Wax Content Research Articles

Characterization of Areva javanica fiber – A possible replacement for synthetic acrylic fiber in the disc brake pad

Areva javanica (AJ), a natural cotton flowers fiber of Amaranthaceae family was taken up for the study of its possible utilization in a friction composite. The chemical composition of Areva javanica fiber (AJF) such as cellulose, lignin, ash, moisture, wax content, and density was evaluated. In addition to these, Fourier transform infrared (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and differential scanning calorimeter (DSC) tests were performed. The surface roughness of AJ fiber was estimated using atomic force microscopy (AFM) and the statistical analysis using Weibull distribution was carried out to identify the diameter of AJ fiber. TGA studies revealed its moderate thermal resistance upto 219℃, and a density of 1.4005 g/cc was estimated of AJF. An attempt was made to make use of the AJF as a potential reinforcement material for acrylic fibers in an organic disc brake pad formulation. Upon fibrization, AJ fibrillates and forms a dense structure, a vital property required for the production of a brake pad. The role of AJ fiber in brake pad was studied by investigating the behavior of fibers from the mixing stage to the cured brake pad. Results revealed that the developed brake pad had a density of 2.01 g/cc, hardness HRS 91, Loss on ignition 21.68%, and cold and hot shear strengths of 44 and 27 kg/cm2, respectively. These values were very close to that of an Acrylic fiber based brake pad. The wear test using Friction Assessment and Screening test (FAST) gave the wear percentage of 0.0187 in3/Hp-h which was found to be 16% higher than AJF (0.0159 in3/Hp-hr) based brake pad.

Wax appearance temperature (WAT) determinations of different origin crude oils by differential scanning calorimetry

In this research, wax appearance temperatures (WAT) of eight different crude oils from south-eastern region of Turkey were determined by differential scanning calorimetry. The experiments were performed at a heating/cooling-rate of 2 °C/min from 60 to −20 °C It was observed that the wax appearance temperature of different origin crude oils was varied between 14.2 and 37.8 °C depending on the API gravity and wax content. It was also observed that the crude oils have enthalpy of precipitation ranging from −3.42 to +6.39 mW and melting enthalpy from – 2.5 to +7.46 mW, respectively.

An investigation on gas hydrate formation and slurry viscosity in the presence of wax crystals

Clarifying the interaction effect between hydrate and wax is of great significance to guarantee operation safety in deep water petroleum fields. Experiments in a high‐pressure hydrate slurry rheological measurement system were carried out to investigate hydrate formation and slurry viscosity in the presence of wax crystals. Results indicate that the presence of wax crystals can prolong hydrate nucleation induction time, and its influence on hydrate growth depends on multiple factors. Higher stirring rate can obviously promote hydrate growth rate, while its influence on hydrate nucleation induction time is complicated. Higher initial pressure will promote hydrate formation. Gas hydrate slurry shows a shear‐thinning behavior, and slurry viscosity increases with the increase of wax content and initial pressure. A semiempirical viscosity model showing a well‐fitting is established for hydrate slurry with wax crystals by considering the aggregation and breakage of hydrate particles, wax crystals, and water droplets. © 2018 American Institute of Chemical Engineers AIChE J, 64: 3502–3518, 2018

Fatty Acid Composition of Mahogany Seed Oil and its Suitability for Biodiesel Production

Fatty acids components and compositions of Khaya senegalensis Nigerian specie of Mahogany were investigated to determine the suitability of its oil for biodiesel production. The most suitable feedstock for biodiesel production is one that has high proportion of monounsaturated fatty acid, very low wax content and also low gum. The extraction was done by pounding the kernels and mechanically pressed oil out of the pounded kernel. The oil yield was73.56 % which is higher than other species found in the literatures. The major fatty acids of the oil were myristoleic acid 34.56, palmitic acid 20.561, oleic acid 17.132 and erucic acid 17.132 %. It also has the following minor fatty acids; capric acid 0.244, undecyclic acid 0.246; Myristic acid 1.592, stearic acid 1.592, arachidic acid 1.838, isooleic acid 1.028, Vaccenic acid 1.028, Petrolinic acid 1.028, elaidic acid 1.028 and 13-octadecenoic acid 1.028 %. This Khaya senegalensis has has 73.9% monounsaturated fatty acids and no polyunsaturated fatty acids; this makes it suitable for biodiesel production. Keywords : biodiesel, components, composition, fatty acids, mahogany seed oil

