AGROBIODIVERSITY f o r i m p r o v i n g n u t r i t i o n , h e a l t h a n d l i f e q u a l i t y 2017

This study aimed to evaluate the antibacterial activity of ethanolic extracts obtained from the leaves of Aglaonema commutatum Schott and its cultivars («Malay Beauty», «Silver Queen», and «Silver King») against Escherichia coli (Migula) Castellani and Chalmers (ATCC® 25922™) strain. The leaves of Aglaonema commutatum plants and its cultivars, cultivated under glasshouse conditions, were sampled at M. M. Gryshko National Botanic Garden (NBG), National Academy of Science of Ukraine (Kyiv, Ukraine). The leaves were brought into the laboratory for antimicrobial studies. Freshly sampled leaves were washed, weighed, and homogenized in 96% ethanol (in proportion 1:19) at room temperature. The extracts were then filtered and investigated for their antimicrobial activity. Escherichia coli (Migula) Castellani and Chalmers (ATCC® 25922™) strain was used in our study. Antimicrobial activities of various ethanolic extracts obtained from leaves of Aglaonema commutatum plants and its cultivars («Malay Beauty», «Silver Queen», and «Silver King») against Escherichia coli (Migula) Castellani and Chalmers (ATCC® 25922™) strain was screened in the current study. The testing of the antibacterial activity of the plant extracts was carried out in vitro by the Kirby-Bauer disc diffusion technique. The leaf extracts from A. commutatum «Silver Queen» and A. commutatum 'Silver King' exhibited higher inhibitory activity than the extracts from A. commutatum and A. commutatum «Malay Beauty». Maximum in vitro inhibition was scored by A. commutatum «Silver Queen», followed by A. commutatum «Silver King», A. commutatum, and A. commutatum «Malay Beauty». In particular, the leaf extracts from A. commutatum «Silver Queen» and A. commutatum 'Silver King' exhibited higher inhibitory activity than the extracts from A. commutatum and A. commutatum «Malay Beauty». Maximum in vitro inhibition was scored by A. commutatum «Silver Queen», followed by A. commutatum «Silver King», A. commutatum, and A. commutatum «Malay Beauty», which presented inhibition zones of (18.6±1.2) mm, (16.1±0.9) mm, (15.7±1.1) mm, and (13.5±1.0) mm, respectively. In the case of the positive controls, 96% ethanol possesses a mild anti-E. coli effect, which presented inhibition zones of (9.5±1.2) mm. The inhibition zone diameters were increased by 96% (p<0.05) for A. commutatum «Silver Queen», by 69 % (p<0.05) for A. commutatum «Silver King», by 65 % (p<0.05) for A. commutatum, and by 42 % (p<0.05) for A. commutatum «Malay Beauty». Thus, the use of these plants in traditional medicine and veterinary medicine was experimentally confirmed as a potential source of raw materials for the development of medicines in the future, as well as for the development of innovative feed for farm animals.

This research aimed to evaluate the in vitro effect of buffer extract obtained from leaves and pseudobulbs (modified shoots) of Dendrobium parishii Rchb. f. on the 2-thiobarbituric acid reactive substances (TBARS) as lipid peroxidation biomarker, aldehydic and ketonic derivatives of oxidatively modified proteins, and total antioxidant capacity (TAC) in the muscle tissue of the rainbow trout (Oncorhynchus mykiss Walbaum). The shoots (pseudobulbs) with leaves of Dendrobium parishii cultivated under glasshouse conditions were sampled at M.M. Gryshko National Botanic Garden (NBG) (Kyiv, Ukraine). Since 1999, the whole collection of tropical and subtropical plants (including orchids) has had the status of a National Heritage Collection of Ukraine and is supported through State funding. Besides, NBG’s collection of tropical orchids was registered at the Administrative Organ of CITES in Ukraine (Ministry of Environment Protection, registration No. 6939/19/1-10 of 23 June 2004). The collected pseudobulbs and leaves were brought into the laboratory for biochemical studies. Freshly collected leaves were washed, weighed, crushed, and homogenized in 0.1M phosphate buffer (pH 7.4) (in proportion 1:19, w/w) at room temperature. The extract was then filtered and investigated for its antioxidant capacity. The extract was stored at -20°C until use. The increase in TBARS level in the muscle tissue exposed to extracts derived from leaves and pseudobulbs of D. parishii was insignificant. The level of ketonic derivatives of oxidatively modified proteins was non-significantly decreased both for leaf and pseudobulb extracts compared to the untreated samples. The extracts obtained from leaves and pseudobulbs of D. parishii significantly increased the TAC level in muscle tissue due to inhibited the Fe2+/ascorbate-induced oxidation of Tween 80. Overall, these findings demonstrate that aqueous extracts of vegetative organs of Dendrobium parishii can enhance the total antioxidant capacity in the muscle tissue of the rainbow trout. Moreover, this antioxidant effect was more intensive for pseudobulb extracts.

