Phlomis crinita Cav. from Algeria: A source of bioactive compounds possessing antioxidant and wound healing activities.

ETHNOPHARMACOLOGICAL RELEVANCE: Phlomis crinita Cav. (Lamiaceae), locally known as "El Khayata" or "Kayat El Adjarah", is traditionally used in Algeria for its wound-healing properties.

AIM OF THE STUDY: Investigate, for the first time, the phytochemical profile, safety, antioxidant and wound-healing activities of the flowering tops methanolic extract of P. crinita (PCME) collected from Bouira Province in the North of Algeria.

MATERIALS AND METHODS: Preliminary phytochemical assays were carried out on PCME to quantify the main classes of bioactive compounds, such as total phenols, flavonoids, and tannins. An in-depth LC-DAD-ESI-MS analysis was carried out to elucidate the phytochemical profile of this plant species. Antioxidant activity was investigated by several colorimetric and fluorimetric assays (DPPH, TEAC, FRAP, ORAC, β-carotene bleaching and ferrozine assay). The acute oral toxicity of PCME (2000 mg/kg b.w.) was tested in vivo on Swiss albino mice, whereas the acute dermal toxicity and wound-healing properties of the PCME ointment (1-5% PCMO) were tested in vivo on Wistar albino rats. Biochemical and histological analyses were carried out on biological samples.

RESULTS: The phytochemical screening highlighted a high content of phenolic compounds (175.49 ± 0.8 mg of gallic acid equivalents/g of dry extract), mainly flavonoids (82.28 ± 0.44 mg of quercetin equivalents/g of dry extract). Fifty-seven compounds were identified by LC-DAD-ESI-MS analysis, belonging mainly to the class of flavones (32.27%), with luteolin 7-(6''-acetylglucoside) as the most abundant compound and phenolic acids (32.54%), with salvianolic acid C as the most abundant compound. A conspicuous presence of phenylethanoids (15.26%) was also found, of which the major constituent is forsythoside B. PCME showed a strong antioxidant activity with half-inhibitory activity (IC50 ) ranging from 1.88 to 37.88 μg/mL and a moderate iron chelating activity (IC50 327.44 μg/mL). PCME appears to be safe with Lethal Dose 50 (LD50 ) ≥ 2000 mg/kg b.w. No mortality or toxicity signs, including any statistically significant changes in body weight gain and relative organs' weight with respect to the control group, were recorded. A significant (p < 0.001) wound contraction was observed in the 5% PCMO-treated group with respect to the untreated and petroleum jelly groups between 8 and 20 days, whereas no statistically significant results were observed at the two lower doses (1 and 2% PCMO). In addition, the 5% PCMO-treated group showed a statistically significant (p < 0.05) wound healing activity with respect to the reference drug-treated group, showing, at the end of the study, the highest wound contraction percentage (88.00 ± 0.16%).

CONCLUSION: PCME was safe and showed strong antioxidant and wound-healing properties, suggesting new interesting pharmaceutical applications for P. crinita based on its traditional use.