Influence of nano-formulations of clove bud (Syzygium aromaticum) extract on freezing ability, antioxidant capacity, caspase-3 activity, acrosome reaction and fertility of frozen rabbit semen

The current study aimed to investigate the impact of nano-formulations of clove bud ethanolic extract (CBENF) in the extender on sperm characteristics, antioxidant capacity, oxidative biomarkers, enzymatic activity, apoptosis and fertility of post-thawed rabbit semen. Twelve mature male rabbits semen samples were pooled and cryopreserved in a Tris-egg yolk-based extender containing varying concentrations of CBENF (0, 25, 50, 75 and 100 μg/mL). After the equilibration and freezing-thawing process, CBENF (100 μg /mL) significantly enhanced progressive motility, viability and membrane integrity. Conversely, sperm abnormality was significantly reduced by CBENF supplementation. Total antioxidant capacity was increased in the post-thawed sperm medium, while nitric oxide and malondialdehyde were decreased in all CBENF concentrations. The lactic dehydrogenase and caspase-3 activities were decreased, whereas the number of live spermatozoa with an intact acrosome was increased in all CBENF concentrations. Conception rate and litter size per doe were higher in doe rabbits inseminated with semen supplemented with 100 μg CBENF/mL than un-supplemented group (76% vs. 52% and 8.4 vs. 7.7/doe), with no statistical differences. These findings suggest that supplementing rabbit extenders with 100 μg of CBENF/mL could be an effective strategy for enhancing freeze-thawing rabbit sperm attributes and fertility.

Formulation and Evaluation of a Clove Oil-Encapsulated Nanofiber Formulation for Effective Wound-Healing

Wound-healing is complicated process that is affected by many factors, especially bacterial infiltration at the site and not only the need for the regeneration of damaged tissues but also the requirement for antibacterial, anti-inflammatory, and analgesic activity at the injured site. The objective of the present study was to develop and evaluate the natural essential oil-containing nanofiber (NF) mat with enhanced antibacterial activity, regenerative, non-cytotoxic, and wound-healing potential. Clove essential oil (CEO) encapsulated in chitosan and poly-ethylene oxide (PEO) polymers to form NFs and their morphology was analyzed using scanning electron microscopy (SEM) that confirmed the finest NFs prepared with a diameter of 154 ± 35 nm. The successful incorporation of CEO was characterized by Fourier transform infra-red spectroscopy (FTIR) and X-ray diffractometry (XRD). The 87.6 ± 13.1% encapsulation efficiency and 8.9 ± 0.98% loading of CEO was observed. A total of 79% release of CEO was observed in acidic pH 5.5 with 117% high degree of swelling. The prepared NF mat showed good antibacterial activity against Staphylococcus aureus and Escherichia coli and non-cytotoxic behavior against human fibroblast cell lines and showed good wound-healing potential.

Combined Toxicity of Three Essential Oils Against Aedes aegypti (Diptera: Culicidae) Larvae

Essential oils are potential alternatives to synthetic insecticides because they have low mammalian toxicity, degrade rapidly in the environment, and possess complex mixtures of bioactive constituents with multi-modal activity against the target insect populations. Twenty-one essential oils were initially screened for their toxicity against Aedes aegypti (L.) larvae and three out of the seven most toxic essential oils (Manuka, oregano, and clove bud essential oils) were examined for their chemical composition and combined toxicity against Ae. aegypti larvae. Manuka essential oil interacted synergistically with oregano essential oil and antagonistically with clove bud essential oil. GC-MS analysis revealed the presence of 21 components in Manuka essential oil and three components each in oregano and clove bud essential oils. Eugenol (84.9%) and eugenol acetate (9.6%) were the principal constituents in clove bud essential oil while carvacrol (75.8%) and m-isopropyltoluene (15.5%) were the major constituents in oregano essential oil. The major constituents in Manuka essential oil were calamenene (20%) and 3-dodecyl-furandione (11.4%). Manuka essential oil interacted synergistically with eugenol acetate and antagonistically with eugenol, suggesting that eugenol was a major contributor to the antagonistic interaction between Manuka and clove bud essential oils. In addition, Manuka interacted synergistically with carvacrol suggesting its contribution to the synergistic interaction between Manuka and oregano essential oils. These findings provide novel insights that can be used to develop new and safer alternatives to synthetic insecticides.

