Abstract
Purpose :
Previous studies have shown that butanolic extract of the bark of Stryphnodendron adstringens (barbatimão) was efficient to increase the denaturation temperature of the cornea. In this experiment, the effect of the same plant extract was demonstrated as a bioactive-ink (BBB) on top of the sclera, eventually arresting the myopia progression and its deleterious anatomical effects.
Methods :
Butanolic extract was prepared by sequential solvent extraction of barbatimão (hexane, ethyl acetate, butanol and water) for 30 min in an ultrasonic bath and the proanthocyanidin content was determined by the butanol-HCl methodology. Differential scanning calorimetry (DSC - 60 Shimadzu) was used to access the denaturation temperature porcine and human sclera. DSC conditions were: temperature range from 25 to 110 °C, heating rate of 10 °C/min, dynamic N2 atmosphere (50 mL/min) and aluminium crucibles containing 2-3 mg of samples. TissueJet 100 3D bioprinter (MicroFab Technologies) running JetLab4 controller software and 80 µm diameter microdispenser were used to spread either a single or double pass 10 x 8 sequential array under 0.5 mm spacing containing 12,264 BBB drops at each of the 160 dot matrix (100µL total volume per excursion). 50µL micropipette drops were also tested in hourly intervals in either human and porcine scleras. No BBB drops and 2 h immersion served as negative and positive controls.
Results :
Butanolic extract presented a Proanthocyanidin content of 10.12 ± 0.01 %. A progressive effect was achieved with higher and wider temperature denaturation peaks (Figure 1 and 2) related to the exposure time and surface covered area.
Conclusions :
This is the first time that a natural agent (barbatimão) BBB was effectively used to modify the sclera biomechanical properties. Different patterns and studies using animals are under development as the toxicity of the barbatimão extract showed promising preliminary results in vitro.
This is a 2020 ARVO Annual Meeting abstract.