Chemical Composition and In vitro Studies of the Essential Oil and Aqueous Extract of Pelargonium graveolens Growing in Jordan for Hypoglycaemic and Hypolipidemic Properties

Abstract

Aims: This study aimed to analyze the chemical composition of essential oil of Pelargonium graveolens L. Her. ex Ait. growing in Jordan and to test the efficacy of the leaves aqueous extract and essential oil against pancreatic triacylglycerol lipase (PL), α-amylase and α-glucosidase. Study Design: GC-MS analysis of the essential oil obtained by hydrodistillation and Solid Phase Microextraction (SPME) methods as well as in vitro enzymatic investigations. Place and Duration of Study: Faculty of Pharmacy, The University of Jordan, between November 2012 and August 2013. Results: The hydrodistilled oil of P. graveolens fresh leaves yielded twenty eight components, accounting for 95.83 % of the total oil content, while thirty seven components were detected from the fresh leaves by SPME (98.86%). Twenty six and thirty one components were identified in the hydrodistilled and SPME oils of the dried leaves amounting to 96.08 % and 97.83 %, respectively. Oxygenated monoterpenes predominated the volatile fractions of the leaves of both methods with citronellol, citronellyl formate and menthone/isomenthone as the major constituents.  Similar to orlistat (PL IC50 of 114.0 ± 4.0 ng/mL), P. graveolens extract and volatile oil  as well as their purified phyto-constituents inhibited highly substantially in a dose dependent trend PL in vitro (n=3). The P. graveolens extract PL- IC50 was 207.4±15.2 µg/mL. As for their volatile oils’ components, PL- IC50 (%) (V/V) in an ascending order were: menthone; 0.01±0.0 <geraniol; 0.34±0.02 < linalool; 0.7 ± 0.0 < caryophyllene; 1.17±0.12 <P. graveolens oil; 2.93 ± 0.27. Comparable to acarbose, P. graveolens leaves aqueous extracts (AEs) were identified as in vitro potent and efficacious dual inhibitors of α-amylase and α-glucosidase with IC50: 4.6±0.1 mg/mL  (p<0.001, n=3). Conclusion: Taken together, P. graveolens leaves, as a nutraceutical modulating gastrointestinal carbohydrate and lipid digestion and absorption, maybe advocated as candidate for obesity-diabetes/metabolic syndrome management.