Studies on Antimicrobial and Immunomodulatory Effects of Hot Aqueous Extract of Acacia nilotica L. Leaves against Common Veterinary Pathogens

Anti-quorum sensing and biofilm inhibitory effect of some medicinal plants against gram-negative bacterial pathogens: in vitro and in silico investigations

Multidrug resistance (MDR) in pathogenic bacteria have become a major clinical issue. Quorum sensing regulated bacterial virulence is a promising key drug target for MDR infections. Therefore, the aim of the present work was to assess the anti-quorum sensing properties of selected medicinal plants against bacterial pathogens as well in silico interaction of selected bioactive phytocompounds with QS and biofilm-associated proteins. Based on the ethnopharmacological usage, 18 plants were selected using methanolic extract against Chromobacterium violaceum 12472. The most active extract (Acacia nilotica) was fractionated in increasing polarity solvents (n-hexane, chloroform and ethyl acetate) and tested for anti-QS activity. The most active fraction i.e. ethyl acetate fraction was evaluated for their activity at sub-MICs against QS-associated virulence factors of Pseudomonas aeruginosa PAO1 and Serretia marcescens MTCC 97. Microtiter plate assay and light microscopy was used to determine inhibition of biofilm. Phytochemicals of the ethyl acetate fraction were analysed by GC/MS and LC/MS. Phytocompounds were docked with QS (LasI, LasR, CviR, and rhlR) and biofilm proteins (PilY1 and PilT) using Auto dock vina. The MIC of ethyl acetate fraction determined was 250, 500, and 1000 μg/ml against C. violaceum 12472, P. aeruginosa PAO1, and S. marcescens MTCC97 respectively. At sub-MICs QS regulated virulence factors production and inhibited biofilms broadly (more than 50 percent). GC/MS detected the major bioactive compound benzoic acid, 3,4,5-trihydroxy-, methyl ester (61.24 %) and LC-MS detected Retronecine for the first time in A. nilotica pods. In silico, dehydroabietic acid occupied the same cavity as its antagonist in the CviR ligand binding domain. Also, betulin and epicatechin gallate interact with biofilm proteins PilY1 and PilT, preventing biofilm formation. The findings suggest that the phytochemicals of A. nilotica pod could be exploited as an anti-QS agent against Gram-negative pathogens. To discover therapeutic efficacy of standardised bioactive extract/phytochemicals must be tested under in vivo condition.

Streptococcosis a Re-Emerging Disease in Aquaculture: Significance and Phytotherapy

Simple Summary

Streptococcosis is an economical important bacterial disease that can seriously cause huge losses in the global aquaculture sector. In recent years studies have focused on to use extracts or essences of medicinal herbs and plants to control or treat the disease outbreaks and, in most cases the results were promising. The essential oils of the herbs or plants are more effective than the extracts and, the extracts examined have moderate efficacy in term of increasing fish survival against fish streptococcosis that could be due to the enhancement of fish immunity by the herb bio-compounds. The lack of dosage optimization, toxicity and bioavailability assays of a specific herb/plant or its bioactive compound in fish organs make it difficult to judge the validation of clinical efficacy of a particular herb/plant against fish streptococcosis, and thus, required further investigations.

Abstract

Streptococcosis, particularly that caused by S. iniae and S. agalactiae, is a major re-emerging bacterial disease seriously affecting the global sustainability of aquaculture development. Despite a wide spread of the disease in aquaculture, few studies have been directed at assessing the in vitro antagonistic activity and in vivo efficacy of medicinal herbs and other plants against streptococcal agents. Most in vitro studies of plant extractives against S. iniae and S. agalactiae have found antibacterial activity, but essential oils, especially those containing eugenol, carvacrol or thymol, are more effective. Although essential oils have shown better anti-streptococcal activity in in vitro assays, in vivo bioassays require more attention. The extracts examined under in vivo conditions show moderate efficacy, increasing the survival rate of infected fish, probably through the enhancement of immunity before challenge bioassays. The available data, however, lack dosage optimization, toxicity and bioavailability assays of a specific plant or its bioactive compound in fish organs; hence, it is difficult to judge the validation of clinical efficacy for the prevention or treatment of fish streptococcosis. Despite the known bioactive compounds of many tested plants, few data are available on their mode of action towards streptococcal agents. This review addresses the efficacy of medicinal plants to fish streptococcosis and discusses the current gaps.

