Non-destructive, reverse iontophoretic extraction of phytochemicals from Mangifera indica, Centella asiatica, Punica granatum, and Citrus sinensis

For the commercial-scale isolation of phytochemicals, a suitable plant biomass source (including species, origin, growing season, etc.) must be identified, and frequent analytical verification is required to ensure that the phytochemicals are present at predefined minimum threshold concentrations. While the latter are typically assessed in the laboratory, a more efficient and less resource-intensive approach would involve non-destructive and environmentally friendly measurements in situ. Reverse iontophoretic (RI) sampling offers a potential solution to this challenge.

OBJECTIVE

We aimed to demonstrate the non-destructive, RI sampling of phytochemicals of interest from biomass from four different sources.

MATERIALS AND METHODS

RI experiments were performed in side-by-side diffusion cells using a current density of 0.5 mA/cm² , for a predetermined time in a defined pH environment, using (1) fresh leaves from Mangifera indica and Centella asiatica and (2) isolated peel from Punica granatum and Citrus sinensis.

RESULTS

Mangiferin, madecassoside, punicalagin, ellagic acid, and hesperidin were extracted from the different biomasses by RI. The amounts extracted ranged from 0.03 mg/100 mg of biomass for the cathodal extraction of madecassoside to 0.63 mg/100 mg of biomass for the anodal extraction of punicalagin. A linear relationship (r²  = 0.73) between the RI-extracted quantities of punicalagin and those determined using conventional methods was demonstrated.

CONCLUSION

The non-destructive, in situ measurement of phytochemical levels by RI represents a feasible approach for timing the harvesting process.

Comprehensive characterization of naturally occurring antioxidants from the twigs of mulberry (Morus alba) using on-line high-performance liquid chromatography coupled with chemical detection and high-resolution mass spectrometry

INTRODUCTION

The mulberry tree (Morus alba L.) is a prolific source of biologically active compounds. There is considerable growing interest in probing M. alba twigs as a source of disruptive antioxidant lead candidates for cosmetic skin care product development.

OBJECTIVE

An integrated approach using high-performance liquid chromatography (HPLC) coupled with either chemical detection (CD) or high-resolution mass spectrometry (HRMS) was applied to the hydroalcoholic extract of M. alba to detect and identify lead antioxidant compounds, respectively.

MATERIAL AND METHODS

The twigs were weighed, powdered and homogenized using a mill and the extract was prepared using 70% aqueous ethanol. The antioxidant metabolites were detected with HPLC coupled with CD (based on the ORAC assay) and their structural identification was carried out using a Q-Exactive Orbitrap MS instrument.

RESULTS

Using this approach, 13 peaks were detected as overall contributors to the antioxidant activity of M. alba, i.e. mulberrosides (A & E), oxyresveratrol & its derivatives, moracin & its derivatives and a dihydroxy-octadecadienoic acid, which together accounted for >90% of the antioxidant activity, highlighting the effectiveness of the integrated approach based on HPLC-CD and HPLC-HRMS. Additionally, a (3,4-dimethoxyphenyl-1-O-β-D-apiofuranosyl-(1″ → 6')-O-β-D-glucopyranoside was also discovered for the first time from the twig extract and is presented here.

CONCLUSION

To our knowledge, this is the first report from M. alba twigs using HPLC-CD and HPLC-HRMS that identifies key compounds responsible for the antioxidant property of this native Chinese medicinal plant.