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N-trans-feruloyltyramine and flavonol glycosides from the leaves of Solanum sordidum

Abstract

Chemical investigation of the leaves of Solanum sordidum Sendtn., Solanaceae, resulted in the isolation and identification of sitosterol, stigmasterol, 3β-O-β-glycopyranosyl stigmasterol, 3β-O-β-glycopyranosyl sitosterol, kaempferol-3-O-α-rhamnopyranosyl-(1-6)-α-glycopyranoside, rutin, and N-trans-feruloyltyramine. The structures of these compounds were established by analysis of 1D and 2D NMR spectrometric data and comparison with data in the literature. The evaluation of antioxidant activity showed an IC50 of 159.5 ppm for the chloroformic fraction and IC50 of 77.5 ppm for the hydromethanolic fraction.

Solanum sordidum; flavonol glycosides; alkamide


N-trans-feruloyltyramine and flavonol glycosides from the leaves of Solanum sordidum

Regina Mikie KanadaI; Julliana Izabelle SimionatoII; Rafael Ferraz de ArrudaI; Silvana Maria de Oliveira SantinI; Maria Conceição de SouzaIII; Cleuza Conceição da SilvaI, * * Correspondence: Cleuza Conceição da Silva. Departamento de Química. Universidade Estadual de Maringá. Av. Colombo, 5790, 87020-900 Maringá-PR, Brazil. ccsilva@uem.br

IDepartamento de Química, Universidade Estadual de Maringá, Brazil

IIDepartamento de Estudos Básicos e Instrumentais, Universidade Estadual do Sudoeste da Bahia, Brazil

IIIDepartamento de Biologia, Universidade Estadual de Maringá, Brazil

ABSTRACT

Chemical investigation of the leaves of Solanum sordidum Sendtn., Solanaceae, resulted in the isolation and identification of sitosterol, stigmasterol, 3β-O-β-glycopyranosyl stigmasterol, 3β-O-β-glycopyranosyl sitosterol, kaempferol-3-O-α-rhamnopyranosyl-(1-6)-α-glycopyranoside, rutin, and N-trans-feruloyltyramine. The structures of these compounds were established by analysis of 1D and 2D NMR spectrometric data and comparison with data in the literature. The evaluation of antioxidant activity showed an IC50 of 159.5 ppm for the chloroformic fraction and IC50 of 77.5 ppm for the hydromethanolic fraction.

Keywords:Solanum sordidum, flavonol glycosides, alkamide

Introduction

Solanum is the most representative genus of Solanaceae and comprises about 1700 species distributed all over the world. Plants in the genus are distributed in the tropical and subtropical regions and an estimated 1000-1100 species of the genus are found in South America regions (Willis, 1980). Due to the large number of species in the genus, the family was named Solanaceae.

Many species of the genus are known for its economic importance, such as tomato (S. lycopersicum), egg-plant (S. melongena) and potato (S. tuberosum), and some are used in folk and traditional medicine, like S. paniculatum ("jurubeba"), used for treatment of anemia and liver and digestion problems, and S. americanum, ("maria-pretinha"), used in the treatment of gastralgia, bladder spasm, joint pains, and as an effective vermifuge (Lorenzi & Matos, 2002).

Phytochemical studies of the Solanum species report the occurrence of flavonoids, free flavones and their glycosides (Silva et al., 2003), in addition to steroid alkaloids with spirosolane and solanidane skeletons, such as solasodine and solanine, as well as non-steroids constituted of amines and amides (Evans & Somanabandhu, 1980; Costa, 1994).

The present work describes the isolation of two flavonoids and an alkamide from Solanum sordidum Sendtn., Solanaceae, popularly named "falsa-jurubeba".

Material and Methods

The 1H and 13C NMR spectra were obtained in a Varian spectrometer model Mercury Plus at 300 MHz for 1H, and 75.5 MHz for 13C, using tetramethylsilane (TMS) or the solvent itself as internal reference. The chemical shifts (Δ) were recorded in ppm and the deuterated solvents CDCl3, CD3OD, C5D5N, and D2O were used. Glass chromatography columns (CC) of various sizes with silica gel (0.063-0.200 mm) stationary phase from Merk and silica gel 60 (0.04-0.063 mm) from Fluka were used.

In the analytic and preparative thin layer chromatography (TLC), glass plates with silica gel 60 GF254 from Merck were visualized with ultraviolet radiation Λ=254 and 366 nm, followed by nebulization with either an H2SO4/MeOH (1:1) or H2SO4 anisaldehyde/acetic acid (1:0.5:50) solution and heating.

Plant material

Solanum sordidum Sendtn., Solanaceae, was collected on the island of Porto Rico, in the municipality of Taquaruçu, Mato Grosso do Sul State. A voucher of the vegetable material was deposited in the herbarium of the State University of Maringá under HUM 2482.

