Chemical Composition and Enzymes Inhibitory, Brine Shrimp Larvae Toxicity, Antimicrobial and Antioxidant Activities of Caloplaca biatorina

Background This study evaluated the brine shrimp larvae toxicity and enzymes inhibitory especially anti-diabetic potential of Caloplaca biatorina via in vitro inhibition of α-amylase and α-glucosidase using the methanol extracts. Also aldehyde oxidase and xanthine oxidase enzymes inhibitory, cytotoxicity, and antioxidant activities of the species were determined. Methods In this experimental study, different concentrations of the extracts (0.2, 5.0, 1 and 1.5 mg/mL) were incubated with enzyme substrate solution and the percentage of enzyme inhibitory activity and IC₅₀ was calculated. Folin- Ciocalteu reagent and aluminium chloride colorimetric methods were used to estimate total phenolic and flavonoid content of extracts. The toxicity of the extract was assessed using the brine shrimp lethality bioassay. The minimal inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined. High-performance liquid chromatography and Thin-layer chromatography analysis were evaluated. The data were analyzed by SPSS V.21 software. Results Parietin, Emodin, 1,8-Dihydroxy-3-(hydroxymethyl)-6- methoxy-9.10-anthracenedione and Rhein were identified. The extract showed strong α-glucosidase, aldehyde oxidase and xanthine oxidase inhibitory activities with IC₅₀ value of 17.12, 40.09 and 11.02 µg/mL respectively. Also methanol extract displayed the strongest DPPH radical scavenging and brine shrimp toxicity (IC₅₀ = 91.11) properties. Conclusions The result obtained suggests that the C. biatorina extract can be classified as non-toxic. Also, it revealed the antioxidant and antidiabetic potential of the lichen.