Lichenochemical analysis, cytotoxic, antimicrbial, antioxidant and cytotoxic activities of different extracts of the lichen Cladonia coniocraea

This study investigates the chemical composition and potential biological activity of the fruticose lichen Cladonia coniocraea , commonly referred to as the common powderhorn or powderhorn cup lichen. Different solvents with varying polarity, such as n-hexane, chloroform, methanol, and water, were used to prepare various extracts of C. coniocraea . The total phenolic and total flavonoid contents were measured. Results showed that the methanol extract exhibited greater values of total phenolic content (TPC) at 129.95 mg gallic acid equivalents per gram (mg GA/g) and total flavonoid content (TFC) at 44.94 mg rutin equivalents per gram (mg RE/g) or 19.05 mg quercetin equivalents per gram (mg QE/g), regardless of whether quercetin or rutin was employed as the standard. An examination of lichenochemicals was performed using liquid chromatography-mass spectrometry (LC-MS). During the analysis of the tested extracts, 17 compounds were identified. Among the analyzed samples, the methanol extract exhibited significant efficacy in eliminating ABTS radicals (IC ₅₀  = 62.66 µg/mL) and moderate efficacy in eliminating DPPH radicals (IC ₅₀  = 305.12 µg/mL). The findings demonstrated notable antioxidant capacity, especially in the methanol extract, which displayed a strong ability to scavenge radicals and reduce oxidative stress. The findings of the antibacterial study reveal that all solvents demonstrate antibacterial properties against both E. coli and B. subtilis . Methanol, in particular, exhibits the most potent antibacterial effect, with the lowest MIC values of 0.58 µg/mL and 0.63 µg/mL against E.coli and B. subtilis , respectively. This suggests that the methanol is more effective in combating these bacterial strains. The chloroform extracts exhibited greater inhibition zones, specifically measuring 27.04 mm for F. solani , 21.29 mm for F. graminearum , and 18.56 mm for F. culmorum , compared to the methanol extracts. This indicates a stronger antifungal effectiveness of the chloroform extracts. To assess the efficacy of the extracts in inhibiting tumor growth, the cytotoxic properties of the extracts were examined on a range of human cancer cell lines, such as MCF-7 (breast cancer) and A549 (lung cancer) cells, using the cytotoxic assay. The n-hexane had the most pronounced cytotoxicity, as shown by the lowest IC ₅₀ values, followed by the chloroform, methanol, and water extracts. Specifically, the MCF-7 and A549 cell lines displayed IC ₅₀ values of 7.98 ± 0.16 and 9.29 ± 0.14 (µg/mL), respectively. Additional mechanistic investigations demonstrated that the n-hexane extract triggered apoptosis in cancer cells, as confirmed by the heightened expression of pro-apoptotic markers and the initiation of caspase pathways. The results indicate that C. coniocraea possesses bioactive substances with notable antioxidant, antibacterial, and anticancer characteristics. The results emphasize the potential of C. coniocraea as a valuable source of natural antioxidants and anticancer agents. This warrants further research to investigate its active components and their mechanisms of action.