Formulation and evaluation of the effects of ophthalmic nanoemulsion of Nigella sativa seed extract on atropine-induced dry eye in mice

Abstract

BackgroundNigella sativa L. seed from the Ranunculaceae family, whose many therapeutic effects have been stated in recent research, is one of the herbs with known anti-inflammatory effects. Nigella sativa L. seed may have therapeutic effects on dry eye, a disease that manifests with symptoms of redness, burning, foreign body sensation, and sensitivity to light. Aim of the studyTo evaluate the effects of Nigella sativa L. seed extract nanoemulsion on atropine-induced dry eye in mice. Material and methodsThe hydro-alcoholic extract of the Nigella sativa seed was prepared using the maceration method (10% w/w). Subsequently, by using Tween 20 and Tween 80 surfactants with different ratios, the desired nanoemulsion was achieved. DLS, Zeta potential, TEM, and FT-IR tests were used to determine the size and morphology of nanoparticles.A total number of 36 adult male mice were used in this study divided equally into six groups, each receiving a different compound according to the protocol with three groups receiving therapeutic nanoemulsion eye drops daily. Tear production was evaluated by Schirmer's test and reported as a ratio to the first-day tear production on days 1, 7, and 14. ResultsAccording to the investigations by the DLS method, the Nanoparticles' size was reported 10.4 nm. The TEM image revealed that the nanoparticle of Nigella sativa seed extract emulsion has a spherical shape with an approximate size of 10 nm. Zeta test results in -37.6 mv, which was evaluated as sufficient quality. The final composition of nanoemulsion was chosen as 5 % of Nigella sativa seed extract, 75 % of water, and 20 % of surfactant with a ratio of 1:4.Schirmer's test results indicated that the highest dose of nanoemulsion (1 %) resulted in the most significant amount of tear production, compared to lower doses (0.5 % and 0.1 %) and the control group. ConclusionThis study showed that Nigella sativa seed extract nanoemulsion has a potentially positive effect on the amount of tear production in atropine-induced dry eyes. Thus, the employment of this nanoemulsion should be considered in the treatment of dry eye.