Antioxidant, Antimicrobial and In Silico NADPH Oxidase Inhibition of Chemically-Analyzed Essential Oils Derived from Ballota deserti (Noë) Jury

Ballota deserti (Noë) Jury (B. deserti) is a medicinal plant used in Ayurvedic medicine. The chemical composition, antioxidant, antibacterial, and antifungal properties of essential oils from B. deserti (EOBD) against drug-resistant microorganisms were examined in this work. Hydrodistillation was used to extract EOBD, and gas chromatography–mass spectrometry was used to identify its constituents. Ferric reducing antioxidant power (FRAP), 1,1-diphenyl-2-picrylhydrazyl (DPPH), and total antioxidant capacity (TAC) were used to assess the antioxidant effect of EOBD. The disc diffusion agar and the microdilution tests were used in the assessment of the antibacterial properties of EOBD against clinically resistant pathogenic microorganisms. An in silico approach was used to evaluate the inhibitory potential of EOBD against NADPH oxidase. The yield of EOBD was 0.41%, and was primarily composed of linalool (37.82%), cineole (12.04%), and borneol (11.07%). EOBD had good antioxidant potency, with calculated values of 19.82 ± 1.14 µg/mL (DPPH), 64.78 ± 5.21 µg/mL (FRAP), 996.84 ± 20.18 µg EAA/ mg (TAC). Both Gram-negative and Gram-positive bacteria were inhibited by EOBD with inhibition zones ranging from 17.481.75 mm to 28.471.44 mm. EOBD exhibited MICs ranging from 10.78 g/mL to 22.48 g/mL when tested against bacteria using the minimum inhibitory concentration (MIC) assay. Similarly, impressive antifungal activity was observed against fungal strains with inhibition zone widths ranging from 16.761.83 to 36.791.35 mm. Results of MICs assay against fungi showed that EOBD had MICs values ranging from 15.32 ± 1.47 to 23.74 ± 1.54 µg/mL. Docking results showed that thujone, o-cymene, and butanoic acid contained in EOBD possessed strong activity against NADPH oxidase, with glide scores of −5.403, −5.344, and −4.973 Kcal/mol, respectively. In light of these findings, the EOBD may be seen as a potential source of chemical compounds with significant biological capabilities that can be advantageous as natural antioxidants and develop an effective weapon against a wide range of pathogenic bacteria.

In Vitro Antibacterial Activity of Myrtus communis L. and Marrubium vulgare L. Leaves against Aggregatibacter actinomycetemcomitans and Eikenella corrodens

Materials and Methods

Clinical strains of Aggregatibacter actinomycetemcomitans and Eikenella corrodens and two reference strains of A. actinomycetemcomitans were tested. The antibacterial activity of each studied plant extract was evaluated using agar diffusion and broth microdilution assays.

Results

Both aqueous and methanolic extracts of M. communis exhibited high antibacterial activity against periodontal pathogens as compared to M. vulgare extracts. At concentrations of 2.5-0.32 mg/disc, inhibition zones of the methanolic extract of M. communis ranged from 19.66 ± 0.57 to 12.33 ± 0.57 mm. The methanolic extract of M. vulgare showed at concentrations of 5-0.63 mg/disc inhibition zones ranging from 15.66 ± 0.57 to 12 ± 0.00 mm. Its aqueous extract at concentration of 0.63 mg/disc showed no antimicrobial activity against the clinical and reference strain of A. actinomycetemcomitans. Conclusion. This study showed that methanolic and aqueous extracts of M. communis and M. vulgare have in vitro an antibacterial activity against periodontal pathogens. They could be use as ingredients of an oral antimicrobial agent for prevention or treatment of periodontal diseases. Further research on isolating the compounds from these plant extracts and their toxicity effect could be conducted.

Chemical Characterization of Marrubium vulgare Volatiles from Serbia

Marrubium vulgare is a cosmopolitan medicinal plant from the Lamiaceae family, which produces structurally highly diverse groups of secondary metabolites. A total of 160 compounds were determined in the volatiles from Serbia during two investigated years (2019 and 2020). The main components were E-caryophyllene, followed by germacrene D, α-humulene and α-copaene. All these compounds are from sesquiterpene hydrocarbons class which was dominant in both investigated years. This variation in volatiles composition could be a consequence of weather conditions, as in the case of other aromatic plants. According to the unrooted cluster tree with 37 samples of Marrubium sp. volatiles from literature and average values from this study, it could be said that there are several chemotypes: E-caryophyllene, β-bisabolene, α-pinene, β-farnesene, E-caryophyllene + caryophyllene oxide chemotype, and diverse (unclassified) chemotypes. However, occurring polymorphism could be consequence of adaptation to grow in different environment, especially ecological conditions such as humidity, temperature and altitude, as well as hybridization strongly affected the chemotypes. In addition, this paper aimed to obtain validated models for prediction of retention indices (RIs) of compounds isolated from M. vulgare volatiles. A total of 160 experimentally obtained RIs of volatile compounds was used to build the prediction models. The coefficients of determination were 0.956 and 0.964, demonstrating that these models could be used for predicting RIs, due to low prediction error and high r².