Resistance modulation studies of vernolide from Vernonia colorata (Drake) on ciprofloxacin, amoxicillin, tetracycline and erythromycin

Abstract

Resistance modulatory activities of natural products on traditional antibiotics have gained scientific interest in recent years. This is aimed at maximizing antimicrobial potency with major strides in curbing microbial resistance and leading to potential drug discovery. The antimicrobial activity of vernolide, a compound isolated from Vernonia colorata was investigated following its forklore use as antibiotic. The compound Vernolide was isolated from the leaves of Vernonia colorata and the identity was confirmed by appearance, melting point, 1H and 13C NMR as well as UV-Vis and IR spectroscopy. The antimicrobial activity of the isolate was evaluated with MTT (3-[4, 5-dimethylthiazol-2-yl]-2, 5 diphenyl tetrazolium bromide) assay using micro broth dilution and 96 well microtiter plates against standardized bacteria suspensions of selected inoculum. Vernolide showed activity against Escherichia coli, Staphylococcus aureus and Enterococcus faecalis with minimum inhibitory concentrations (MICs) of 0.3, 0.3 and 0.4 mg/ml respectively. The MIC of the selected antibiotics, namely on ciprofloxacin, amoxicillin, tetracycline and erythromycin were subsequently determined as a range between 0.1µg/ml to 16 µg/ml. Modulation studies between vernolide and the selected antibiotics showed that all antibiotics were able to prevent growth of the microorganisms at a concentration of 0.2 mg/mL vernolide and varying concentrations of the standard antibiotics in the range of 4.00 µg/ml to 0.0005 µg/ml which are far well below their observed MICs. Vernolide has therefore been shown to possess strong resistance modulatory activity on ciprofloxacin, amoxicillin, tetracycline and erythromycin against Escherichia coli, Staphylococcus aureus and Enterococcus faecalis

Phytochemical composition and toxicity study of the aqueous extract of the leaves of Vernonia colorata (Willd.) Drake in Wistar rats

“…These results are in agreement with those of Siaka [16] except for the flavonoids which was not found in our study. Studies have shown that methanolic and ethanolic extracts of Vernonia colorata leaves contain alkaloids and flavonoids [5,7,13]. The absence of alkaloids and flavonoids in the aqueous extract could be explained by the type of extraction used and also by the existence of chemotype within the species of Vernonia colorara [16,17].…”

“…The presence in AEVC of the compounds such as, phenols, triterpenes, saponoids, glycosides, steroids, whose main properties are antiplasmodial, antioxidant, antibacterial and anti-inflammatory and hepatoprotective and antimicrobial, would justify its traditional use for the treatment of certain diseases [8,9,13]. Saponosides are also known to help lower blood cholesterol levels and reduce the incidence of cardiovascular disease [5]. Triterpenoids exhibit cytotoxicity against a variety of tumor cells as well as anticancer properties [1].…”

“…Furthermore, the leaves of Vernonia colorata are used locally in decoction for the treatment of malaria and as an antibiotic in disease of the liver, stomach, gastrointestinal disorders and skin rashes [5]. In addition the decoction of stem, root and trunk barks of Vernonia colorata are used in the treatment of schistosomiasis, sterility and frigidity [6].…”

Vernonia amygdalina: a comprehensive review of the nutritional makeup, traditional medicinal use, and pharmacology of isolated phytochemicals and compounds

“… (2012),Paul et al (2018),Alara et al (2019),Adebayo et al (2014),Aremu et al (2018),Adu et al (2018),Zubairu et al (2019). Oluyege (2019),Momoh et al (2012),Ogunnowo and Alao-Sanni (2010),Okeke et al (2015),Johnson et al (2015),Ali et al (2019),Udochukwu et al (2015) RootTula et al (2012),Inusa et al (2018),Oluyege (2019),Okeke et al (2015, Johnson et al (2015), Udochukwu et al -Sanni (2010), Tula et al (2012), Alara et al (2019), Adebayo et al (2014), Aremu et al (2018), Adu et al (2018), Zubairu et al (2019), Momoh et al (2012), Johnson et al (2015), Udochukwu et al -Sanni (2010), Tula et al (2012), Kaur et al (2019), Paul et al (2018), Alara et al (2019), Adebayo et al (2014), Aremu et al (2018), Adu et al (2018), Zubairu et al (2019), Oluyege (2019), Momoh et al (2012), Okeke et al (2015), Johnson et al (2015), Ali et al (2019), Udochukwu et al (2015) Root Tula et al (2012), Inusa et al (2018), Okeke et al (2015), Andrew (-Sanni (2010), Tula et al (2012), Kaur et al (2019), Paul et al (2018), Adebayo et al (2014), Aremu et al (2018), Zubairu et al (2019), Oluyege (2019), Momoh et al (2012), Okeke et al (2015), Johnson et al (2015), Ali et al (2019), Udochukwu et al (2015) (Continued on following page) Frontiers in Natural Products frontiersin.org…”