Impact of acacia arabica topical gel on skin wound healing: An experimental study

Aim of the study: To estimate the influence of Acacia Arabica gel abstract on skin wound healing. Material and method: 28male adult rabbits were included, 2 incisions of 1cm length were made on the skin of the rabbit’s back, one is treated by acacia gel while another left for normal healing, histopathological examination was done at 24h, 3, 7 and 14 days intervals. Results: The inflammatory reactions showed no significant results for both the control group and the study group during the study intervals. Granulation tissue in the control group was absent after 24h but increased to become profound after 7 days then become moderate, while the study group showed scanty granulation tissue from the first day and increased through study intervals. Re-epithelialization mean scores in the study group were higher than control one. Conclusions: Acacia arabica has the efficacy of hastening the wound healing process.

Strategies to combat antimicrobial resistance in Indian scenario

Antimicrobial resistance (AMR) is one of the major public health crisis recognised globally. Microbial infections cause significant productivity losses in animals and humans. In livestock, these microbial infections reduce the growth rates and fertility, diminish production of meat and milk, and occasionally lead to mortality, and are therefore, a major concern for animal welfare. In the dearth of alternative prophylactic measures, antibiotics remain the principal tool for their management. Once an antibiotic is used rampantly, resistance against it is inevidently seen in the microbe population and the hunt for a new drug grows. Discovery and development of a new antimicrobial drug is a time taking and expensive procedure with limited assurance of success. As a result, the past few decades have witnessed only a very few new classes of antibiotics. If the AMR can be restricted or reverted, the success rate of antimicrobial therapy can be boosted and many public health issues be avoided. All these ask for a comprehensive plan to prevent or reduce the antimicrobial resistance and economic losses to the animal husbandry sector. The present review provides an overview of AMR in India, mechanism of its occurrence and the possible roadmap to combat the emerging threat of AMR in Indian scenario.

Potassium Dichromate-Induced Hepato- and Hematotoxicity in Rats: Nutritive Composition and Ameliorative Role of Acacia nilotica L. Leaf

Background: Chromium and its salts, as well as chromium-containing compounds, play a major role in numerous manufacturing processes and have been contraindicated in carcinogenic, toxic, and mutagenic conditions in people involved in these processes. Objectives: This study investigated the ameliorative role of Acacia nilotica aqueous leave extract (ANLA) on potassium dichromate-induced liver and blood toxicity in male and female rats. Phytochemical screening and nutrient composition of ANLA were also evaluated. Methods: Phytochemical and proximate analysis of ANLA were carried out. Twenty adult male and female rats each were divided into four groups (n = 10): (1) control; (2) potassium dichromate (PDC; 0.625 mg/kg body weight); (3) PDC co-treated with ANLA after seven days (650 mg/kg bwt); and (4) PDC co-treated with ANLA (650 mg/kg bwt) simultaneously for 21 days. Biomarkers of liver injury, lipid, and hematological imbalance were assessed. Tissue histology and toxicant retention were done. Results: Various plant secondary metabolites (flavonoids, terpenoids, tannins, phenols, saponins, cardiac glycosides, alkaloids, and anthraquinones) and nutrients (protein = 67.41 ± 2.44%; carbohydrate = 9.87 ± 1.87%; fiber = 10.01 ± 1.21%; mineral = 6.41 ± 1.08%; fat and oil = 6.63 ± 0.93%) were identified in the leave. Exposure to chromium significantly (P < 0.05) increased plasma alanine aminotransferase (ALT) and aspartate aminotransferase (AST) with a concomitant decrease in the activity of these enzymes in the liver of both male and female rats. The exposure also altered protein, triglyceride, and cholesterol levels in the plasma and liver as well as hematological indices. Organ chromium retention and pathological changes were also observed. ANLA modulated these chromium-induced alterations in the rats. Conclusions: Based on the results, ANLA possesses ameliorative property against PDC-induced toxicity in rats. Thus it may be used to combat chromium poisoning. The nutritive potential of A. nilotica leaves may also be maximized.

