Chemical composition and antimycobacterial, anti-Malassezia furfur and cytotoxic activities of essential oils from Callistemon viminalis (Sol. ex Gaertn.) G. Don leaves and flowers.

Callistemon viminalis has been widely known due to its therapeutic properties. Tuberculosis is a deadly infectious disease caused predominantly by Mycobacterium tuberculosis. Other respiratory diseases may also be caused by nontuberculous mycobacteria. Malassezia furfur causes dermal inflammation and tissue damage. This study aimed to evaluate in vitro inhibitory effects of essential oils (EOs) from C. viminalis leaves (EO-CL) and flowers (EO-CF) against M. tuberculosis, Mycobacterium kansasii, Mycobacterium avium and M. furfur strains. Their cytotoxic activity was evaluated by the brine shrimp assay. Resulting MIC values of all EOs under study were promising since they ranged from 50 to 100 µg/mL. Both EO-CL and EO-CF showed nontoxicity against Artemia salina by the brine shrimp assay (LC50 > 1000 µg/mL). GC-FID and GC-MS analyses showed that 1,8-cineole was the major component of both EOs. These results revealed the promising potential of EO-CL and EO-CF to develop new antibacterial and antifungal drugs.

Volatile compounds of hexane extract from Pterodon pubescens Benth seeds and its significant in vitro potential against different bacterial strains.

Pterodon pubescens Benth is a Brazilian medicinal plant (sucupira, in Brazilian Portuguese). This paper aims to determine the volatile composition and antibacterial activities of hexane extract from P. pubescens seeds (HE-PP). Antibacterial activities were screened by the microdilution broth method in 96-well culture plates and MIC values were expressed as µg/mL. HE-PP was active against several oral bacteria whose MIC values ranged between 12.5 µg/mL and 50 µg/mL and against three mycobacterial strains (MIC = 125 µg/mL and 500 µg/mL). In addition, HE-PP was active against Xanthomonas citri strain (MIC = 100 µg/mL). Cytotoxic activity of the extract was evaluated in human tumour and non-tumour cell lines. HE-PP showed selective cytotoxicity to cervical adenocarcinoma (HeLa cells - IC50 = 53.47 µg/mL). Its major constituents were identified by GC-MS and GC-FID: E-caryophyllene, vouacapane, E-geranylgeraniol and dehydroabietol. Results reinforce the biological potential of HE-PP against a broad spectrum of pathogenic and phytopathogenic bacteria.