Isolation of Antimicrobial Compounds From Cnestis ferruginea Vahl ex. DC (Connaraceae) Leaves Through Bioassay-Guided Fractionation

Antimicrobial properties of Cnestis ferruginea Vahl ex DC

Scientific research into developing new antimicrobials from plants continues to be an interesting area for many scientists. This is because the resistance of microorganisms to anti-infective agents has affected a wide range of conditions, some of which are life-threatening. This study aimed to investigate the antimicrobial properties of Cnestis ferruginea (CF). Powdered roots of Cnestis ferruginea were extracted with petroleum ether (CFP), ethyl acetate (CFE) and methanol (CFM). The antimicrobial and microbial resistance modifying activity profiles of the extracts were studied against Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 4853, Staphylococcus aureus ATCC 25923, clinical strains of Methicillin-Resistant Staphylococcus aureus, Streptococcus pyogenes, Klebsiella pneumonia, Staphylococcus epidermidis, Proteus mirabilis and Candida albicans. CFP and CFE showed no activity against the test organisms. CFM had mean zones of growth inhibition in the range of 11.0 ± 0.5 to 22.17 ± 0.24 mm against the test organisms. The MIC of CFM was within the range of 0.31 and 5.0 mg/mL, with MBC/MFC range of 2.5-20.0 mg/mL. The time-kill kinetics studies showed CFM is a static agent. At sub-inhibitory concentrations, CFM was able to increase the susceptibility of the test organisms to standard antibiotics from the range of 1-8 folds. CFM reduced the formation of biofilms from 100% to 56.59%, 62.33%, 65.89% and 71.88% against K. pneumonia, S. aureus, E. coli and P. aeruginosa, respectively. The findings of this study show that C. ferruginea possesses antimicrobial activity and therefore gives credence to its folkloric use.

Chemical Profile and Antimicrobial Activity of the Fungus-Growing Termite Strain Macrotermes Bellicosus Used in Traditional Medicine in the Republic of Benin

The fungus growing termite species Macrotermes bellicosus (M. bellicosus) is used in nutrition and traditional medicine in the Republic of Benin for the treatment of infectious and inflammatory diseases. Previous findings demonstrated evidence of anti-inflammatory and spasmolytic properties of M. bellicosus. The aim of the present study was to evaluate the antimicrobial potential of different extracts of M. bellicosus samples and determine the chemical profile of an ethanolic M. bellicosus extract. Chemical profiling was conducted using centrifugal partition chromatography and ¹³C-NMR, followed by MALDI-TOF MS. Major identified compounds include hydroquinone (HQ), methylhydroquinone (MHQ), 3,4-dihydroxyphenethyl glycol (DHPG), N-acetyldopamine (NADA) and niacinamide. The fatty acid mixture of the extract was mainly composed of linoleic and oleic acid and highlights the nutritional purpose of M. bellicosus. Using the Kirby–Bauer disc diffusion and broth microdilution assay, an antibacterial activity of M. bellicosus samples was observed against various clinical strains with a highest growth inhibition of S. aureus. In addition, HQ and MHQ as well as fractions containing DHPG, niacinamide and NADA inhibited S. aureus growth. The reported antimicrobial activity of M. bellicosus and identified active substances provide a rationale for the traditional medicinal use of M. bellicosus.

Natural Anti-biofilm Agents: Strategies to Control Biofilm-Forming Pathogens

Pathogenic microorganisms and their chronic pathogenicity are significant concerns in biomedical research. Biofilm-linked persistent infections are not easy to treat due to resident multidrug-resistant microbes. Low efficiency of various treatments and in vivo toxicity of available antibiotics drive the researchers toward the discovery of many effective natural anti-biofilm agents. Natural extracts and natural product-based anti-biofilm agents are more efficient than the chemically synthesized counterparts with lesser side effects. The present review primarily focuses on various natural anti-biofilm agents, i.e., phytochemicals, biosurfactants, antimicrobial peptides, and microbial enzymes along with their sources, mechanism of action via interfering in the quorum-sensing pathways, disruption of extracellular polymeric substance, adhesion mechanism, and their inhibitory concentrations existing in literature so far. This study provides a better understanding that a particular natural anti-biofilm molecule exhibits a different mode of actions and biofilm inhibitory activity against more than one pathogenic species. This information can be exploited further to improve the therapeutic strategy by a combination of more than one natural anti-biofilm compounds from diverse sources.

Connaraceae: An updated overview of research and the pharmacological potential of 39 species

ETHNOPHARMACOLOGICAL RELEVANCE

An interdisciplinary scientific investigation of biologically active agents is fundamental to search for natural substances with therapeutic action. This review collected the most relevant information on traditional knowledge related to the use of plants of the Connaraceae family. This work is the first to compile all the published ethnobotanical, chemical, pharmacological, and toxicological information about this important plant family.

AIM OF THE STUDY

Our objective was to provide the scientific community with an up-to-date overview of the pharmacological potential of Connaraceae species.

