Biomolecules of Algerian propolis

Abstract

This study aimed to investigate the chemical composition and the biological properties of propolis collected from different regions of Algeria. The total bioactive content, antioxidant, antienzymatic, antimicrobial, toxicity and anticancer effects were evaluated. The chemical composition of propolis extracts and essential oils (EOs) was also analyzed. The results demonstrated the richness of propolis extracts in phenolic and flavonoid compounds. Antioxidant tests (DPPH, ABTS, alkaline DMSO, CUPRAC, ferric reducing power and β-carotene-linoleic acid tests) revealed the strong radical scavenging, ion reducing and lipid peroxidation inhibition abilities of the extracts, whereas EOs were the least active. Anti-enzymatic assays against acetylcholinesterase (AChE), butyrylcholinesterase (BChE) and -glucosidase showed that all propolis extracts possessed a potent inhibitory effect on α-glucosidase better than acarbose and revealed the ability of extracts to inhibit BChE more effectively than AChE. However, the tested oil was more effective on AChE than BChE. The antimicrobial assay indicated that all extracts were mainly active against Gram-positive bacteria and yeast. The inhibition of bacterial growth by propolis extracts and EOs was found to be through bactericidal or bacteriostatic mechanism, whereas the inhibition of yeast growth was through fungicidal or fungistatic mode. The toxicity test against brine shrimp larvae indicated that propolis extracts possess moderate toxic properties. In addition, anticancer effect of propolis extracts on HepG2 human hepatocellular carcinoma cells (HepG2) determined using CCK-8 assay revealed the strong cytotoxic activity of the extracts against HepG2 with IC50 values ranged from 12.22±0.05 to 60.39±1.82 µg/mL. The GC-MS analysis of three EOs allowed the identification of a total of 112 compounds, in which α-pinene, limonene, trans-pinocarveol, α-terpinenyl acetate and δ-Cadinene were common between the three oils. The LC-MS/MS analysis of propolis extracts that showed potent anticancer effect revealed the richness of these extracts in phenolic acids such as caffeic and ferulic acids, and flavonoids such as kaempferol, apigenin and quercetin. These findings indicate the importance of Algerian propolis as a source of bioactive principles for the development of pharmaceutical products.