Phytochemical analysis, bioactivity, and molecular docking studies of Myrtus communis L. seeds and fruit peel extracts demonstrating antioxidant and anti-tyrosinase properties

Myrtus communis L, is an edible medicinal plant with fruit berries used to manufacture liquors, aromatise wine, and sweet foods, beside several folk-medicinal uses. The plant is also endemic to Libya, holds promise for its medicinal properties, including anti-inflammatory, antioxidant, wound healing, and appetising effects. This work aims to explore the phytoconstituents present in the seeds and fruit peels of Myrtus communis L by GC-MS and LC-ESI-MS analysis, respectively. The work also demonstrated the in vitro and in silico antioxidant and anti-tyrosinase activities of the plant extracts. GC-MS analysis indicated the presence of 11 fatty acids in the myrtle seeds representing 78.61% of the total seeds' fatty acid contents, where the unsaturated linolenic acid (C_18:3) was the major fatty acid (23.11%). Moreover, seven anthocyanins were identified by the LC-ESI-MS analysis in the fruit peels with relative percentage of 59.84% related to the total peaks area in the positive ion mode chromatogram. Among the identified compounds, petunidin 3-O-glucoside and Malvidin 3-O-rutinoside were the most abundant anthocyanins at the relative percentage of 12.48% and11.87%, respectively. Antioxidant assay showed that the ethanolic extract of the Myrtus fruit peels exhibited higher DPPH-free radical scavenging activities compared to the chloroform extract of the seeds (6.89 ± 0.12 and 2.65 ± 0.03, respectively). Similarly, the fruit peels extract was induced higher ferric reducing antioxidant power (FRAP) compared to the seeds extract (4.87 ± 1.02 and 2.10 ± 0.9, respectively. The fruit peels ethanolic extract was exhibited greatest inhibitory effect against tyrosinase enzyme with IC₅₀ 126.35 ± 0.92 compared to the activity of seeds extract at the IC₅₀ 135.27 ± 1.23. The tested extracts displayed lower level of tyrosinase inhibition activity compared to the standard arbutin (IC₅₀ 76.9 ± 0.0). The results of molecular docking simulations suggest that anthocyanins, particularly Cyanidin-3-O-rutinoside, exhibit significant binding affinity to the tyrosinase enzyme and could potentially serve as effective natural inhibitors. These compounds may interfere with the enzyme's catalytic activity by interacting with key residues in the active site.