Extraction and isolation of the chemical constituents of S. sordidum

Pulverized dried leaves from S. sordidum (785 g) were extensively extracted using MeOH at room temperature. The combined extracts were concentrated in vacuo to give 166.2 g of methanolic extract. Part of the extract (81.4 g) was chromatographed on a silica gel column eluted with CHCl3/MeOH with increasing polarity gradient. The fraction of CHCl3/MeOH 99.5:0.5 of this treatment yielded a mixture of stigmasterol and sitosterol. The fraction CHCl3/MeOH 95:05 was recrystallized in methanol, giving a mixture of the same glycosylated steroids. The second part of the extract (84.8 g) was dissolved in water and partitioned in butanol. Next, the butanolic fraction was concentrated, diluted in MeOH/H2O 80:20 and partitioned with hexane. The resulting hydromethanolic fraction was concentrated, diluted in MeOH/H2O 60:40, and extracted with CHCl3. The chloroform fraction was submitted to column chromatography in eluted neutral alumina with CHCl3/MeOH with increasing polarity gradient, leading to the isolation of alkamide 3. The remaining aqueous MeOH fraction was chromatographed on silica gel CC with CHCl3/MeOH, with increasing polarity gradient, and yielded the flavonol 1 after recrystallization in MeOH, and the flavonol 2 after silica gel preparative TLC with CHCl3/MeOH 7:3.

Antioxidant activity

The antioxidant activity was evaluated using chloroform and hydromethanolic fractions of the vegetable species S. sordidum, by monitoring the consumption of the free radical DPPH by measuring the decrease in absorbance of the samples in different concentrations. Absorbance measurements were performed in an UV-Vis spectrophotometer at wavelength 517 nm. Catechin and 3 mL of HPLC-grade methanol were used as controls. Solutions of the chloroform fraction were diluted in HPLC-grade methanol at the concentrations of 25, 50, 75, 100, 125, 150, 175, and 200 ppm, and the hydromethanolic fraction was diluted in HPLC-grade methanol at concentrations of 25, 50, 75, 90, and 100 ppm. The tests were performed in triplicate for all concentrations for obtaining the IC50. Absorbance was measured 30 min after the addition of DPPH to the sample at intervals of 3 min for each concentration.

Results and Discussion

The phytochemical study of the leaves of Solanum sordidum Sendtn., Solanaceae, led to the isolation of flavonoids rutin (1) and 3-O-rhamnopyranosyl-(1→6)-β-glycopyranosyl kaempferol (2), of the alkaloid N-trans-feruloyltyramin (3), of mixture of steroid saponins 3β-O-glycopyranosyl-24α-ethylcolesta-5-enol (4) and 3β-O-β-D-glycopyranosyl-24α-ethylcolesta-5,22 E-dien-3β-ol (5) (Alam et al., 1996) and of the steroids sitosterol and stigmasterol (Goulart et al., 1993).

Substances 1 and 2 were characterized as being glycosylated flavonoids containing the same sugar unit at position 3 and different levels of oxidation of the C ring of the genins, which had substitution patterns of quercetin and kaempferol. These substances were identified as being rutin and 3-O-rhamnopyranosyl-(1→6)-β-glycopyranosyl kaempferol by comparison of the 1H and 13C NMR data to those in the literature (Niassy et al., 2004).

Substance 3 was isolated from the chloroform fraction as colorless crystals. In the 1H NMR spectrum of 3 (Table 1), two duplets at Δ 7.43 and 6.40 characteristic of hydrogens of α,β-unsaturated carbonyl system with constant coupling (J=15.8 Hz) can be observed, indicated by the trans configuration, also three-substituted benzene ring signals at Δ 7.12 (d, J=2.1 Hz), 7.01 (dd, J=8.3, 2.1 Hz) and 6.79 (d, J=8.3 Hz) and the methoxyl group signal at Δ 3.88, evidencing the presence of a trans feruloyl group. The two duplets at Δ 7.05 (J=8.3) and 6.71 (J=8.3) attributed to hydrogens of para substituted benzene ring and the triplets at Δ 2.75 and 3.46 of two methylenes are indicative of a four-hydroxyphenyl ethyl system. The carbons of the α,β-unsaturated carboxamide system were observed in the 13C NMR spectrum (Table 1) at Δ 169.4, 142.2, and 118.8, the methylenes of 4-hidroxyphenilethyl at Δ 35.8, 42.5, and the methoxyl at Δ 56.4. The correlations of the signals at Δ 2.75 and 3.46 and at Δ 6.40 and 7.43 observed in the COSY confirmed the presence of the saturated and vinyl systems of the hydroxyphenyl ethyl and trans-feruloyl groups. The analysis of one- and two-dimensional NMR data combined with the data in the literature (Muñoz et al., 1996; King & Calhoun, 2005) allowed the characterization of substance 3 as being N-trans-feruloyltyramine.

