The Effect of Temperature on Pressurised Hot Water Extraction of Pharmacologically Important Metabolites as Analysed by UPLC‐qTOF‐MS and PCA

Abstract

Metabolite extraction methods have been shown to be a critical consideration for pharmacometabolomics studies and, as such, optimization and development of new extraction methods are crucial. In the current study, an organic solvent-free method, namely, pressurised hot water extraction (PHWE), was used to extract pharmacologically important metabolites from dried Moringa oleifera leaves. Here, the temperature of the extraction solvent (pure water) was altered while keeping other factors constant using a homemade PHWE system. Samples extracted at different temperatures (50, 100, and 150°C) were assayed for antioxidant activities and the effect of the temperature on the extraction process was evaluated. The samples were further analysed by mass spectrometry to elucidate their metabolite compositions. Principal component analysis (PCA) evaluation of the UPLC-MS data showed distinctive differential metabolite patterns. Here, temperature changes during PHWE were shown to affect the levels of metabolites with known pharmacological activities, such as chlorogenic acids and flavonoids. Our overall findings suggest that, if not well optimised, the extraction temperature could compromise the “pharmacological potency” of the extracts. The use of MS in combination with PCA was furthermore shown to be an excellent approach to evaluate the quality and content of pharmacologically important extracts.

Optimization of Pressurized Hot Water Extraction of Flavonoids from Momordica foetida Using UHPLC-qTOF-MS and Multivariate Chemometric Approaches

“…For maximum data output, the analysis was carried out using previously optimized parameters (Khoza et al 2014). Briefly, the following parameters were chosen: retention time (Rt) of 1-30 min, mass range of 100-1000 Da, mass tolerance of 0.02 Da, and Rt window of 0.2 min.…”

“…As such, to reveal the underlying differences of the metabolite profiles obtained at different temperatures, PCA models were computed. Previously, PCA was used to reveal the extraction efficiency of pharmacologically relevant metabolites by PHWE in M. oleifera (Khoza et al 2014). In a separate study, Liu et al (2013) used PCA to authenticate (by characterization) quality control concepts of ubiquitous functional foods, by means of PHW extracted metabolites analyzed by HPLC with UV spectroscopy detection.…”

“…We have previously shown that pressurized hot water extraction (PHWE) is a feasible method for the extraction of pharmacologically relevant metabolites such as flavonoids from Moringa oleifera (Khoza et al 2014). Flavonoids are predominantly found in the plant kingdom as secondary metabolites derived from the phenylpropanoid pathway (Patel 2010).…”

“…The physico-chemical changes are due to the fact that at higher temperature and pressure, the dielectric constant of water (thus the polarity) drops significantly closer to that of common alcohols (Teo et al 2010;Penttilä et al 2013). For maximum metabolite extraction, several factors of the PHWE method need to be optimized, the most important factor being the temperature control (Mazaheri et al 2010;Khoza et al 2014;Matshediso et al 2015).…”

Metal Analysis, Phytochemical and Antibacterial Investigation of Crinum Macowanii Bulb

“…BTNST01) is available at the UJ herbarium. The plant was subsequently extracted using solvents according to the method described by [9] and Pressurized Hot Water Extraction (PHWE) according to [10].…”