Characterization of untreated and alkali treated new cellulosic fiber from an Areca palm leaf stalk as potential reinforcement in polymer composites

The research article addresses, a new natural fibers namely Areca Palm Leaf Stalk Fibers (APLSF) were extracted from an Areca palm tree (Dypsis lutescens) and subjected to various concentrations of alkali treatment (NaOH) such as 5%, 10% and 15% by weight. The effects of this treatment on various properties of the fibers such as physical, chemical and mechanical properties were studied. However, the density of the fibers increased and diameter of the fibers reduced. The chemical result showed that the cellulose content was increased while hemicellulose, lignin, wax and ash contents were reduced. The chemical functional groups present in the fibers were confirmed by FTIR. The 5% alkali treated APLSF exhibited a highest tensile strength of 486.41 ± 35.57 MPa, tensile modulus of 9.89 ± 1.46 GPa and elongation at break of 4.91 ± 1.82%. The surface morphology, surface roughness and thermal stability of fibers were examined by SEM, AFM and TGA/DTG.

Expression of ovate family protein 8 affects epicuticular waxes accumulation in Arabidopsis thaliana

BackgroundTranscription factors could regulate multiple aspects of plants growth and development, which is significant to plants. Ovate family proteins (OFPs) that are named due to contain OVATE domain, a 70-AA C-terminal conserved domain from the protein OVATE gene encodes, are plant-specific transcription factors family. Some members of OFPs have been shown to function as transcription factors to regulate plant growth and development, but little is known about the function of AtOFP8.ResultsHere, we found AtOFP8 maybe involve in transcriptional regulation of the epicuticular waxes in Arabidopsis thaliana. First, we observed that the distribution of epicuticular waxes of wild type plants was more than that of Atofp8-1 deletion mutants, but less than that of 35S:HA-AtOFP8 transgenic overexpression lines not only on the leaves but also on the stems utilizing scanning electron microscopes. Second, we extracted waxes from leaves and stems of three types of plants respectively to measure the waxes content and composition by gas chromatography–mass spectrometer (GC–MS), and the results of the total content of waxes were consistent with the results of scanning electron microscopes. Finally, we found that the expression of 12 genes related to the synthesis and metabolism of waxes was changed in the Atofp8-1 mutants and 35S:HA-AtOFP8 transgenic lines compared with wild type plants.ConclusionsThese findings suggest that AtOFP8 could change the accumulation of epicuticular waxes.

Review of the Factors that Influence the Condition of Wax Deposition in Subsea Pipelines

When crude oil is transported via sub-sea pipeline, the temperature of the pipeline decreases at a deep depth which causes a difference in temperature with the crude oil inside. This causes the crude oil to dissipate its heat to the surrounding until thermal equilibrium is achieved. This is also known as the cloud point where wax begins to precipitate and solidifies at the walls of the pipeline which obstruct the flow of fluid. The main objective of this review is to quantify the factors that influence wax deposition such as temperature difference between the wall of the pipeline and the fluid flowing within, the flow rate of the fluid in the pipeline and residence time of the fluid in the pipeline. It is found the main factor that causes wax deposition in the pipeline is the difference in temperature between the petroleum pipeline and the fluid flowing within. Most Literature deduces that decreasing temperature difference results in lower wax content deposited on the wall of the pipeline. The wax content increases with rising flow rate. As for the residence time, the amount of deposited wax initially increases when residence time increases until it reaches a peak value and gradually decreases. Flow-loop system and cold finger apparatus were used in literature investigations to determine the trends above. Three new models are generated through a regression analysis based on the results from other authors. These new models form a relationship between temperature difference, flow rate, residence time and Reynolds number with wax deposition. These models have high values of R-square and adjusted R-square which demonstrate the reliability of these models.

