Effects of Encapsulation of Caesalpinia sappan L. with Cyclodextrins for Bovine Mastitis.

The main components of Caesalpinia sappan L. (CS) are brazilin and brazilein, which show high potential in pharmacologic applications. However, these have been drastically limited by the poor water solubility and stability. The present study investigates the formation of inclusion complexes F1, F2, and F3 between CS and ß-cyclodextrin (ßCD), hydroxypropyl-ß-cyclodextrin (HPßCD), and methyl-ß-cyclodextrin (MßCD), respectively. These complexes were characterized by Fourier transform infrared spectroscopy (FT-IR). The results showed that the highest encapsulation efficiency and loading capacity of CS extract were 44.24% and 9.67%, respectively. The solubility and stability of CS extract were significantly increased through complexation in phase solubility and stability studies. The complexes F1-F3 showed mainly significant antibacterial activities on gram-positive bacteria pathogens causing mastitis. Moreover, the expression levels of COX-2 and iNOS were significantly decreased in LPS-induced inflammatory cells at concentrations of 50 and 100 µg/mL. In addition, treatment of complex F3 (CS/MßCD) in bovine endothelial cells remarkably increased the chemokine gene expression of CXCL3 and CXCL8, which were responsible for immune cell recruitment (9.92 to 11.17 and 8.23 to 9.51-fold relative to that of the LPS-treated group, respectively). This study provides a complete characterization of inclusion complexes between CS extract and ßCD, HPßCD, and MßCD for the first time, highlighting the impact of complex formation on the pharmacologic activities of bovine mastitis.

Factors in Dry Period Associated with Intramammary Infection and Subsequent Clinical Mastitis in Early Postpartum Cows.

The objective of this study was to determine cow characteristics and farm management factors during the dry period associated with early postparturient intramammary infection (IMI) and subsequent clinical mastitis (CM). Data were collected three times: before drying off (P1), during the dry period (P2), and 5 to 14 days after calving (P3), using questionnaires and farm investigation. Milk samples were aseptically collected for bacterial identification at P1 and P3. Factors associated with IMI and CM were analyzed using multiple logistic regression models. The final model showed that IMI in early postpartum was significantly associated with full insertion of dry cow antibiotic, dry cows in barns with a combination of tie and free stalls, body condition score (BCS) in dry period and after calving, and milk yield before drying off. For IMI cows, factors significantly associated with clinical expression of mastitis were having daily barn cleaning, teat disinfected with alcohol before administration of dry cow therapy, BCS before drying off, milk yield before drying off, and days in milk at drying off. In conclusion, both cow and farm management factors are associated with the IMI rate and subsequent expression of clinical signs of mastitis in early postpartum cows.

Synergistic Effect between Eugenol and 1,8-Cineole on Anesthesia in Guppy Fish (Poecilia reticulata).

This study aimed to evaluate the synergistic effect between eugenol and 1,8-cineole on anesthesia in female guppy fish (Poecilia reticulata). Experiment I evaluated the concentrations of 0, 12.5, 25, 50, and 75 mg/L of eugenol and 0, 100, 200, 300, and 400 mg/L of 1,8-cineole for times of induction and recovery from anesthesia. Experiment II divided fish into 16 study groups, combining eugenol and 1,8-cineole in pairs at varying concentrations, based on the dosage of the chemicals in experiment I. The results of the anesthesia showed that eugenol induced fish anesthesia at concentrations of 50 and 70 mg/L, with durations of 256.5 and 171.5 s, respectively. In contrast, 1,8-cineole did not induce fish anesthesia. In combination, using eugenol at 12.5 mg/L along with 1,8-cineole at 400 mg/L resulted in fish anesthesia at a time of 224.5 s. Increasing the eugenol concentration to 25 mg/L, combined with 1,8-cineole at 300 and 400 mg/L, induced fish anesthesia at times of 259.0 and 230.5 s, respectively. For treatments with eugenol at 50 mg/L combined with 1,8-cineole at 100 to 400 mg/L, fish exhibited anesthesia at times of 189.5, 181.5, 166.0, and 157.5 s. In the case of eugenol at 75 mg/L, fish showed anesthesia at times of 175.5, 156.5, 140.5, and 121.5 s, respectively. The testing results revealed that 1,8-cineole as a single treatment could not induce fish anesthesia. However, when supplementing 1,8-cineole in formulations containing eugenol, fish exhibited a significantly faster induction of anesthesia (p < 0.05). Furthermore, all fish that underwent anesthesia were able to fully recover without any mortality. However, the shorter anesthesia duration resulted in a significantly prolonged recovery time. In conclusion, eugenol and 1,8-cineole work better together as anesthetics than when used separately, and demonstrated the safety of using these anesthetic agents on guppy fish.

