Anti-elastase, Anti-tyrosinase, and Anti-inflammatory Activities of Three Compounds Isolated from Psorospermum aurantiacum: In Silico and In Vitro Assays

The hexane fraction of Psorospermum aurantiacum Engl., Hypericaceae, was found to prevent photo aging in skin cells lines. Therefore, this research aimed to evaluate the anti-skin aging potentials of compounds isolated from the most bioactive fraction using in silico and in vitro models. Compounds were isolated by column chromatography, and their structures were determined using spectroscopic techniques such as 1D and 2D NMR analysis coupled to mass spectrometry. Molecular docking was conducted to determine the interactions between compounds and selected targets: elastase, 15-lipoxygenase, activator protein-1, and nuclear factor kappa B involved in skin aging processes. Furthermore, the in vitro anti-elastase and anti-tyrosinase activities of compounds as well as their anti-inflammatory effect were evaluated on 15-lipoxygenase and nitric oxide production in lipopolysaccharide-stimulated RAW 264.7 macrophage cells. Chromatographic purification of P. aurantiacum yielded three known compounds namely 3-geranyloxyemodinanthrone, 3-geranyloxyemodine, and lupeol. The in silico study showed that lupeol (− 12.83 kcal/mol) had high affinity with elastase while 3-geranyloxyemodine (− 8.98 kcal/mol) effectively interacted with lipoxygenase. The in vitro assays revealed that 3-geranyloxyemodinanthrone significantly (p < 0.05) inhibited tyrosinase (IC₅₀ 65.00 µg/ml) and lipoxygenase (IC₅₀ 35.35 µg/ml) with lower activities as compared with vitamin C (IC₅₀ 41.85 µg/ml) and quercetin (IC₅₀ 26.79 µg/ml), respectively, used as positive controls. Additionally, lupeol showed a high percentage of elastase inhibition (88.09%) at 10 µg/ml and significantly (p < 0.05) inhibited nitric oxide production with IC₅₀ of 28.74 µg/ml compared to quercetin (IC₅₀ 15.13 µg/ ml). Compounds 3-geranyloxyemodinanthrone and lupeol showed anti-elastase, anti-tyrosinase, and anti-inflammatory properties through in vitro study. Molecular docking results confirmed the elastase inhibitory activity demonstrated by lupeol. These compounds demonstrated prominent inhibitory activities and could be incorporated into skin care products after further studies.