Synergic evaluation of associations of crude Pterodon pubescens Benth dichloromethane extract and Varronia spp essential oil in antinociceptive experimental models

Use of phytocomplex can be an alternative for treatment of pain and inflammatory diseases. Their therapeutic action can reduce significantly the side effects caused by conventional treatment. Pterodon pubescens Benth and Varronia spp species are widely used by Brazilian population for treatment of pain and inflammation with effective pharmacological activities1,2. The purpose of this study was to assess the possible synergistic effect between dichloromethane crude extract (DCE) from fruits of Pterodon pubescens Benth and essential oil (EO) from leaves of Varronia spp in the mice abdominal writhing induced by acid acetic test by injection of 1 µl/g of acid acetic solution (0.8%) into the peritoneal cavity of Male Swiss mice (n = 8 per group)3.(Ethics Commitee n°3181 – 1). Reduction of writhing was considered as measurement of antinociception. The ED₅₀ of DCE and EO determined separately were 65 and 165 mg/kg respectably and whereas association of both extract reduce the doses necessary. The isobologram were constructed to define the functional interaction between both extracts plotting their ED50 values (Figure 1A). The inhibition of nociception is shown on Figure 1B.

Fig. 1: (A) Isobologram showing the antinociceptive interaction between Pterodon pubescens and Varronia spp on writhing induced by acid acetic test. The oblique line, between the x and y axes, is the theoretical additive line. The points denoted by (♦) are the theoretical additive point calculated for the combination extracts ED50 values. The experimental points denoted by ( ) is the actual observed ED50 values for the mixture.(B) The bars represent the mean ± SEM (n = 8). Data was analyzed by one way ANOVA followed by Dunnett's test ***p < 0.001. The values (%) correspond at inhibition when compared with vehicle.

The experimental values found were significantly lower than the estimated ED₅₀ values indicating a synergistic interaction and inhibitory effect in lower doses, showing a significant antinociceptive activity (***p < 0.001, Dunnett's test). In previous studies of acute dose toxicity and open field test, the combination DCE-EO 500 mg/kg each, had absence of toxicity signals or locomotor activity changes. Therefore this extracts association may represent a potential therapeutic advantage for the clinical treatment of pain and inflammation.

Acknowledgements: Fapesp n°2013/15709 – 5, CAPES, Graduate Program in Medicine Science – FCM/Unicamp.

Keywords: Pterodon pubescens, essential oil, antinociceptive, synergism, isobologram.

References:

[1] Spindola, HM et al. (2011) Eur J Pharmacol 656:45 – 51.

[2] Michielin, EMZ et al. (2011)J Supercritical Fluids 56:89 – 96.

[3] Koster, R et al. (1959) Fed Proc 18:412.