Antimicrobial activity of the Flo peptide produced in Scenedesmus acutus and Nannochloropsis oculata.

The continuous increase of bacterial pathogen resistance to conventional antibiotics has challenged the research community to develop new antimicrobial strategies. Antimicrobial peptides (AMP) are a promising alternative to combat multidrug-resistant strains compared to conventional antibiotics because of their biocompatibility. In the present study, the Flo peptide, an AMP from the Moringa oleifera tree, was expressed in the chloroplast of the microalgae Nannochloropsis oculata and Scenedesmus acutus. The transgene insertion was verified by PCR amplification, and the homoplasmy was corroborated in spectinomycin-resistant lines. The identification and quantification of the peptide were performed using ELISA. The antimicrobial activity was studied against the Gram-negative Escherichia coli (ATCC 25,922) and Klebsiella pneumoniae (ATCC 700,603). The inflammatory response of the total soluble proteins of transplastomic N. oculata was assessed by measuring secretion of the cytokines IL-6, IL-10, and alpha-tumor necrosis (TNF-α), and cytotoxicity was assessed. These results provide a potential strategy to produce the Flo peptide in microalgae with antibacterial activities.

Antimycobacterial, cytotoxic, and anti-inflammatory activities of Artemisialudoviciana.

ETHNOPHARMACOLOGICAL RELEVANCE: A third part of the world population has been exposed to the pathogen Mycobacterium tuberculosis, the etiological agent of tuberculosis (TB). TB is a deadly disease, and its treatment has been hampered because of the lack of new antibiotics or the development of new antimycobacterial agents against this pathogen. The situation is aggravated because of the appearance of multidrug-resistant strains. In Mexican traditional medicine, records showed Artemisia ludoviciana for the treatment of TB. Thus, the combination of antibiotics and plant extracts might represent new antimycobacterial agents as an attractive alternative. MATERIALS AND METHODS: The biological activities of ethanol extract obtained from A. ludoviciana were evaluated for its antimycobacterial activities using an M. tuberculosis clinical isolate. Also, the toxicity of the extracts was assessed ex vivo and in vivo using the human-derived macrophages cell line (THP-1) and the Artemia spp. model, respectively. Lastly, the inflammatory response of macrophages exposed to the extracts was also evaluated. RESULTS: The ethanol extract of A. ludoviciana showed antimycobacterial activity with a MIC of 250 µg/mL against a clinical strain of M. tuberculosis. Ex vivo cytotoxicity using the THP-1 cell line incubated with the ethanol extract showed an IC50 of 20 µg/mL. On the other hand, the Artemia model's toxicity test showed moderate toxicity when the A. ludoviciana extract was tested with LC50 of 195.64 µg/mL. Analysis of the inflammatory response of THP-1 cells exposed to the same extract showed no increase in secreted interleukine-6 and -10. Also, no effect was observed in the pro-inflammatory tumor necrosis factor-α cytokine level. Moreover, a chemical profile of the extracts identified achillin as the major component in the ethanol extract, along with other minor components such as thujone and stigmasterol. CONCLUSIONS: We showed that the ethanol extract of A. ludoviciana possessed antimycobacterial activity and could potentially be used to supplement the antibiotic treatment of TB.