Antiobesity and antihyperglycaemic effects of Adiantum capillus-veneris extracts: in vitro and in vivo evaluations

Abstract

Context: Adiantum capillus-veneris L. (Adiantaceae) hypocholesterolemic activity is therapeutically praised.

Objectives: Pharmacological modulation of pancreatic triacylglycerol lipase (PL) and α-amylase/α-glucosidase by A. capillus-veneris are evaluated.

Materials and methods: Using positive controls (acarbose, orlistat, guar gum, atorvastatin, glipizide and metformin) as appropriate, crude aqueous extracts (AEs) of A. capillus-veneris aerial parts were tested via a combination of in vitro enzymatic (0.24–100 mg/mL), acute in vivo carbohydrate tolerance tests (125, 250 or 500 mg/kg body weight [b.wt]) and chronic in vivo studies (500 mg/kg b.wt) in high cholesterol diet (HCD) fed Wistar rats.

Results: Like acarbose, A. capillus-veneris as well as chlorogenic acid, with respective IC₅₀ values (mg/mL) of 0.8 ± 0.0 and 0.2 ± 0.0, were identified as in vitro potent dual inhibitors of α-amylase/α-glucosidase. Unlike guar gum, A. capillus-veneris had no glucose diffusion hindrance capacity. Equivalent to orlistat, A. capillus-veneris and its phytoconstituents inhibited PL in vitro with an ascending order of PL- IC₅₀ values (μg/mL): ferulic acid; 0.48 ± 0.06 < ellagic acid; 13.53 ± 1.83 < chlorogenic acid; 38.4 ± 2.8 < A. capillus-veneris; 1600 ± 100. Incomparable to acarbose or metformin and glipizide, A. capillus-veneris (125, 250 and 500 mg/kg b.wt) lacked antihyperglycaemic efficacies in acute starch- or glucose-evoked postprandial hyperglycaemia increments in normoglycaemic overnight fasting rats. Superior to atorvastatin; A. capillus-veneris exerted significant antiobesity (p < 0.001) with marked triacylglycerol-reducing capacities (p < 0.001) in comparison to rats fed with HCD for 10 weeks.

Discussion and conclusion: A. capillus-veneris, modulating pancreatic digestive enzymes, may be advocated as a combinatorial diabesity prevention/phytotherapy agent.

Keywords:

• Adiantaceae
• pancreatic lipase and amylase
• high cholesterol diet
• phenolics

Acknowledgements

Professor Yusuf Al-Hiari, The University of Jordan is gratefully thanked for the kind gift of ferulic acid. The technical assistance of Dana AlQudah, Esra Fodah, Haneen Ramadan and Hazar Shawash is acknowledged.

Disclosure statement

The authors declare that they have no conflict of interest concerning this article.

Funding

We are grateful for the Scientific Research Fund, Ministry of Higher Education [grant No. MPH/1/05/2014] and the Deanship of Academic Research, The University of Jordan [grant No. 1347, 1348] for funding this work.