Effect of Different Drying Treatments and Solvent Ratios on Phytochemical Constituents of <i>Ipomoea aquatica</i> and Correlation with α-Glucosidase Inhibitory Activity

<p><i>Ipomoea aquatica</i> is an aquatic plant that is widely consumed in Southeast Asia as a vegetable. In this study, the influence of various ethanol ratios (0, 20, 50, 80, and 100%) as an extraction solvent and different drying methods including air drying, sun drying, and oven drying on phytochemical constituents of <i>I. aquatica</i> was investigated using a proton nuclear magnetic resonance-based metabolomics approach. The effect on α-glucosidase inhibitory activity and total phenolic content was also examined. Clear discrimination was observed between different ethanol ratios and different drying processes by principal component analysis. The highest α-glucosidase inhibitory activity was observed for absolute ethanol extract from the oven drying method with IC₅₀ value of 204.0 ± 59.0 µg/mL and total phenolic content value of 22.0 ± 0.7 µg gallic acid equivalent/mg extract. Correlation between the α-glucosidase inhibitory activity and the metabolite were analyzed using a partial least square analysis. The metabolites that are responsible for the activity were quercetin derivatives, chlorogenic acid derivatives, sucrose, and fructose. This study highlights the basis for future investigations of <i>I. aquatica</i> as a source of food that has the potential for nutraceutical enhancement and as ingredient in medicinal preparation.</p

Protective effect of defatted CO extracts on depletion of NAD⁺ in H₂O₂-induced Chang liver cells.

<p>Values are expressed as % of control incubation (without H₂O₂). High, low, and IC₅₀ concentrations of defatted CO peel and pericarp (PP) extracts were tested. Cyanidin-3-glucoside (C3G–200 µg/ml) was for comparison. Similar lower case letters (a–d) show no significant differences between two different extracts or between extract and H₂O₂/C3G (p≥0.05).</p

TBARS values of LDL oxidation inhibition by defatted CO extracts.

<p>IC₅₀ concentrations of the defatted CO pericarp and pericarp (PP) extracts were applied. Cyanidin-3-glucoside (C3G, 10 µg/ml) was for comparison. Red blood cells were obtained from a pool of blood from both normal healthy fasting and obese fasting rats (n = 5 each). No significant difference was found for the TBARS values between normal and obese rats. Different lower case letters (a–c) show significant differences between two different extracts or between extract and control as well as C3G for either normal or obese rats (p<0.05).</p

Inhibition of CD36 binding to oxidized LDL by defatted CO extracts.

<p>Values are expressed as % of inhibition. High, low and IC₅₀ of concentration of defatted CO peel and pericarp (PP) extracts were tested. Cyanidin-3-glucoside (C3G–10 µg/ml) was for comparison. Similar lower case letters (a–c) show no significant differences between two different extracts or between extract and C3G (p≥0.05).</p

TBARS values of hemoglobin oxidation inhibition by defatted CO extracts.

<p>IC₅₀ concentrations of the defatted CO pericarp and pericarp (PP) extracts were applied. Cyanidin-3-glucoside (C3G, 10 µg/ml) was for comparison. Red blood cells were obtained from a pool of blood from both normal healthy fasting and obese fasting rats (n = 5 each). No significant difference was found for the TBARS values between normal and obese rats. Different lower case letters (a–c) show significant differences between two different extracts or between extract and control/C3G for either normal or obese rats (p<0.05).</p

Percentages of cell viability of Chang liver cells by defatted CO extracts.

<p>Chang liver cells were treated with different concentrations of defatted CO peel and pericarp (PP) extracts (A) and cyanidin-3-glucoside (B) for comparison. Different lower case letters (a, b) show a significant difference between peel and pericarp (PP) (p<0.05), while similar upper case letters (X–Z) show no significant difference between two different extract concentrations of C3G (p≥0.05).</p

Inhibition of LDL-binding to endothelial cells by defatted CO extracts.

<p>IC₅₀ concentrations of the defatted CO pericarp and pericarp (PP) extracts were used. Endothelial cells were treated with 80 µg/ml of LDL protein and incubated together with defatted CO peel and pericarp (PP) at IC₅₀ extract concentration. Different lower case letters (a, b) show significant differences between two different extracts or between extract and control (p<0.05).</p

Inhibition of <i>t</i>-BHP-induced cell death by defatted CO extracts.

<p>HUVEC (A) and Chang liver cell line (B) were treated with different concentrations of defatted CO peel and pericarp (PP) extracts. Different upper case letters (X–Y) show significant differences between the extract concentrations and <i>t</i>-BHP-induced control (p≥0.05), while similar lower case letter (a or b) of the same extract concentration shows no significant difference between the peel and pericarp (PP) (p≥0.05).</p

Prioritization of Natural Extracts by LC–MS-PCA for the Identification of New Photosensitizers for Photodynamic Therapy

Photodynamic therapy (PDT) is an alternative treatment for cancer that involves administration of a photosensitive drug or photosensitizer that localizes at the tumor tissue followed by in situ excitation at an appropriate wavelength of light. Tumour tissues are then killed by cytotoxic reactive oxygen species generated by the photosensitizer. Targeted excitation and photokilling of affected tissues is achieved through focal light irradiation, thereby minimizing systemic side effects to the normal healthy tissues. Currently, there are only a small number of photosensitizers that are in the clinic and many of these share the same structural core based on cyclic tetrapyrroles. This paper describes how metabolic tools are utilized to prioritize natural extracts to search for structurally new photosensitizers from Malaysian biodiversity. As proof of concept, we analyzed 278 photocytotoxic extracts using a hyphenated technique of liquid chromatography–mass spectrometry coupled with principal component analysis (LC–MS-PCA) and prioritized 27 extracts that potentially contained new photosensitizers for chemical dereplication using an in-house UPLC-PDA-MS-Photocytotoxic assay platform. This led to the identification of 2 new photosensitizers with cyclic tetrapyrrolic structures, thereby demonstrating the feasibility of the metabolic approach