The oxidation patterns of the oxidation of the flavonoid rings 3-O-α-rhamnopyranosyl-(1→6)-β-glycopyranosyl kaempferol and of rutin isolated from S. sordidum agree with the patterns of the flavonoids found in other species of the genus, as described by Silva et al. (2003) and Steinharter et al. (1986), who reported glycosylated flavonols quercetin and kaempferol as the most frequent. N-trans-feruloyltyramine has been reported in plants and cell cultures of Solanum species. This alkamide has also been associated with the cell walls of some Solanaceae species and seems to play an important role in the defense of the plant (Keller et al., 1996; Muhlenbeck et al., 1996; Negrel et al., 1996; Turnock et al., 2001; Syu et al., 2001). The isolation of these substances corroborates the classification of this species in the Solanum genus.

The antioxidant activity was evaluated by the DPPH radical scavenging method. The activity was determined through the capacity of the fractions to bleach diluted solutions of the DPPH radical. IC50, which corresponds to 50% of the inhibition of the DPPH radical, was calculated from the plot of percent inhibition versus the concentration of the extract or fraction in µg/mL. The antioxidant used as a reference was catechin, which had an IC50 of 8.25 ppm. The results obtained show that the chloroform fraction had moderate antioxidant activity, with an IC50 of 159.5 ppm. The hydromethanolic fraction had significant antioxidant activity, with an IC50 of 77.5 ppm, as shown in Figure 1. The flavonoids present in this species may be responsible for the significant antioxidant activity of the hydromethanolic fraction, as the literature cites them as being the most potent antioxidants (Furusawa et al., 2005; Alves et al., 2007; Rosa et al., 2010).


Spectroscopic data of substances 1 and 2

Rutin (1): 1H NMR (300 MHz, CD3OD) Δ ppm (multiplicity, J): 6.20 (d, J=2.1 Hz, 1H, H-6), 6.38 (d, J=2.1 Hz, 1H, H-8), 7.67 (d, J=2.05 Hz, 1H, H-2'), 6.88 (d, J=8.4 Hz, 1H, H-5'), 7.63 (dd, J=8.5 and 2.2 Hz, 1H, H-6'), 5.10 (d, J=7.5 Hz, 1H, H-1"), 4.52 (d, J=1.5 Hz, 1H, H-1"'), 1.12 (d, J=6.3 Hz, 3H, H-6"'), 3.30- 3.85 (m); NMR 13C (75.5 MHz, CD3OD) Δ ppm: 158.8 (C-2), 135.9 (C-3), 179.7 (C-4), 163.3 (C-5), 100.2 (C-6), 166.3 (C-7), 95.1 (C-8), 159.7 (C-9), 105.8 (C-10), 123.4 (C-1'), 118.0 (C-2'), 146.1 (C-3'), 150.1 (C-4'), 116.3 (C-5'), 123.8 (C-6'), 105.0 (C-1''), 75.9 (C-2''), 78.3 (C-3''), 71.5 (C-4''), 77.4 (C-5''), 68.7 (C-6''), 102.6 (C-1"'), 72.3 (C-2"'), 72.4 (C-3"'), 74.1 (C-4"'), 69.9 (C-5"'), 18.0 (C-6"').

3-O-rhamnopyranosyl-(1→6 )-β-glycopyranosyl kaempferol (2): 1H NMR (300 MHz, CD3OD) Δ ppm (multiplicity, J): 6.21 (d, J=1.5 Hz, 1H, H-6), 6.40 (d, J=1.5 Hz, 1H, H-8), 8.06 (d, J=8.7 Hz, 2H, H-2' and 6'), 6.89 (d, J=8.7 Hz, 2H, H-3' and 5'), 5.10 (d, J=7.5 Hz, 1H, H-1"), 4.50 (d, J=1.2 Hz, 1H, H-1"'), 1.12 (d, J=6, 0 Hz, 3H, H-6"') 3.25- 3.78 (m); 13C NMR (75.5 MHz, CD3OD) Δ ppm: 159.6 (C-2), 136.6 (C-3), 180.6 (C-4), 167.3 (C-5), 101.2 (C-6), 164.0 (C-7), 96.1 (C-8), 160.7 (C-9), 106.7 (C-10), 123.8 (C-1'), 133.5 (C-2' and 6'), 117.3 (C-3' and 5'), 162.7 (C-4'), 105.7 (C-1''), 74.9 (C-2''), 79.1 (C-3''), 72.4 (C-4''), 78.2 (C-5''), 69.6 (C-6''), 103.5 (C-1"'), 73.1 (C-2"'), 73.3 (C-3"'), 76.7 (C-4"'), 70.7 (C-5"'), 18.8 (C-6"').

Acknowledgements

The authors thank the founding institutions CNPq, for the financial support, and CAPES, for a scholarship.

