<Emphasis Type="Italic">In vitro</Emphasis> effects of fat,FA, and cholesterol on sphingomyelin hydrolysis induced by rat intestinal alkaline sphingomyelinase

Dietary sphingomyelin (SM) may have regulatory effects on cell proliferation and tumorigenesis in the colon. Alkaline sphingomyelinase (SMase) is the major enzyme responsible for hydrolysis of SM in the gut. Previously we purified the enzyme and showed that the presence of glycerophospholipids inhibited SM hydrolysis induced by alkaline SMase in vitro. In the present work, we studied the effects of TG, DG, FA, ceramide, and cholesterol on SM hydrolysis catalyzed by purified alkaline SMase. The results showed that both TG (triolein and tristearin) and DG (1,2-dioleoyl-sn-glycerol and 1,2-distearoyl-rac-glycerol) inhibited the activity of alkaline SMase. 1-Mono-oleoyl-rac-glycerol, 1-monostearoyl-rac-glycerol, stearic acid, oleic acid, linoleic acid, linolenic acid, and arachidonic acid stimulated the activity of alkaline SMase at 0.4–0.8 mM concentrations but inhibited the enzyme at higher concentrations. There was no difference between the effects induced by saturated and unsaturated FA. A short-chain FA such as lauric acid had a stronger stimulatory effect at low concentrations and weaker inhibitory effect at high concentrations than long-chain FA. Choosing linoleic acid as an example, we found that FA had similar effects on both alkaline SMase and neutral SMase. Cholesterol and ceramide when mixed with FA to increase its solubility in bile salt micelles inhibited SMase activity. In conclusion, glycerides, FA, ceramide, and cholesterol influence SM hydrolysis catalyzed by intestinal alkaline SMase. The presence of lipids in the diet may thus influence the course of SM digestion in the gut and thereby the exposure of colon to SM metabolites.     

Design and Development of a New Type of Hybrid PLGA/Lipid Nanoparticle as an Ursolic Acid Delivery System against Pancreatic Ductal Adenocarcinoma Cells

Despite many attempts, trials, and treatment procedures, pancreatic ductal adenocarcinoma (PDAC) still ranks among the most deadly and treatment-resistant types of cancer. Hence, there is still an urgent need to develop new molecules, drugs, and therapeutic methods against PDAC. Naturally derived compounds, such as pentacyclic terpenoids, have gained attention because of their high cytotoxic activity toward pancreatic cancer cells. Ursolic acid (UA), as an example, possesses a wide anticancer activity spectrum and can potentially be a good candidate for anti-PDAC therapy. However, due to its minimal water solubility, it is necessary to prepare an optimal nano-sized vehicle to overcome the low bioavailability issue. Poly(lactic-co-glycolic acid) (PLGA) polymeric nanocarriers seem to be an essential tool for ursolic acid delivery and can overcome the lack of biological activity observed after being incorporated within liposomes. PLGA modification, with the addition of PEGylated phospholipids forming the lipid shell around the polymeric core, can provide additional beneficial properties to the designed nanocarrier. We prepared UA-loaded hybrid PLGA/lipid nanoparticles using a nanoprecipitation method and subsequently performed an MTT cytotoxicity assay for AsPC-1 and BxPC-3 cells and determined the hemolytic effect on human erythrocytes with transmission electron microscopic (TEM) visualization of the nanoparticles and their cellular uptake. Hybrid UA-loaded lipid nanoparticles were also examined in terms of their stability, coating dynamics, and ursolic acid loading. We established innovative and repeatable preparation procedures for novel hybrid nanoparticles and obtained biologically active nanocarriers for ursolic acid with an IC50 below 20 µM, with an appropriate size for intravenous dosage (around 150 nm), high homogeneity of the sample (below 0.2), satisfactory encapsulation efficiency (up to 70%) and excellent stability. The new type of hybrid UA-PLGA nanoparticles represents a further step in the development of potentially effective PDAC therapies based on novel, biologically active, and promising triterpenoids.     

