Polyphenolic Composition and Antioxidant Activity of Aqueous and Ethanolic Extracts from Uncaria tomentosa Bark and Leaves

Abstract

Uncaria tomentosa constitutes an important source of secondary metabolites with diverse biological activities mainly attributed until recently to alkaloids and triterpenes. We have previously reported for the first-time the polyphenolic profile of extracts from U. tomentosa, using a multi-step process involving organic solvents, as well as their antioxidant capacity, antimicrobial activity on aerial bacteria, and cytotoxicity on cancer cell lines. These promising results prompted the present study using food grade solvents suitable for the elaboration of commercial extracts. We report a detailed study on the polyphenolic composition of aqueous and ethanolic extracts of U. tomentosa bark and leaves (n = 16), using High Performance Liquid Chromatography coupled with Mass Spectrometry (HPLC-DAD/TQ-ESI-MS). A total of 32 compounds were identified, including hydroxybenzoic and hydroxycinnamic acids, flavan-3-ols monomers, procyanidin dimers and trimers, flavalignans–cinchonains and propelargonidin dimers. Our findings showed that the leaves were the richest source of total phenolics and proanthocyanidins, in particular propelargonidin dimers. Two-way Analysis of Variance (ANOVA) indicated that the contents of procyanidin and propelargonidin dimers were significantly different (p < 0.05) in function of the plant part, and leaves extracts showed higher contents. Oxygen Radical Absorbance Capacity (ORAC) and 2,2-diphenyl-1-picrylhidrazyl (DPPH) values indicated higher antioxidant capacity for the leaves (p < 0.05). Further, correlation between both methods and procyanidin dimers was found, particularly between ORAC and propelargonidin dimers. Finally, Principal Component Analysis (PCA) analysis results clearly indicated that the leaves are the richest plant part in proanthocyanidins and a very homogenous material, regardless of their origin. Therefore, our findings revealed that both ethanol and water extraction processes are adequate for the elaboration of potential commercial extracts from U. tomentosa leaves rich in proanthocyanidins and exhibiting high antioxidant activity.

In Vitro Antioxidant, Antityrosinase, and Cytotoxic Activities of Astaxanthin from Shrimp Waste

“…The radical scavenging activity of astaxanthin was evaluated using a modified 2, 2-diphenyl-1-picryl-hydrazyl (DPPH) radical scavenging assay following previous report [17]. One hundred microliters of the DPPH solution in methanol was added to 100 µL of various concentrations of the astaxanthin in methanol (3–50 µg/mL), then shaken vigorously and allowed to stand in the dark at room temperature for 30 min.…”

Extraction, separation, and evaluation of antioxidant effect of the different fractions of polyphenols from cocoa beans

“…Non-conventional technologies are microwave-assisted extraction, supercritical fluids, and ultrasonic waves [16,17]. In general, most of these studies aimed at finding the best conditions to obtain the highest extraction yield as well as identifying GRAS degree solvents that soon would expand the use of polyphenol extracts in food, cosmetics, or pharmaceutical applications [18].…”

“…Solid-liquid extraction of polyphenols was done using the methodology proposed by various authors [18,19] with some modifications. The milled cocoa beans obtained were mixed with an ethanol:water solution (1:1 v/v) using a mass:solvent ratio of 1:120 (w:v).…”

“…The TPC was determined following the procedure described by various authors [3,10,14,18]. In sum, 50 μL of polyphenol extract were mixed with 1.5 mL of Folin-Ciocalteu phenol reagent (10% v/v) and incubated for 5 min in darkness.…”

Pharmacokinetics of isocorynoxeine in rat plasma after intraperitoneal administration by UPLC–MS/MS

“…It is widely distributed in the southern provinces of China [4,5]. It is used in traditional Chinese medicine for headache, dizziness, cold, convulsions, convulsions, and pregnancy [6][7][8][9][10], as well as in treatment of conditions such as eclampsia and hypertension. Alkaloids are the main medicinal ingredients of U. rhynchophylla, and the changes and distribution characteristics of medicinal ingredients in the body are closely related to their pharmacological effects [11][12][13][14][15].…”