Received 7 Jun 2011

Accepted 23 Sep 2011

  • Alam MS, Chopra N, Ali M, Niwa M 1996. Oleanen and stigmasterol derivatives from Ambroma augusta. Phytochemistry 41: 1197-1200.
  • Alves CQ, Brandão HN, David JM, David JP, Lima LS 2007. Avaliação da atividade antioxidante de flavonóides. Diálogos & Ciência 12: 1-8.
  • Costa AF 1994. Farmacognosia Lisboa: Fundação Calouste Gulbenkian.
  • Evans WC, Somanabandhu A 1980. Nitrogen-containing non-steroidal secondary metabolites of Solanum cyphomandra, Lycianthes and Margaranthus. Phytochemistry 19: 2351-2356.
  • Furusawa M, Tanaka T, Ito T, Nishikawa A, Yamasaki N, Nakaya K, Matssura N, Tsuchiya H, Nagayama M, Iinuma M 2005. Antioxidant activity of hydroxyflavonoids. J Health Sci 51: 376-378.
  • Goulart MOF, Sant'Ana AEG, Lima RA, Cavalcante SH, Carvalho MG, Braz-Filho R 1993. Fitoconstituintes químicos isolados de Jatropha elliptica. Atribuição dos deslocamentos químicos dos átomos de carbono e hidrogênio dos diterpenos jatrofolonas A e B. Quím Nova 16: 95-100.
  • Keller H, Hohlfeld H, Wray V, Hahlbrock K, Scheel D, Strack D 1996. Changes in the accumulation of soluble and cell wall-bound phenolics in elicitor-treated cell suspension cultures and fungus-infected leaves of Solanum tuberosum. Phytochemistry 42: 389-396.
  • King RR, Calhoun LA 2005.Characterization of cross-linked hydroxycinnamic acid amides isolated from potato common scab lesions. Phytochemistry 66: 2468-2473.
  • Lorenzi H, Matos FJA 2002. Plantas Medicinais no Brasil, 1Ş ed, Nova Odessa: Inst. Plantarum de Estudos da Flora Ltda.
  • Muhlenbeck U, Kortenbusch A, Barz W 1996. Formation of hydroxycinamoyl amides and alpha-hydroxyacetovanillone in cell cultures of Solanum khasianum. Phytochemistry 42: 1573-1579.
  • Muñoz O, Piovano M, Garrarino J, Hellwing V, Breitmaier E 1996. Tropane alkaloids from Schizanthus litoralis. Phytochemistry 43: 709-713.
  • Negrel J, Pollet B, Lapierre C 1996. Ether-linked ferulic acid amides in natural and wound periderms of potato tuber. Phytochemistry 43: 1195-1199.
  • Niassy B, Um BH, Lobstein A, Weniger B, Koné M, Anton R 2004. Flavonoides de Tephrosia deflexa et Tephrosia albifoliolis. C R Chim 7: 993-996.
  • Rosa EA, Silva BC, Silva FM, Tanaka CMA, Peralta RM, Oliveira CMA, Kato L, Ferreira HD, Silva CC 2010, Flavonóides e atividade antioxidante em Palicourea rigida Kunth. Rev Bras Farmacogn 20: 484-488.
  • Silva TMS, Carvalho MG, Agra MF, Braz-Filho R 2003. Ocorrência de flavonas, flavonóis e seus glicosídeos em espécies do gênero Solanum (Solanaceae). Quím Nova 26: 517-522.
  • Steinharter TP, Cooper-Driver GA, Anderson GJ 1986. The phylogenetic relationship of Solanum flavonols. Biochem Syst Ecol 14: 299-305.
  • Syu WJ, Don MJ, Lee GH, Sun CM 2001. Cytotoxic and novel compounds from Solanum indicum. J Nat Prod 64: 1232-1233.
  • Turnock J, Cowan S, Watson A, Bartholomew, B, Bright C, Latif Z, Sarker SD, Nash RJ 2001. N-trans-feruloyltyramine from 2 species of the Solanaceae. Biochem Syst Ecol 29: 209-211.
  • Vieira RF, Carvalho LDAF 1993, Espécies medicinais do gênero Solanum produtoras de alcalóides esteroidais. Rev Bras Farmacogn 74: 97-111.
  • Willis JC 1980. A Dictionary of the Flowering Plants and Ferns. 8Ş ed., Londres: Cambridge University Press.
  • *
    Correspondence: Cleuza Conceição da Silva. Departamento de Química. Universidade Estadual de Maringá. Av. Colombo, 5790, 87020-900 Maringá-PR, Brazil.
  • Publication Dates

    • Publication in this collection
      08 Mar 2012
    • Date of issue
      June 2012

    History

    • Received
      07 June 2011
    • Accepted
      23 Sept 2011
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