Efficacy of Acacia nilotica aqueous extract in treating biofilm-forming and multidrug resistant uropathogens isolated from patients with UTI syndrome

Escherichia coli is the dominant bacterial cause of UTI among the uropathogens in both developed and developing countries. This study is to investigate the effect of Acacia nilotica aqueous extract on the survival and biofilm of isolated pathogens to reduce UTIs diseases. A total of 170 urine samples were collected from Luxor general hospital and private medical analysis laboratories in Luxor providence, Egypt. Samples were screened for the incidence of uropathogens by biochemical tests, antibiotics susceptibility, detection of virulence, and antibiotic-resistant genes by multiplex PCR, biofilm formation, and time-killing assay. Escherichia coli is by far the most prevalent causative agent with the percentage of 73.7% followed by Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeuroginosa, and Acinetobacter baumanii. Isolates were multidrug-resistant containing blaTEM, blaSHV, blaCTX, qnrs, and aac(3)-Ia resistant genes. All isolates were sensitive to 15-16.7 mg ml-1 of Acacia nilotica aqueous extract. Time killing assay confirmed the bactericidal effect of the extract over time (20-24 h). A high percentage of 3-Cyclohexane-1-Carboxaldehyde, 2,6,6-trimethyl (23.5%); á-Selinene (15.12%); Oleic Acid (14.52%); Globulol (11.35%) were detected among 19 bioactive phytochemical compounds in the aqueous extract of A. nilotica over the GC-mass spectra analysis. The plant extract reduced significantly the biofilm activity of E. coli, K. pneumoniae, P. mirabilis, and P. aeuroginosa by 62.6, 59. 03, 48.9 and 39.2%, respectively. The challenge to improve the production of A. nilotica phytochemicals is considered a very low price for the return.

The traditional use of Vachellia nilotica for sexually transmitted diseases is substantiated by the antiviral activity of its bark extract against sexually transmitted viruses

ETHNOPHARMACOLOGICAL RELEVANCE

Vachellia (Acacia) nilotica and other plants of this genus have been used in traditional medicine of Asian and African countries to treat many disorders, including sexually transmitted diseases, but few studies were performed to validate their anti-microbial and anti-viral activity against sexually transmitted infections.

AIM OF THE STUDY

The present study was undertaken to explore whether the ethnomedical use of V.nilotica to treat genital lesions is substantiated by its antiviral activity against the human immunodeficiency virus (HIV), the herpes simplex virus (HSV) and the human papillomavirus (HPV).

MATERIALS AND METHODS

The antiviral activity of V.nilotica was tested in vitro by virus-specific inhibition assays using HSV-2 strains, sensible or resistant to acyclovir, HIV-1IIIb strain and HPV-16 pseudovirion (PsV). The potential mode of action of extract against HSV-2 and HPV-16 was further investigated by virus inactivation and time-of-addition assays on cell cultures.

RESULTS

V.nilotica chloroform, methanolic and water bark extracts exerted antiviral activity against HSV-2 and HPV-16 PsV infections; among these, methanolic extract showed the best EC50s with values of 4.71 and 1.80µg/ml against HSV-2 and HPV-16, respectively, and it was also active against an acyclovir-resistant HSV-2 strain with an EC50 of 6.71µg/ml. By contrast, no suppression of HIV infection was observed. Investigation of the mechanism of action revealed that the methanolic extract directly inactivated the infectivity of the HPV-16 particles, whereas a partial virus inactivation and interference with virus attachment (EC50 of 2.74µg/ml) were both found to contribute to the anti-HSV-2 activity.

CONCLUSIONS

These results support the traditional use of V.nilotica applied externally for the treatment of genital lesions. Further work remains to be done in order to identify the bioactive components.

