Wound healing properties, antimicrobial and antioxidant activities of Salvia kronenburgii Rech. f. and Salvia euphratica Montbret, Aucher & Rech. f. var. euphratica on excision and incision wound models in diabetic rats

Diabetic patients suffer from persistent and non-healing wounds. Salvia species are traditionally used for the treatment of wounds and colds. The aims of the present study were to evaluate the in vivo wound healing potential, in vitro antimicrobial and antioxidant activities, and total phenolic and flavonoid contents of the aerial parts of two endemic taxa, Salvia kronenburgii Rech. f. (SK) and Salvia euphratica Montbret, Aucher & Rech. f. var. euphratica (SE). Two different concentrations (0.5% and 1% (w/w)) of ethanol extracts were investigated in incision and excision wound models on Streptozotocin-induced diabetic rats using biomechanical, biochemical, histopathological, macroscopic, and genotoxic methods for 7 and 14 days. Antimicrobial activity was evaluated against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Acinetobacter baumannii, Aeromonas hydrophila, Mycobacterium tuberculosis, Candida glabrata, Candida parapsilosis, and Candida tropicalis using the broth microdilution and the resazurin microtiter assay plate methods. Fito^®, Ampicillin, Ethambutol, Isoniazid, and Fluconazole were used as reference drugs. Antioxidant capacities and total phenolic and flavonoid contents of both extracts were detected using DPPH free radical scavenging assay, Folin-Ciocalteu, and Al(NO₃)₃ methods, respectively. SK ointment at 0.5% and 1% (w/w) concentrations and SE ointment at 1% (w/w) concentration showed 99.9%, 99.5%, and 99.7% contraction, respectively for excision wounds, and SK and SE ointments at 1% (w/w) concentration showed 99.4% and 99.2% contraction for incision wounds while Fito^® showed 98.9% and 98.5% contraction, respectively. Increased re-epithelialization (P < 0.01 and P < 0.001), angiogenesis, and decreased dermal inflammation (P < 0.001) were determined for SK and SE ointments at both 7 and 14 days. SE ointment on day 7 and SK ointment on day 14 reduced oxidative damage to DNA when compared to control (P < 0.01 and P < 0.001). Both tested plants had greater antibacterial activity against A. baumannii (62.5 μg/mL MIC value) and SE had greater antimycobacterial activity against M. tuberculosis (0.24 μg/mL MIC value) when compared to reference drugs Ampicillin, Isoniazid, and Ethambutol (125, 0.97, and 1.95 μg/mL MIC values, respectively). Antioxidant capacities, total phenolic and flavonoid contents of SE and SK were 87.08%, 76.21 μg GAE/mg, 43.43 μg QE/mg and 72.17%, 41.81 μg GAE/mg, 33.62 μg QE/mg, respectively. SK and SE had strong wound healing effects while SK found to be more effective than SE at both 7 and 14 days.