Ursolic Acid Accelerates Paclitaxel-Induced Cell Death in Esophageal Cancer Cells by Suppressing Akt/FOXM1 Signaling Cascade

Ursolic acid (UA), a pentacyclic triterpenoid extracted from various plants, inhibits cell growth, metastasis, and tumorigenesis in various cancers. Chemotherapy resistance and the side effects of paclitaxel (PTX), a traditional chemotherapy reagent, have limited the curative effect of PTX in esophageal cancer. In this study, we investigate whether UA promotes the anti-tumor effect of PTX and explore the underlying mechanism of their combined effect in esophageal squamous cell carcinoma (ESCC). Combination treatment with UA and PTX inhibited cell proliferation and cell growth more effectively than either treatment alone by inducing more significant apoptosis, as indicated by increased sub-G1 phase distribution and protein levels of cleaved-PARP and cleaved caspase-9. Similar to the cell growth suppressive effect, the combination of UA and PTX significantly inhibited cell migration by targeting uPA, MMP-9, and E-cadherin in ESCC cells. In addition, combination treatment with UA and PTX significantly activated p-GSK-3β and suppressed the activation of Akt and FOXM1 in ESCC cells. Those effects were enhanced by the Akt inhibitor LY2940002 and inverted by the Akt agonist SC79. In an in vivo evaluation of a murine xenograft model of esophageal cancer, combination treatment with UA and PTX suppressed tumor growth significantly better than UA or PTX treatment alone. Thus, UA effectively potentiates the anti-tumor efficacy of PTX by targeting the Akt/FOXM1 cascade since combination treatment shows significantly more anti-tumor potential than PTX alone both in vitro and in vivo. Combination treatment with UA and PTX could be a new strategy for curing esophageal cancer patients.     

The Role of Pentacyclic Triterpenoids in the Allelopathic Effects of Alstonia scholaris

Alstonia scholaris is a tropical evergreen tree native to South and Southeast Asia. Alstonia forests frequently lack understory species. However, potential mechanisms—particularly the allelochemicals involved—remain unclear. In the present study, we identified allelochemicals of A. scholaris, and clarified the role of allelopathic substances from A. scholaris in interactions with neighboring plants. We showed that the leaves, litter, and soil from A. scholaris inhibited growth of Bidens pilosa—a weed found growing abundantly near A. scholaris forests. The allelochemicals were identified as pentacyclic triterpenoids, including betulinic acid, oleanolic acid, and ursolic acid by using ¹H and ¹³C-NMR spectroscopy. The half-maximal inhibitory concentration (IC₅₀) for radicle growth of B. pilosa and Lactuca sativa ranged from 78.8 μM to 735.2 μM, and ursolic acid inhibited seed germination of B. pilosa. The triterpenoid concentrations in the leaves, litter, and soil were quantified with liquid chromatography-electrospray ionization/tandem mass spectrometry. Ursolic acid was present in forest soil at a concentration of 3,095 μg/g, i.e., exceeding the IC₅₀. In the field, ursolic acid accumulated abundantly in the soil in A. scholaris forests, and suppressed weed growth during summer and winter. Our results indicate that A. scholaris pentacyclic triterpenoids influence the growth of neighboring weeds by inhibiting seed germination, radicle growth, and functioning of photosystem II.     

Inhibitory Effects of Ursolic Acid on the Stemness and Progression of Human Breast Cancer Cells by Modulating Argonaute-2

The stemness and metastasis of cancer cells are crucial features in determining cancer progression. Argonaute-2 (AGO2) overexpression was reported to be associated with microRNA (miRNA) biogenesis, supporting the self-renewal and differentiation characteristics of cancer stem cells (CSCs). Ursolic acid (UA), a triterpene compound, has multiple biological functions, including anticancer activity. In this study, we find that UA inhibits the proliferation of MDA-MB-231 and MCF-7 breast cancer cell lines using the CCK-8 assay. UA induced a significant decrease in the fraction of CSC in which it was examined by changes in the expression of stemness biomarkers, including the Nanog and Oct4 genes. UA altered invasion and migration capacities by significant decreases in the levels of epithelial-to-mesenchymal transition (EMT) proteins of slug and vimentin. Furthermore, the co-reduction in oncogenic miRNA levels (miR-9 and miR-221) was a result of the down-modulation in AGO2 in breast cancer cells in vitro. Mechanically, UA increases PTEN expression to inactivate the FAK/PI3K/Akt/mTOR signaling pathway and the decreased level of c-Myc in quantitative RT-PCR and Western blot imaging analyses. Our current understanding of the anticancer potential of UA in interrupting between EMT programming and the state of CSC suggests that UA can contribute to improvements in the clinical practice of breast cancer.     