Self-emulsifying drug delivery systems (SEDDS) containing Cymbopogon citratus essential oil: Enhancing the stability and acaricide efficacy against Rhipicephalus (Boophilus) microplus.

The objectives of this study were to develop a self-emulsifying drug delivery system (SEDDS) to enhance the stability and efficacy of Cymbopogon citratus essential oil or lemongrass oil (LEO) against cattle tick larvae and engorged females. The system with the highest oil loading in SEDDS was composed of LEO (23.33%w/w), Tween 80: SGKH 4000 in a 2:1 ratio as surfactant (66.67%w/w), and propylene glycol as co-surfactant (10%w/w). The selected SEDDS-LEO has a particle size of 18.78 nm with a narrow size distribution (polydispersity index of 0.27). Notably, the stability of SEDDS was superior to that of the original oil, both during long-term storage and under accelerated conditions. SEDDS-LEO at oil concentrations ranging from 1.458% to 5.833% w/v showed a significantly higher percentage of egg-laying reduction against adult ticks compared with the original oil at the same concentrations (p < 0.05). Furthermore, SEDDS-LEO demonstrated greater larvicidal efficacy than the original oil, with lower LC50 and LC90 values of 0.91 mg/mL and 1.20 mg/mL, respectively, whereas the original oil's LC50 and LC90 values were 1.17 mg/mL and 1.74 mg/mL, respectively. Our findings indicate that SEDDS-LEO is a promising candidate for use as an acaricide in the control of tick populations in dairy cattle.

In Vitro Bacterial Competition of Staphylococcus aureus, Streptococcus agalactiae, and Escherichia coli against Coagulase-Negative Staphylococci from Bovine Mastitis Milk.

Intramammary infection (IMI) from the environment and infected quarters can cause co-infection. The objective of this study was to determine the ability of coagulase-negative staphylococci (CNS) to survive in the same environment as Staphylococcus aureus, Streptococcus agalactiae, and Escherichia coli as major pathogens. In total, 15 and 242 CNS strains were used in Experiment I and Experiment II, respectively. Both experiments were separated into three conditions: culture with CNS 24 h before (PRIOR), after (AFTER), and at the same time (EQUAL). The lack of a clear zone, regardless of size, was determined to be the key to the survival of both. The CNS species' percentages of survival against major pathogens were tested using Fisher's exact test. Differences in the percentages of survival were evident among the CNS species in all conditions. For the PRIOR condition, all CNS mostly survived when living with major strains; however, S. chromogenes could degrade S. agalactiae. Although most CNS strains were degraded in the AFTER and EQUAL conditions, some strains of S. hominis and S. simulans could resist S. aureus and S. agalactiae. In conclusion, some specific strains of CNS are able to survive in an environment with major pathogens. Research into the survival strains may indicate that the concept of novel bacteria with bacteriolytic capabilities might be possible as a novel mastitis treatment.

Clinical field trial of parenteral amoxicillin for the treatment of clinical and subclinical mastitis in smallholder dairy farms in the upper region of Northern Thailand.

