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17-11-2011 | Article

Plant extract is promising treatment for nail psoriasis


Free abstract

MedWire News: An ointment extracted from the leaves of indigo-bearing plants may one day be used to treat nail disease in people with psoriasis, say Taiwanese researchers.

In a preliminary study, indigo naturalis oil extract was effective in reducing the severity of nail psoriasis - a notoriously hard-to-treat disease.

"Although preliminary, these results indicate that it could provide a novel therapeutic option for nail psoriasis," write Yin-Ku Lin (Chang Gung Memorial Hospital, Keelung, Taiwan) and colleagues.

Nail psoriasis affects certain individuals with psoriasis, an autoimmune condition that primarily affects the skin. Nail psoriasis can cause a translucent discolouration of the nail bed, nail thickening, and nail ridges and pits.

Indigo naturalis ointment - a dark blue extract from plants such as Baphicacanthus cusia and Polygonum tinctorium - is widely used in traditional Chinese medicine and has recently been shown to be effective for clearing skin symptoms in patients with psoriasis.

In this study, Dr Lin's group developed a new formulation of the ointment, designed to reduce blue staining, which some people find offputting. They then tested it on 28 patients with nail psoriasis. Each patient applied one drop of ointment twice daily to each nail for 24 weeks.

Before starting treatment, the average severity of nail psoriasis symptoms (scored using the National Psoriasis Severity Index) was 36.1 and the average score for the most severely affected nail was 11.7.

By the end of the 24-week treatment period, the severity score had fallen to just 14.9, while the score for the worst affected nail had fallen to just 3.6.

The changes in both scores was statistically significant, say the researchers, supporting the effectiveness of the ointment.

"Further study is required to confirm safety and efficacy with a larger and more rigorously controlled trial, as well as to elucidate the pharmacological mechanisms of the observed antipsoriasis effects," write Lin et al in the journal Dermatology.

They conclude: "If further trials are successful, indigo naturalis may become an important tool in the treatment of a notoriously difficult disease."

MedWire ( is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited. © Springer Healthcare Ltd; 2010

By Joanna Lyford