Abstract:
Aim: The aim was to investigate the antiallergic effect of an aqueous leaf extract of Pistia
stratiotes (ALPS) in a murine model of ovalbumin (OVA)‑induced allergic conjunctivitis
(AC). Materials and Methods: Prior to topical challenge (instillation of 1.5 mg OVA in 10 μL
phosphate buffered saline into their conjunctival sacs) to induce AC, groups of sensitized
Imprinting Control Region mice (injected IP, on day 1 and 7, with 0.2 ml solution of
100 μg OVA and 0.01 mg aluminum hydroxide in phosphate buffered saline), were treated
with 5 mg/kg cetirizine, 10, 50 or 100 mg/kg of ALPS, or 2 ml/kg normal saline per os.
Conjunctival redness, lid edema, tearing and lid scratching (clinical symptoms of AC) were
scored. Serum OVA specific immunoglobulins were determined using ELISA. Histopathological
assessment of the conjunctival mucosal tissue was conducted. The extract was screened
for secondary plant metabolites. Results: Pretreatment with the extract significantly
(P ≤ 0.05–0.01) and dose‑dependently reduced the scores for clinical symptoms, which
were marked in vehicle‑pretreated mice. Pretreatment also lowered (P ≤ 0.01–0.001) serum
OVA specific immunoglobulins. Mast cell infiltration and degranulation in conjunctival stroma
(measured by an inflammatory score) in histopathological studies was also significantly low
(P ≤ 0.05–0.01) on pretreatment. Conclusion: The ALPS exhibited interesting antiallergic
activity and hence could be useful in managing AC.
