ABSTRACT
Uncaria tomentosa (Willd.) is a medicinal plant largely used in folk medicine due to its wide range of biological activities, many of which are usually ascribed to the two main classes of secondary metabolites, namely, alkaloids and quinovic acid glycosides. In this work, a reversed phase HPLC-PDA method was developed and validated for the assay of quinovic acid glycosides in crude and dried extracts of Uncaria tomentosa (Cat's claw) bark. The validation comprised tests of specificity, accuracy, linearity, intermediate precision, repeatability and limits of detection and of quantification. Alpha-hederin was used as the external standard. High coefficients of determination with lower R.S.D. were achieved for both external standard and crude extract. The structural characterization of the main quinovic acid glycosides presented in the crude extract was carried out through UPLC/Q-TOF-MS. The identities of the compounds were obtained through the comparison of their fragmentation patterns with those reported in the literature. The analytical method was successfully applied for quantifying quinovic acid glycosides in two different dried extracts from U. tomentosa and in one quinovic acid glycosides purified fraction.
Subject(s)
Cat's Claw/chemistry , Chromatography, High Pressure Liquid/methods , Glycosides/analysis , Spectrometry, Mass, Electrospray Ionization/methods , Triterpenes/analysisABSTRACT
INTRODUCTION: Ilex paraguariensis A. St. Hil. (mate) is known in several South American countries because of the use of its leaves in stimulant herbal beverages. High saponin contents were reported in mate leaves and unripe fruits that possess a dissimilar composition. Two LC-UV methods previously reported for mate saponins assay focused on mate leaves and the quantification of the less polar saponin fraction in mate fruits. OBJECTIVE: To develop and validate a LC-UV method to assay the total content of saponins in unripe mate fruits and characterise the chemical structure of triterpenic saponins by UPLC/Q-TOF-MS. METHODOLOGY: From unripe fruits of mate a crude ethanolic extract was prepared (EX40) and the mate saponin fraction (MSF) purified by solid phase extraction. The LC-UV method was validated using ilexoside II as external standard. UPLC/Q-TOF-MS was adjusted from the LC-UV method to obtain the fragmentation patterns of the main saponins present in unripe fruits. RESULTS: Both LC-UV and UPLC/Q-TOF-MS methods indicate a wide range of Ilex saponins polarity. The ilexoside II and total saponin content of EX40 were 8.20% (w/w) and 47.60% (w/w), respectively. The total saponin content in unripe fruits was 7.28% (w/w). The saponins present in MSF characterised by UPLC/Q-TOF-MS are derived mainly from ursolic/oleanolic, acetyl ursolic or pomolic acid. CONCLUSION: The validated LC-UV method was shown to be linear, precise, accurate and to cover several saponins previously isolated from Ilex species and could be applied for the quality control of unripe fruit saponins.
Subject(s)
Fruit/chemistry , Ilex paraguariensis/chemistry , Mass Spectrometry/methods , Saponins/chemistry , Ultraviolet Rays , Chromatography, Liquid/methods , Ethanol/chemistry , Glycosides/chemistry , Limit of Detection , Molecular Structure , Oleanolic Acid/analogs & derivatives , Oleanolic Acid/chemistry , Plant Extracts/chemistry , Quality Control , Reference Standards , Reproducibility of Results , Saponins/analysis , Solid Phase Extraction , Triterpenes/chemistry , Ursolic AcidABSTRACT
Saponins are natural compounds able to form abundant foam, a desirable quality required in some chemical, foods, cosmetic and pharmaceutical processes. Ilex paraguariensis A. St. Hil. (Aquifoliaceae) known as mate, is a South American widely cultivated specie due to the preparation of a tea-like beverage from its leaves. Moreover, its green fruits are a rich source of non-toxic and very low haemolytic saponins. In this study, mate saponin fraction (MSF) was evaluated as a foam former, focusing on its foamability, foam lifetime, and film drainage in the presence of different electrolytes (ionic strength I = 0.024 M). Sodium dodecyl sulphate (SDS) and polysorbate 80 (Poly-80) were used as reference surfactants. The critical micelle concentration (CMC), the minimum attainable surface tension (γCMC), surface excess concentration (Γ) and cross-section molecular surface (A) values of MSF were comparable to those of Poly-80. The foamability of MSF and both reference surfactants was equivalent. The addition of MgCl2 resulted in a negative effect on MSF foamability. The salts NaCl, KBr, and KNO3 exhibited a negative influence on MSF foam lifetime. Similar behavior was observed for MSF film drainage (order of activity: Na2HPO4 > MgCl2 ≈ NaCl ≈ KNO3 > KBr), where a primary fast film drainage rate was followed by film thinning stabilization after around 5 min. The behavior described above seems to be uncorrelated to the solutions' zeta potential.
As saponinas são compostos naturais capazes de formar espuma abundante, qualidade desejável exigida em alguns processos químicos, alimentícios, cosméticos e farmacêuticos. Ilex paraguariensis A. St. Hil. (Aquifoliaceae), mais conhecida como mate, é uma espécie largamente cultivada devido ao consumo do chimarrão. Além disso, seus frutos verdes representam uma fonte rica de saponinas pouco tóxicas e pouco hemolíticas. Nesse trabalho avaliou-se a fração de saponinas de mate (MSF) como formadora de espuma, com ênfase na espumabilidade, permanência da espuma e drenagem do filme na presença de diferentes eletrólitos (I = 0,024 M). Dodecil sulfato de sódio (SDS) e polissorbato 80 (Poly-80) foram utilizados como tensoativos-referência. Os valores de concentração micelar crítica (CMC), tensão superficial na CMC (γCMC), concentração de excesso de superfície (Γ) e área do grupamento polar na interface (A) referente à MSF foram comparáveis ao Poly-80. A espumabilidade da MSF e de ambos os tensoativos-referência foram equivalentes. A adição de MgCl2 resultou em um efeito negativo sobre a espumabilidade de MSF. Os sais NaCl, KBr e KNO3 tiveram influência negativa sobre a estabilidade da espuma. Em relação à drenagem do filme de MSF, após 60 min. seguiu-se a ordem Na2HPO4 > MgCl2 ≈ NaCl ≈ KNO3 > KBr, caracterizando uma drenagem inicial acelerada seguida pelo equilíbrio hidrodinâmico do filme após 5 min. O comportamento observado parece não estar relacionado com o potencial zeta das soluções.
