Evaluation of the inhibition of carbohydrate hydrolysing enzymes, antioxidant activity and polyphenolic content of extracts of ten African Ficus species (Moraceae) used traditionally to treat diabetes

Abstract

BackgroundSome Ficus species have been used in traditional African medicine in the treatment of diabetes. The antidiabetic potential of certain species has been confirmed in vivo but the mechanism of activity remains uncertain. The aim of this study was to determine the activity and to investigate the mechanism of antidiabetic activity of ten selected Ficus species through inhibition of α-amylase and α-glucosidase activity, and the possible relationship between these activities, the total polyphenolic content and the antioxidant activity.MethodsDried acetone leaf extracts were reconstituted with appropriate solvents and used to determine total polyphenolic content antioxidant activity, α-amylase and α-glucosidase inhibitory activity.ResultsThe crude acetone extract of F. lutea had the highest polyphenolic content (56.85 ± 1.82 mg GAE/g of dry material) and the strongest antioxidant activity with a TEAC value of 4.80 ± 0.90. The antioxidant activity of the acetone extracts of the Ficus species may not be ascribed to total polyphenolic content alone. The crude extract at a concentration of 0.5 mg/ml of F. lutea (64.3 ± 3.6%) had the best α-glucosidase (sucrase) inhibitory activity. The EC50 of F. lutea (290 ± 111 μg/ml) was not significantly different from that of F. sycomorus (217 ± 69 μg/ml). The α-amylase inhibitory activity of F. lutea (95.4 ± 1.2%) at a concentration of 1 mg/ml was the highest among the Ficus species screened. The EC50 for F. lutea (9.42 ± 2.01 μ g/ml), though the highest, was not significantly different (p < 0.05) from that of F. craterostoma and F. natalensis. It was apparent that the crude acetone extract of F. lutea is a partially non-competitive inhibitor of α-amylase and α-glucosidase. Based on correlation coefficients polyphenolics may be responsible for α-glucosidase activity but probably not for α-amylase activity.ConclusionAntidiabetic activity potential via inhibition of α-amylase and α-glucosidase was discovered in Ficus lutea which has not been previously reported. The acetone extract of the leaves was high in total polyphenolic content and antioxidant activity, and was a potent inhibitor of α-amylase activity. Research is underway to isolate the active compound(s) responsible for the antidiabetic activity and to confirm the in vitro antidiabetic activity and to investigate in vitro toxicity.

Anti-proliferative effect of Ficus pumila Linn. on human leukemic cell lines

“…This is comparable to previous work done, 12 which revealed that the TPC in acetone extract of Ficus capreifolia and Ficus coralata were 4.73 and 8.23 mg GAE/g dry weight, respectively. The differences in the TPC could be due to the type of solvent used in the extraction and the specie variety.…”

Phytochemical Screening, Antioxidant, Anti-inflammatory, and Glucose Utilization Activities of Three South African Plants Used Traditionally to Treat Diseases

“…some authors found correlation between the polyphenol content and antioxidant activity, others found no relationship. However, studies have shown that high polyphenol content does not always translate to high antioxidant activity [38]. Moreover, the antioxidant efficiency of the polyphenol depends, in part, on the position and extent of hydroxylation and conjugation [39].…”

Antifungal activity and brine shrimp toxicity assessment of <i>Bulbine abyssinica</i> used in the folk medicine in the Eastern Cape Province, South Africa

“…Acetone was also selected as an extractant because it dissolves both hydrophilic and lipophilic components from plants. Acetone is also volatile and has low toxicity for use in microbial bioassays (Olaokun et al, 2013).…”

“…The essential oil and water extraction was selected on the basis that the traditional practitioners prepare this herbal medicine as a decoction (Olaokun et al, 2013). Acetone was also selected as an extractant because it dissolves both hydrophilic and lipophilic components from plants.…”