A chemical and biological investigation of Lepidium latifolium L. (pepperweed)

The genus Lepidium (Brassicaceae) includes about 175 different plant species strikingly characterized by glucosinolates (GLs) as molecular tags [1]. The cultivated Lepidium latifolium L. (perennial pepperweed) was investigated to decipher its GL profile using 1) an indirect method with GC-MS analysis of the GL degradation volatile products (mostly isothiocyanates and nitriles) obtained by hydrodistillation and organic solvent extraction, and 2) a direct method with LC-MS analysis of intact GLs. GC-MS analysis showed that the most abundant GLs were sinigrin and glucotropaeolin, and a minor one was glucocochlearin. LC-MS analysis confirmed the presence of the above-mentioned GLs but also detected 4-methoxyglucobrassicin. In recent years, studies have been directed towards isothiocyanates due to the broad range of their biological effects [1-3]. Taking that into account, L. latifolium leaf extract and hydrodistillate containing GL degradation products were evaluated for their anticarcinogenic activity against two human tumor cell lines - glioblastoma cell line LN-229 and bladder cancer cell line UM-UC-3. Their antimicrobial activity against pathogenic and food spoilage bacteria and fungi was also assessed. The extract and distillate exhibited very similar anticarcinogenic and antibacterial activities, but with a somewhat better effect for the extract. On the other hand, both extract and distillate were found to exert very strong antifungal activity against Candida albicans (MIC50 8 and 16 µg/mL).