Antibacterial effect of Libanstine from Ilex paraguariensis (Yerba Mate)

Antibacterial effect

Lebanon from Ilex paraguariensis (Yerba Mate)

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According to reports, infectious diseases are one of the leading causes of death in the world. The World Health Organization (WHO) warns of an increase in deaths due to antimicrobial resistance. Recently, there has been a tendency to search for new active antibacterial compounds in plants. Ilex paraguariensis  , known as Yerba Mate, is a plant known for being rich in numerous bioactive compounds that play an important role in human health. In this study, Yerba Mate was extracted  with a mixture of acetone  : water (1:1) and then fractionated with  hexane  , chloroform and  ethyl acetate  . The obtained fractions were tested for  antibacterial activity against Staphylococcus aureus  and  Salmonella  species  Minimum inhibitory concentration  (MIC)  values  ​​for S. aureus  S. aureus  and 1.56 mg/mL to 3.12 mg/mL for  Salmonella species. The aqueous fraction was further treated with various enzymes to mimic  in vivo digestion  . The active metabolite  ranged from 1.56 to 3.12 mg/mL for both the chloroform and  ethyl acetate  fractions. For the water fraction, the MIC values ​​ranged from 0.78 to 3.12 mg/mL on digestion and the fractions obtained were then tested for  antibacterial activity . Furthermore, the Yerba Mate aqueous fraction was run on High Performance Liquid Chromatography (HPLC) and collected fractions were tested for antibacterial activity, to identify the . Fraction 3 was tested on various  S. aureus strains  and the MIC values ​​ranged from 0.19 to 1.56 μg/ml. A new pyrazinone, Libanstin, was identified from Ilex paraguariensis using NMR spectroscopy   .

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Staphylococcus aureus  is a Gram-positive bacterium. It is a human pathogen that causes minor and major diseases. This bacterium is resistant to many antibiotics due to mutations leading to changes in antibiotic binding sites and high expression of efflux pumps [10]. Salmonella species  are Gram-negative bacteria. They cause infections leading to many clinical syndromes. The risk of infection with multidrug-resistant  Salmonella  occurs when antibacterial agents are used against these bacteria [7].

Herbal medicines are widely used as therapeutic agents due to their availability, increasing demand for natural and organic products, and proven synergistic effects [26]. Ilex paraguariensis  is a herb commonly used in Latin American countries. The leaves of this plant contain high concentrations of many bioactive molecules: phenolic compounds, mainly tannins, flavonoids and phenolic acids [2]. It is also rich in theobromine, caffeine, caffeoylquinic acid and dicaffeoylquinic acid derivatives [18].

Polyphenols present in Yerba Mate contribute to its antioxidant effect [5] and protect body tissues against oxidative stress [20]. Saponins are glycoside compounds that have both hydrophobic and hydrophilic parts. Metasaponins from  Ilex paraguariensis  have anticancer [19], antiparasitic [23,24] and anti-inflammatory effects [18]. A synergistic anti-inflammatory effect is also observed between Yerba Mate saponins and quercetin [18].

Xanthines are purine alkaloids found in various plant extracts. Caffeine, theobromine and theophylline are the three xanthines found in Yerba Mate [27]. These alkaloids constitute a source of “energy dietary supplements” for the plant [21].

In this study, the antibacterial activity  of Ilex paraguariensis was investigated  after liquid-liquid partitioning into  S. aureus  and  Salmonella species. Furthermore, the bioactive compound(s) responsible for this antibacterial activity were investigated.

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General experimental

All 1D (  1H  and  13C  ) and 2D (COSY, HSQC-DEPT and HMBC) NMR spectra were recorded on a Bruker 500 MHz Avance HD spectrometer with a 5-mm BBFO Smart probe with a  Z gradient  (  1H  at 500 MHz,  13  °C at 125, 7MHz). 2D experiments were recorded using standard pulse programs. The samples were dissolved in CDCl3  and  the chemical shifts of the solvent signals at 7.24 ppm (δH) and  77.0  ppm (δC  )  were considered as the internal standard (reference signal). Observed chemical shift (δ) values ​​are given in ppm i

MIC values ​​of the Yerba Mate fraction against  S. aureus  and  Salmonella strains

Yerba Mate leaves were first extracted with various solvents to test the strongest antibacterial activity against several strains of bacteria. It was extracted with ethanol and further subfractionated with hexane, chloroform, ethyl acetate and water. MIC values ​​were not detected in these extracts at the highest concentration tested (4.375 mg/ml). Yerba Mate was then extracted with pure acetone and then subfractionated. Comparison of MIC values ​​(2.5 mg/ml) of fractions with their fractions


Plant extracts or their bioactive compounds have been extensively studied for their antimicrobial activity, especially for the growth of multidrug-resistant bacteria [16]. Ilex paraguariensis  (Yerba Mate) has recently gained popularity due to increased consumption and biological activity. Marcin et al. [15] tested methanolic and ethanolic extracts of Yerba Mate against  S. aureus  ,  S. enteritidis  ,  L. monocytogenes  and  E. coli  [15]. The ethanol extract had a lower MIC value than


Plants have been used to treat many infectious diseases since ancient times. Numerous studies demonstrate the antiproliferative, antioxidant, anti-inflammatory, antifungal and antibacterial effects of various plant extracts. In this study, the aqueous fraction, after liquid-liquid separation of acetone:water (1:1) extract from  Ilex paraguariensis stems and leaves  , showed the highest antibacterial activity. Moreover, a bioactive compound responsible for this effect has been demonstrated


This research received no specific grant from funding agencies in the public, commercial or not-for-profit sectors.

Author contributions

SE-S and EF performed the experimental procedures and helped prepare the manuscript. GP and AAF helped with compound identification, NMR analysis, and manuscript revision. RAM conceived the design of the work and was involved in the interpretation of results and revision of the manuscript. All authors have read and approved the final version of the manuscript.

The content on the website comes from  the National Library of Medicine and has been translated into Polish.

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