Background and Aim: Mastitis, primarily caused by intramammary bacterial infection, is the most expensive disease in the global dairy industry due to its negative impact on milk composition and manufacturing properties. This study aimed to evaluate the efficacy of parenteral amoxicillin in the treatment of clinical and subclinical mastitis in smallholder dairy farms in Northern Thailand. Materials and Methods: A total of 51 cows with clinical and subclinical mastitis from dairy cooperatives in Lamphun and Chiang Mai provinces, Northern Thailand, were enrolled in this study. Conventional bacteriological procedures were applied to identify the causative bacteria in milk samples from these cows before and 7 days after treatment, and antibiotic susceptibility tests were conducted using the disk diffusion method for all bacteria isolated before treatment. All cows with mastitis were administered 15 mg/kg of amoxicillin (LONGAMOX®, Syva Laboratories SA, Spain) intramuscularly every other day for 3 days. Results: Environmental streptococcal bacteria (Streptococcus uberis and Streptococcus spp.) were commonly isolated from infected quarters and were highly susceptible to amoxicillin (100%). The clinical efficacy of amoxicillin treatment for clinical mastitis cases was 80.43%, and the bacteriological efficacy was 47.82%, with opportunistic staphylococcal bacteria (coagulase-negative staphylococci) and contagious streptococcal bacteria (Streptococcus agalactiae) being the most sensitive microorganisms (100%). In subclinical mastitis cases, the bacteriological efficacy of parenteral amoxicillin was 70.45%, with environmental streptococcal bacteria (S. uberis) being the most (100%) sensitive microorganisms. Conclusion: Amoxicillin is highly efficacious and can be used to treat clinical and subclinical mastitis in dairy cows, particularly mastitis caused by environmental Streptococcus spp. These findings could be used to guide treatment regimens in veterinary practice in smallholder dairy farms in Thailand.

In vitro and in vivo action of turmeric oil (Curcuma longa L.) against Argulus spp. in goldfish (Carassius auratus).

Background: Argulus is a common and widespread ectoparasite that causes major parasitic diseases and is a virus and bacteria carrier in the ornamental fish trade. Aim: The purpose of this study is to determine what types of phytochemicals are present in the essential oil extracted from turmeric rhizome (Curcuma longa L.) and to assess the efficacy of turmeric oil in eliminating Argulus spp. infestations in goldfish (Carassius auratus). Methods: The chemical composition and quantity of the major substances in essential oils from fresh turmeric rhizome were detected by gas chromatography/mass spectrometry (GC-MS). The antiparasitic effect of turmeric oils on Argulus spp. was tested at 12.5, 25, 50, 100, and 200 ppm and compared to 0.25 ppm Neguvon® (the positive control). The percentage of Argulus spp. killed, the percentage of the mean mortality rate, and the effectiveness of each test were evaluated. Results: By using GC-MS analysis, it was possible to identify the primary phytochemical component of turmeric essential oil as b-turmerone. The results obtained from the in vitro test indicated that there was a correlation between the concentration of turmeric essential oil and the average mortality rate of fish lice. The mean mortality of fish louse exposed to 200 ppm turmeric essential oil was higher than the mean mortality of fish louse exposed to Neguvon® (p < 0.05). In an in vivo study, the effectiveness of 12.5 ppm turmeric essential oil against parasites was 44.44%, 55.46%, and 62.83% at 24, 48, and 72 hours, respectively. Conclusion: In summary, the efficacy of turmeric essential oil against fish louse has been shown both in vitro and in vivo studies.

Titanium Dioxide Nano-Formulation: Characterization, Antimicrobial Activity, and Wound Healing in Animals.

The use of metal oxide nanoparticles as an alternative antimicrobial agent has gained attention due to the increasing problem of antimicrobial resistance. Understanding its properties and potential benefits can contribute to the development of more effective and sustainable treatments in veterinary medicine. The aim of this study was to characterize TiO2-NP formulations and evaluate their antibacterial and wound healing abilities. The diameters and zeta potentials were determined using the Zetasizer in conjunction with dynamic light scattering. The agar-well diffusion method, time-kill kinetic assay and crystal violet assay were used to evaluate their antimicrobial activities. Wound healing assays were conducted both in vitro and in vivo. The study demonstrated that TiO2-NP formulations exhibit significant antimicrobial properties against various bacterial strains such as S. aureus and E. coli. No measurable E. coli growth was observed within a 15-min period following exposure to TiO2-NP formulations. The TiO2-NP formation can improve wound healing by enhancing cell migration and collagen formation in both in vitro and in vivo conditions. In summary, our study suggests that TiO2-NP has the potential for use as an antimicrobial agent for animal wound treatment due to its ability to suppress bacterial growth and biofilm formation, as well as to enhance wound healing.

