Chemical composition, antioxidant and antifungal activities of essential oils and extracts from Plectranthus spp. against dermatophytes fungi

Abstract

SUMMARY Resistance to use antifungal drugs is a great concern seeking for scientists to discover new products to treat fungal infections. The aim of this study was to evaluate the antioxidant and antifungal activities of essential oils and extracts of Plectranthus grandis and Plectranthus ornatus against Trichophyton rubrum and Microsporum canis dermatophytes strains. Extracts were obtained from leaves by maceration in ethanol (96%) during 7 days. The oils were obtained by hydrodistillation and analyzed by gas chromatography/mass spectrometry. A total of 25 components were identified, as major constituents the sesquiterpenes β-caryophyllene, α-copaene, germacrene, β-caryophyllene and caryophyllene oxide. Antioxidant activities were evaluated using DPPH scavenging assay and antifungal action was determined by the broth microdilution method. The decocts obtained from the extraction of essential oil presented a greater antioxidant action when compared with the essential oils, with IC50 values of 12.35 μg/mL and 15.69 μg/mL to P. ornatus and P. grandis, respectively. Natural products presented significant antifungal activity, with MIC values ranging from 0.078 mg/mL to 0.31 mg/mL for all strains. The synergistic activity between Plectranthus spp. extracts and ketoconazole demonstrated a fungal growth inhibitory action when combined with a standard antifungal drug, indicating its potential for use in preventive veterinary medicine to treat dermatophytoses.

HPLC/DAD, Antibacterial and Antioxidant Activities of Plectranthus Species (Lamiaceae) Combined with the Chemometric Calculations

“…The ethanol extract of the aerial parts of P. barbatus and its chloroform fraction obtained DPPH inhibition percentages of 81.2 and 80.1% at the concentration of 1000 µg/mL, proving to be close to that obtained by ascorbic acid of 94.4% [30]. As for the ethanol extract, lyophilized decoct and acetate fraction of P. ornatus leaf decoct showed potential DPPH free radical scavenging, with IC50 of 67.04, 66.62 and 12.35 µg/mL, respectively [38].…”

Medical cannabis dimethyl ether, ethanol and butane extracts inhibit the in vitro growth of bacteria and dermatophytes causing common skin diseases

“…Tavares et al (2010) reported a strong MIC (1-5 µg/mL) of myrcene against a variety of microorganisms, including dermatophytes. Moreover, limonene, α-pinene, γ-eudesmol, germacrene (separated or as a apart of essential oil) also proved significant to moderate antidermatophytic activity (MIC = 0.8-250 µg/mL) which was sometimes even better than some used antifungals, e.g., griseofulvin (Sanguinetti et al, 2007;Singh et al, 2010;Pinto et al, 2013;Alves et al, 2018;Danielli et al, 2018). It is very probable that both groups of biologically active substances, i.e., cannabinoids and terpenes, have an important role in the antifungal activity of cannabis extract.…”

“…For example, 17–32% of clinical Trichophyton isolates in India were identified to be resistant to the widely used antibiotic terbinafine (TB) ( Singh et al, 2018 ). The situation is even more alarming in the case of bacteria, as the increasing number of multidrug-resistant strains such as Methicillin-resistant S. aureus (MRSA) ( Alves et al, 2018 ) is identified every year. The international strategies to tackle the antimicrobial resistance are known and slowly adopted by countries worldwide ( WHO, 2019 ).…”

Atividades biológicas de plantas medicinais utilizadas na Medicina Veterinária no Brasil entre 2000 e 2020: Uma revisão de literatura

“…O combate é feito com o uso de fungicidas, contudo, são poucas a opções de fungicidas no mercado farmacêutico para pets. Além disso, são necessárias altas concentrações para que os produtos apresentem o efeito desejado, o que traz riscos para a saúde do animal, necessitando de outras alternativas de fungicidas disponíveis (Frias & Kozusny-Andreani, 2009;Soares et al, 2015;Alves et al, 2018). Nesse sentido, muitos pesquisadores vêm trabalhando na tentativa de resolver esses problemas.…”

“…Alguns estudos já comprovaram as propriedades antifúngicas de plantas medicinais. É o caso de Alves et al (2018), que avaliaram a ação antifúngica de óleos essenciais e extratos de Plectranthus grandis e Plectranthus ornatos contra Trichophyton rubrum e Microsporum canis, fungos dermatófitos. Todas as plantas testadas apresentaram resultados significativos nos testes de concentração inibitória mínima, que variou de 0,078 mg/mL a 0,31 mg/mL para todas as cepas testadas, indicando seus potenciais usos como antifúngicos na medicina veterinária.…”