Vilcacora (Uncaria Tomentosa, Cat’s Claw)
Polyphenolic Composition and Antioxidant Activity of Aqueous and Ethanolic Extracts from Uncaria tomentosa Bark and Leaves
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.
This paper describes successful methods to obtain enriched polyphenolic extracts of U. tomentosa bark and leaves with solvents adequate for human consumption. Using advanced analytical techniques such as UPLC-DAD/TQ-ESI-MS, results showed selective distribution of 32 non-flavonoid and flavonoid phenolics among the different samples, proanthocyanidins being predominant in leaves, independently of their origin or solvent used. Among proanthocyanidins, propelargonidin dimers are characteristic marker compounds in leaves, showing significant correlation with ORAC and DPPH antioxidant activity. PCA analysis also revealed that the phenolic composition of the leaves tends to be less variable than that of barks, also suggesting that leaves constitute a more homogenous material for extraction procedures like the ones used in this study. While most of products already commercialized are pulverized bark material, our results suggest that leaves constitute the part of U. tomentosa more suitable for use in the elaboration of standardize phenolic extracts with potential applications in the nutraceutical industry.
Phenolic Assessment of Uncaria tomentosa L. (Cat’s Claw): Leaves, Stem, Bark and Wood Extracts
The phenolic composition of extracts from Uncaria tomentosa L. from different regions of Costa Rica was studied using advanced analytical techniques such as UPLC/TQ-ESI-MS and 13C-NMR. Samples from leaves, stems, bark and wood (n = 22) were subjected to extraction to obtain phenolic and alkaloid extracts, separately. Comparatively, higher values of total phenolic content were observed for leaves, stems and bark (225–494 gallic acid equivalents/g) than for wood extracts (40–167 gallic acid equivalents/g). A total of 32 non-flavonoid and flavonoid compounds were identified in the phenolic extracts: hydroxybenzoic acids (benzoic, salicylic, 4-hydroxybenzoic, prochatechuic, gallic, syringic and vanillic acids), hydroxycinnamic acids (p-coumaric, caffeic, ferulic and isoferulic acids), flavan-3-ols monomers [(+)-catechin and (−)-epicatechin)], procyanidin dimers (B1, B2, B3, B4, B5, B7 and two other of unknown structure) and trimers (C1, T2 and one of unknown structure), flavalignans (four unknown structures pertaining to the cinchonain family) and propelargonidin dimers (four unknown structures, reported for the first time in U. tomentosa). Additionally, alkaloid extracts obtained from the plant residue after phenolic extraction exhibited a content of tetracyclic and pentacyclic alkaloids ranging between 95 and 275 mg/100 g of dry material for bark extracts, and between 30 and 704 mg/100 g for leaves extracts. In addition, a minor alkaloid was isolated and characterized, namely 18,19-dehydrocorynoxinoic acid. Our results confirmed the feasibility of U. tomentosa as a suitable raw material for obtaining phenolic- and alkaloid-rich extracts of potential interest.
This paper reports valuable information about the phenolic and alkaloid composition of the plant U. tomentosa. Using advanced analytical techniques such as UPLC/TQ-ESI-MS and 13C-NMR, a total of 32 phenolic compounds have been identified, including hydroxybenzoic acids, hydroxycinnamic acids, flavan-3-ols monomers, procyanidin dimers and trimers, flavalignans, and propelargonidin dimers; these later were reported for the first time in U. tomentosa. Concerning alkaloids, eight main previously-reported tetracyclic and pentacyclic alkaloids were quantified in the extract, as well as the detection of other minor ones. For both phenolic and alkaloid extracts, the part of the plant used (leaves, stems, bark and wood) conditions their composition. In addition, as expected, some variability was observed in the content of phenolic compounds among the different origins/locations of the plants.
The extraction procedure used was successful in obtaining added-value extracts from U. tomentosa. The phenolic extracts obtained, particularly rich in proanthocyanidins, may exert the health benefits attributed to these compounds, mainly in cardiovascular diseases [24,25] due to its anti-platelet properties and its effect in lipids metabolism and vascular function . In addition, their content in flavalignans (cinchonains) might be extra value as recent reports on insulinotropic effects of cinchonain 1b suggest their possible use in the treatment of diabetes type 2 . Leaves are particularly the part of U. tomentosa plants with the highest feasibility for use in the elaboration of standardizing phenolic extracts in a sustainable way, thus susceptible to application in the food, cosmetic and/or pharmaceutical industries.
Effect of Uncaria tomentosa extract on purinergic enzyme activities in lymphocytes of rats submitted to experimental adjuvant arthritis model
Considering that adjuvant arthritis is an experimental model of arthritis widely used for preclinical testing of numerous anti-arthritic agents, which were taken by a large number of patients worldwide, it is of great interest to investigate the therapeutic action of compounds with anti-inflammatory properties, such as Uncaria tomentosa extract. Moreover, there are no studies demonstrating the effect of U. tomentosa on the metabolism of adenine nucleotides published so far. Thus, the purpose of the present study is to investigate the effects of U. tomentosa extract on E-NTPDase and E-ADA activities in lymphocytes of Complete Freund’s Adjuvant (CFA) arthritis induced rats.
In summary, our data demonstrate that the U. tomentosa extract was able to reduce partially the mechanical thresholds, paw thickness and MPO activity in a model of induced arthritis. In addition, the extract was able to prevent the increase on the E-NTPDase activity in lymphocytes of rats submitted to an experimental adjuvant arthritis model. In view of this, U. tomentosa extract had an actual effect against arthritis and for the first time we demonstrate that the purinergic signaling is involved in these responses.