Ezetimibe Inhibits Expression of Acid Sphingomyelinase in Liver and Intestine

Ezetimibe inhibits cholesterol absorption in the intestine. Sphingomyelin has strong interactions with cholesterol. We investigated the effects of ezetimibe on Sphingomyelinase (SMase) expression in intestine and liver. After feeding rats with ezetimibe (5 mg/kg per day) for 14 days, acid SMase activities in the liver and in the proximal part of small intestine were reduced by 34 and 25%, respectively. Alkaline SMase (alk-SMase) was increased in the proximal part of the small intestine. Administration of lower doses of ezetimibe reduced acid SMase only in the liver by 14% (P < 0.05). In cell culture studies, ezetimibe decreased acid SMase activity in Hep G2 and Caco-2 cells dose-dependently. The reductions were more rapid for Hep G2 cells than for Caco-2 cells. Western blot showed that acid SMase protein was decreased in both Hep G2 and Caco-2 cells by 100 μM ezetimibe. The SM content was increased in Hep G2 cells but not Caco-2 cells, and total cholesterol content was increased in both cell lines 24 h after stimulation with 100 μM ezetimibe. Mevastatin, the inhibitor of cholesterol synthesis, induced a mild increase in acid SMase activity in Hep G2 cells but not Caco-2 cells. Following the reduction of acid SMase, ezetimibe at high dose slightly increased alk-SMase activity. In conclusion, the study demonstrates an inhibitory effect of ezetimibe on acid SMase activity and expression in both liver and intestine.     

Enhanced Water Solubility and Anti-Tumor Activity of Oleanolic Acid through Chemical Structure Modification

Cancer has been a major health problem in the world in the past decades. It is urgent to develop new, effective and safe drugs for the treatment of cancer. There are many pentacyclic triterpenoids with positive anti-tumor activity and safety in nature. Oleanolic acid (OA), as one of the pentacyclic triterpenoids, also has broad biological activities including liver protection, anti-inflammatory, hypoglycemic, antiviral and anti-tumor. Therefore, to investigate its anti-tumor activity and mechanism, many OA derivatives have been developed. Some derivatives are less toxic to normal hepatocytes, which may be due to the strong liver protection ability of OA. However, the poor water solubility of OA is one of the main reasons for the weak anti-tumor activity. It is reported that some OA derivatives could enhance solubility by chemically linking some hydrophilic groups to improve anti-tumor activity. This review not only summarizes the highly water-soluble OA derivatives that can improve anti-tumor activity reported in recent years, but also introduces their possible anti-tumor mechanisms.     

熊果酸的抗肿瘤活性及作用机理研究进展

熊果酸属五环三萜类化合物,来源丰富,具有广泛的生物活性。概述了熊果酸在医药领域的研究进展,着重论述了熊果酸的抗肿瘤活性及其抗肿瘤作用机理,并对熊果酸的研究开发前景进行了探讨。     

