Phytochemical characterization and biological activities of Plectranthus barbatus Andrews/Caracterizacao fitoquimica e atividades biologicas de Plectranthus barbatus Andrews

Plectranthus barbatus Andrews (Lamiaceae) is widely distributed in the world and has a range of popular therapeutic indications. This work aimed to evaluate the phytochemical characterization of two leaf extracts of P. barbatus, and their antimicrobial, antineoplastic and immunomodulatory potential. After collection, herborization and obtainment of the P. barbatus aqueous extract (PBA) and acetone:water 7:3 P. barbatus organic extract (PBO), the phytochemical characterization was performed by high-performance liquid chromatography (HPLC). The antimicrobial activity was performed to determine the minimum inhibitory concentration (MIC) against eight bacterial strains using the microdilution test and the fungus Trichophyton rubrum by disc diffusion assay and microdilution test. Cytotoxicity was assessed by MTT and trypan blue methods in normal peripheral blood mononuclear cells (PBMCs) at concentrations ranged between 0.1 to 100 [micro]g.[mL.sup.-1] and in neoplastic cell lines Toledo, K562, DU-145 and PANC-1 at 1, 10 and 100 [micro]g.[mL.sup.-1]. Immunomodulatory activity, was evaluated by sandwich ELISA of proinflammatory cytokines at BALB/c mice splenocytes cultures supernatant. Both extracts presented flavonoids, cinnamic derivatives, steroids and ellagic acid. PBO showed bacteriostatic activity against Acinetobacter baumannii (MIC = 250 [micro]g.[mL.sup.-1]) clinical isolate and PBA fungistatic activity against Trichophyton rubrum (MIC = 800 [micro]g.[mL.sup.-1]). The extracts did not exhibit toxicity to PBMCs and neoplastic cells (IC50 > 100 [micro]g.[mL.sup.- 1]). Additionally, PBO at 100 [micro]g.[mL.sup.-1] significantly inhibited IFN-[gamma] and IL-17A cytokines (p = 0.03). Plectranthus barbatus is a potential candidate for therapeutic use due to its low toxicity in healthy human cells and exhibits biological activities of medical interest as bacteriostatic, fungistatic and immunomodulatory.