Unveiling the antibacterial and antioxidant potential of Hedera helix leaf extracts: recent findings.

Hedera helix L., a member of the Araliaceae family, is a commonly known decorative plant with recognized medicinal activities. In this study, the ethanolic extract from H. helix leaves was investigated for its total polyphenolic and flavonoid contents, as well as its antioxidant and antibacterial properties. The aim was to evaluate its potential for controlling certain infections by screening its antibacterial activity against selected pathogenic bacteria. The total phenolic and flavonoid contents of the extract were determined using colorimetric methods. The antioxidant activity was assessed through two assay methods: the 1, 1-diphenyl-2-picryl hydrazyl (DPPH) free radical scavenging activity and the reducing power ferric reducing/antioxidant power (FRAP). The antibacterial activity against different pathogenic bacteria, including Staphylococcus aureus, Escherichia coli, Klebsiella pneumonia, and Pseudomonas aeruginosa, was evaluated using the well diffusion method. The total phenolic and flavonoid contents of the H. helix extract were found to be 134.3 ± 4.9 mg gallic acid/g and 42.4 ± 3.6 mg catechin/g, respectively. The extract exhibited antioxidant activity, with a reducing power represented by an FRAP value of 9.5 ± 0.9 mmol Fe+2/g DW and a percentage inhibition of DPPH of 64.7 ± 3.8 at 80 µg/mL. The extract demonstrated antibacterial activity, inhibiting the growth of K. pneumoniae and S. aureus with zone of inhibition values of 18.5 and 23.2 mm, respectively, using 25 mg/well. However, E. coli and P. aeruginosa exhibited resistance to the extract. The findings of this study highlight the antibacterial and antioxidant properties of the ethanolic extract from H. helix leaves. The extract exhibited significant phenolic and flavonoid contents, as well as antioxidant activity. It also demonstrated antibacterial activity against selected pathogenic bacteria, suggesting its potential for controlling certain infections. Further research is warranted to identify the active compounds responsible for these activities and to explore their mechanisms of action.

Evaluation of the effectiveness of natural extract as a substituent for synthetic preservatives and antioxidants in pharmaceutical preparations.

Background: Despite the fact that synthetic preservatives and antioxidants have strong antibacterial and antioxidant activity, they are frequently associated with negative health consequences. Currently, there is an increasing interest in pharmaceutical products that are excellent in quality and free of synthetic preservatives. Methods: As a result, the purpose of this research is to assess the antibacterial and antioxidant activities of olive leaf extract, oleuropein, and thymol in various pharmaceutical products. Furthermore, the efficacy of these natural extracts to substitute synthetic preservatives (methyl-propylparaben and benzalkonium chloride) and antioxidants (butylhydroxytoluene) will be investigated. Results: The results revealed that oleuropein, olive leaf extract, and a blend of oleuropein and thyme oil may be utilized as preservatives at concentrations of (0.6 % w/v), (0.4 % w/v), and (0.4 %/0.1 % v/v), respectively. The results demonstrated that thyme oil and oleuropein have synergistic efficacy against the studied microorganisms. By assessing antibacterial activity, and physical properties, the results demonstrated that pharmaceutical formulations containing natural preservatives were stable and effective for three months under accelerated settings (40 °C/75 % RH). Conclusion: Natural compounds such as oleuropein, olive leaf extract, and thyme oil have shown antibacterial effectiveness equivalent to synthetic preservatives in selected pharmaceutical products. Furthermore, there was synergy in antimicrobial activity between thyme oil and oleuropein and this facilitates the use of these compounds at different levels.

Biosynthesized silver nanoparticle-coated electro-membrane extraction of perchlorate in different seafood samples.

