and 200 µg·mL⁻¹). Data reported as mean values ± standard deviations (n = 6). ** p < 0.01, and *** p < 0.001 express the statistical difference between groups based on the ANOVA Tuckey comparison. Letters indicate statistical differences within each group based on ANOVA with Tukey’s post hoc test.

Figure 4

The viability of Caco-2 cells stressed with H₂O₂ and treated with Spirulina extract dispersion or vesicles at 20 and 200 μg·mL⁻¹. Data are reported as mean percentages relative to untreated healthy cells (n = 8). Letters indicated statistical differences within untreated cells (control) and each group. * indicate statistical differences between H₂O₂ damaged cells (stressed) and cells treated with dispersion, Lps, Bls, and G-Bls (* p < 0.05, ** p < 0.01) based on ANOVA with Tukey’s post hoc test (p ˂ 0.05).