Analysis of leaf tissue structures between rust-resistant and rust-susceptible Zoysia grass (Zoysia japonica)

The differences of leaf anatomic structures between rust-susceptible and -resistant zoysia (Zoysia japonica) were compared to reveal the physical defense mechanism of rust-resistant zoysia against Puccinia zoysiae. Zoysias were screened in greenhouse and fields of Beijing, Qingdao and Yangzhou from 2009 to 2012. After identified by inoculation test, rust-susceptible and rust-resistant zoysias were transplanted to flowerpots in Shangzhuang test field (Beijing, China) and were divided into indoor and outdoor groups. Leaves in the same position and formed in the same growth period of both rust-susceptible and rust-resistant zoysia strains were chosen for the current study. Wax content, the number and size of stomata, and the thickness of palisade tissue, spongy tissue, upper epidermis and lower epidermis were analyzed. All the anatomic structures of leaves stained with toluidine blue were observed under microscope. Leaf epidermis wax contents of rust-susceptible zoysia in indoor and outdoor groups were 30 and 39% lower than that of rust-resistant zoysia (p < 0.05), respectively. The number of stomata in rust-resistant zoysia was 68% more than that in susceptible ones (p < 0.05). Stomata of rust-resistant zoysia were 45% shorter and 65% narrower than those of rust-susceptible zoysia (p < 0.05). The thickness of spongy parenchyma and palisade tissue in rust-resistant zoysia was significantly higher than that of the susceptible samples (p < 0.05). Cell structure tightness and cell structure looseness of rust-resistant zoysia were tighter than that of rust-susceptible zoysia. Our study provides a histological understanding of the resistance mechanism of rust-resistant zoysia and might be useful for the identification of resistant varieties.

Cuticular wax variants in a population of switchgrass (Panicum virgatum L.)

Leaf cuticular waxes are known to influence both biotic and abiotic stress tolerances of plants. The objective of this work was to characterize the wax phenotypic diversity present in a population of 1849 switchgrass plants. We identified 92 visually distinct variant plants that possessed altered leaf glaucousness relative to the common standard type (ST), which exhibited a bluish-white (glaucous) leaf color. The variants could be grouped into three classes: 1) non-glaucous types (NG) that possessed a shiny green leaf surface, 2) reduced glaucous types (RG) that appeared less glaucous than ST, and 3) highly glaucous types (HG) that exhibited more intense bluish-white color than ST. Analyses of total cuticular wax content averaged over each of three NG (mean 304.79 ± 15.16 μg/dm2), RG (mean 533.33 ± 21.62 μg/dm2) and HG types (mean 1228.23 ± 45.74 μg/dm2) showed significant differences (P < 0.001) from three selected STs (mean 810.92 ± 30.57 μg/dm2). Analysis of wax composition among these selected types revealed that the C33 β-diketones were the most abundant wax compounds in all but NG types. Field emission scanning electron microscopy showed that abaxial leaf surfaces exhibited predominantly rod-shaped crystals, and adaxial surfaces exhibited predominantly plate-shaped wax crystals on all lines, except for NG that lacked wax crystals on the abaxial leaf surface. As a target for crop improvement, this study reveals that a large amount of variation for cuticle waxes exists within this switchgrass germplasm.

Genetic differentiation in cauline-leaf-specific wettability of a rosette-forming perennial Arabidopsis from two contrasting montane habitats.

An altitudinal gradient of leaf wettability is often observed between and within species. To understand its functional significance, positional variation of leaf surfaces within plants should be taken into account. In rosette-forming plants, rosette leaves are near the ground and their adaxial surfaces are exposed, whereas cauline leaves are lifted from the ground throughout the reproductive season, and their abaxial surfaces are more exposed. Here, we investigated leaf wettability of cauline and rosette leaves of Arabidopsis halleri subsp. gemmifera growing in contrasting montane habitats along an altitudinal gradient at Mt Ibuki, Japan. We conducted field investigations and a growth chamber experiment to determine whether field-observed variation in leaf wettability was caused by genetic differentiation. We further performed gene expression analysis of a wax-related gene, i.e. AhgCER1, a homologue of A. thaliana ECERIFERUM1 (CER1) that may be involved in differentiation of leaf wettability. We found cauline-leaf specific genetic differentiation in leaf wettability between contrasting montane habitats. Cauline leaves of semi-alpine plants, especially on abaxial surfaces, were non-wettable. Cauline leaves of low-altitudinal understorey plants were wettable, and rosette leaves were also wettable in both habitats. AhgCER1 expression corresponded to observed leaf wettability patterns. Low wettability of cauline leaves is hypothesized to keep exposed surfaces dry when they are wrapping flowering buds in early spring, and presumably protects flowering buds from frost damage. The genetic system that controls wax content, specifically for cauline leaves, should be involved in the observed genetic differentiation, and AhgCER1 control is a strong candidate for the underlying genetic mechanism.