In this work we developed a rapid and straightforward technique in which biosynthesized silver nanoparticles (Ag-NPs) were coated on a porous membrane utilizing electrical potential to extract perchlorate from seafood samples. The biosynthesized Ag-NPs were well characterized using UV-Vis. spectrophotometry, X-ray diffraction, and scanning electron microscopy. After extraction, analyses were performed using ion chromatography. The Ag-NP-coated porous polypropylene membrane shows higher extraction efficiency due to the high electrical conductivity of the Ag-NPs. The performance of this efficient technique was compared with those previously reported in the literature. The extraction variables that affect extraction of the target analyte and influence percentage recovery, such as pH of the sample solution, extraction time, and applied voltage, were investigated and optimized. The results demonstrated optimum conditions to achieve low detection limits [LODs (limits of detection)]: sample solution (pH = 6), short extraction time (10 min), and applied voltage (5 V). The developed method shows excellent linearity for perchlorate ion in the range from 0.001 to 350 µg L-1 with a coefficient of determination (r2 ) of 0.9991. The detection limit (LODs) and quantification limits (limits of quantification) were found to be 0.04 and 0.1225 µg kg-1 , respectively. The mean recovery percentages for three replicates of 10 different spiked fish samples by 3 µg g-1 of perchlorate were between 92.2 and 106.2%, with an observed relative standard deviation in the range of 0.8-3.7%. The proposed method is rapid, sensitive, inexpensive, environmentally friendly, and highly effective in extracting perchlorate from different seafood samples.

Development and Validation of an HPLC-UV Method for Determination of Eight Phenolic Compounds in Date Palms.

A simple, precise, accurate, and selective method was developed and validated for determination of eight phenolic compounds (gallic acid, p-hydroxybenzoic acid, vanilic acid, caffeic acid, syringic acid, p-coumaric acid, ferulic acid, and sinapic acid) in date palms. Separation was achieved on an RP C18 column using the mobile phase methanol-water with 2% acetic acid (18+82, v/v). This method was validated according to the requirements for new methods, which include accuracy, precision, selectivity, robustness, LOD, LOQ, linearity, and range. The method demonstrated good linearity over the range 1-1000 ppm of gallic acid, p-hydroxybenzoic acid, vanilic acid, caffeic acid, and syringic acid with r2 greater than 0.99, and in the range of 3-1000 ppm for p-coumaric acid, ferulic acid, and sinapic acid with r2 greater than 0.99. The recovery of the eight phenolic compounds ranged from 97.1 to 102.2%. The method is selective because adjacent peaks of phenolic compounds were well separated with good resolution. The degree of reproducibility of the results obtained as a result of small deliberate variations in the method parameters and by changing analytical operators proved that the method is robust and rugged.

Removal of amoxicillin and cefuroxime axetil by advanced membranes technology, activated carbon and micelle-clay complex.

Two antibacterials, amoxicillin trihydrate and cefuroxime axetil spiked into wastewater were completely removed by sequential wastewater treatment plant's membranes, which included activated sludge, ultrafiltration (hollow fibre and spiral wound membranes with 100 and 20 kDa cut-offs), activated carbon column and reverse osmosis. Adsorption isotherms in synthetic water which employed activated carbon and micelle-clay complex (octadecyltrimethylammonium-montmorillonite) as adsorbents fitted the Langmuir equation. Qmax of 100 and 90.9 mg g(-1), and K values of 0.158 and 0.229 L mg(-1) were obtained for amoxicillin trihydrate using activated carbon and micelle-clay complex, respectively. Filtration of antibacterials in the ppm range, which yielded variable degrees of removal depending on the volumes passed and flow rates, was simulated and capacities for the ppb range were estimated. Stability study in pure water and wastewater revealed that amoxicillin was totally stable for one month when kept at 37°C, whereas cefuroxime axetil underwent slow hydrolysis to cefuroxime.

Determination of trace heavy metals in harvested rainwater used for drinking in Hebron (south West Bank, Palestine) by ICP-MS.

Rainwater samples harvested for drinking from the west part of Hebron (south of West Bank in Palestine), the largest city in the West Bank, were analyzed for the content of different trace heavy metals (Cr, Mn, Co, Ni, Cu, Zn, Mo, Ag, Cd, Bi, and Pb) by inductively coupled plasma mass spectrometry (ICP-MS). This study was conducted to determine the water quality of harvested rainwater used for drinking of south West Bank (case study, Hebron area). A total of 44 water samples were collected in November 2012 from 44 house cisterns used to collect rainwater from the roofs of houses. The samples were analyzed for their pH, temperature, electrical conductivity, total dissolved solids, and different heavy metal contents. The pH of all water samples was within the US Environmental Protection Agency limits (6.5-8.5), while some water samples were found to exceed the allowed WHO limit for total dissolved solids (TDSs) in drinking water. Results showed that concentrations of the heavy metals vary significantly between the 44 samples. Results also showed that the concentration of five heavy metals (Cr, Mn, Ni, Ag, and Pb) is higher than the WHO limits for these heavy metals in drinking water. Overall, our findings revealed that harvested rainwater used for drinking of this part of south West Bank is contaminated with heavy metals that might affect human health.