Pentacyclic triterpenic acids from Argania spinosa

This work reports for the first time the presence of pentacyclic triterpenic acids in Argania spinosa. By solid/liquid extraction with absolute ethanol and GC‐FID analysis, we report that ursolic acid is the major triterpene in the leaf and fruit of argan (0.10–0.44% DW), followed by significant amounts of oleanolic acid (0.05–0.19% DW). Their contents in the leaf were four times higher than in the fruit. Minor levels of betulinic and maslinic acids were also determined in the fruit pulp. Our results suggest that the developmental stage of the plant organ and the environmental conditions modulate the biosynthesis of triterpenic acids in argan. Advanced stages of ontogeny and severe climatic conditions induced a selective production of lupenyl and ursanyl structures. Argan fruits and leaves constitute interesting raw materials for the obtaining of ursolic and oleanolic acids that are strongly demanded by the functional food and pharmaceutical industries. The utilization of dry pulp of argan fruits, a by‐product of the argan oil industry, for the obtaining of new triterpene‐based formulations of high added value would increase the profitability of these crops and might help to guarantee the survival of the A. spinosa forests in the long term. Practical applications: Argan fruits and leaves constitute interesting raw materials for obtaining ursolic and oleanolic acids. Morocco accumulates every year more than 44 500 tons of dry fruit pulp as a by‐product of the argan oil industry. The utilization of this biomass for the obtaining of bioactive compounds of high added value that could be used in the design of new functional food and drugs would help to increase the profitability of the argan crops and represent an intelligent manner of contributing to the A. spinosa survival.     

Concentrations and Composition of Sphagnum Peat Lipids Depending on Temperature in the Climatic Zones of Western Siberia

The composition of n-alkanes; sesqui-, di-, and triterpenoids; steroids; carboxylic acids; and tocopherols of sphagnum peat from the southern, middle, and northern taiga and forest-tundra of Western Siberia was studied by gas chromatography–mass spectrometry. It was shown that the latitudinal shift to the north leads to the preservation of the peat lipid components and sufficiently high values of carbon preference index (CPI) close to those of mire plants. This can be caused by a decrease in microbiological activity due to a decrease in the mean annual temperature. Towards the north, the total concentrations of n-alkanes, steroids, pentacyclic triterpenoids, squalene, and tocopherols increased, and a ratio of the total concentration of steroids to the concentrations of pentacyclic triterpenoids and hopanes decreased.     

n-3 Fatty Acids Abrogate Dyslipidemia-Induced Changes in Bile Acid Uptake,Synthesis, and Transport in Young and Aged Dyslipidemic Rats

In this study, the effect of n-3 fatty acids (FA) [α-linolenic acid (ALA) and eicosapentaenoic acid (EPA) + docosahexaenoic acid (DHA)] on the intestinal bile acid (BA) uptake, hepatic BA synthesis, and enterohepatic bile acid transporters (BAT) was assessed in young and aged dyslipidemic rats. Dyslipidemia was induced in young and aged rats by feeding a high-fat (HF) diet. Experimental groups received diets containing canola oil (HF + CNO) and fish oil (HF + FO) as a source of ALA and EPA + DHA, respectively. After 60 days of feeding, intestinal BA uptake and expression of apical sodium-dependent bile acid transporter (Asbt), organic solute transporter-alpha/beta (Osta/b) messenger RNA (mRNA), and hepatic expression of Na⁺ taurocholate cotransporting polypeptide (Ntcp), bile salt export pump (Bsep), cholesterol 7-α hydroxylase A1 (Cyp7a1), Farnesoid X receptor (Fxr), small heterodimer partner-1 (Shp), liver receptor homolog-1 (Lrh-1), and hepatic nuclear factor-4 alpha (Hnf4a) mRNA were measured. Hepatic 3-hydroxy-3-methyl-glutaryl-coenzyme A (HMG-CoA) reductase activity and total BA in serum, liver, and feces were assessed. The dyslipidemic HF group had: (1) increased intestinal BA uptake and Asbt and Osta/b mRNA expression, (2) increased BA in serum, (3) decreased hepatic expression of Ntcp, Bsep, and Cyp7a1 mRNA, (4) increased activity of HMG-CoA reductase, (5) increased hepatic expression of Fxr and Shp mRNA, (6) decreased hepatic expression of Lrh-1 and Hnf4a mRNA, and (7) decreased BA in feces, when compared to control, HF + CNO, and HF + FO groups. Immunostaining revealed increased expression of intestinal Asbt and hepatic Ntcp protein in the HF group when compared to control, HF + CNO, and HF + FO groups. n-3 FA abrogated dyslipidemia-induced changes in the intestinal uptake, hepatic synthesis, and enterohepatic transporters of BA in both young and aged rats. EPA + DHA was more effective than ALA in modulating dyslipidemia-induced changes.     