Impact of Storage Conditions and Mold Types on Aflatoxin B1 Concentration in Corn Residue used as Dairy Feed in Small Holder Dairy Farms, Thailand.

The aims of this study were to determine the impact of storage practice and mold types on mold growth and aflatoxin B1 (AFB1) concentration in corn residue from local seed corn plants, the main roughage source of dairy farms in the northern region in Thailand. A total of 223 samples from 2 types of corn residue - dried and wet - were collected. Mold contamination was determined by spread plate technique, and aflatoxin B1 (AFB1) quantification was performed by a commercial enzyme-linked immunosorbent assay. Multivariate linear models were created to determine factors associated with fungal quantity and AFB1 concentration. Results showed that the presence of Cladosporium spp. in the samples was associated with a lower risk of AFB1 contamination (P<0.05). In addition, appropriate storage practices, e.g. keeping feeds under a roof and using floor canvas under feed piles, gave lower risk of mold contamination and decreasing AFB1 contamination.

Cephalexin microspheres for dairy mastitis: effect of preparation method and surfactant type on physicochemical properties of the microspheres.

The aim of this study was to evaluate the effects of preparation method and the type of surfactant on the properties of cephalexin (CPX) microspheres in order to obtain delivery systems suitable for the treatment of dairy mastitis. Microspheres were obtained using various preparation conditions and their physicochemical characteristics such as size, loading efficiency, morphology, and drug crystallinity were investigated. Antibacterial activity of microspheres from the optimum preparation condition was also studied. CPX microspheres were prepared by two different W/O/W emulsion solvent evaporation methods using PLGA as a matrix forming polymer. Several types of surfactants including nonionic, cationic, and anionic at different concentrations were used for preparation of the particles. The type and concentration of surfactant did neither affect the size nor morphology of the microspheres but showed a pronounced effect on the CPX encapsulation efficiency. It was found that Tween 80 showed the highest drug encapsulation efficiency (66.5%). Results from X-ray diffraction diffractograms and differential scanning calorimetry thermograms indicated that CPX entrapped in these microparticles was amorphous. Assessment of antibacterial activity showed that the obtained CPX microspheres exhibited good inhibition with minimum inhibitory concentration and minimum bactericidal concentration values of 128 microg/mL and 2,048 mg/mL against Staphylococcus aureus ATCC 25923, 512 microg/mL and 4,096 mg/mL against Escherichia coli ATCC 25922, respectively.

Antibacterial Activities of Acetic Acid against Major and Minor Pathogens Isolated from Mastitis in Dairy Cows.

The present study evaluated the antimicrobial activities of acetic acid against bovine mastitis pathogens compared to lactic acid and lauric and caprylic saturated fatty acids. Eleven mastitis pathogens were isolated from sub-clinical and clinical bovine mastitis cases for the study. An initial screening of their antibacterial activities by agar well diffusion method was performed. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of each acid were obtained using a microdilution method; each acid was diluted from stock solution and then were diluted with culture broth to reach concentrations ranging from 4 to 0.004% w/v. The results showed acetic acid had the highest zone of inhibition against all pathogens except Escherichia coli compared with lauric and caprylic acids. The MIC and MBC were lowest for acetic acid against both Gram-positive (except Staphylococcus chromogenes from the coagulase negative staphylococci (CNS) group) and Gram-negative pathogens, intermediate for lactic and caprylic acids and greatest for lauric acid. In conclusion, acetic acid had antimicrobial activities against most mastitis pathogens compared with other acids. Further studies are needed to optimize the formulation and concentration of acetic acid for teat-dipping agent in the future.

