Scientists test medicinal plant that treats cataract

CURRENTLY, the only clinically accepted approach for the treatment of cataract is surgery. But the cost of the surgery hinders many individuals access to treatment in different parts of the world and has increased the need for less expensive, non-surgical approach to cataract treatment.

Now, researchers, in providing an alternative approach to treat cataract, have identified Costus spectabilis, a common plant, as helpful in ameliorating the effect of cataract at low doses.

To validate its use as an eye drop in traditional medicine for the treatment of cataract, the researchers tested its extract on rats made to develop cataract in the laboratory.

The researchers included Salisu Shehu, Umar F. Shehu, Umar H. Danmalam and Nuhu M. Danjuma at the Ahmadu Bello University, Zaria, in collaboration with Sani Shehu at Kaduna State University.

The different doses of the rhizome of Costus spectabilis extract was applied to isolated lenses from adult Sprague-Dawley albino rats for 24 hours. Cataract or lens opacity was assessed by scoring and measurement of pixel intensity.

They found that 0.5 mg/mL of Costus spectabilis extract significantly decreased the opacity of the lens. Other doses of Costus spectabilis demonstrated a mild decrease in cataract formation or opacity of the lens.

Data from this study thus suggests the efficacy of the extract in reducing opacity and possibly restoring the lens bio-molecules and consequently prevention of cataract induction at a lower dose (0.5 mg/mL) but not at the higher doses.

The 2019 study, published in the Tropical Journal of Natural Products Research, said the reason for the significant reduction in the severity of cataract by the extract at a lower dose, when compared with the higher doses, is not yet understood.

The study said its extract contains chemical substances such as steroids, triterpenes, saponins and flavonoids

According to them, “the observed activity of the extract may be exerted by one or a combination of these chemical compounds. The information provided could be useful in providing the scientific basis for the reported use of the plant in folk medicine.”

Costus spectabilis, commonly known as yellow trumpet, is sometimes harvested from the wild for local use of its edible leaves. It is used by traditional medicine to treat internal and external wounds, coughs, inflammation, arthritis, rheumatism, fever, maternal and neonatal infections. It is also recommended for its laxative, purgative and diuretic properties.

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In Tanzania, the juice from the stem of Costus spectabilis is used to treat worm infection alone or in combination with the juice of Dissotus rotundifolia or the stalk of Aframomum species.

Plant extracts, such as extract of scent leaf, aqueous garlic extract, onion juice, as well as a fraction of substances extracted from Emilia sonchifolia and polyphenolic compounds of Camelia sinensis have been proven to ameliorate cataract induced by chemical substances such as selenite.

Previously, other researchers reported also that fresh sap from the rhizome of Costus spectabilis or the water extract had been used as an eye drop in traditional medicine for the treatment of cataract.

This 2018 study was an inventory of medicinal plants used in the treatment of eye ailments in Zaria metropolis and published in the Nigerian Journal of Pharmaceutical Science.

Scientists are not entirely sure what causes cataracts, but most cases are related to age. Cataract is the leading cause of blindness worldwide accounting for 50 per cent of all cases.

It causes the lens of the eye to become progressively cloudy, and when left untreated, can lead to total blindness. While cataracts cannot spread from one eye to the other, they can occur independently in both eyes.

A fifth of adults 40 years and above in Nigeria are reported to have some degree of lens opacity. In 2005, data from the Ophthalmological Society of Nigeria indicated that about 1.2 million people in Nigeria were blind due to cataract and about 4.08 million people had low vision.

The report also estimated that the number of blind and low-vision people would almost double by the year 2020 unless concerted action is taken.

Previous studies had associated some flavonoids and polyphenolic compounds of some plant extract with the ability to prevent cataract. For example, extracts of scent leaf, Hydrocotyl bonariensis, Camelia sinensis and ginger contain antioxidants or other components that may slow down the oxidation process.