Evaluation of the antibacterial and antifungal properties of oleuropein, olea Europea leaf extract, and thymus vulgaris oil.

BACKGROUND: Although synthetic preservatives and antioxidants may have high antimicrobial and antioxidant activity, they are usually associated with adverse effects on human health. Currently, there is a growing interest in natural antimicrobial and antioxidant agents. This study aimed to evaluate the antimicrobial activity of two medicinal plant extracts and one active compound. Olive leaf extracts (0.2, 0.3, and 0.4% w/v), oleuropein (0.2, 0.4, and 0.6% w/v), thyme oil (0.1%), and oleuropein in combination with thyme oil (0.4% w/v and 0.1% v/v) were used against three bacterial strains (Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus) and two fungal strains (Candida albicans and Aspergillus niger). RESULTS: The use of oleuropein resulted in complete antimicrobial activity against Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli. In this context, a reduction of 7 logs was achieved during the storage period (4 weeks). Oleuropein showed no fungal activity at low concentrations (0.2%), but Aspergillus niger was reduced by 2.35 logs at higher concentrations (0.6% w/v). Similar antibacterial and antifungal properties were observed for the olive leaf extracts. Oleuropein at a concentration of 0.4 w/v and a mixture of oleuropein and thyme at concentrations of 0.4 and 0.1 (v/v) showed strong antimicrobial activity against the studied microorganisms. CONCLUSION: Olive leaf extract, thyme oil, and oleuropein have strong antibacterial and weak antifungal properties. There was a good synergistic effect between oleuropein and thymol.

Ephedra alte extracts' GC-MS profiles and antimicrobial activity against multidrug-resistant pathogens (MRSA).

The extracts of E. alte offer promising potential as renewable resources for various chemical derivative products aimed at addressing antibiotic resistance. These extracts exhibited significant activity against methicillin-resistant Staphylococcus aureus (MRSA), a strain known for its resistance to multiple antibiotics. The extracts were found to be effective against several common antibiotics, including Imipenem, Ampicillin, Penicillin G, Oxacillin, and Amoxicillin-clavulanate. GC-MS analysis revealed that the phytoconstituents of E. alte extracts, obtained using both methanol and ethyl acetate, consist of a diverse range of 83 and 160 phytocompounds, respectively. These organic compounds serve as important biochemical precursors for the synthesis of vitamins E and K1, and exhibit antioxidant, antimicrobial, and anti-inflammatory properties in both plants and microorganisms. Notable compounds identified include fatty acids (such as palmitic acid, dodecanoic acid, sebacic acid, pentadecanoic acid, myristic acid, stearic acid, behenic acid, and linoelaidic acid), phytosterols (Campesterol, ß-sitosterol, Stigmast-5-ene), sugars (D-fructose, Fructofuranans), terpenoids (Phytol, citronellol), and phenolic acids (Protocatechoic acid, shikimic acid). The antimicrobial activity of all E. alte extracts was found to be superior to that of mupirocin and ciprofloxacin, as observed in susceptibility testing against MRSA ATCC 43300 and other pathogenic bacteria and fungi. It is likely that the combined action of the antimicrobial components within the E. alte extract bypasses the mechanisms employed by MRSA to protect itself from antibiotics. Further experiments are needed to investigate the individual effects of each pure compound and their potential synergistic interactions, which may enhance their overall performance.

Anticancer, antioxidant, and antibacterial activity of chemically fingerprinted extract from Cyclamen persicum Mill.

