Abstract:The antiviral activity of extracts obtained from Ageratina havanensis (Kunth) R.M.King & H.Rob., Asteraceae, against rabbit vesivirus (RaV) (Caliciviridae) and human herpes simplex viruses type 1 and 2 (HSV-1, HSV-2) (Herpesviridae) were analyzed, and the main metabolites from the most active extract were isolated and characterized. The antiviral properties were investigated by measuring the inhibition of viral-induced cytopathic effect in Vero cells. The strongest inhibitory effects were found for ethyl acetate extract from leaves (SI=5 for RaV and SI=5.4 for HSV-1). The crude ethyl acetate extract was further fractionated by chromatographic methods and the structures of isolated compounds were established through comprehensive spectroscopic analyses, including IR, 2D NMR and MS. Four flavonoids were identified: 5,4'-dihydroxy-7-methoxyflavanone (sakuranetin), 3,5,4'-trihydroxy-7-methoxyflavanone (7-methoxyaromadendrin), 4'-O-β-D-glucosyl-5,3'-dihydroxy-7-methoxyflavanone (4'-O-β-D-glucosyl-7-methoxy-eriodictyol) and 4'-O-β-D-glucosyl-5-hydroxy-7-methoxyflavanone (4'-O-β-D-glucosylsakuranetin). This is the first report on antiviral activity for Ageratina havanensis.
The structure of the known 2''-O-α-rhamnosyl-4''-O-methylvitexin (apigenin-8-C-α-rhamnosyl-(1→2)-β-4-O-methylglucopyranoside), isolated from the leaves of Piper ossanum, was revised to acacetin-8-C-neohesperidoside (acacetin-8-C-α-rhamnosyl-(1→2)-β-glucopyranoside or 2''-O-α-rhamnosyl-4'-O-methylvitexin) (1). The NMR data and theoretical calculations established the preferred conformation of 1, which is controlled by CH/π interactions. This phenomenon explains the unusual chemical shifts of some protons in the molecule, besides other weak intramolecular interactions such as the anomeric effect, the Δ2 effect, and several hydrogen bonds.
The flowers and leaves of Ageratina havanensis (Kunth) R. M. King & H. Robinson are traditionally used as a tea to cure several diseases. The production of active secondary metabolites can be affected by several environmental factors such as climate, altitude, rainfall, phenological stage and other conditions that may influence the growth of plants. In this sense, the development of a methodology to compare the chemical composition of plant extracts is needed. The qualitative chemical composition of the ethyl acetate extracts of flowers and leaves, collected in both reproductive and non-reproductive season, was determined by flow injection analysis-electrospray ionization-ion trap tandem mass spectrometry (FIA-ESI-IT-MS n) and ultra-high-performance liquid chromatography coupled to electrospray negative ionization mass spectrometry (UPLC/ESI-MS n). The qualitative chemical composition of the ethyl acetate extracts of flowers and leaves was very similar in all cases. Also the antiviral activity of flowers against human herpes simplex viruses type 1 and 2 (HSV-1, HSV-2) (Herpesviridae) was analyzed. Three glucoside flavonoids were isolated from the ethyl acetate extract of the leaves of A. havanensis collected in flowering season using chromatographic methods and their structures were elucidated by physical and spectroscopic data measurements, and by comparing the obtained data with previously published values. The compounds were identified as 3-O-β-D-glucosyl-7-methoxyaromadendrin (5), 7-O-β-D-glucosyl-4'dihydroxy-5-methoxyflavanone (6) and 5-O-β-D-glucosylsakuranetin (7); this is the first report of the isolation of these compounds in the Asteraceae family. Since the qualitative composition of the extracts of A. havanensis was similar in all cases, it can be expected that the ethyl acetate extract of the leaves collected in the non-reproductive season has anti-herpetic activity similar to that obtained in the reproductive season.
Medium and high polarity extracts from Maytenus species are known to contain polyphenolic compounds such as proanthocyanidins. The high polarity and structural complexity of these compounds make very difficult their isolation even by modern chromatographic techniques.
Maytenus cajalbanicaSo far, there are reports neither of phytochemical work nor of biological evaluation of extracts from this subspecies. The goal of this work is to determine the polyphenolic profile and the antioxidant capacity of the ethanolic extract from the barks of Maytenus cajalbanica.FIA/ESI/IT/MS n analysis allowed the identification of 5 flavan-3-ol monomers, 33 proanthocyanidins, 2 free flavonoids and their respective glycosides as major compounds of the ethanolic extract, which showed a strong radical scavenging capacity and a significant ferric reduction power. FIA/ESI/IT/MS n technique led the rapid, effective and sensitive determination of the polyphenolic profile of Maytenus cajalbanica without previous separation.
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