Planta Med 2015; 81 - PM_93
DOI: 10.1055/s-0035-1565470

Rhamnosyl gallates and proanthocyanidins produced by Inga species and their antioxidant and antitumoral potential

DHS Silva 1, NM Lima 1, SR Marqui 1, JI Rodrigues 1, LH Rakotondraibe 2, CP Soares 3
  • 1Sao Paulo State University – UNESP, Institute of Chemistry, Araraquara, Brazil
  • 2Ohio State University, OSU, College of Pharmacy, Columbus, United States
  • 3São Paulo State University-UNESP, School of Pharmacy, Araraquara, Brazil

Fabaceae species are widespread in tropical/subtropical regions as shrubs and trees [1] and used as medicinal plants in Brazil to treat inflammation. The presence of flavonoids and phenolics in Inga extracts has been reported previously and might be associated to their popular uses [1,2]. Preliminary analysis of EtOAc fraction from crude extracts of Inga laurina (S.W.) Willd, I. edulis Martius, and I. marginata Willd. indicated phenolics as major compounds by HPLC-DAD-UV. Such fractions were submitted to antiradicalar evaluation in the DPPH assay and liposome model which indicated their antioxidant potential. In addition, the cytotoxic activity was evaluated by the MTT assay using HT-29 cancer cells (human colon) and best results for cytotoxicity were shown by the EtOH extract from I. laurina leaves (ED50 7.20 µg/mL), which led to its selection for further work. RP-HPLC of this extract afforded gallic acid rhamnosyl derivatives whereas the fruits extract afforded proanthocyanidins. Their structures were determined by NMR and MS analysis as 2-rhamnopyranosyl-3,5-dihydroxyphenyl gallate, 2-rhamnopyranosyl-4,6-dihydroxyphenyl gallate, and proanthocyanidin A2. Literature data highlight the prevalence of phenolics in leaves extracts of Inga species and their antioxidant activity associated to the chemopreventive potential which corroborates our data [3]. Cytotoxicity evaluation of the isolated compounds indicated low activity towards HT-29 cell line whereas their strong free radical scavenging activities (IC50 22.6 µM, 19.9 µM and 25.2 µM, respectively) were confirmed by the DPPH assay and compared to quercetin (IC50 18.9 µM), evidencing the antiradicalar potential of Inga laurina and the importance of bioprospecting studies in the search of novel bioactive compounds.

References:

[1] Lokvam J et al. J Chemical Ecol. 2005; 31: 11

[2] Lokvam J et al. J Nat Prod 2007; 70: 134

[3] Cuendet M et al. J Nat Prod 2006; 69: 460

[4] Furtado FB et al. Molecules 2014; 4: 4560