Selective detection of dopamine on poly(indole-5-carboxylic acid)/tyrosinase electrode

We report here on a simple tyrosinase (TYR) modified electrode designed through the covalent bonding of the enzyme with poly (indole-5-carboxylic acid) (PIn5COOH) conducting polymer. This electrode was applied to the amperometric detection of dopamine (DA) in the presence of ascorbic acid (AA), uric acid (UA) and their mixtures, in the concentration range and ratios similar to those found in blood serum. Our experiments demonstrate that the presence of these interferents (AA, UA) does not affect the selectivity of such electrode towards dopamine with linear concentration dependence in the range of 0.5–20 μM, depending on the experimental conditions, however its sensitivity depends on the type and amount of interferent present. The lower limit of detection of DA in the presence of high AA (1000 fold) or UA (500 fold) concentration was found to be 0.1–0.5 μM. The sensitivity for DA detection is 6.2 A/M cm² with UA and 2.3 A/M cm² with AA present as interfering agents. For both interferents present in the ratio 12.5:1 (AA:UA), the sensitivity drops to the value of ca. 1.3 A/M cm². The Michaelis–Menten (K_M) constant and I_max values were evaluated, showing improved electrode sensitivity towards dopamine as judged from the decrease of the Michaelis–Menten constant.     

Inducing Effect of Clofibric Acid on Stearoyl‐CoA Desaturase in Intestinal Mucosa of Rats

Fibrates have been reported to elevate the hepatic proportion of oleic acid (18:1n‐9) through inducing stearoyl‐CoA desaturase (SCD). Despite abundant studies on the regulation of SCD in the liver, little is known about this issue in the small intestine. The present study aimed to investigate the effect of clofibric acid on the fatty acid profile, particularly monounsaturated fatty acids (MUFA), and the SCD expression in intestinal mucosa. Treatment of rats with a diet containing 0.5 % (w/w) clofibric acid for 7 days changed the MUFA profile of total lipids in intestinal mucosa; the proportion of 18:1n‐9 was significantly increased, whereas those of palmitoleic (16:1n‐7) and cis‐vaccenic (18:1n‐7) acids were not changed. Upon the treatment with clofibric acid, SCD was induced and the gene expression of SCD1, SCD2, and fatty acid elongase (Elovl) 6 was up‐regulated, but that of Elovl5 was unaffected. Fat‐free diet feeding for 28 days increased the proportions of 16:1n‐7 and 18:1n‐7, but did not effectively change that of 18:1n‐9, in intestinal mucosa. Fat‐free diet feeding up‐regulated the gene expression of SCD1, but not that of SCD2, Elovl6, or Elovl5. These results indicate that intestinal mucosa significantly changes its MUFA profile in response to challenges by clofibric acid and a fat‐free diet and suggest that up‐regulation of the gene expression of SCD along with Elovl6 is indispensable to elevate the proportion of 18:1n‐9 in intestinal mucosa.     

Composition and thermal properties of cattle fats

The physical‐chemical properties, fatty acid composition and thermal properties of cattle subcutaneous, tallow and intestinal fats were determined. Subcutaneous fat differed from the other fat types with respect to its lower melting point (29.0 °C) and higher saponification (211.4 mg KOH/g) and iodine (50.55) values. The cattle fat types contained palmitic acid (16:0), stearic acid (18:0), oleic acid (18:1n‐9) and linoleic acid (18:2n‐6) as the major components of fatty acid composition (24.58–25.90%, 10.21–33.33%, 28.18–46.05%, 1.54–1.73%, respectively). A differential scanning calorimetry (DSC) study revealed that two characteristic peaks were detected in both crystallization and melting curves. Major peaks (T_peak) of tallow and intestinal fats were similar and determined as 24.10–27.71 °C and 2.16–4.75 °C, respectively, for crystallization peaks and 7.09–9.39 °C and 43.28–46.49 °C, respectively, for melting peaks in DSC curves; however, those of subcutaneous fat (12.48 °C and –6.79 °C for crystallization peaks and 3.56 °C and 23.55 °C for melting peaks) differed remarkably from those of the other fat types.     