Optical and electrical characterization of gamma irradiated low density polyethylene/paraffin wax blend

Blends of LDPE/wax in ratios of 100/0, 98/2, 96/4, 94/6, 92/8, 90/10 and 85/15 (w/w) were prepared by melt-mixing method at the temperature of 150 °C. It was found that increasing the wax content more than 15% leads to phase separation. Optical and electrical properties of pure LDPE, pure paraffin wax and LDPE/paraffin wax blends were studied before and after gamma irradiation. The optical band gap (Egopt) and Urbacht energy (Eu) in the LDPE/paraffin wax blends were determined. The results show a decrease in Egopt and increase in Eu by increasing paraffin wax ratio. The transition energy for electrons is an allowed indirect. The electrical properties including dielectric constant (ε'), dielectric loss (εʺ) and the ac conductivity (σac) in the frequency range (50 KHz–1 MHz) at room temperature were investigated. ε′, εʺ and σac increase with increasing paraffin wax ratio. ε′ and εʺ values are higher at low frequencies, while at high frequencies the trend is reversed. Influence of gamma radiation on the optical and electrical properties for the pure samples and LDPE/paraffin wax blends has been evaluated at different gamma irradiation doses (25 kGy, 50 kGy and 75 kGy). It was found that Egopt decreases, while Eu increases with increasing irradiation dose. Also, we report an increase in ε′, εʺ and σac with increasing irradiation dose. The results of the optical and electrical characteristics indicate a relation between the amorphous nature of the samples and electrical conductivity.

Changes in Cuticular Wax Composition of Two Blueberry Cultivars during Fruit Ripening and Postharvest Cold Storage.

Cuticular wax plays an important role for the quality of blueberry fruits. In this study, the cuticular wax composition of two blueberry cultivars, 'Legacy' ( Vaccinium corymbosum) and 'Brightwell' ( Vaccinium ashei), was examined during fruit ripening and postharvest cold storage. The results showed that wax was gradually deposited on the epidermis of blueberry fruits and the content of major wax compounds, except that for diketones, increased significantly during fruit ripening. The total wax content was 2-fold greater in 'Brightwell' blueberries than that in 'Legacy' blueberries during fruit ripening. The total wax content of both cultivars decreased during 30 days of storage at 4 °C, and the variation of cuticular wax composition was cultivar-dependent. The content of diketones decreased significantly in 'Legacy' blueberries, while the content of triterpenoids and aliphatic compounds showed different fold changes in 'Brightwell' blueberries after 30 days of storage at 4 °C. Overall, our study provided a quantitative and qualitative overview of cuticular wax compounds of blueberry fruits during ripening and postharvest cold storage.

Investigating molecular conformation and packing of oxidized asphaltene molecules in presence of paraffin wax

This study investigates the effect of paraffinic wax (as a base component in many commercial rejuvenators) on the rheological and intermolecular properties of aged asphalt binder. Samples of oxidized asphalt binder doped with (1%, 3%, 5%, and 10%) paraffin wax were characterized using the rotational viscometer (RV), dynamic shear rheometer (DSR), bending beam rheometer (BBR) and direct tension test (DTT). The RV results showed an improvement trend in workability of aged binder as wax content increased. The DSR results (for a temperature range of 10–76 °C) showed lower complex modules for wax-doped specimen than control specimen. The BBR test results performed at sub-zero temperature showed that an increase of wax dosage led to higher creep stiffness modulus indicating that the asphalt binder became generally stiffer in presence of wax at low temperature. However, fracture energy measured through DTT test showed a significant reduction in presence of wax. The latter can be attributed to plausible weak secondary bonds between wax and asphaltene molecules as well as crystallization of wax molecules at low temperature within the asphalt matrix. This in turn can lead to wax crystals playing as stress localization point giving rise to crack nucleation at the wax-asphalt interface reducing overall fracture energy; it was further observed that as the wax content increased, the asphalt binder became more brittle.To further investigate the effect of wax on the molecular conformation and packing in aged asphalt binder, a molecular simulation was performed on a system of wax and oxidized asphaltene. The results of molecular simulations showed a reduction in formation of oxidized asphaltene nano-aggregates as the amount of wax increased in the wax-doped oxidized asphaltene matrix at room temperature, which was also confirmed by size exclusion chromatography. Furthermore, the radial distribution function results showed a less packed structure of oxidized asphaltene molecules in presence of wax molecules. Increasing the wax content also increased the diffusion coefficient of wax into the oxidized asphaltene matrix within a solvent medium. It was also showed that interaction energy of a dimer of oxidized asphaltene is at a lower energy state in presence of wax molecules, which suggests that wax molecules can promote dimerization of oxidized asphaltene molecules while suppressing nano-aggregates formation.