In the last few decades, researchers have thoroughly studied the use of plants in Palestine, one of them is Cyclamen persicum Mill. (C. persicum). Cyclamen persicum has been historically cultivated since the 1700s due to its tuber. The tuber is known to stimulate the nasal receptors, thus triggering the sensory neurons. Cyclamen persicum has anti-inflammatory effects, reduces cholesterol levels, treats diabetes, and inhibits tumor growth. In this respect, in-vitro examination of antibacterial and anticancer activities and antioxidative potency of C. persicum ethanolic extract were evaluated. The antioxidative potency of the extracted plant material was determined spectrophotometrically using the DPPH free radical scavenging method and the HPLC-PDA method to evaluate its total phenolic content (TPC) and total flavonoid content (TFC). The experimental results revealed weak antibacterial activity of C. persicum extract against both gram negative (E. coli) and gram positive (Streptococcus aureus and S. aureus) bacterial strains, with the zones of inhibition found to be less than 8 mm. On the other hand, powerful activity against MCF7 breast cancer as well as HT29 colon cancer cell lines was obtained. The findings also revealed potent inhibition of free radicals and the presence of maximal levels of natural products such as phenolic compounds and flavonoids, which supportits biological activities and powerful ability to scavenge free radicals. HPLC results showed the presence of numerous flavonoid and phenolic compounds such as rutin, chlorogenic acid, kaempferol, trans-cinnamic acid, quercetin, sinapic acid, and p-coumaric acid.

Efficiency of membrane technology, activated charcoal, and a micelle-clay complex for removal of the acidic pharmaceutical mefenamic acid.

The efficiency of sequential advanced membrane technology wastewater treatment plant towards removal of a widely used non-steroid anti-inflammatory drug (NSAID) mefenamic acid was investigated. The sequential system included activated sludge, ultrafiltration by hollow fibre membranes with 100 kDa cutoff, and spiral wound membranes with 20 kDa cutoff, activated carbon and a reverse osmosis (RO) unit. The performance of the integrated plant showed complete removal of mefenamic acid from spiked wastewater samples. The activated carbon column was the most effective component in removing mefenamic acid with a removal efficiency of 97.2%. Stability study of mefenamic acid in pure water and Al-Quds activated sludge revealed that the anti-inflammatory drug was resistant to degradation in both environments. Batch adsorption of mefenamic acid by activated charcoal and a composite micelle (otadecyltrimethylammonium (ODTMA)-clay (montmorillonite) was determined at 25.0°C. Langmuir isotherm was found to fit the data with Qmax of 90.9 mg g(-1) and 100.0 mg g(-1) for activated carbon and micelle-clay complex, respectively. Filtration experiment by micelle-clay columns mixed with sand in the mg L(-1) range revealed complete removal of the drug with much larger capacity than activated carbon column. The combined results demonstrated that an integration of a micelle-clay column in the plant system has a good potential to improve the removal efficiency of the plant towards NSAID drugs such as mefenamic acid.

Efficiency of advanced wastewater treatment plant system and laboratory-scale micelle-clay filtration for the removal of ibuprofen residues.

The efficiency of Al-Quds Waste Water Treatment Plant (WWTP), which includes sequential elements as activated sludge, ultrafiltration, activated carbon column and reverse osmosis, to remove spiked ibuprofen, a non steroid anti inflammatory drug (NSAID), was investigated. Kinetic studies in pure water and in the activated sludge indicated that the drug was stable during one month of observation. Besides, the overall performance of the integrated plant showed complete removal of ibuprofen from wastewater. Activated carbon column, which was the last element in the sequence before the reverse osmosis system, yielded 95.7% removal of ibuprofen. Batch adsorptions of the drug by using either activated charcoal or composite micelle-clay system were determined at 25°C and well described by Langmuir isotherms. Octadecyltrimethylammonium (ODTMA) bromide and montmorillonite were used to prepare the micelle-clay adsorbent, for which the adsorption kinetics are much faster than activated charcoal. Results suggest that integrating clay-micelle complex filters within the existing WWTP may be promising in improving removal efficiency of the NSAID.

Assessment of antioxidant, antimicrobial, and anticancer activities of Sisymbrium officinale plant extract.

