Biologically Active Preparations from the Leaves of Wild Plant Species of the Genus Rubus

Abstract

The plants of the genus Rubus (R.) are applied as antiseptic agents in the treatment of skin diseases. Despite the great interest in plants of this genus, there are few reports on the antioxidant and biological activities of preparations obtained from the leaves of these plants. Therefore, we decided to evaluate the antioxidant activity of preparations from leaves of wild plant species of the genus Rubus using the frequently applied DPPH, ABTS, and FRAP methods, as well as to determine the total polyphenol content using the Folin−Ciocalteau method and perform qualitative evaluation by gas chromatography−mass spectrometry (GC-MS). The bactericidal and fungicidal activities of the obtained preparations were evaluated by applying laboratory tests: using the disc and the well methods based on the standards EN 13697:2019, EN 13697:2015, and EN 1500:2013. Microbiological tests of the plant preparations against bacteria, fungi, and yeasts isolated from the environment and against reference strains were performed. Moreover, antimicrobial testing of antibiotics against the tested strains was performed for comparison. The n-octanol/water partition coefficient of the obtained preparations was determined by the shake-flask method to determine their lipophilicity. According to the results, a high content of polyphenols and other antioxidant and biologically active compounds can be thought of as the parameter responsible for the effective activity of plant preparations obtained from wild plant species of the genus Rubus. The methods for determining bactericidal and fungicidal activity clearly demonstrates that preparations with reduced ethanol content exhibit bactericidal and fungicidal activity on surfaces. Testing of hand disinfection by means of rubbing with the preparations confirmed their antimicrobial activity against Escherichia coli K12 NCTC 10538. The obtained results show that the tested preparations exhibit on average two times lower activity against the reference bacterial strains than comparable antibiotics. The preparations obtained from the leaves of R. idaeus L. and R. fruticosus L. could complement classical antibiotics. While environmental bacteria showed a similar response to the preparations and antibiotics, their sensitivity was about one-third less than that of the reference strains. Our studies have shown that the obtained preparations are highly hydrophilic (logP < 0). Thus, these preparations can only be used in lipid bilayers in the aqueous core of liposomes, not in the lipid envelope.

Keywords: antimicrobial activity; antioxidative potential; bioactive compounds; biologically active preparations; leaves of Rubus fruticosus L.; leaves of Rubus idaeus L..

Figure 1

ATR-FTIR absorption spectra of (a) preparation 1 obtained from the leaves of R. idaeus L. and (b) preparation 2 obtained from the leaves of R. fruticosus L.

Figure 2

Methods of application of plant preparation to Trypticase Soy Agar using the well method against (a) Escherichia coli and (b) Bacillus sp.

Figure 3

Interaction of P1, P2, and antibiotics with isolated yeast and fungal strains.

Figure 4

Interaction of P1, P2, and antibiotics with the isolated bacterial strains.

Figure 5

An example of the UV-Vis spectrum of the preparation obtained from the leaves of Rubus idaeus L.