Inhibition of pterygium fibroblasts viability by a Siempre viva plant extract partitioned in Aqueous-Two Phase Systems

Abstract

Purpose : The only available treatment for pterygium is surgical removal, which produces high recurrence rates. Pharmaceutical approaches focus in post-surgical treatment to avoid recurrence. Siempre viva is an endemic Mexican plant with healing and anti-inflammatory properties. We partitioned Siempre viva plant extract in ethanol-salt Aqueous-Two Phase Systems (ATPS) in order to characterize its composition and test viability inhibition over pterygium fibroblasts.

Methods : Lyophilized Siempre viva extracts was obtained from leaves and stems. All ATPS were constructed with ethanol and potassium buffer phosphate (K₂HPO₄–KH₂PO₄) , and a total weight of 2 g with 10% w/w of sample. Each ATPS was loaded with 1 mg of the extract. The effect of the tie line length (TLL) on the extract partition was evaluated (TLL 40, 50, 60 and 70). Each phase was collected for determination of total phenolics concentration, total protein and antioxidant capacity by Folin-Ciocalteu method, Bradford technique and 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonate) (ABTS) assay. Pterygium fibroblasts obtained from human surgically removed samples were cultivated with DMEM-F12 medium. Cell viability inhibition was determined using Cell Titer at 24h post-treatment with the top phase of the ATPS.

Results : The highest percentage of total phenolics was recovered in the top phase (67.8%) of the alcohol-salt ATPS at TLL of 70. The highest recovery percentage of total protein in the top phase was obtained at TLL of 60 (60%) and the lowest percentage was obtained at a TLL of 70 (19.6%). For the antioxidant activity, at TLL of 40 the highest activity was determined in the top phase, whereas the lowest was obtained at TLL of 60. The highest inhibition of cell viability was observed with the top phase at TLL of 50 (25%), while the lowest percentage of inhibition was observed with the top phase at TLL of 60 (105%).

Conclusions : The compounds obtained through partition of the Siempre viva plant extract with ATPS inhibited cell viability in pterygium fibroblasts. Further analysis of their biological effect will provide more information about the potential use of the Siempre viva plant extract as a therapeutic approach for pterygium treatment.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.