RESUMEN
Plant natural products offer promise in combating multi-drug resistance by acting as antibacterial agents through various mechanisms. A metabolomic-guided phytochemical investigation, based on a LC-HRMS/MS and Molecular Networking combined approach, was carried out on an extract of M. alba L. (mulberry) twigs, a common of byproduct of mulberry utilization. Molecular networking uncovered different clusters of prenylated polyphenols, glycosylated phenolic compounds, and Diels-Alder dimers, steering the phytochemical profiling of this extract. This led to the swift annotation and subsequent isolation of 17 secondary metabolites including stilbenoids, flavonoids, and flavanones. Isolated metabolites were tested for their antimicrobial activity against Staphylococcus species. The most active compound resulted to be kuwanon C, exhibiting a MIC value of 8⯵g/mL against the methicillin resistant S. aureus (MRSA) strain and a biofilm producer strain of S. epidermidis. We also observed an interaction between 4⯵g/mL of kuwanon C in combination with low oxacillin dosage against the MRSA. Thanks to the high chemical structure similarity of isolated metabolites, structure-activity relationships of these versatile scaffolds have been postulated.
RESUMEN
A madecassoside-rich fraction obtained from the industrial purification of Centella asiatica leaves afforded a new triterpene glycoside, named isomadecassoside (4), characterized by an ursane-type skeleton and migration of the double bond at Δ20(21) in ring E. The structure of isomadecassoside was established by means of HR-ESIMS and detailed analysis of 1D and 2D NMR spectra, which allowed a complete NMR assignment. Studies on isolated J774A.1 macrophages stimulated by LPS revealed that isomadecassoside (4) inhibited nitrite production at non-cytotoxic concentrations, thus indicating an anti-inflammatory effect similar to that of madecassoside.
Asunto(s)
Centella/química , Glicósidos/farmacología , Macrófagos/efectos de los fármacos , Nitritos/metabolismo , Triterpenos/química , Supervivencia Celular/efectos de los fármacos , Centella/metabolismo , Glicósidos/química , Glicósidos/aislamiento & purificación , Humanos , Lipopolisacáridos/farmacología , Macrófagos/citología , Macrófagos/metabolismo , Espectroscopía de Resonancia Magnética , Conformación Molecular , Extractos Vegetales/química , Hojas de la Planta/metabolismoRESUMEN
The Vaccinium myrtillus fruits (bilberry) are a well-known anthocyanins source, and their extracts are widely used in dietary botanicals and pharmaceutical products for the treatment of vascular and vision disorders. Different analytical methods used for standardization of the bilberry extracts and their preparations are available from pharmacopeias and from the literature. However, the methods reported in the literature do not allow the detection of free anthocyanidins, which are markers of poor product quality. A new liquid chromatography method was developed and validated for the identification and quantification of both anthocyanins and anthocyanidins present in bilberry extracts and products. The method shows a good reproducibility and, due to its high specificity, is suitable to identify unequivocally the botanical raw materials used for manufacturing and to evaluate the extract composition, thus ensuring a high degree of product consistency and quality. Forty typical bilberry preparations belonging to 24 different brands were purchased in the marketplace and evaluated for their quality by using the developed method. Results revealed marked differences among the brands despite a common origin and labeling.