RESUMO

Baicalin is one of the bioactive flavonoid glycosides isolated from the dried root of Scutellaria baicalensis Georgi, Lamiaceae, with antiviral properties. In recent years, the antiviral activity of baicalin has been widely investigated to explore its molecular mechanism of action. In this mini-review, the molecular mechanisms of action of baicalin as an antiviral agent are evaluated, which included three categories: the inhibition or stimulation of JAK/STAT, TLRs, and NF-κB pathways; up or down modulation of the expression levels of IFN, IL, SOCS1/3, PKR protein, Mx1 protein, and AP-1 protein; and inhibition of cell apoptosis caused by virus infection. In addition, clinical studies of baicalin are also discussed. This literature search suggested that baicalin can serve as a potential candidate for the development of a novel broad-spectrum antiviral drug. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s43450-021-00182-1.

RESUMO

Abstract The leaves of Garcinia gracilis Pierre, Clusiaceae, have been used as flavouring materials in food, with no previous reports of their biological activities and chemical constituents. In this study, the methanolic extract of G. gracilis afforded three compounds namely apigenin-8-C-α-L-rhamnopyranosyl-(1→2)-β-D-glucopyranoside (1), 5-hydroxymethyl-2-furaldehyde, and vanillic acid. All of the isolates were initially evaluated for superoxide anion radical scavenging activity and α-glucosidase inhibitory effects. Compound 1, which was the major component, showed the most potent activities among these three isolates. Further biological evaluations revealed that compound 1 could prevent the pBR322 plasmid DNA damage induced by the photochemical reaction of riboflavin and protect P19-derived neurons from the oxidative stress condition induced by serum deprivation. It was concluded that the potent biological activities of G. gracilis could be attributed to the synergistic effect of compound 1 with other constituents found in the plant.

RESUMO

Introducción: los extractos de Calendula officinalis se utilizan como materia prima natural en diversidad de preparaciones farmacéuticas y cosméticas, sin embargo, no existen métodos oficiales para el control de calidad de dichos extractos. Objetivo: se validó una metodología analítica por HPLC para la cuantificación de quercetina total en extractos glicólicos e hidroalcohólicos de Calendula officinalis. Métodos: para cuantificar el contenido de quercetina total en las matrices, fue necesario hidrolizar los flavonoides glicósidos en condiciones óptimas. La separación cromatográfica se realizó en una columna SiliaChrom C-18 5 µm 4.6x150 mm, adaptada a una precolumna SiliaChrom C-18 5 µm 4.6x10 mm, con un sistema de detección UV a 370 nm. El sistema de elución fue en gradiente, donde la fase móvil se compuso de Metanol (MeOH) y ácido fosfórico (H3PO4) (0.08 por ciento p/v), la cuantificación se efectuó con el método de estándar externo y comparación con un estándar de quercetina de referencia. Resultados: la selectividad de la metodología frente los componentes del extracto y a los productos de degradación en condiciones de hidrólisis ácida - básica, oxidación y exposición a la luz, mostró que no hay señales que interfieran con la cuantificación de la quercetina. Se comprobó estadísticamente que el método es lineal entre 1,0 y 5,0 µg / mL. La precisión intermedia expresada como coeficiente de variación fue de 1,8 y 1,74 por ciento y el porciento de recuperación fue de 102.15 y 101.32 por ciento, para los extractos glicólico e hidroalcohólico, respectivamente. Conclusiones: la metodología propuesta cumple con los parámetros de calidad requeridos para la cuantificación de quercetina total, lo cual la convierte en una herramienta útil para el control de calidad de extractos glicólicos e hidroalcohólicos de C. officinalis(AU)

Introduction: calendula officinalis extracts are used as natural raw material in a wide range of pharmaceutical and cosmetic preparations; however, there are no official methods for quality control of these extracts. Objective: to validate an HPLC-based analytical method for quantification total quercetin in glycolic and hydroalcoholic extracts of Calendula officinalis. Methods: to quantify total quercetin content in the matrices, it was necessary to hydrolyze flavonoid glycosides under optimal conditions. The chromatographic separation was performed on a C-18 SiliaChrom 4.6x150 mm 5 µm column, adapted to a SiliaChrom 5 um C-18 4.6x10 mm precolumn, with UV detection at 370 nm. The gradient elution was performed with a mobile phase consisting of methanol (MeOH) and phosphoric acid (H3PO4) (0.08 percent w/v). The quantification was performed through the external standard method and comparison with quercetin reference standard. Results: the studied method selectivity against extract components and degradation products under acid/basic hydrolysis, oxidation and light exposure conditions showed no signals that interfere with the quercetin quantification. It was statistically proved that the method is linear from 1.0 to 5.0 mg/mL. Intermediate precision expressed as a variation coefficient was 1.8 and 1.74 percent and the recovery percentage was 102.15 and 101.32 percent, for glycolic and hydroalcoholic extracts, respectively. Conclusions: the suggested methodology meets the quality parameters required for quantifying total quercetin, which makes it a useful tool for quality control of C. officinalis extracts(AU)

Assuntos

RESUMO

BACKGROUND: Graptopetalum paraguayense E. Walther is a popular traditional Chinese herb and possesses several health benefits. In earlier studies, we demonstrated that G. paraguayense showed no genotoxicity and showed several biological activities. However, the constituents of G. paraguayense have not been studied yet. In this present study, we isolated and identified the constituents of the leaves of G. paraguayense E. Walther. RESULTS: A total of seven flavonoid compounds were isolated from the methanolic extract of G. paraguayense. The four major compounds isolated were flavonoid glucoside derivatives of quercetin (1, 3) and kampferol (2, 4), each presenting a 3-hydroxyl-3-methylglutaroyl (HMG) substituent; compounds 3 and 4-the 2´´-acetyl derivatives of 1 and 2, respectively-are novel compounds isolated from nature for the first time. High-performance liquid chromatography for the quantitative analyses of the four major HMG-substituted flavonoid glycosides in G. paraguayense E. Walther were accomplished to acquire the high yields of 1-4 in the methanolic extract (4.8, 5.7, 4.3, and 2.5 mg/g, respectively). Furthermore, the antioxidant activities, including radical-scavenging, reducing power and lipid peroxidation inhibitory effects of these isolated flavonoids were also evaluated. All seven of the isolated flavonoid compounds possessed antioxdative activity. CONCLUSIONS: In this study of the constituents of the leaves of G. paraguayense E. Walther, we isolated four major components from its methanolic extract and determined their structures to be (acetylated) HMG-substituted flavonol glycosides, which are rare in nature. All seven of the isolated compounds possessed antioxdative activity, and those flavonoid compounds may be responsible for the functional ingredients in G. paraguayense. Further investigation of their bioactivities or pharmacological activities will be continued.