Antimicrobial screening of Plectranthus madagascariensis and P. neochilus extracts

Abstract

127 Biomedical and Biopharmaceutical Research J o r n a l d e I n v e s t i g a ç ã o B i o m é d i c a e B i o f a r m a c ê u t i c a Antimicrobial screening of Plectranthus madagascariensis and P. neochilus extracts AbstractNatural products are widely used as traditional medicines and are a common source of bioactive molecules for the treatment of bacterial infections. In particular, some plants of the genus Plectranthus (Lamiaceae) have demonstrated several applications, including the treatment of various infections. In this work, aqueous, acetonic and methanolic extracts of P. madagascariensis and P. neochilus were prepared using several extraction methods (infusion, decoction, maceration, microwave-and ultrasoundassisted and supercritical fluids). All extracts were screened for their antimicrobial activity against Gram positive bacteria (Enterococcus faecalis, Staphylococcus aureus, Bacillus subtilis and Mycobacterium smegmatis) and Gram negative bacteria (Pseudomonas aeruginosa, Klebsiella pneumoniae and Escherichia coli) and two yeast (Candida albicans and Saccharomyces cerevisiae) strains. The P. madagascariensis acetonic extracts obtained using ultrasound and maceration methods and P. neochilus acetonic extract obtained by ultrasound technique showed activity against the five tested Gram positive bacteria (5-24 mm of inhibition zone using the well diffusion test). The antimicrobial activity was further evaluated by the microdilution method (MIC values were between 250-0.49 μg/mL) and the bioautography assay against S. aureus. The P. madagascariensis ultrasound acetonic extract was the most active extract against all the tested Gram positive bacteria (MIC values ranged between 31.25 -0.49 μg/mL). It was also active against resistant MRSA and VRE strains (MIC values ranged between 31.25-0.98 μg/mL). The S. aureus bioautography assay showed that the more polar compounds were the responsible for the antimicrobial activity.Keywords: Antimicrobial activity; natural products; Plectranthus spp; extraction methods. ResumoOs produtos naturais são amplamente utilizados como remédios tradicionais e são uma fonte comum de moléculas bioativas para o tratamento de infeções bacterianas. Em particular, algumas plantas do género Plectranthus (Lamiaceae) demonstraram diversas aplicações, incluindo no tratamento de várias infeções. Neste trabalho, foram preparados extratos aquosos, acetónicos e metanólicos de P. madagascariensis e P. neochilus utilizando vários métodos de extração (infusão, decocção, maceração, extração assistida por micro-ondas e por ultrassom e com fluidos no estado supercrítico). Todos os extratos foram testados quanto à atividade antimicrobiana face a bactérias de Gram-positivo (Enterococcus faecalis, Staphylococcus aureus, Staphylococcus epidermidis Bacillus subtilis e Mycobacterium smegmatis) e de Gram-negativo (Pseudomonas aeruginosa, Klebsiella pneumoniae e Escherichia coli) e duas estirpes de leveduras (Candida albicans e Saccharomyces cerevisiae). O extrato acetónico de P. madagascariensis obtid...

Screening the dermatological potential of Plectranthus species components: antioxidant and inhibitory capacities over elastase, collagenase and tyrosinase

“…and P. prostratus Gürke) medicinal plants from South Africa were cultivated at “Instituto Superior de Agronomia” campus (Lisbon). Extraction methods were performed according to previously established literature procedures, with slight modifications 44 .…”

“…using bioassay-guided fractionation of extracts, were the abietane diterpenoids 7-acetoxy-6-hydroxyroyleanone ( 1 ) from P. grandidentatus 34 , 46 , 6,7-dihydroxyroyleanone ( 2 ) and 6,7-dehydroroyleanone ( 3 ) from P. madagascariensis 22 , Parvifloron D ( 4 ), the phytosterol 1:1 mixture of -sitosterol ( 5 ) and stigmasterol ( 6 ), and the 4:1 mixture of oleanolic ( 7 ) and ursolic acids ( 8 ), from P. ecklonii 31 , 46 , (13 S ,15 S )-6,7,12,19-tetrahydroxy-13,16-cyclo-8-abietene-11,14-dione ( 9 ) from P. porcatus 32 , the halimane diterpene (11 R *,13 E )-11-acetoxyhalima-5,13-dien-15-oic acid ( 10 ), the labdane diterpenoids Plectrornatin C ( 11 ) and the 1:1 mixture of 1,6-di- O -acetylforskolin ( 12 ) and 1,6-di- O -acetyl-9-deoxyforskolin ( 13 ), the triterpene 3:1 mixture of -amyrin ( 14 ) and -amyrin ( 15 ) from P. ornatus 30 , 33 , 45 , 47 , chlorogenic acid ( 16 ) from P. saccatus 22 and rosmarinic acid ( 17 ), the main polyphenol isolated from the aqueous extracts of Plectranthus spp. 44 . The chemical structures of these compounds have been established by comparing their spectral data with those in the literature and/or with authentic samples isolated by our group.…”

“…Organic and aqueous extracts of several Plectranthus spp. plants, as well as their isolated compounds ( Figure 2) were obtained, characterised and screened by our team, following the procedures described in previous phytochemical studies 23,[30][31][32][33][34][44][45][46] . Their antioxidant and specific anti-enzymatic activities were tested in support of their potential interest for application in preventive dermatology and/or synergistic therapeutics.…”

Anti-mycobacterial activity of labdane and halimane diterpenes obtained from Plectranthus ornatus Codd

“…I Recently, there has been a renewed interest in compounds of natural origin to find TB lead compounds. Natural products are a unique source of compounds for medicinal chemistry drug development, as they present complex chemical structures which may be important for specific interactions and recognition of potential macromolecular targets in the pathogenic microorganisms (8). M. smegmatis is an easy to grow, non-pathogenic mycobacterium often used as a first approach to anti-tubercular studies, as it is an attractive model organism of the pathogen M. tuberculosis (9).…”

“…Na verdade, houve um interesse renovado em compostos de origem natural para encontrar compostos protótipo (para o tratamento da tuberculose) para o desenvolvimento de fármacos em química medicinal. Estes compostos apresentam estruturas químicas complexas que podem ser importantes para interações específicas e reconhecimento de potenciais alvos macromoleculares nos microrganismos patogénicos (8). M. smegmatis é uma micobactéria não patogênica, fácil de semear, e frequentemente usada como primeira abordagem para estudos anti-tuberculares, pois é um bom organismo modelo do patogéneo mundial M. tuberculosis (9).…”