Extraction, profiling, and evaluation of cytoprotective, and photoprotective activities of phytosterols from Pistacia vera L. var. Damghan green hull

Phytosterols are bioactive triterpenes with well-documented health benefits and are found in pistachio green hull (PGH), a major by-product of the pistachio industry. This study aimed to characterize and quantify phytosterols in the kernels and PGHs of three pistachio cultivars from Damghan, Iran, and to evaluate the cytoprotective and photoprotective effects of PGH phytosterol fractions in normal human dermal fibroblast (HDF) cells. Total phytosterols, extracted using a modified Soxhlet method, were analyzed using gas chromatography/flame ionization detection. In vitro antioxidant activity of phytosterol fractions was assessed, and the cytoprotective and photoprotective effects of PGH phytosterol fractions were examined against oxidative stress induced by H 2 O 2 or ultraviolet B (UVB) in HDF cells. β-sitosterol (the most abundant phytosterol), campesterol, Δ 5 -avenasterol, stigmasterol, and Δ 7 -avenasterol were identified in the kernels and PGHs, with PGH exhibiting significantly higher antioxidant activity than the kernels. Pretreatment with PGH phytosterol fractions significantly enhanced cell growth by ~ 70% and ~ 80% against H₂O₂- and UVB-induced stress, respectively. According to fluorescent microscopy imaging and flow cytometry data, the pretreatment of the cells with PGH phytosterols fraction effectively protected cells against the cytotoxic effects of H₂O₂ and UVB irradiation. However, the pretreatment mitigated oxidative damage by reducing malondialdehyde levels, and suppressing ROS production, following exposure to H₂O₂ and UVB. Furthermore, PGH phytosterol fractions enhanced the specific activities of catalase and GPx in H 2 O 2 treated and UVB exposed cells relative to controls. Pretreatment of the cells with PGH phytosterol-enriched fractions protected them against the cytotoxic effects of H₂O₂ and UVB irradiation. PGH represents a valuable source of phytosterols, and our in vitro results suggest potential protective effects. Further studies, including in vivo models and clinical evaluations, are needed to explore possible applications in pharmaceuticals and cosmetics.