Effect of curry leaf and clove bud essential oils on textural and oxidative stability of chill stored sutchi catfish fillets

Effect of coating with curry leaf and clove essential oils (EO) on oxidative and textural stability of sutchi catfish fillets were evaluated during chilled storage. The changes in parameters associated with textural and lipid degradation was also evaluated to ascertain the interactive effect of polyphenols with muscle proteins. Further, the results were compared against vacuum and conventional polyethylene packaging practices. Prior to coating, the properties of antioxidants were evaluated in vitro based on total phenolic and flavonoid contents, 2, 2-diphenyl-1- picrylhydrazyl radical scavenging activity, inhibition of linoleic acid peroxidation, iron reducing power, and metal chelating ability. Coating with clove bud EO was found to be more effective in protecting the textural quality and retarding lipid oxidation of the fillets during chilled storage. Curry leaf EO was found to have only moderate effect.

PRACTICAL APPLICATIONS

In addition to the well-studied antibacterial and antioxidant properties, plant polyphenols have become an intense focus of research for their ability to cross-link proteins that widens their applications for textural and functional modification of food and beverages. Currently, a number of carcinogenic chemicals such as ammonia and formalin are hazardously used to prevent texture deterioration in chilled fish associated with post-rigor changes and microbial reactions. This study evaluates the efficacy of polyphenols present in culinary herbs such as clove bud and curry leaf EO, in stabilising the texture of fish meat during chilled storage. From the results, it could be inferred that both the EO at 0.25% level mediated protein cross-linking/complexation and maintained textural integrity during chilled storage apart from exhibiting antioxidant activities.

Evaluating the Effectiveness of Essential Oils and Combination of Copper and Lactic Acid on the Growth of E. coli O157:H7 in Laboratory Medium

In this study, we compared the effectiveness of armoise and clove bud essential oils (EOs) and the combination of low concentrations of copper (Cu) and lactic acid (LA) against E. coli O157:H7 in a laboratory medium. Three strains of Escherichia coli O157:H7 (ATCC700599, ATCC51659, and ATCC43895) were used in this study. Antibacterial activity was determined by measuring the turbidity of a broth medium and by determination of bacterial populations. Our results showed that armoise (0.15% v/v), clove bud (0.1% v/v) EOs, or Cu (50 ppm) in combination with LA (0.2% v/v) caused a minimum 5.0 log reduction of E. coli O157:H7 in the laboratory medium. Cu in combination with LA may thus be preferable to EOs in food in order to control the growth of foodborne pathogens. In addition, the combination treatment of Cu and LA could provide the food industry with a practical approach to reducing the risk of foodborne pathogens.

Alteration of starch hydrolyzing enzyme inhibitory properties, antioxidant activities, and phenolic profile of clove buds (Syzygium aromaticum L.) by cooking duration

This study assessed the effect of cooking duration on starch hydrolyzing enzyme (α-amylase and α-glucosidase) activities, antioxidant (1,1-diphenyl-2 picrylhydrazyl [DPPH*], hydroxyl [OH*] radicals scavenging abilities and reducing power) properties, and phenolic profile of clove buds. Clove buds (raw) were cooked for 10 (SC 10) and 20 min (SC 20) and subsequently, their effects were assessed on enzyme activities, antioxidant properties, and phenolic profile. Inhibition of α-amylase and α-glucosidase activities and radicals scavenging abilities were altered by cooking in the trend; raw < SC 10 > SC 20, with IC 50 values ranging from 0.25 to 0.52 mg/mL and 0.10 to 1.50 mg/mL respectively. HPLC phenolic profile of the clove buds revealed significant (P < 0.05) changes in the amount of chlorogenic acid, quercitrin, quercetin, and kaempferol at different cooking duration. Thus, cooking duration may alter the phenolic compositions and nutraceutical potentials of clove bud by activation and/or deactivation of redox-active metabolites.