Gallic acid and myricetin-rich Labisia pumila extract mitigated multiple diabetic eye disorders in rats

Diabetes affected about a quarter of a billion people globally, and one out of four diabetics has eye or vision problems. This study investigated whether gallic acid and myricetin-rich Labisia pumila extract (LP) consumption would help prevent diabetic eye disorders and some probable biochemistry involved relating to inflammation, vascular leakage, and oxidative tension. Male rats were divided into four groups (n = 6), namely healthy control, diabetic non-treated control, and hyperglycemic rats treated with 150 or 300 mg/kg LP. Intraperitoneal injection of 60 mg/kg streptozotocin was used to induce diabetes. Rats were fed in the morning and evening. Diabetic retinopathy was graded in rats using a dilated retinal digital ophthalmoscopy. Rats were sacrificed at 12 weeks and the retina, optic nerve, cornea, lens, sclera, ciliary bodies, iris, and conjunctiva were examined histologically. The diabetic rats consuming LP for 10 weeks showed dose-dependent, histopathologically-reduced eye abnormalities (keratopathy, cataract, sclera, conjunctiva, ciliary bodies, iris, limbus, corneal edema, epithelial barrier inefficiency, shallow punctate keratitis, lower basal layer cell density, retinopathy, glaucoma, and corneal changes). The LP significantly suppressed inflammation [increased serum tumor necrosis factor-α (TNF-α), prostaglandin-E2 (PGE2)], vascular leakage [claudin-1], abnormal vascularization [vascular endothelial growth factor (VEGF)], oxidative tension [malondialdehyde/reduced glutathione ratio], and hyperglycemia [fasting blood glucose] of the diabetic rats. The LP consumption was significantly protective against diabetic eye disorders and optic nerve dysfunction which were related to inflammation, vascular leakage, abnormal vascularization, and oxidative tension, which most likely influenced eye hemorrhage and collagen cross-linkage. PRACTICAL APPLICATIONS: The study shows that gallic acid and myricetin-rich Labisia pumila (LP) leaf consumption may be used as a complementary therapy for managing diabetes (fasting blood glucose) and preventing diabetic eye disorders (keratopathy, cataract, sclera, conjunctiva, ciliary bodies, iris, limbus, corneal edema, epithelial barrier inefficiency, shallow punctate keratitis, lower basal layer cell density, retinopathy, glaucoma, and corneal abnormalities). The LP consumptions reduced the serum biomarkers for inflammation (serum tumor necrosis factor-α TNF-α; prostaglandin-E2), vascular leakage/abnormalities (claudin-1 and vascular endothelial growth factor VEGF), and oxidative tension (malondialdehyde/reduced glutathione MDA/GSH ratio). The LP was eye-protective probably by normalizing fasting blood glucose, reducing inflammation, oxidative tension, vascular leakage, and irregular vascularization.