Chemical compositions, antioxidant potentials and enzyme inhibitory activities of essential oil and solvent extracts of Anchomane difformis (Blume) Engl. leaf

Abstract

Leaves of Anchomane difformis, an herbaceous medicinal plant commonly used in west tropical Africa for treatment of diabetes were collected, extracted with aqueous methanol to give crude methanol extract which was fractionated with nhexane. Also, the volatile oil of the leaf was extracted by hydro-distillation method. The fractionated extracts, derivatised by silylation, and the volatile oil were separately analysed using GC-MS. The total phenolic content (TPC), total flavonoid content (TFC) and total antioxidant capacity (TAC) of each extract were estimated using standard procedures. Also, ferric reducing antioxidant power (FRAP) and DPPH radical scavenging assays were used to evaluate the antioxidant potential of the extracts while the enzyme inhibitory activities were determined using alpha glucosidase and porcine pancreatic lipase enzymes. Phytol was found to be predominant in all the extracts at 42.69%, 11.13% and 5.78% for the n-hexane, defatted and volatile oil extracts respectively. Fatty acid derivatives were the major components of the extract fractions while 1-octen-3-ol (19.02%), α-ionone (5.95%), 1,3-di-n-propy ladamantane (5.08%) 3,5.5-trimethyl hex-2-ene (5.01%), hexahydrofarnesyl acetone (4.46%) and trans-geranylacetone (4.24%) were the principal constituents of the volatile oil. The crude had highest TFC (46.43 ± 5.34 mg QuE/g), TAC (81.35 ± 9.61 mg AAE/g) and FRAP (40.36 ± 5.01 mg AAE/g) while the volatile oil scavenged DPPH free radical better than other extracts. All the extracts inhibited alpha glucosidase enzyme and none showed inhibition porcine pancreatic lipase enzymes.