In vitro assessment of antioxidant, antimicrobial, cytotoxic, anti-inflammatory, and antidiabetic activities of Campanula retrorsa crude extracts

Abstract

Background: Campanula retrorsa belongs to the Campanulaceae family and the Campanula genus. The species of this latter are traditionally known for their antiallergic, spasmolytic, antiphlogistic, antioxidant, and antiviral properties. Few studies were realized on the bioactivity of Calicotome villosa crude extracts. Objective: The objective was to investigate, for the first time, the antioxidant, antimicrobial, cytotoxic, antidiabetic, and anti-inflammatory potentials of dichloromethane, methanol, and aqueous crude extracts of C. retrorsa leaves, flowers, and stems. Materials and Methods: The antioxidant activity of different crude extracts was determined using the free radical, 1, 1-diphenyl-2-picrylhydrazyl. Antimicrobial activity against three Gram-positive (Staphylococcus aureus, Bacillus cereus, and Enterococcus faecium), two Gram-negative (Escherichia coli, Pseudomonas aeruginosa, and Acinetobacter baumanii) bacterial strains and a fungal strain (Candida albicans) was evaluated in a plate-hole diffusion assay. Cytotoxic activity of C. retrorsa dichloromethane and methanol crude extracts on Hela cells was realized using the Trypan blue dye exclusion technique. Antidiabetic activity against α-glucosidase and anti-inflammatory activity against bee venom phospholipase A2 (PLA2) were assessed using a colorimetric test. Results: Leaf and flower aqueous extracts possessed very high radical scavenging activity = 90%. The dichloromethane extracts of leaves and flowers were the most active against A. baumanii and C. albicans. After 48 h of treatment, all extracts except the methanol flower extract showed an inhibition of 90% of cell growth at 2 mg/mL. Dichloromethane and methanol stem crude extracts showed a modest inhibition of α-glucosidase. While no inhibition of the PLA2 was displayed by any of the tested extracts. Conclusion: Obtained results give an overall view on C. retrorsa crude extracts' bioactivities. Abbreviations Used: PLA2: Phospholipase A2; DPPH: 2, 2-Diphenyl-1-picrylhydrazy; CFU: Colony-forming unit; DMSO: Dimethyl sulfoxide; IZ: Inhibition zone; DMEM: Dulbecco Modified Eagle Medium; NaCl: Sodium Chloride; NaOH: Sodium Hydroxide; U: Enzyme Unit; CMUL: Microbiological Collection of the Lebanese University; ATCC: American Type Culture Collection; EC: Enzyme Commission number; CH2Cl2: Dichloromethane; CH3OH: Methanol; H2O: Water.