Occurrence and Antimicrobial Susceptibility Profiles of Multidrug-Resistant Aeromonads Isolated from Freshwater Ornamental Fish in Chiang Mai Province.

Antimicrobials are commonly used to prevent and treat disease in the ornamental fish industry. However, the indiscriminate and comprehensive overuse of unregulated antimicrobials without appropriate diagnostic examination could contribute to the development of antimicrobial-resistant strains of bacterial pathogens. Moreover, human infections caused by pathogens transmitted from fish or the aquatic environment are quite common. The frequent detection of antimicrobial resistance in ornamental fish and their environments are inevitable so as to decrease the transfer of antimicrobial-resistant bacteria from aquatic sources to other environments. This study evaluated the prevalence of common bacteria species and the antimicrobial susceptibility profile in ornamental fish that were sold in an ornamental fish shop in Chiang Mai, Thailand. Aeromonas spp. were the most dominant of the isolated species from the ornamental fish samples and accounted for 68.09% of the total. Other species detected included Vibrio spp., Pseudomonas spp., and Citrobacter spp. A high percentage of resistance to amoxicillin (93.75%), oxytetracycline (79.69%), and erythromycin (75.00%) was observed among the Aeromonas spp. The antimicrobial resistance information for ornamental fish is very limited, and the results from this study indicate that the Aeromonas spp. are highly resistant to several important antibiotics. The results suggest that additional steps should be taken to educate store owners to reduce the indiscriminate use of these antibiotics to decrease the antimicrobial resistance in ornamental fish to potentially improve public health.

Preparation and characterization of cephalexin loaded PLGA microspheres.

The aim of this study was to evaluate the effects of emulsion type and process parameters on the properties of CPX-loaded PLGA microspheres in order to obtain delivery systems suitable for the treatment of dairy mastitis. The microsphere size was analyzed by photon correlation spectrophotometry. Determination of the drug loading was achieved by HPLC. It was found that CPX-loaded PLGA microspheres prepared using a w/o/w double emulsion technology were slightly larger (approximately 3-5 microm) but much higher in drug content (approximately 18% w/w) than those obtained using o/w single emulsion preparation technology (average size was 2 microm, encapsulation efficiency was less than 2 %). It was also demonstrated that stirring during emulsification and a change in both the internal and external phase of the emulsion, affected the size and the drug entrapment efficiency of the microspheres obtained. A 60/40 v/v mixture of chloroform and acetone was found to be the best organic solvent system for creating the primary emulsion. To obtain a high yield (>90%) of microspheres with a desirable size and high drug entrapment efficacy, a stirring rate of 8,000-10,000 rpm gave the best results. It is concluded CPX-loaded PLGA microspheres with suitable characteristics for the treatment of cows with dairy mastitis can be prepared by a w/o/w double emulsion preparation method.

Loss of L-ascorbic acid in commercial drinking milk caused by milk processing and storage times.

The goals of this study were to determine L-ascorbic acid concentrations in various milk products, and to evaluate the effect of storage time on L-ascorbic acid in milk. Commercial plain milk samples were obtained from either a raw-food market or a supermarket, in Mae Hia, Mueang District, Chiang Mai Province, Thailand, during July, 2008. The types of milk were separated based on fat percentages (non fat-0%, low fat-1.5%, full fat-3%), and their method of processing (pasteurization, UHT). All samples were collected, transported, and measured for their L-ascorbic acid concentrations on the same day. The expiration date, type of milk, and source of milk were recorded. Pasteurized milk had higher L-ascorbic acid levels than UHT milk (p < 0.05), but no differences of L-ascorbic acid levels were seen among the milk fat percentage groups. The L-ascorbic acid level was significantly positively related to time before the expiration date of the milk, indicating that increased storage time of milk is related to decreased L-ascorbic acid concentration in the milk. Longer milk storage times resulted in lower- L-ascorbic acid levels and pasteurized milk has higher L-ascorbic acid levels than UHT milk.

Bactericidal Effect of Clove Oil against Multidrug-Resistant Streptococcus suis Isolated from Human Patients and Slaughtered Pigs.

