|Year : 1982 | Volume
| Issue : 5 | Page : 441-443
Study of content of redox substances ergothioneine, glutathione and ascorbic acid in normal and senile cataractous lenses in human eyes
Yogesh Shukla, OP Kulshrestha, KP Khuteta
Deptt. of Ophthalmology, S.M.S. Medical College, Jaipur, India
Deptt. of Ophthalmology, S.M.S. Medical College, Jaipur
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Shukla Y, Kulshrestha O P, Khuteta K P. Study of content of redox substances ergothioneine, glutathione and ascorbic acid in normal and senile cataractous lenses in human eyes. Indian J Ophthalmol 1982;30:441-3
With a view to understand the pathophysiology of cataract formation, the quantity of certain substances are estimated in clear and opaque lenses. It is hoped that their differential level could lead to the answer. There are certain substances which are reversibly oxidised and reduced - commonly known as 'Redox' substances are though to be specially vital. Three such substances : glutathione, ascorbic acid and ergothioneine have been estimated in clear lenses immature cataracts and mature cataracts.
| Materials and methods|| |
A study of 125 human lenses was carried out of which 10 were normal transparent lenses, 40 immature cataract (20 nuclear and 20 cortical type), 50 mature cataract and 25 hypermature cataract. The cataractous lenses were obtained from patients operated for cataract and normal lenses from the Eye Bank and removed in either cases by intracapsular extraction. Each lens was weighed immediately after extraction and put to estimation of the three substances.
Determination of ergothioneine was done by the method of Hunter slightly modified by Lawson et all which depends upon precipitation with iodo bismuthous acid and estimation of Ergothioneine in the precipitates by means of phyotocolorimeter. Determination of total glutathione was done by micro titration methods using indicator dye and ascorbic acid by the method of Birch, Harris and Ray sub .
It is seen clearly from our results that the level of all the three substances viz. ergothioneine, glutathione and ascorbic acid is reduced markedly in all types of cataract as compared to the normal transparent lenses.
| Observations and discussion|| |
The value of ergothioneine is reduced from normal 115.68 mg/100 gm to 94.19 mg/100 gm in immature nuclear and to 79.64 mg/I00 gm in immature cortical cataract. In mature and hypermature types the mean level falls further to 71.66 mg/100 gm & 60.81 mg/ 100 gm respectively from normal value. As far as we are aware references of similar estimation done in human lenses is not available in literature.
The value of total glutathione reduces from normal 214.31 mg/100 gm to 51.0 mg/100 gm in immature nuclear type of cataract and to 41.76 mg/I00 gin in immature cortical type. In mature and hypermature cataract the level falls to mere 11.06 mg/100 gm and 8.88 mg/100 gm respectively from normal value. Such severe reduction in level of total glutathione with the occurance of cataract has been reported by almost every worker in the field ,sub . Dische and Zi1 sub showed that lens opacities do not develop by simple oxidation of cysteine (SG group) of soluble protein to cystine (S-S group) but require diminution in quantities of reduced glutathione also. They therefore expressed that glutathione reduction has a major role in cataract formation.
The value of ascorbic acid reduces from normal 27.32 mg/l00 to 11.15 mg/I00 gm. in immature nuclear and 9.36 gm/100 gm in immature cortical cataract and is further reduced to 4.75 mg/ 100 gm and 4.18 mg/ 100 gm in mature and hyper mature cataracts respectively. Most of the workers have reported a decrease in the level of ascorbic acid during cataract formation.
There is thus, a progressive fall of all three substances during cataract formation and the decrease is proportional to the degree of opacification of lens. In immature cataract the fall is less while in totally mature and hypermature cataract the fall is much greater, and this decrease is found to be statistically highly significant in all forms of cataract.
Whether this diminution in content is a cause or simply an effect of cataract formation can not be answered univocally. Whether this significant decrease in cataractous lenses has got arty direct role to play in the genesis of lens opacities is yet to be established. Being redox substances and by virtue of having sulfhydryl group, they take active part in auto-oxdative mechanism and other processes concerning vitality of lens and thus their direct relationship with the formation of cataract could be highly probable but their precise role in the genesis of cataract formation remains to be further explored.
| Summary|| |
A study of level of ergothioneine, total glutathione and ascorbic acid was done on 125 human lenses cataractious and normal. A statistically highly significant decrease in level of all three substances was observed in all types of senile cataract, almost proportionate to the degree of lens opacification. Denser the lens opacity (cataract) greater was the decrease in the value of these substances. These findings are strongly suggestive of a close link of ergothioneine, glutathione and ascorbic acid in the causation of senile cataract.
| Acknowledgement|| |
This work was sponsored by Research grant from the Indian Council of Medical Research.Their help is generously acknowledged.
We are thankful to Mr. V. Srivastava for his technical assistance.
| References|| |
Lawson, A. and Moorley, H.V. 1950: Biochemical J. 47: 513.
Birth, T.W., Harris, A. and Ray, P, 1945, Quoted by Rados, Arch, Ophthalmol. 34 : 202.
Disch, Z. and Zil, H., 1951, Amer J. Ophthalmol, 34: 104.
Davson, H., 1969, The eye-vegetative phNsiology and Biochemistry.
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