Orchids belong to the largest family of angiosperms possessing the antimicrobial, antioxidant, hepatoprotective, anti-inflammatory, anti-arthritic and wound healing properties revealed in preclinical studies. The study of orchids also can provide health professionals with alternative, feasible, and low-cost therapies for treating bacterial and fungal diseases. For this reason, orchids may be used as new antimicrobial agents. Our previous study reported that the selected orchids belonging to the genus Coelogyne Lindl. exhibited fairly strong antioxidant and antimicrobial activities. This paper focused on the assessment of the antibacterial activity of eight plants, i.e. Coelogyne cristata Lindl., C. fimbriata Lindl., С. flaccida Lindl., C. huettneriana Rchb.f., C. ovalis Lindl., C. speciosa (Blume) Lindl., C. tomentosa Lindl. and C. viscosa Lindl. towards clinical cefuroxime-resistant Enterobacter cloacae strain. Antibacterial activity was evaluated qualitatively and quantitatively using disc diffusion assay. The ethanolic extracts obtained from leaves and pseudobulbs of five orchids belonging to the Coelogyne genus were found to exhibit fairly strong antibacterial activity towards Enterobacter cloacae strain used, the diameter of inhibition zones varied from 8.0-25.5 mm. It has been observed that ethanolic extract obtained from pseudobulbs of eight species from the Coelogyne genus revealed the highest antibacterial activity (11.0-25.5 mm as the diameter of inhibition zone) as compared to ethanolic extracts obtained from leaves of the same Coelogyne species. These findings provide a clear demonstration of the generally overlooked importance of the collection of tropical plants accumulated at the Botanic Gardens, orchids collection, in particular, as an important source of new chemical substances with potential therapeutic effects, including antifungal activity. Further studies aimed at the isolation and identification of active substances from the extracts obtained from leaves and pseudobulbs of Coelogyne species could also disclose compounds with better therapeutic value. It is believed that screening of all the investigated plants for other biological activities is essential.

Essential oil and leaf extracts of Melaleuca leucadendra L. demonstrated a series of biological activities of interest, including antioxidant, antimicrobial, antitumoral and anti-inflammatory properties. The aim of the current study was an in vitro evaluation of the antimicrobial activity of the cajeput essential oil against Gram-negative strains such as Escherichia coli (Migula) Castellani and Chalmers (ATCC® 25922™), Escherichia coli (Migula) Castellani and Chalmers (ATCC® 35218™), Pseudomonas aeruginosa (Schroeter) Migula (ATCC® 27853™) and Gram-positive strains such as Staphylococcus aureus subsp. aureus Rosenbach (ATCC® 29213™), Staphylococcus aureus subsp. aureus Rosenbach (ATCC® 25923™), methicillin-resistant (MRSA), mecA positive Staphylococcus aureus (NCTC® 12493), Enterococcus faecalis (Andrewes and Horder) Schleifer and Kilpper-Balz (ATCC® 51299™) (resistant to vancomycin; sensitive to teicoplanin) and Enterococcus faecalis (Andrewes and Horder) Schleifer and Kilpper-Balz (ATCC® 29212™) to assess the possible use of this oil in preventing infections caused by these pathogens. The cajeput essential oil was provided by Polish essential oil manufacturers (Bamer®, Włocławek, Poland). Antimicrobial susceptibility of the tested strains was performed by the Kirby-Bauer disc diffusion method. Our research has shown that cajeput essential oil exhibits antibacterial properties. Gram-positive bacteria were the most susceptible to commercial cajeput oil, which may indicate that the active biological substances in cajeput essential oil (including phenolic acids, tannins, etc.) may be potential agents against bacterial infections. Among Gram-negative bacteria, only Pseudomonas aeruginosa (Schroeter) Migula (ATCC® 27853™) strain was resistant to the cajeput essential oil. We did not observe statistically significant changes in the zone of growth inhibition after the application of cajeput essential oil compared to the control samples (96% ethanol). Our study may suggest that the use of cajeput essential oil may be helpful for a wide range of bacterial infections in veterinary, aquaculture, medicine, and beyond.