Streptococcus suis is a zoonotic pathogen that is currently considered an emerging multidrug-resistant (MDR). Increasing antibiotic resistance can lead to the unsuccessful treatment of S. suis infection. Recently, many investigations of medicinal plants were conducted for the treatment of infection as a result of the increase of antibiotic-resistant bacteria. The aims of this study were to determine the chemical composition of essential oil from Syzygium aromaticum (L.) Merr. & L.M. Perry and the antibacterial activities of clove oil on MDR S. suis. Using gas chromatography coupled to a mass spectrometer, eugenol (97.76%) was found to be the major active ingredient of clove oil. In vitro antibacterial activities of clove oil against MDR S. suis were evaluated. Using the agar disc diffusion test, the clove oil showed a maximum zone of inhibition at 15% (v/v) oil concentration. In a broth microdilution method, the minimum bactericidal concentration of clove oil against all MDR S. suis isolates was 0.1% (v/v). A time-kill analysis was performed, and the killing kinetics of clove oil showed that MDR S. suis was completely reduced after 15 min of exposure to clove oil. In addition, clove oil exhibited a strong antibacterial activity at all pH values applied following incubation of MDR S. suis in pH-adjusted media with clove oil. Moreover, scanning electron microscopy revealed the nonviable S. suis isolates clearly showed atypical form and cell membrane lysis after incubation with clove oil. This study confirms the efficacy of clove oil as a natural antimicrobial against MDR S. suis and suggests the possibility of employing it as a promising alternative product for control of infectious diseases caused by S. suis in animal and human patients.

Nanoemulsion: A suitable nanodelivery system of clove oil for anesthetizing Nile tilapia.

Clove oil ethanolic solution (CL-EtOH) have always been used for fish anesthesia. However, ethanol causes major side effect of fish hypersensivity. In this study, clove oil loaded nanoemulsion (CLN) was developed in order to enhance water miscibility of clove oil without using ethanol in the preparations. The obtained CLN was characterized in terms of droplet size, size distribution expressed as polydispersity index (PDI), and zeta potential. The anesthetic effect of CLN in comparison with CL-EtOH on Oreochromis niloticus (Nile tilapia) was investigated. The results showed that the best CLN was composed of 20% w/w clove oil and 15% w/w polysorbate 20. This CLN has internal droplet size of 63.2 ± 1.0 nm, PDI of 0.31 ± 0.04, and zeta potential of - 30.3 ± 8.1 mV. GC-MS analysis indicated that eugenol was the main compound in clove oil. It was found that the induction time to anesthesia for Nile tilapia that received this CLN was shorter than that received CL-EtOH at the same eugenol concentration. The results of this study showed the potential of nanoemulsion on water miscible and efficacy enhancing of clove oil without using ethanol. The obtained CLN from this study is a promising formulation for fish aquaculture where fish sedation is required.

Effects of Alpinia galanga oil on anesthesia and stress reduction in Oreochromis niloticus.

Oreochromis niloticus (Nile tilapia) is one widely cultured fish in Thailand. Handling processes and transportation causes high stress in Nile tilapia. This study explores anesthetic effect and stress reduction of Alpinia galanga oil (AGO) on Nile tilapia. The anesthetic activity was evaluated by the time for fish induction to anesthesia and full recovery. It was found that the suitable dose of AGO that caused desirable anesthesia of Nile tilapia was 700 mg/L. This dose gave induction and recovery times of approximately 257 and 438 sec, respectively. Blood glucose and plasma cortisol of the fish anesthetized with AGO showed nearly normal levels indicating that the fish stress during handling was not increased. Study on loading densities of fish mimicked general fish transportation and showed that loading density of fish was a crucial factor on fish stress. The highest water quality was found in the lowest loading density of fish. Water containing AGO at a concentration of 150 mg/L showed significantly higher potential for reducing fish activity and water improvement than without AGO. Therefore, AGO is a promising natural edible plant oil for anesthesia in Nile tilapia.

Aflatoxin B1 Contamination of Dairy Feeds after Storage in Farm Practice in Tropical Environmen.