The most efficient and safe source of medications is the natural and traditional medications which are produced from plants and herbs. In this study, Sisymbrium officinale (S. officinale) was tested to explore its total phenolic and flavonoids contents. Antioxidant, antimicrobial, and anticancer activities were assessed as well. S. officinale was bought from a local Palestinian market, air-dried, and extracted with 99% ethanol with the aid of ultrasonication. The extract was tested on three types of bacteria using well diffusion method. The anti-microbial testing included three different types of bacteria, two gram-positive bacteria, Streptococcus and Staphylococcus and E. coli as a gram-negative bacterium. Antioxidant activity of the plant extract was conducted using DPPH method, while total phenolic and flavonoids contents were performed using a well-known assay chemical method. Anticancer activity of the extract was conducted against two cancer cell lines (breast (MCF7) and colon (HCT116) cancer cell lines). Results showed that the extract is rich polyphenolic and flavonoids and has strong antioxidant activity reflected by inhibition of free radicals (DPPH) (193.7 ± 3.4). The plant extract showed also strong antimicrobial activity against both E. coli and Streptococcus bacteria with of inhibition of 10 and 14 mm respectively. The extract of this plant also showed anticancer activity (about 6%) against MCF7 (breast cancer cell line).

Phytochemical composition and bioactivities of Crataegus aronia as antioxidant, antibacterial and antioxidative stress in red blood cells - Is it a window of hope for children with glucose-6-phosphate dehydrogenase deficiency.

Background: Crataegus aronia (C. aronia) extracts have been used medicinally since ancient times and are often utilized in traditional Arab medicine. An extensive study has revealed that Crataegus species have antioxidant, antibacterial, anti-inflammatory, and hypotensive properties. Objectives: This work was performed to explore the phytochemical contents of C. aronia extract, as well as its antioxidant and antibacterial properties, and to assess the lipid peroxidation level as an oxidative stress biomarker in erythrocytes. Methods: Chemical constituents in the methanolic extract of C. aronia were identified by gas chromatography-mass spectrometry and their relative concentrations were determined. The antioxidant activity of C. aronia extract was determined using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) assays. The effect of C. aronia on the concentration of malondialdehyde (MDA) in the erythrocyte hemolysates was studied. Also, the crude extract was assessed for its antimicrobial activity through agar diffusion and microbroth dilution assays. Key findings: The DPPH IC50 value of the extract showed that the antioxidants activity was equal to (14.3 µg/mL) and according to FRAP assay, the antioxidant activity was in the range of 33.9 µmol-82.86 µmol Fe+2/g dw. The extract exerts a protective effect against oxidative stress in RBCs and shows a 50% inhibition of malonyldialdehyde (MDA) at 39.48 µg/mL extract. Minimum inhibitory concentrations were found in the range of 800-1000 µg/mL of leave extracts. The phytochemical analysis showed that the total phenols, flavonoids, and flavonols content were 494.071 mg GAE/g extract, 155.251 mg RE/g extract, and 103.2049 mg RE/g extract). C. aronia extract contains alkaloids, flavonoids, terpenoids, and steroids. Crude extract of C. aronia was more potent in inhibiting the growth of B. subtilis, S. aureus and M. luteus with MIC and MBC values of 800,800 and 1000 µg/mL, respectively. According to GC-MS, 20 compounds were identified: dihydro-3-methylene-5-methyl-2-furanone (14.71%), hexanoic acid (6.57%), ethyl 3,5-ditert-butyl-4-hydroxybenzoate (6.4%), N, N-dimethylheptadecan-1-amine (4.91%), methyl 2-oxobutanoate (4.14%), glyceraldehyde (3.98%), and 2-methoxy-1-(2-nitroethenyl)-3-phenylmethoxybenzene (3.16%), were the major constituents. Conclusion: This study may open a window of hope for children with Glucose-6-phosphate dehydrogenase disorder by possible utilization of the active ingredients of C. aronia to minimize both oxidative stress and infection which negatively impact the disease sequelae.According to these in vitro experiments, this plant extract has a significant amount of natural antioxidants, which may aid in the protection of various oxidative stresses. As a result, employing the active components of C. aronia to minimize oxidative stress and infection, both of which have a detrimental impact on disease sequelae, may bring hope to children with Glucose-6-phosphate dehydrogenase disorder.

The dual impact of Jordanian Ephedra alte for inhibiting pepsin and treating microbial infections.

