New mono-ether of glycerol and triterpenes with DPPH radical scavenging activity from Cameroonian propolis

Abstract

The extracts of some propolis samples were analysed by GC-MS and then purified by column chromatography. The latter led to the isolation of a new mono-ether of glycerol, 1′-O-eicosanyl glycerol and a new triterpene, methyl-3β,27-dihydroxycycloart-24-en-26-oate together with known triterpenoids namely betulin, 3β-hydroxylanostan-9,24-dien-21-oic acid, mangiferonic acid, a mixture of ambolic acid and β-sitosterol, 3β-hydroxycycloartan-12,24(25)-diene and 27-hydroxymangiferonic acid. The DPPH radical scavenging potential of some extracts and compounds were measured. The radical scavenging activity varied from Hexane extract of Foumban propolis (IC₅₀ = 5.6 mg/mL) to Methanol extract of Foumban propolis (IC₅₀ = 1.07 mg/mL) for the extracts and from 3β-hydroxylanostan-9,24-dien-21-oic acid (IC₅₀ = 1.22 mg/mL) to 1′-O-eicosanyl glycerol (IC₅₀ = 0.93 mg/mL) for the compounds. Activities of samples were moderate as they remained closer to those of the standard antioxidants Gallic acid (IC₅₀ = 0.30 mg/mL) and vitamin C (IC₅₀ = 0.80 mg/mL), especially 1′-O-eicosanyl glycerol, the most active compound.

Keywords:

• Propolis
• GC-MS profiles
• NMR analysis
• triterpenes
• 1′-O-eicosanyl glycerol
• DPPH^· radical scavenging activity