Comparison of Soxhlet, accelerated solvent and supercritical fluid extraction techniques for volatile (GC-MS and GC/FID) and phenolic compounds (HPLC-ESI/MS/MS) from Lamiaceae species

INTRODUCTION

Plants from the Lamiaceae family have been known traditionally for their beneficial health-promoting properties, attributed to their anti-inflammatory, anaesthetic and anti-microbial effects.

OBJECTIVE

The purposes of this study was to characterise the essential oils from four Lamiaceae plants by applying different extraction techniques.

METHODS

Accelerated solvent (ASE), Soxhlet and supercritical fluid (SFE) extraction methods were compared for their efficiency in obtaining the essential oils from plants. The volatile compounds were identified by GC-MS and the main chemotype was quantified by GC with flame ionisation detection (FID). Phenolic compounds were identified and quantified by HPLC and electrospray ionisation (ESI) with MS/MS.

RESULTS

The essential oils Mentha piperita (ct. menthol/menthone), Rosmarinus officinalis L. (ct. eucalyptol/camphor) and Origanum vulgare (ct. carvacrol/thymol), whereas Thymus vulgaris L. was found to be a pure chemotype (ct. thymol). All three extracts also contained six phenolic compounds. The highest extraction yields were achieved by the Soxhlet and ASE techniques, with M. piperita and R. officinalis L. producing the highest concentrations of rosmarinic and carnosic acids. Finally, it was observed that M. piperita and O. vulgare produced the highest total phenolic content, whereas R. officinalis L. and T. vulgaris L. produced the highest anti-oxidant activity.

CONCLUSION

The ASE and Soxhlet extraction techniques presented the highest yields of volatile and phenolic compounds, showing their suitability to characterise the chemical profile of aromatic plants.

Polyphenol content and antioxidant activity of California almonds depend on cultivar and harvest year

The polyphenol content and antioxidant activity of Nonpareil, Carmel, Butte, Sonora, Fritz, Mission, and Monterey almond cultivars harvested over three seasons in California were examined. LC-MS was employed to quantify 16 flavonoids and two phenolic acids in acidified methanol extracts of almond skins. The 3-year mean polyphenol content of cultivars ranged from 4.0 to 10.7 mg/100 g almonds. Isorhamnetin-3-O-rutinoside was the most abundant flavonoid, present at 28-49% of total polyphenols among cultivars. Almonds from 2006 and 2007 had 13% fewer polyphenols than 2005, but FRAP and total phenols were comparable. Cultivar, but not season, had a differential impact on individual polyphenol synthesis. Using the results of polyphenol, total phenol, and FRAP, multivariate analysis distinguished harvest years and most cultivars with 80% confidence. Flavonoid content and antioxidant activity of almonds may be more dependent on cultivar than on seasonal differences.

Phytochemical studies and antioxidant properties of four medicinal plants used in Cameroon

Four plants (Amphimas pterocaroides, Harungana madagascariensis, Myrianthus arboreus, and Cussonia barteri) that are commonly used in Cameroon for the management or reversal of anaemia were screened for their phytochemical content and antioxidant potential. Four extracts (methanolic, hydro-ethanolic, aqueous, and hydrolysed) from each of the plants were prepared and analysed. Qualitative phytochemical tests were used to detect the presence of alkaloids, tannins, saponins, flavonoids, glycosides and phenols, while three quantitative methods; Folin, Ferric Reducing Antioxidant Power (FRAP) and diphenyl-1, 2-picryl hydrazyl (DPPH) were used to determine the antioxidant potential of these extracts. With the exception of the extracts of Cussonia barteri (negative for triterpenes and phenols) and the aqueous extract of Harungana madagascariensis (negative result for cardiac glycosides and glycosides), all other extracts contained the phytochemicals tested. The highest antioxidant activities were observed in the hydrolysed extracts of each plant, while the aqueous extract showed the least activity irrespective of the method used. The presence of active phytochemical substances with antioxidant activities may provide substantial basis for the use of these plants in ethnomedicine.