Screening of phytochemical Ephedra alte crude extract by GC-MS and HPLC analysis indicated the presence of alkaloids, tannins, flavonoids, terpenoids, and phenolic acid in the extract. The total phenolic content of E. alte methanol extract was 39.43 mg of Gallic acid eq/g, crude E. alte with 56.74, and 2.42 µg Trolox equivalent antioxidant capacity (TEAC)/g of plant extract according to DPPH and FRAP assay, respectively. The antimicrobial activity of E. alte against Staphylococcus aureus, staphylococcus epidermidis, Escherichia coli, and Klebsiellaoxytoca demonstrated a mean zone diameter of inhibition ranging from 0 to 17 mm. The MIC of the extracts ranged from 0.5 to 1.0 mg/mL. E. alte extract inhibits pepsin enzyme activity with IC50 values of 213.67 µg/ml. This study revealed that E. alte extract has pepsin enzyme inhibitory, antibacterial, antioxidant activities. The current outcomes indicate that E. alte might be employed as a natural agent for managing GERD and infectious diseases.

Normal-phase LC method for simultaneous analysis of pseudophedrine hydrochloride, dextromethorphan hydrobromide, chlorpheniramine maleate, and paracetamol in tablet formulations.

A simple, precise, and accurate method is developed and validated for the analysis of pseudophedrine hydrochloride, dextromethorphan hydrobromide, chlorpheniramine maleate, and paracetamol in tablet formulations. The method has shown adequate separation of the four ingredients from each other. Separation was achieved on a silica column (5 µm, 125 × 4.6 mm inner diameter) using a mobile phase consisting of methanol/ammonium dihydrogen phosphate buffer (90:10, v/v) at a flow rate of 1.0 ml/min and UV detection at 220 nm. This new method is validated in accordance with USP requirements for new methods for assay determination, which include accuracy, precision, selectivity, linearity and range, robustness and ruggedness. The current method demonstrates good linearity over the range of 0.15-0.45 mg/ml of pseudophedrine hydrochloride with r (2) of 0.996, and in the range of 0.075-0.225 mg/ml of dextromethorphan hydrobromide with r (2) of 0.992, and in the range of 0.01-0.03 mg/ml of chlorpheniramine maleate with r (2) of 0.994, and in the range of 0.25-0.75 mg/ml of paracetamol with r (2) of 0.991. The average recovery of the method is 99.7%, 98.6%, 98.1%, and 99.2% for pseudophedrine hydrochloride, dextromethorphan hydrobromide, chlorpheniramine maleate, and paracetamol, respectively. The degree of reproducibility of the results obtained as a result of small deliberate variations in the method parameters and by changing analytical operator has proven that the method is robust and rugged.

Phenolics, flavonoids and antioxidant capacities in Citrus species with different degree of tolerance to Huanglongbing.

Huanglongbing (HLB) is a highly destructive disease to the citrus industry in Florida caused by the bacterium, Candidatus Liberibacter asiaticus(CLas) and is transmitted by Diaphorina citri. It is hypothesized that plants with high phenolic contents show higher tolerance to certain plant pathogens. In this regard, different citrus varieties and plants of genera related to Citrus were analyzed for their total phenolic and flavonoids contents, and their antioxidant capacities. In addition, the secondary metabolites in the leaves of seven citrus species were analyzed using high performance liquid chromatography-mass spectrometry (HPLC-MS). Colorimetric assays showed that curry leaf contained the highest total phenolic content and free radical scavenging activity (DPPH). Curry leaf also contained high concentrations of an unusual class of carbazole alkaloids. Tolerant Citrus species contained high levels of phenolics and flavonoids and showed high antioxidant capacities. Our results suggest that high phenolic and flavonoid leaf contents correlate with increased citrus tolerance to CLas bacterium. The results also suggest that the high level of carbazole alkaloids, known for their strong antimicrobial properties in curry leaf, could make it immune to the CLas bacteria. Understanding the mechanisms underpinning citrus tolerance to HLB will contribute to the development of commercially tolerant citrus cultivars.

The Role of the Xylem in Oxytetracycline Translocation within Citrus Trees.