Potency and selectivity indices of acetone leaf extracts of nine selected South African trees against six opportunistic Enterobacteriaceae isolates from commercial chicken eggs

Background

The rise in antimicrobial resistance in a plethora of nosocomial and opportunistic bacterial pathogens often isolated from commercial eggs, poses a serious public health concern. The existence of these contaminants may also serve as a drawback in the current efforts of improving the well-being of immunocompromised patients. The aim of this study was to determine the efficacy of plant extracts that had good activity on Escherichia coli in previous word on pathogens isolated from eggs for possible use in combating pathogens from eggs.

Methods

Acetone leaf extracts of nine trees with good activities against Escherichia coli were tested for their in vitro antibacterial activity against six opportunistic bacterial isolates from commercial eggs (Stenotrophomonas maltophilia, Klebsiella pneumoniae, Salmonella serotype Typhimurium, Proteus mirabilis, Enterobacter cloacae and Escherichia coli) using a serial microdilution method with tetrazolium violet as indicator of growth. Cytotoxicity was determined using a tetrazolium-based colorimetric assay against Vero kidney cells, and selectivity index calculated.

Results

The MIC values range of the different extracts against Stenotrophomonas maltophilia was 0.08-0.31 mg/ml, Klebsiella pneumonia 0.08-0.63 mg/ml, Salmonella ser. Typhimurium 0.08-0.63 mg/ml, Proteus mirabilis 0.02-1.25 mg/ml, Enterobacter cloacae 0.08-0.31 mg/ml and Escherichia coli 0.08-0.16 mg/ml respectively. Escherichia coli was the most sensitive while Proteus mirabilis was most resistant pathogen to the different test extracts, with mean MIC values of 0.08 mg/ml and 0.46 mg/ml respectively. Cremaspora triflora extracts had good activity against all the pathogenic egg isolates, with the exception of Proteus mirabilis. Maesa lanceolata and Elaeodendron croceum had the best total antibacterial activity (TAA), while generally the selectivity index of the extract was low (SI < 1).

Conclusion

The exceptional activity of C. triflora extracts suggests that the plant has potential as a therapeutic agent against some members of the Enterobacteriaceae. Further pharmacological investigations may be interesting in the search for new antimicrobial leads.

Different modalities for treatment of recurrent aphthous stomatitis. A Randomized clinical trial

Background

The underlying etiology of recurrent aphthous stomatitis (RAS) is unclear and treatment aims to provide symptomatic and faster relief. This study compared the efficacy of diode laser, a herbal combination of Acacia nilotica and Licorice (A and L) and Amlexanox in the management of RAS.

Material and Methods

Sixty patients with minor aphthae were selected and randomly divided into four groups of 15 each. Group I and II received adhesive preparations of a herbal mixture of A and L and a 2 mg Amlexanox paste respectively, group III received diode laser and the fourth group (control) used a placebo. Ulcer size, pain score were recorded on days 1, 2 and 5.

Results

Laser group showed the statistically highest mean percentage (%) of reduction in pain scores and ulcer size than the other groups. The mean % of reduction in pain scores was 43.3+20.0 at day 2 and 67.8+21.5 % at day 5 in the laser group while Amlexanox group demonstrated a 29.8 +11.3 and 61.9+24.5 mean % of reduction in pain scores at day 2 and 5 respectively. A and L group showed a lower mean % of reduction in pain scores than laser and Amlexanox groups with a 22.2+10.5 and 43.4+15.8 mean % reduction in pain scores at day 2 and day 5 respectively. Similarly the highest mean % of reduction in ulcer size was seen in the laser group being 52.7+19.8 at day 2 and 85.1+22.0 at day 5, while it was 48.1+16.5 at day 2 and 77.8+28.7 at day 5 in the Amlexanox group and 42.0+11.5 at day 2 and 63.0+20.5 at day 5 in the A and L group.

Conclusions

All treatment modalities reduced pain and ulcer size than placebo group. Laser therapy demonstrated the highest percentage of reduction of pain score and ulcer size.

Key words:Aphthous stomatitis, laser, herbal plants, Acacia nilotica, Licorice.