Antimicrobial activity, phytochemical characterization and gas chromatography-mass spectrometry analysis of Aspilia pluriseta Schweinf. extracts

Abstract

Aspilia pluriseta is associated with various bioactivities, although with limited scientific justification. In this study, we evaluated the antimicrobial activity, and characterized the phytochemicals of root extracts of A. pluriseta aimed at validating its therapeutic potential. We used BACTEC MGIT™ 960 system to test for antitubercular activity, disc-diffusion together with the microdilution method to evaluate antimicrobial activities and qualitative phytochemical tests together with gas chromatography-mass spectrometry (GC-MS) analysis to determine the phytochemicals that associated with A. pluriseta extracts activity. We show that methanolic crude extract (at 1 g/mL) had high Mycobacterium tuberculosis (MTB) inhibitory activity (0 growth unit) and considerable potency against Escherichia coli (11.7 mm), Staphylococcus aureus (9.0 mm), and Candida albicans (7.7 mm). All the extract fractions exerted remarkable antimycobacterial activities with minimum inhibitory activity of between 6.26 – 25 μg/mL. The highest antimicrobial activity of petroleum ether and dichloromethane fraction was against E. coli at inhibition zone diameters of 8.3 mm, and 8.0 mm, respectively, while ethyl acetate fraction was against S. aureus with an inhibition zone of 8.7 mm. Methanolic fraction exhibited broad-spectrum activity against 87.5% of the tested microbes (inhibition zones 6.3–8.3 mm). Furthermore, we qualitatively detected terpenoids, alkaloids, and phenolics such as flavonoids, and anthraquinones in extract fractions. GC-MS analysis detected an abundance of fatty acid esters, 2-hydroxy-1-(hydroxymethyl) ethyl ester-hexadecanoic acid, and 2,3-dihydroxy propyl ester-octadecanoic acid and four alkanes. Taken together, we show that A. pluriseta extract fractions (especially ethyl acetate and methanolic fractions) have strong selective antitubercular activity, and thus, we scientifically validate the use of A. pluriseta as a potential source for the discovery of novel antitubercular agents.

In vitro cytotoxicity of Aspilia pluriseta Schweinf. extract fractions

“…Here we extend the findings of our previous publications [ 5 , 6 ] by looking at the safety of Aspilia pluriseta Schweinf. ( Asteraceae ) extract fractions in an in vitro system.…”

“…The plant materials were processed, extracted and finally fractionated as described in Njeru and Muema [ 5 ]. Briefly, root materials were cut into small pieces and allowed to air-dry in the dark at 23 ± 2 ℃ until they attained a constant weight.…”

“…Plant-derived products and compounds have been used to treat and manage a wide range of diseases and infections since ancient times. The utilization of plant-derived products and compounds is favoured because these products and compounds exhibit fewer side effects, have improved efficacy and have reduced chances of developing resistance [ 1 – 5 ]. The bioactivity of plant extracts are a result of secondary metabolites, also called phytochemicals [ 3 ].…”

“…( Asteraceae ) extract fractions in an in vitro system. A. pluriseta is a common herb in Kenya [ 5 , 7 ], as well as in East, Central, and Southern Africa, [ 8 , 9 ]. A. pluriseta is traditionally used to manage and treat wounds, cough, stomach illness, burn wounds, pimples, ears-, eye-, nose infections, kwashiorkor, fever, worms disorders, and diabetes mellitus with little or no scientific validation [ 7 , 9 – 14 ].…”

“…A. pluriseta is traditionally used to manage and treat wounds, cough, stomach illness, burn wounds, pimples, ears-, eye-, nose infections, kwashiorkor, fever, worms disorders, and diabetes mellitus with little or no scientific validation [ 7 , 9 – 14 ]. Recently we have reported A. pluriseta selective antitubercular activity [ 5 ]. Other studies have reported A. pluriseta antiviral [ 9 ], antihelmintic [ 15 ], antimalarial, hypoglycaemic [ 7 , 14 , 16 ], molluscicidal [ 17 ] and complement modulating activities [ 18 ].…”