　The objective of this study was to determine the contamination of aflatoxin B1 (AF-B1) when keeping various dairy feeds in a farm environment. The study was carried out from March to May 2011 and involved 63 small holder dairy farms belonging to a single dairy cooperative in Chiang Mai province, Thailand. All feed samples used for milking cows including 4 commercial concentrates (CC1 to CC4), by-products from local corn processing factories fermented in plastic bags (SIL), and corn and cob meal or corn dust (CCD). Feed samples were collected 2 times at before and after storage. Farmers were requested to store CC1 to CC4 and CCD for a month and SIL for a week using their routine on-farm storage arrangements. All samples were measured for their AF-B1 concentrations by ELISA. Results showed that AF-B1 concentrations of CC1 to CC4, SIL and CCD before storage were 5.1, 4.1, 4.0, 4.2, 5.5 and 5.5 µg/kg, respectively, and after storage the concentration of AF-B1 were 9.7, 6.5, 9.8, 12.3, 11.4 and 20.0 µg/kg, respectively. CCD at after storage was the only feed that had mean level more than 20 µg/kg. Concentrations of AF- B1 at before storage in all feeds were significantly lower than after storage (P<0.01), and the increased ratio of AF-B1 levels was approximately 2 to 3 times. The study concluded that increased AF-B1 levels are related to feed types and farm conditions.

Investigation of antiaromatase activity using hepatic microsomes of Nile tilapia (Oreochromis niloticus).

Microsomal aromatase enzymes of humans and rats have been used in antiaromatase assays, but enzyme activity is species-specific. The current study extracted hepatic microsomes of Nile tilapia (Oreochromis niloticus) to investigate and compare the antiaromatase activity of chrysin, quercetin, and quercitrin. This activity was evaluated using a dibenzylfluorescein (DBF) assay. Results revealed that the age and body weight of Nile tilapia affected the yield of extracted microsomes. Extraction of hepatic microsomes of Nile tilapia was most effective when using a reaction medium with a pH of 8.0. A DBF assay using Nile tilapia microsomes revealed significant differences in levels of antiaromatase activity for chrysin, quercetin, and quercitrin. Chrysin was the most potent aromatase inhibitor, with an IC50 of 0.25 mg/mL. In addition, chrysin is an aromatase inhibitor that also inhibits the proliferation of cancer cells. Hepatic microsomes of Nile tilapia can be used to investigate and compare the antiaromatase activity of different compounds.

Enhanced gentamicin loading and release of PLGA and PLHMGA microspheres by varying the formulation parameters.

The purpose of this study was to develop a suitable formulation for gentamicin sulfate (GS) that gives a sustained release of the drug. Therefore this drug was loaded into poly(D,L-lactide-co-glycolide) (PLGA) and poly(lactic-co-hydroxymethyl glycolic acid) (PLHMGA) microspheres. The effects of various formulation parameters (ethanol, surfactant, osmotic value of the external phase, polymer type and concentration) on particle characteristics (size, loading and release) were investigated. The GS loaded microspheres were prepared using a double emulsion evaporation technique. The results demonstrate that neither ethanol nor surfactants had beneficial effects on the drug loading efficiency (around 4-10%). However, an increase in buffer concentration (and thus osmotic pressure) of the external phase resulted in a substantial increase of GS-loading (from 10 to 28%). Further, an increase of concentration of PLGA in DCM from 10% to 15/20% caused a 4-time increase of the drug loading. The best formulation identified in this study had a loading efficiency of around 70% resulting in PLGA microspheres with a 6% (w/w) loading. The particles showed a burst release of the drug depending on their porosity, followed by a phase of 35 days where hardly any release occurred. The drug was then slowly released for around 25 days likely due to degradation of the microspheres. The drug loading efficiency of GS in PLHMGA was not significantly different from PLGA microspheres (64%). The release of GS from PLHMGA microspheres was faster than that of PLGA because the degradation rate of PLHMGA is more rapid than PLGA. This study shows that prolonged release of gentamicin can be obtained by loading this drug into microspheres made of biodegradable aliphatic polyesters.