Antibiotics have been successfully used to control plant diseases for more than fifty years. Recently, oxytetracycline and streptomycin have been approved for the treatment of Huanglongbing, which is threatening the citrus industry in many regions. Because the efficiency of antibiotics in planta is highly affected by their movement and distribution, understanding the mechanism of antibiotics' uptake and distribution could lead to a better control of plant pathogens. Herein, we investigated the movement of oxytetracycline within citrus plants. Oxytetracycline was applied by root drenching to both girdled and non-girdled citrus seedlings. In addition, oxytetracycline was applied by trunk injection to girdled and non-girdled citrus trees. After the exposure time (24 h), citrus seedlings were dissected and the levels of oxytetracycline in the different tissues were measured using an oxytetracycline ELISA kit. Upon root application (laboratory experiment), oxytetracycline was detected in the inner part of the stem (xylem-associated tissue), cortex (phloem-associated tissue), and leaves above and below the girdled area. Likewise, oxytetracycline was also detected in leaves of trunk-injected field trees (girdled and non-girdled) three days post treatment. Interestingly, cortex girdling did not affect the distribution and translocation of oxytetracycline, indicating that the xylem is the main path for oxytetracycline translocation. Taken together, our results indicate that oxytetracycline translocation mainly occurs via xylem vessels, and that movement into the phloem occurs subsequent to xylem translocation. Our findings also clearly demonstrated that upon trunk injection, only trace levels of oxytetracycline reached the roots, minimizing its therapeutic value there. Thus, our recommendation is to time tree injections to coincide with the flushing periods when the bacteria are moving into new shoots to maximize the efficiency of oxytetracycline.

Uptake, Translocation, and Stability of Oxytetracycline and Streptomycin in Citrus Plants.

Huanglongbing (HLB), or citrus greening, is the most destructive disease to the citrus industry. In Florida, it is caused by the bacterium, Candidatus Liberibacter asiaticus (CLas) and is transmitted by the Asian citrus psyllid, Diaphorina citri. Recent studies suggested that antibiotics could inhibit the growth of the CLas pathogen in planta. In the current study, we investigated the uptake and translocation of oxytetracycline and streptomycin in citrus seedlings. Oxytetracycline and streptomycin were delivered via root and stem and their level in various tissues was monitored using enzyme-linked immunosorbent assay (ELISA). Oxytetracycline and streptomycin were detected in the leaves, xylem, phloem, and root after root drench and stem delivery. High levels of antibiotics were detected in the roots after root drench, whereas high levels of antibiotics were detected in the canopy after stem delivery. The level of oxytetracycline detected in the phloem, xylem, and leaves after root drench was higher than that of streptomycin. Whereas the level of streptomycin in root was higher than that of oxytetracycline, indicating that streptomycin was bound to the xylem tissues. Oxytetracycline and streptomycin were detected in the phloem, xylem, leaves, and root tissues thirty-five days after the root incubation in 200 µg·mL-1 solution. These results demonstrated that oxytetracycline and streptomycin were relatively stable and could inhibit CLas growth for a couple of months in citrus trees. Observations reported in this study regarding the distribution and stability of oxytetracycline and streptomycin in citrus plants could be useful for designing an effective program for the control of HLB disease using antibiotics.

Tracing Penicillin Movement in Citrus Plants Using Fluorescence-Labeled Penicillin.

Huánglóngbìng (HLB), citrus greening, is one of the most destructive diseases of citrus plants worldwide. In North America, HLB is caused by the phloem-limited bacterium Candidatus Liberibacter asiaticus and is transmitted by the Asian citrus psyllid, Diaphorina citri. No cure exists at present, and the use of antibiotics for the control of HLB has gained interest due to the significant losses to the citrus industry. Because of unsatisfactory results when using foliar applications of antibiotics, concerns were raised regarding the uptake and translocation of these materials within trees. We, therefore, investigated a method that allows us to study the movement of antibiotic materials in citrus plants. Herein, we utilized a fluorescence-labeled penicillin, BOCILLINTM FL-Penicillin (FL-penicillin), to study the uptake and translocation of penicillin in citrus plants. FL-penicillin was applied by puncture to the stem of young citrus seedlings and was traced by using fluorescence microscopy. After application, we detected FL-penicillin in the leaves and in the stem xylem and phloem tissues above and below the application site in both intact and partially bark-girdled citrus seedlings, indicating that it is easily taken up and transported through the plant vascular system. In addition, we detected FL-penicillin in the gut of D. citri, which were allowed to feed on the treated plants, suggesting translocation of this molecule into the vascular tissue. We propose that the use of fluorescent-labeled molecules could be an effective tool for understanding the uptake and translocation of antibiotics and other macromolecules in plants and insects.