Gut Microbial Fatty Acid Metabolites Reduce Triacylglycerol Levels in Hepatocytes

Hydroxy and oxo fatty acids were recently found to be produced as intermediates during gut microbial fatty acid metabolism. Lactobacillus plantarum produces these fatty acids from unsaturated fatty acids such as linoleic acid. In this study, we investigated the effects of these gut microbial fatty acid metabolites on the lipogenesis in liver cells. We screened their effect on sterol regulatory element binding protein‐1c (SREBP‐1c) expression in HepG2 cells treated with a synthetic liver X receptor α (LXRα) agonist (T0901317). The results showed that 10‐hydroxy‐12(Z)‐octadecenoic acid (18:1) (HYA), 10‐hydroxy‐6(Z),12(Z)‐octadecadienoic acid (18:2) (γHYA), 10‐oxo‐12(Z)‐18:1 (KetoA), and 10‐oxo‐6(Z),12(Z)‐18:2 (γKetoA) significantly decreased SREBP‐1c mRNA expression induced by T0901317. These fatty acids also downregulated the mRNA expression of lipogenic genes by suppressing LXRα activity and inhibiting SREBP‐1 maturation. Oral administration of KetoA, which effectively reduced triacylglycerol accumulation and acetyl‐CoA carboxylase 2 (ACC2) expression in HepG2 cells, for 2 weeks significantly decreased Srebp‐1c, Scd‐1, and Acc2 expression in the liver of mice fed a high‐sucrose diet. Our findings suggest that the hypolipidemic effect of the fatty acid metabolites produced by L. plantarum can be exploited in the treatment of cardiovascular diseases or dyslipidemia.     

Effect of Lactobacillus plantarum P‐8 on lipid metabolism in hyperlipidemic rat model

Probiotics have been reported to play an important role in the prevention of metabolic disorders. We recently identified a novel probiotic strain Lactobacillus plantarum (L. plantarum) P‐8. The objective of this study was to determine the effects of L. plantarum P‐8 on lipid metabolism of rats fed with high fat diet. All experimental rats were divided into three groups: control group, model group, and L. plantarum P‐8 group. Changes in serum lipid levels, hepatic lipid deposition, serum oxidative stress‐related parameters, activities of liver function marker enzymes, organ indices, gut microflora, and fecal lipids were assessed. Compared with model group, L. plantarum P‐8 exhibited hypolipidemic effects by lowering serum total cholesterol (TC), triglyceride (TG), and low‐density lipoprotein cholesterol levels, accompanied with elevation of high‐density lipoprotein cholesterol level. L. plantarum P‐8 also exerted beneficial effects against high‐fat diet‐induced oxidative stress, curtailed the accumulation of liver lipids and protected healthy liver function. Moreover, L. plantarum P‐8 was able to regulate intestinal bacteria and enhance the fecal excretion of TC, TG, and bile acid. These findings indicate that L. plantarum P‐8 may represent a potential therapeutic agent for controlling hyperlipidemia.     

Inhibition of Human Group IIA-Secreted Phospholipase A2 and THP-1 Monocyte Recruitment by Maslinic Acid

