Cytotoxicity of Senecio in macrophages is mediated via its induction of oxidative stress

A comparative study on phenolic components and biological activity of some Senecio species in Turkey

OBJECTIVE

The phenolic components and biological activity of nine Senecio species growing in Turkey were investigated.

METHODS

Senecio species were extracted with methanol. The content of total phenols was determined using Folin-Ciocalteu method, while individual phenolic acids and flavonoids were detected using HPLC analysis. Also, to determine the antioxidant capacity, phosphomolybdenum assay and 1,1-diphenyl picrylhydrazyl (DPPH) radical-scavenging activity assay were used. Antimicrobial activity of extract was determined using agar diffusion and broth microdilution method.

KEY FINDINGS

The total phenolic contents of the extracts were found to be highest in Senecio cilicius and Senecio mollis extracts (117.45 and 113.40 mg equivalent to gallic acid/g, respectively). S. salsuginea showed the strongest free radical-scavenging activity with IC50 (the concentration providing 50% inhibition) = 26.23 μg/ml and S. mollis showed the highest antioxidant capacity in the phosphomolybdenum method (434.48 mg equivalent to ascorbic acid/g). The extracts exerted promising antibacterial activity against most of the test bacteria (minimal inhibitory concentration = 6.25-12.5 mg/ml), but no activity was observed against Candida albicans.

CONCLUSION

The results demonstrated that nine Senecio species possess high antioxidant and antimicrobial activity in accordance with the high amount of phenolic contents in the extracts that might be natural agencies used in many areas such as food, pharmacy and alternative medicine.

Monitoring of intracellular nitric oxide in leishmaniasis: its applicability in patients with visceral leishmaniasis

Nitric oxide (NO) has been demonstrated to be a principal effector molecule responsible for mediating intracellular killing of Leishmania parasites, the causative organism of leishmaniasis. As measurement of intracellular NO remains a challenge to biologists, we have developed a flow cytometric approach to perform real time biological detection of NO within Leishmania parasites and parasitized macrophages using a membrane permeable derivative of diaminofluorescein [4,5-diaminofluorescein diacetate (DAF-2DA)]. Initially, assay optimization was performed in Leishmania donovani promastigotes, assay specificity being confirmed using both a NO donor [S-nitroso-N-acetyl-penicillamine (SNAP)] and a NO scavenger [2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, C-PTIO]. Using 40 μM DAF-2DA, basal levels of intracellular NO were measured which varied in different Leishmania species; addition of conventional anti-leishmanial drugs, antimony and miltefosine translated into a dramatic increase in DAF-2T fluorescence. Furthermore, the assay also measured levels of NO in macrophages, but needed a 20 fold lower concentration of DAF-2DA, being 2 μM. Following parasitization, levels of NO decreased which was normalized following treatment with anti-leishmanial drugs. Similarly monocytes of patients with visceral leishmaniasis at disease presentation showed decreased levels of NO which too reverted on completion of treatment. Taken together, this study opens new perspectives of research regarding monocyte function and provides a real time approach for monitoring the effect of anti-leishmanial compounds.