Morpho-physiological diversity in Annona species

Abstract Variation in leaf morphology and physiological characteristics was studied in six genotypes of Annona, namely A. atemoya, A. cherimola, A. glabra, A. muricata, A. reticulata, and A. squamosa (‘Balanagar’). The genotypes differed significantly in their leaf morphology and gas exchange: specific leaf weight was maximum in A. muricata and A. reticulata; leaf area, in A. cherimola; and net photosynthesis, in A. squamosa. Water use efficiency, relative water content, epicuticular wax content, and stomatal density on abaxial and adaxial surfaces of leaves were maximum in A. glabra (although the density was equally high in A. squamosa) whereas chlorophyll a, chlorophyll b, and total chlorophyll content were maximum in A. squamosa. These differences may prove relevant in selecting Annona genotypes for adaptation to different agro-climatic regions.

Chemical properties and oxidative stability of Arjan (Amygdalus reuteri) kernel oil as emerging edible oil

The oxidative stability, as well as the chemical composition of Amygdalus reuteri kernel oil (ARKO), were evaluated and compared to those of Amygdalus scoparia kernel oil (ASKO) and extra virgin olive oil (EVOO) during and after holding in the oven (170 °C for 8 h). The oxidative stability analysis was carried out by measuring the changes in conjugated dienes, carbonyl and acid values as well as oil/oxidative stability index and their correlation with the antioxidant compounds (tocopherol, polyphenols, and sterol compounds). The oleic acid was determined as the predominant fatty acid of ARKO (65.5%). Calculated oxidizability value and an iodine value of ARKO, ASKO and EVOO were reported as 3.29 and 3.24, 2.00 and 100.0, 101.4 and 81.9, respectively. Due to the high wax content (4.5% and 3.3%, respectively), the saponification number of ARKO and ASKO (96.4 and 99.8, respectively) was lower than that of EVOO (169.7). ARKO had the highest oxidative stability, followed by ASKO and EVOO. Therefore, ARKO can be introduced as a new source of edible oil with high oxidative stability.

Characterization of raw and alkali treated new natural cellulosic fiber from Coccinia grandis.L

The physical, chemical, tensile, crystalline, thermal, and surface morphological properties of raw and alkali treated Coccinia Grandis.L Fibers (CGFs) were characterized for the first time in this work. The results of the chemical analysis indicate that, after alkali treatment, the cellulose content of CGFs increased whereas hemicelluloses, lignin and wax contents decreased. This directly influenced the tensile strength, crystallinity index, thermal stability and the roughness of alkali-treated CGFs. The thermal stability and activation energy of the CGFs improved from 213.4 °C to 220.6 °C and 67.02 kJ/mol to 73.43 kJ/mol, respectively, due to alkali treatment. The statistical approach, Weibull distribution was adopted to analyze the tensile properties. The improved properties of the alkali treated CGF indicate that it could be an appropriate material for reinforcement in polymer composites.

Resistance of Seven Cabbage Cultivars to Green Peach Aphid (Hemiptera: Aphididae).

The green peach aphid, Myzus persicae (Sulzer) (Hemiptera: Aphididae), is an important pest of many crops in the world and a vector of more than 100 plant viruses. It is a major pest of Brassica vegetables such as Chinese cabbage in northern China. Chemical control is extensively used to manage this aphid around the world; however, development of insecticide resistance has been a major obstacle facing growers. Host plant resistance in Chinese cabbage against M. persicae has not been reported yet. In this study, we investigated the resistance categories in seven Chinese cabbage cultivars against M. persicae. The resistance categories of these cultivars included antixenosis, antibiosis, and tolerance related to leaf color and wax content. The cultivar 'Yuanbao' had antibiotic and tolerance effects on the aphid. The rate of intrinsic increase (rm) of M. persicae was lower on Yuanbao compared with the other six cultivars. Yuanbao also had the highest antibiosis against the aphid. The aphid preferred 'Qingan 80', which had the highest wavelength (green) in leaf color. The highest wax content was found in Yuanbao, which had a significantly negative correlation with the preference of M. persicae. The cabbage cultivar Yuanbao was resistant to M. persicae and could be used in the development of integrated pest management (IPM) programs against the aphid in the field.