Maslinic acid is a natural pentacyclic triterpenoid which has anti‐inflammatory properties. A recent study showed that secretory phospholipase A₂ (sPLA₂) may be a potential binding target of maslinic acid. The human group IIA (hGIIA)‐sPLA₂ is found in human sera and their levels are correlated with severity of inflammation. This study aims to determine whether maslinic acid interacts with hGIIA‐sPLA₂ and inhibits inflammatory response induced by this enzyme. It is shown that maslinic acid enhanced intrinsic fluorescence of hGIIA‐sPLA₂ and inhibited its enzyme activity in a concentration‐dependent manner. Molecular docking revealed that maslinic acid binds to calcium binding and interfacial phospholipid binding site, suggesting that it inhibit access of catalytic calcium ion for enzymatic reaction and block binding of the enzyme to membrane phospholipid. The hGIIA‐sPLA₂ enzyme is also responsible in mediating monocyte recruitment and differentiation. Results showed that maslinic acid inhibit hGIIA‐sPLA₂‐induced THP‐1 cell differentiation and migration, and the effect observed is specific to hGIIA‐sPLA₂ as cells treated with maslinic acid alone did not significantly affect the number of adherent and migrated cells. Considering that hGIIA‐sPLA₂ enzyme is known to hydrolyze glyceroacylphospholipids present in lipoproteins and cell membranes, maslinic acid may bind and inhibit hGIIA‐sPLA₂ enzymatic activity, thereby reduces the release of fatty acids and lysophospholipids which stimulates monocyte migration and differentiation. This study is the first to report on the molecular interaction between maslinic acid and inflammatory target hGIIA‐sPLA₂ as well as its effect towards hGIIA‐sPLA₂‐induced THP‐1 monocyte adhesive and migratory capabilities, an important immune‐inflammation process in atherosclerosis.     

Development of tunable biodegradable polyhydroxyalkanoates microspheres for controlled delivery of tetracycline for treating periodontal disease

This article was aimed at preparation and characterization of drug delivery carriers made from biodegradable polyhydroxyalkanoates (PHAs) for slow release of tetracycline (TC) for periodontal treatment. Four PHA variants; polyhydroxybutyrate (PHB), poly(hydroxybutyrate‐co‐hydroxyvalerate) with 5, 12, and 50% hydroxyvalerate were used to formulate TC‐loaded PHA microspheres by double emulsion‐solvent evaporation method. We also compared the effect of different molecular weight (M_w) of polyvinyl alcohol (PVA) acting as surface stabilizer on particle size, drug loading, encapsulation efficiency, and drug release profile. The TC‐loaded PHA microspheres exhibited microscale and nanoscale spherical morphology under scanning electron microscopy. Among formulations, TC‐loaded PHB:low M_w PVA demonstrated the highest TC loading with slow release behavior. Our results showed that the release rate from PHA microspheres was influenced by both the type of PHA and M_w of PVA stabilizer. Lastly, TC‐loaded PHB microspheres showed efficient killing activity against periodontitis‐causing bacteria, suggesting its potential application for treating periodontal disease. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44128.     

A critical review of methods used to estimate linoleic acid Δ6‐desaturation ex vivo and in vivo

Δ6‐desaturase is located in a pivotal position in the metabolism of essential fatty acids (EFA). Various methods have been used to estimate Δ6‐desaturase activity, including the assessment of: (i) tissue fatty acid compositions (and associated product/precursor ratios), (ii) Δ6‐desaturase activities ex vivo, and (iii) isotopically labelled linoleic acid metabolism in vivo. This review critically examines these methods and considers their appropriateness and reliability in assessing linoleic acid metabolism in diabetes and cardiovascular disease. In general, there was a good agreement between the three methods and the effect of experimental diabetes on linoleic acid metabolism. In humans, however, the effect of diabetes on tissue fatty acid composition was inconsistent, and there was a paucity of data on linoleic acid metabolism ex vivo and in vivo. The inconsistency in human fatty acid compositional data may relate to variable and uncontrolled intakes of linoleic acid and its n‐6 metabolites, but also to a less extreme insulin deficiency as studied in animals. Risk markers for cardiovascular disease generally reduced rat liver Δ6‐desaturase activity ex vivo. This was not, however, reflected in tissue fatty acid compositions in these controlled studies. Linoleic acid metabolism, as determined by tissue fatty acid composition in humans, is reduced in cardiovascular disease; however, the omnivorous dietary patterns and decreased linoleic acid intakes make this conclusion potentially unreliable. Few stable‐isotope studies have been conducted on the effect of cardiovascular risk markers on linoleic acid metabolism, and there is a requirement for this type of work to be standardised to facilitate inter‐study comparisons. These studies may eventually help optimise EFA intake in health and disease conditions.