In vitro protective effect of Pandanus ordoratissimus extract on ultraviolet B (UVB)-induced DNA damage
Pandanus ordoratissimus is an herb which has been widely used in Thai traditional medicines. A number of studies provided experimental evidence indicating that extracts from roots and leaves of P. ordoratissimus had powerful antioxidant and anti-inflammatory activities. However, the protective effects of extract from P. ordoratissimus flowers on ultraviolet B (UVB)-induced DNA damage have not yet been reported. This study focused on assessing the protective effect of P. odoratissimus extract (POE) against UVB by using human keratinocyte stem cells (KSCs) as an in vitro testing system. The keratinocytes were pre-treated with POE before being assayed for DNA damages caused by UVB (290 to 315 nm). Ascorbyl glucoside and DN-AGE®, reagents commonly used in cosmetic products to protect the skin against UV exposure due to their abilities to scavenge free radicals, were used as positive controls. The alkaline comet assay was used to quantify DNA damage. Photo-dependent cytogenetic lesions were assessed by the micronucleus test (MNT). It was found that POE effectively reduced the extent of DNA breakages and cytogenetic lesions upon exposure to UVB (erythemal ultraviolet (EUV); 17.09 mJ/cm2). POE significantly decreased tail DNA (TD%), tail length (TL) and micronucleus frequencies (MNFs) which is similar to the protective effects provided by ascorbyl glucoside and DN-AGE®.
Key words: Pandanus odoratissimus, comet assay, micronucleus test.