GC-MS Metabolomics to Evaluate the Composition of Plant Cuticular Waxes for Four Triticum aestivum Cultivars.

Wheat (Triticum aestivum L.) is an important food crop, and biotic and abiotic stresses significantly impact grain yield. Wheat leaf and stem surface waxes are associated with traits of biological importance, including stress resistance. Past studies have characterized the composition of wheat cuticular waxes, however protocols can be relatively low-throughput and narrow in the range of metabolites detected. Here, gas chromatography-mass spectrometry (GC-MS) metabolomics methods were utilized to provide a comprehensive characterization of the chemical composition of cuticular waxes in wheat leaves and stems. Further, waxes from four wheat cultivars were assayed to evaluate the potential for GC-MS metabolomics to describe wax composition attributed to differences in wheat genotype. A total of 263 putative compounds were detected and included 58 wax compounds that can be classified (e.g., alkanes and fatty acids). Many of the detected wax metabolites have known associations to important biological functions. Principal component analysis and ANOVA were used to evaluate metabolite distribution, which was attributed to both tissue type (leaf, stem) and cultivar differences. Leaves contained more primary alcohols than stems such as 6-methylheptacosan-1-ol and octacosan-1-ol. The metabolite data were validated using scanning electron microscopy of epicuticular wax crystals which detected wax tubules and platelets. Conan was the only cultivar to display alcohol-associated platelet-shaped crystals on its abaxial leaf surface. Taken together, application of GC-MS metabolomics enabled the characterization of cuticular wax content in wheat tissues and provided relative quantitative comparisons among sample types, thus contributing to the understanding of wax composition associated with important phenotypic traits in a major crop.

Ethylene–Vinyl Acetate Copolymer and Resin-Stabilized Asphaltenes Synergistically Improve the Flow Behavior of Model Waxy Oils. 1. Effect of Wax Content and the Synergistic Mechanism

Both polymeric pour point depressants (PPDs) and asphaltenes can improve the flowability of waxy oils. However, the effect of polymeric PPDs together with asphaltenes on the flowability of waxy oils is not clear. In this paper, the synergistic effect of ethylene–vinyl acetate (EVA) PPD (100 ppm) and resin-stabilized asphaltenes (0.75 wt %) on the flow behavior of model waxy oils (10–20 wt % wax content) was investigated through rheological tests, DSC analysis, microscopic observation, and asphaltenes precipitation tests. The results showed that the asphaltenes disperse well in the xylene/mineral oil solvent as small aggregates (around 550 nm) with the aid of resins. The EVA or asphaltenes alone moderately improve the flow behavior of waxy oils by changing the wax crystals’ morphology from long and needlelike to a large, radial pattern or fine particles, respectively. The wax precipitation temperatures (WPTs) of waxy oils are also slightly decreased by adding EVA or asphaltenes, meaning that the cocrystall...

Chemical analysis and antioxidant content of various propolis samples collected from different regions and their impact on antimicrobial activities

Objective: To assess the antioxidant content, antimicrobial and antioxidant activities of various propolis samples. Methods: Seven propolis samples were collected from different locations in Morocco, which are characterized by different plant predominant vegetations. The resin, wax and balsam of hydroalcoholic extract of propolis content were identified, and the antioxidant content was analyzed with the use of HPLC and colorimetric methods. The antioxidant activity was assessed by DPPH, ABTS.+ and ferric reducing power assays. The antimicrobial activity was assessed against bacterial species, including methicillin resistant Staphylococcus aureus and Candida albicans, and expressed as the minimal inhibitory concentration. Results: The propolis samples showed significant variations in the chemical composition and in the antioxidant or antimicrobial activities even when the samples were collected from the same location. Propolis with high resin and low wax content had high level of antioxidant compounds, and strong antioxidant and antimicrobial activities. Gram-positive bacteria, especially, methicillin resistant Staphylococcus aureus were more sensitive to all propolis samples than Gram-negative bacteria and Candida albicans. Conclusions: The chemical composition and the antioxidant and antimicrobial activities of various propolis samples are different and rely on the geographic and plant origin of propolis collection. Propolis samples with low wax and high resin content might be more suitable to be used in future preclinical or clinical investigations.