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Knight Scientific Limited (KSL) is a UK biotechnology company based in Plymouth, Devon. The work of the founders, Drs Jan and Robert Knight, over a period of some 20 years, has led to a range of unique analytical products put to a variety of uses in all the continents of the world by a wide variety of companies and research workers.

KSL’s trade mark ABEL® is an acronym for Analysis By Emitted Light. The light emitter, unique to KSL, is the photoprotein, Pholasin® that is isolated and purified by KSL from a species of bioluminescent marine mollusc farmed by the company. Pholasin® is exquisitely sensitive to free radicals and it is this property that is exploited in the following kits.

ABEL® kits are being used in the personal care and nutraceutical markets to measure the antioxidant and pro-oxidant properties of materials and finished products. The various tests provide complementary information. A complete profile of the way the material on its own, or in synergy with other components in the formulation, behaves when challenged with particular free radicals and oxidants can be built.

ABEL® kits are presently in use for:

  • assessment of the antioxidant and pro-oxidant capacity of raw materials, ingredients and finished products
  • assessment of batch to batch uniformity
  • assessment of the biocompatibility of raw materials, ingredients and finished products
  • assessment of the antioxidant status of blood and other fluids
  • assessment of the biocompatibility of medical devices and their components
  • a wide range of research related to oxidative stress, especially to the 150 or so free radical mediated diseases, including diabetes, heart disease and some cancers

There are two types of kit:


Each type isprovided in two forms, for use in microplate luminometers or in tube luminometers. Kits come in several sizes.



ABEL® series Antioxidant Tests in which superoxide and other free radicals are generated to elicit light from Pholasin®. Antioxidants are measured by the degree to which this light is reduced. Each test takes less than 10 seconds. Results can be quantified against ascorbate standards. This series is excellent for measuring pro-oxidant activity as well.

ABEL® series Antioxidant Tests in which the halogenated oxidant hypochlorous acid is generated. The assay takes about 30 seconds and can be used on ingredients in either aqueous or organic solvents.

ABEL® series Antioxidant Tests generate peroxynitrite. These tests are Total Antioxidant Capacity (TAC) tests. They measure lipophilic antioxidants such as Vitamin E as well as hydrophilic antioxidants such a glutathione. Samples can be tested in aqueous or organic solvents. Pro-oxidants can also be measured with this test.

This assay is used extensively to measure TAC of people using only a finger prick of blood.

ABEL® series Antioxidant Tests generate hydroxyl radicals. These are rapid – ten second – and simple tests and are used to assess antioxidants in a variety of materials including plants.

ABEL® series Superoxide test generates a constant stream of superoxide at a range of concentrations, some as low as those produced by individual cells. This assay can be used to assess the activity of superoxide against a test substance or the activity of superoxide dismutase and its mimetics.




ABEL® series Cell Activation Tests are used to measure free radicals produced by stimulated white blood cells in whole blood. They are simple to use and require minute samples, for example 1μL of blood. Among the many applications is the assessment of the biocompatibility of ingredients and formulations and their actions on free radicals produced by living cells.

ABEL® series Cell Activation Tests for use with different types of isolated cell.


As well as selling kits and providing help with assay design, KSL itself carries out in its own laboratories contract testing on behalf of companies and research workers.

To tap in to these unique products and KSL’s vast experience of their development and use contact:

Dr Jan Knight, Knight Scientific Limited, 15 Wolseley Close Business Park, Plymouth, UK, PL2 3BY

Telephone : +44 (0)1752 565 676

Fax : +44(0)1752 561672



Contact Details

Knight Scientific Limited
15 Wolseley Close
Wolseley Business Park
United Kingdom

Tel: +44 (0) 1752 565 676
Fax: +44 (0) 1752 561 672