Evaluation of antimicrobial, antioxidant properties and toxicity of 𝘖𝘤𝘪𝘮𝘶𝘮 𝘵𝘦𝘯𝘶𝘪𝘧𝘭𝘰𝘳𝘶𝘮 L. extracts

Abstract

Oral health is altered by pathogens and is a global health concern due to antimicrobial resistance. 𝘖𝘤𝘪𝘮𝘶𝘮 𝘵𝘦𝘯𝘶𝘪𝘧𝘭𝘰𝘳𝘶𝘮 L. is widely recognized for its therapeutic potential in traditional medical systems. The objectives of the current study were to evaluate the antimicrobial, antioxidant properties and toxicity of crude ethanolic and aqueous extracts of the leaves of 𝘖. 𝘵𝘦𝘯𝘶𝘪𝘧𝘭𝘰𝘳𝘶𝘮. Ethanolic extracts of young, fresh leaves were prepared using ultrasonication (35 – 40 °C, 20 kHz, 15 min) and vacuum infiltration (25 – 30 ℃, 1400 rpm, one h). Cold extraction was done by soaking paste in sterile distilled water at 27 ± 1 ℃ overnight and the filtrate was used as the aqueous extract. The antimicrobial activity was assessed using agar well diffusion bioassay in Mueller Hinton Agar against reference cultures of oral pathogens; 𝘚𝘵𝘢𝘱𝘩𝘺𝘭𝘰𝘤𝘰𝘤𝘤𝘶𝘴 𝘢𝘶𝘳𝘦𝘶𝘴, 𝘚𝘵𝘳𝘦𝘱𝘵𝘰𝘤𝘰𝘤𝘤𝘶𝘴 𝘱𝘺𝘰𝘨𝘦𝘯𝘦𝘴 and 𝘊𝘢𝘯𝘥𝘪𝘥𝘢 𝘢𝘭𝘣𝘪𝘤𝘢𝘯𝘴, 𝘊. 𝘨𝘭𝘢𝘣𝘳𝘢𝘵𝘢, 𝘊. 𝘬𝘳𝘶𝘴𝘦𝘪, 𝘊. 𝘵𝘳𝘰𝘱𝘪𝘤𝘢𝘭𝘪𝘴, 𝘊. 𝘱𝘢𝘳𝘢𝘱𝘴𝘪𝘭𝘰𝘴𝘪𝘴 and 30 clinical isolates of 𝘊𝘢𝘯𝘥𝘪𝘥𝘢 spp. The minimum inhibitory concentrations (MICs) were determined using the agar dilution method. Antioxidant capacity was analysed using 1,1-diphenyl-2 picryl-hydrazyl (DPPH) free-radical scavenging assay, while toxicity was assessed using the brine shrimp lethality assay. A significant antimicrobial activity was observed with ultrasonicated ethanolic extracts (𝘱 < 0.05) over vacuum infiltrated extracts. The ultrasonicated extracts showed a higher mean inhibition for 𝘊𝘢𝘯𝘥𝘪𝘥𝘢 clinical isolates than vacuum infiltrated extracts (𝘱 = 9.24×10-5). The lowest MIC of 2.56 mg mL⁻¹ was observed against 𝘚. 𝘢𝘶𝘳𝘦𝘶𝘴. Aqueous extracts did not show antimicrobial activity. Antioxidant capacity was higher in ultrasonicated extracts (IC₅₀ = 45.53 mg mL⁻¹) over vacuum infiltrated extracts (IC₅₀ = 60.96 mg mL⁻¹), though the difference was not significant (𝘱 = 0.40). Ultrasonicated extracts showed significantly low toxicity (LC₅₀ of 9.20×10⁵ mg kg⁻¹), markedly lower than atropine, confirming its safe profile. Overall, ethanolic extracts of 𝘖. 𝘵𝘦𝘯𝘶𝘪𝘧𝘭𝘰𝘳𝘶𝘮 possess antimicrobial and antioxidant properties, and ultrasonication is a more effective extraction method than vacuum infiltration for isolating bioactive compounds.