Assessment of antibacterial activity of crude leaf and root extracts of Cassia alata against Neisseria gonorrhea

Essential oils of Pinus sylvestris, Citrus limon and Origanum vulgare exhibit high bactericidal and anti-biofilm activities against Neisseria gonorrhoeae and Streptococcus suis

Antimicrobial resistance is a worldwide problem that urges novel alternatives to treat infections. In attempts to find novel molecules, we assess the antimicrobial potential of seven essential oils (EO) of different plants (Pinus sylvestris, Citrus limon, Origanum vulgare, Cymbopogon martini, Cinnamomum cassia, Melaleuca alternifolia and Eucalyptus globulus) against two multidrug-resistant bacteria species, i.e. Neisseria gonorrhoeae and Streptococcus suis. EOs of P. sylvestris and C. limon revealed higher bactericidal activity (MIC ≤ 0.5 mg/mL) and capacity to rapidly disperse biofilms of several N. gonorrhoeae clinical isolates than other EOs. Examination of biofilms exposed to both EO by electron microscopy revealed a reduction of bacterial aggregates, high production of extracellular vesicles, and alteration of cell integrity. This activity was dose-dependent and was enhanced in DNase I-treated biofilms. Antibiotic susceptibility studies confirmed that both EOs affected the outer membrane permeability, and analysis of EO- susceptibility of an LPS-deficient mutant suggested that both EO target the LPS bilayer. Further analysis revealed that α- and β-pinene and d-limonene, components of both EO, contribute to such activity. EO of C. martini, C. cassia, and O. vulgare exhibited promising antimicrobial activity (MIC ≤ 0.5 mg/mL) against S. suis, but only EO of O. vulgare exhibited a high biofilm dispersal activity, which was also confirmed by electron microscopy studies. To conclude, the EO of P. sylvestris, C. limon and O. vulgare studied in this work exhibit bactericidal and anti-biofilm activities against gonococcus and streptococcus, respectively.

In vitro antimicrobial efficacy of Cassia alata (Linn.) leaves, stem, and root extracts against cellulitis causative agent Staphylococcus aureus

BACKGROUND

Cellulitis is a common skin disease encountered in medical emergencies in hospitals. It can be treated using a combination of antibiotics therapy; however, the causative agent Staphylococcus aureus has been reported to develop resistance towards the currently used antibiotics. Therefore, the search for more alternative herbal origin antimicrobial agents is critical.

AIM

In this study, maceration and Soxhlet extraction of the whole plant of Cassia alata Linn. (leaves, roots, and stem) were performed using four solvents with different polarities, namely n-hexane, ethyl acetate, ethanol and distilled water. The crude extracts were screened using agar well diffusion, colorimetric broth microdilution, grid culture and bacterial growth curve analysis against Staphylococcus aureus. The phytochemicals in the crude extracts were identified using Gas Chromatography-Mass Spectrometry (GC-MS).

RESULTS

Agar-well diffusion analysis revealed that extraction using ethyl acetate showed the largest inhibition zone with an average diameter of 15.30 mm (root Soxhlet extract) followed by 14.70 mm (leaf Soxhlet extract) and 13.70 mm (root maceration extract). The lowest minimum inhibitory and minimum bactericidal concentration in root Soxhlet extract using ethyl acetate was 0.313 and 0.625 µg µL^-1, respectively. Our study proved that crude extract of the plant suppressed the growth of S. aureus as evidenced from a significant regression extension (p < 0.06, p = 0.00003) of lag phase for 6 h after the treatment with increased concentration. Based on the GC-MS analysis, 88 phytochemicals consist of fatty acids, esters, alkanes, phenols, fatty alcohols, sesquiterpenoids and macrocycle that possibly contributed to the antimicrobial properties were identified, 32 of which were previously characterized for their antimicrobial, antioxidant, and anti-inflammatory activities.

CONCLUSION

Ethyl acetate crude extract was better than the other investigated solvents. The root and stem of C. alata showed significant antimicrobial efficacy against S. aureus in this study. The remaining 56 out of 88 phytochemicals of the plant should be intensively studied for more medicinal uses.

Chemical constituents, usage and pharmacological activity of Cassia alata

Cassia alata or locally known as Ketepeng Cina (Indonesia) and Gelenggang (Malaysia) has been used as a traditional medicine to treat various diseases, especially skin diseases. In addition, C. alata has been reported to have potential anti allergic, anti inflammatory, antioxidant, anticancer, antidiabetic, and antifungal. Metabolite compounds that have been isolated from C. alata include flavones, flavonols, flavonoids glycosides, alatinon, alanonal and β-sitosterol-β-D-glucoside. The compounds have been isolated mainly from the leaves. Further identification is needed to discover the secondary metabolites from other parts of the plant such as seed, flower and bark which are reported to have potent antibacterial and antifungal activity. Therefore, this article highlights the secondary metabolites and biological activity of this plant which has been shown to have pharmacological properties against selected diseases.

Ethnobotanical Description and Biological Activities of Senna alata

Senna alata is a medicinal herb of Leguminosae family. It is distributed in the tropical and humid regions. The plant is traditionally used in the treatment of typhoid, diabetes, malaria, asthma, ringworms, tinea infections, scabies, blotch, herpes, and eczema. The review is aimed at unveiling the ethnobotanical description and pharmacological activities of S. alata. Different parts of the plant are reported in folk medicine as therapeutic substances for remediation of diverse diseases and infections. The extracts and isolated compounds displayed pronounced pharmacological activities. Display of antibacterial, antioxidant, antifungal, dermatophytic, anticancer, hepatoprotective, antilipogenic, anticonvulsant, antidiabetic, antihyperlipidemic, antimalarial, anthelmintic, and antiviral activities could be due to the array of secondary metabolites such as tannins, alkaloids, flavonoids, terpenes, anthraquinone, saponins, phenolics, cannabinoid alkaloids, 1,8-cineole, caryophyllene, limonene, α-selinene, β-caryophyllene, germacrene D, cinnamic acid, pyrazol-5-ol, methaqualone, isoquinoline, quinones, reducing sugars, steroids, and volatile oils present in different parts of the plant. The review divulges the ethnobotanical and pharmacological activities of the plant and also justifies the ethnomedical claims. The significant medicinal value of this plant necessitates a scientific adventure into the bioactive metabolites which constitute various extracts.