Bioactive fraction of Saraca indica prevents diabetes induced cataractogenesis: An aldose reductase inhibitory activity

Abstract

Background: The present study was designed to investigate the effect of Saraca indica (SI) flowers extract and different bioactive fraction on in vitro aldose reductase (AR) inhibitory activity, high glucose-induced cataract in goat lens and in vivo streptozotocin (STZ; 45 mg/kg, i.p) induced cataract in rats.

Methods: Extract of flowers of SI tested for inhibition against rat lens AR. Furthermore, bioactive fraction was investigated against high glucose-induced opacification of the lens in vitro lens culture and STZ induced diabetic cataract in rats. Identification of the bioactive component was attempted through high-performance thin-layer chromatography, high-performance liquid chromatography and liquid chromatography-mass spectrometry analysis.

Results: Ethyl acetate fraction of S. indica (EASI) produced maximum inhibition that may be due to high phenolic content. Goat lenses in media containing glucose developed a distinctly opaque ring in 72 h and treatment with EASI fraction lowered lens opacity in 72 h. Prolonged treatment with EASI to STZ-induced diabetic rats inhibited the AR activity and delayed cataract progression in a dose dependent manner.

Conclusion: Ethyl acetate fraction of S. indica fraction has potential to inhibit rat lens AR enzyme and prevent cataractogenesis not only in goat lens model (in vitro), but also in STZ induced diabetic rats (in vivo). This study is suggestive of the anticataract activity of EASI fraction that could be attributed to the phytoconstituents present in the same.

Keywords: Cataractogenesis; Saraca indica; streptozotocin.

Figure 1

Fractionation scheme for Saraca indica flower

Figure 2

Representative digitized illustrations of the anticataract activity of ethyl acetate fraction of Saraca indica (EASI) lenses for incubated (a) with 5.5 mM glucose (Normal control) (b) high glucose (c) high glucose + Quercetin (1 mg/ml) (d) high glucose + EASI (0.5 mg/ml) (e) high glucose + EASI (1 mg/ml)

Figure 3

Representative photograph lens of (a) normal control (b) diabetic control (c) ethyl acetate fraction of Saraca indica (EASI) 200 mg/kg treatment (d) EASI 400 mg/kg treatment

Figure 4

The effect of ethyl acetate fraction of Saraca indica fraction on streptozotocin-induced diabetic cataract. Representation of cataract progression in each group with the duration of diabetes in weeks. Stage of cataract in each group was averaged at a given time and the average stage of cataract was plotted as a function of time

Figure 5

High-performance thin-layer chromatography (HPTLC) fingerprint of ethyl acetate fraction of Saraca indica (EASI) fraction (image at 580 nm, after derivatization). HPTLC finger print of EASI showed presence of gallic acid (GA) at Rf = 4.1, EASI of the individual samples (2 mg/ml) was spotted onto the activated thin-layer chromatography plate. Toluene: Ethyl acetate: Formic acid 5:4:1 (v/v/v) as solvent system. Ferric chloride was used as derivatizing agent. (The track number 1-EASI 5 μl, 2-EASI 10 μl, 3-EASI 20 μl, 4-GA 5 μl, 5-GA 10 μl)

Figure 6

High performance liquid chromatography chromatogram for reference standard gallic acid (GA) and ellagic acid (a) and ethyl acetate fraction of Saraca indica (EASI) fraction (b). Both peaks have similar retention time of about 1.9 min indicating that EASI fraction sample contains GA as the active phytoconstituent

Figure 7

Mass spectral data of the different phytoconstituents present in the ethyl acetate fraction of Saraca indica (Tentative identification)