Evaluating antimicrobial activities of Acanthus ilicifolius L. and Heliotropium curassavicum L against bacterial pathogens: an in-vitro study

BACKGROUND

Biomedical research, recently, focus more on searching for biomasses that contain extractable biologically active components for formulating new drugs. Halophytes growing in hyper saline conditions are expected to produce stress alleviating bioactive compounds. These phytochemicals could be the better raw materials for formulating new drugs.

METHODS

The purpose of this work was to describe physiologically active compounds from Acanthus ilicifolius and Heliotropium curassavicum that had antimicrobial, antioxidant and nutraceutical properties utilizing a variety of solvents. Analysis of bioactive compounds included the application of common phytochemical screening assays, proximate analysis, FTIR analysis and antioxidant assays. The disc diffusion technique was used to determine the antibacterial activity of the plant extracts.

RESULTS

Highest extraction yield was observed with methanol. A. ilicifolius methanolic extracts included a variety of bioactive components, including alkaloids, saponins, phenolics, flavonoids, steroids, cardiac glycosides, tannins, and terpenoids. H. curassavicum extracts showed the presence of all the phytochemicals except cardiac glycosides. The overall phenolic concentration and antioxidant capacity of A. ilicifolius were substantially greater. The antimicrobial assays explored that among the tested bacterial pathogens viz., Bacillus subtilis, Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, Streptococcus pneumoniae, significant level of control was observed in E. coli, K. pneumoniae and B. subtilis, which were significantly susceptible to both the plant extracts at a concentration of 50 μg/ml.

CONCLUSION

The reports from the current investigation explored the possibility of utilizing these halophytes in nutraceutical formulations. The current study sheds light on the possibility of halophytes as natural secondary metabolites and bioactive chemicals with potential for antimicrobials.

Evaluation of the Structure and Biological Activities of Condensed Tannins from Acanthus ilicifolius Linn and Their Effect on Fresh-Cut Fuji Apples

Condensed tannins (CT_S) have been isolated and purified from leaves of Acanthus ilicifolius Linn. And their structures were investigated by three methods: ¹³C nuclear magnetic resonance (¹³C NMR), reversed-phase high-performance liquid chromatography (RP-HPLC), and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The results showed that the CT_S were a mixture of catechin/epicatechin, galatechin/epicatechin, and amphicin/epigalin, and that the polymer chain lengths were 3-mers to 14-mers. Antityrosinase activities and antioxidant activities of the CT_S from A. ilicifolius leaves were further studied. The IC₅₀ of the CT_S on mushroom tyrosinase activity was determined to be 19.7 ± 0.13 μg/mL, and inhibition type analyses indicated that the CT_S were mixed type inhibitors and their inhibition CT_S was reversible. The CT_S from A. ilicifolius leaves also exhibited potential antioxidant activity. The IC₅₀ of DPPH and ABTS scavenging activities were 104 ± 0.894 μg/mL and 86 ± 0.616 μg/mL, respectively. And the FRAP value was 758.28 ± 2.42 mg AAE/g. In addition, we found that the CT_S from A. ilicifolius leaves had an excellent effect on preserving the quality of fresh-cut apples by preventing apples from browning through reducing polyphenol oxidase activities in apples.