MATERIAL AND METHODS

We searched NCBI Pubmed Central, Google Scholar, Scientific Electronic Library Online (SciELO), ScienceDirect, SciFinder, and Scopus databases to review the research on ethnobotanical, chemical, pharmacognostical, pharmacological, and toxicological studies with Connaraceaes. Books that address the theme were also included.

DISCUSSION AND CONCLUSION

The literature review indicated that 39 species of Connaraceaes have pharmacological potentiality. Ethnobotany reports listed 36 of the 39 species discussed. Pharmacognostical studies have been conducted with 23 species and isolates, and chemical compounds have been identified for only 15 species. At least one study has been published concerning the pharmacological activities for 20 of the 39 species analyzed. For Agelaea pentagyna, Cnestis ferruginea, Connars suberosus, and Rourea minor, pharmacological activity experiments were performed using isolated compounds, which have the highest current pharmacological potential. Studies employing a toxicological approach cover only 10 of the 39 Connaraceaes species. Thus, scientific community should conduct much more research for a broader understanding of this plant family.

Assessment of in vitro anthelmintic activity and bio-guided chemical analysis of BRS Boyrá pineapple leaf extracts

Species of the Bromeliaceae are known for their pharmacological actions, including anthelmintic effects. The aim of this study was to investigate the in vitro anthelmintic activity of extracts and fractions of BRS Boyrá pineapple leaf against the eggs and infective larvae of gastrointestinal nematodes (Trichostrongylidae) of goats and to identify the compounds involved in this activity. Crude methanol, hexane, dichloromethane, ethyl acetate and residual hydromethanol extracts were investigated by quantitative analysis of phenolic and flavonoid contents, antioxidant activity, anthelmintic activity against gastrointestinal nematodes of goats. The extracts were submitted to chromatographic methods for substance isolation and spectrometric techniques to identify their structures. The anthelmintic activity was performed by in vitro assays with eggs and larvae of nematodes obtained from naturally infected donor goats. All extracts contained phenolic (2.22-14.12 g of gallic acid equivalent per 100 g of dry extract) and flavonoid compounds (0.13-1.45 g of quercetin equivalent per 100 g of dry extract). Bio-guided fractionation of the BRS Boyrá pineapple leaves showed high antioxidant activity (EC₅₀ for DPPH of 2.16-21.38 mg mL^-1 and inhibition of co-oxidation of β-carotene of 36.40-74.86%) and anthelmintic activity (15.69-100% inhibition of egg hatching). The ethyl acetate extract exhibited greatest activity in all assays. Through chromatographic column analysis it was possible to isolate three substances: β-sitosterol and stigmasterol mixture in dichloromethane and hexane extracts, identified by NMR and p-coumaric acid in the ethyl acetate extract, identified by HPLC-DAD. The isolated p-coumaric acid exhibited high ovicidal effect against goat gastrointestinal nematodes (IC₅₀: 0.12 mg mL^-1) and can be considered the active substance of the ethyl acetate extract. This study revealed for the first time that the pineapple BRS Boyrá possesses inhibitory activity against gastrointestinal nematodes (Haemonchus spp., Oesophagostomum spp. and Trichostrongylus spp.), and that p-coumaric acid is an important bioactive.

Catechin isolated from cashew nut shell exhibits antibacterial activity against clinical isolates of MRSA through ROS-mediated oxidative stress

Staphylococcus aureus causes severe infections and among all methicillin-resistant S. aureus (MRSA) remains a great challenge in spite of decade research of antibacterial compounds. Even though some synthetic antibiotics have been developed, they are not effective against MRSA, and hence, there is a search for natural, alternative and plant-based antibacterial compound. In this connection, catechin isolated from cashew nut shell was investigated for its antibacterial potential against MRSA. Catechin exhibited zone of inhibition (ZOI) and minimum inhibitory concentration (MIC) in a range of 15.1-19.5 mm and 78.1-156.2 μg/ml, respectively, against ATCC and clinical isolates of MRSA. Among all clinical isolates, clinical isolate-3 exhibited highest sensitivity to catechin. Catechin has arrested the growth of MRSA strains and also caused toxicity by membrane disruption which was illustrated by AO/EB fluorescence staining. Increased nucleic acid leakage (1.58-28.6-fold) and protein leakage (1.40-23.50-fold) was noticed in MRSA due to catechin treatment when compared to methicillin. Bacteria treated with catechin at its MIC showed 1.52-, 1.87- and 1.74-fold increase of ROS production in methicillin susceptible S. aureus (MSSA), MRSA and clinical isolate-3 strains, respectively, as compared to control. Superoxide dismutase (5.31-9.63 U/mg protein) and catalase (1573-3930 U/mg protein) were significantly decreased as compared to control in catechin-treated S. aureus. Thus, catechin exhibited antibacterial activity through oxidative stress by increased production of ROS and decreased antioxidant enzymes. Altogether results suggest that catechin is a promising lead compound with antibacterial potential against MRSA. KEY POINTS: • Catechin was isolated and identified as active compound in cashew nut shell. • Catechin exhibited antimicrobial activity against clinical isolates of MRSA. • Bacterial cell wall damage was caused by catechin in MRSA strains. • Catechin increased the oxidative stress in MRSA by intracellular ROS production.