Posidonia oceanica (L.) Delile Ethanolic Extract Modulates Cell Activities with Skin Health Applications

Abstract

Seagrasses are high plants sharing adaptive metabolic features with both terrestrial plants and marine algae, resulting in a phytocomplex possibly endowed with interesting biological properties. The aim of this study is to evaluate the in vitro activities on skin cells of an ethanolic extract obtained from the leaves of Posidonia oceanica (L.) Delile, family Potamogetonaceae, herein named Posidonia ethanolic extract (PEE). PEE showed high radical scavenging activity, high phenolic content, and resulted rich in chicoric acid, as determined through HPLC-MS analysis. The use of MTT assay on fibroblasts showed a PEE cytotoxicity threshold (IC₀₅) of 50 µg/mL at 48 h, while a sub-toxic dose of 20 µg/mL induced a significant increase of fibroblast growth rate after 10 days. In addition, an ELISA assay revealed that PEE doses of 5 and 10 µg/mL induced collagen production in fibroblasts. PEE induced dose-dependent mushroom tyrosinase inhibition, up to about 45% inhibition at 1000 µg/mL, while 50% reduction of melanin was observed in melanoma cells exposed to 50 µg/mL PEE. Finally, PEE lipolytic activity was assessed by measuring glycerol release from adipocytes following triglyceride degradation. In conclusion, we have collected new data about the biological activities of the phytocomplex of P. oceanica seagrass on skin cells. Our findings indicate that PEE could be profitably used in the development of products for skin aging, undesired hyperpigmentation, and cellulite.

Keywords: adipocytes; chicoric acid; collagen type I; fibroblasts; lipolysis; melanin; tyrosinase.

Figure 1

(A) Full scan acquired in negative ion mode and (B) tandem mass spectra relative to the peak at retention time (RT) = 32.5 min, in the HPLC-MS total ion chromatogram of Posidonia Ethanolic Extract (PEE). The molecular mass and fragment ions present are consistent with those expected for chicoric acid. (C) Extracted ion chromatograms acquired in positive ion mode, relative to other major PEE constituents identified by MS/MS spectra.

Figure 2

(A) Dose-response curve of the effect of PEE on fibroblast cell viability. Data are percent cell viabilities recorded in n = 6 replicates of MTT assay after 48-h incubations with different PEE concentrations. Downhill logistic best fit (continuous line), IC₅₀ value (dashed vertical line), and its 95% CI (horizontal bar) are shown. (B) Fibroblast growth rate curves derived from the MTT assay and expressed in terms of cell densities. Data are mean 550 nm absorbances ± SD from six replicates in two independent experiments. * = p < 0.01 with respect to other groups at the same endpoint. (C) Induction of fibroblast collagen production determined by an ELISA assay after 48-h incubations with 5 and 10 µg/mL PEE. Data are mean 620 nm absorbances ± SEM from six replicates in two independent experiments. * = p < 0.01 with respect to the control.

Figure 3

(A) Dose-dependent curves of mushroom tyrosinase inhibition exerted by kojic acid as a positive control (dashed line) and by PEE (continuous line). Tyrosinase activity was determined in a cell-free, in vitro assay using l-tyrosine as a substrate. Data are mean percent inhibitions ± SD from six replicates in two independent experiments (see Materials and Methods). (B) Inhibition of melanin production in MeWo melanoma cells after 72 h incubation with 1 mg/mL arbutin, or with 50 µg/mL PEE. Cell melanin production was quantified as mean 505 nm absorbances ± SD from three replicates in two independent experiments. * = p < 0.01 with respect to the control.

Figure 4

Induction of lipolysis in human adipocytes evaluated by glycerol release. (A) Standard curve of glycerol determined by the ZenBio Kit Human Adipocyte Lipolysis Assay Kit (see Materials and Methods). (B) Assay of glycerol released from adipocytes determined as above after exposure for 3 h to different concentrations of PEE, or to 1 µM isoproterenol (isoprot). Data are mean fold inductions of lipolysis ± SD, calculated as the ratio between µmoles/L of glycerol released by treated cells and by controls, obtained from three replicates in two independent experiments (* = p < 0.05).