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Nowadays, the enhancement of electrical conductivity in natural rubber has been widely studied by incorporating conductive particles with various techniques into rubber latex. Acetylene black is one of the carbon nanoparticles known for its electrical conductivity property. However, its hydrophobicity leads to poor dispersion in rubber latex. Therefore, admicellar polymerization (AP) technique was chosen to modify particle surface without changing the molecular structure. This technique alters surface hydrophobicity by means of coating ultrathin film of polymer onto the particles. Polypyrrole, a conductive polymer, was chosen to enhance the dispersion of acetylene black. The modified acetylene black was used as the electrically conductive additives in natural rubber. There were four variables in this study: i. the carbon particle-to-surfactant ratio, ii. the agitation speed during the AP step, iii. polymerization temperature, and iv. the surfactant agent-to-monomer ratio. The morphologies of modified particles were observed by SEM and TEM. The results showed that the best conditions yielding the lowest resistivity of conductive rubber at 1:3 for the carbon particle-to-surfactant mass ratio, at 1000 rpm for the agitator speed, in AP step was 4°C for the polymerization, and 1:5 for the mass ratio of the surfactant agent-to-monomer.

AbstractA microalbuminuria level acts as a good index to screen and monitor diabetes and renal failure. However, the urinary albumin loss after sample preservation and storage is the major bottleneck to obtain the accurate microalbuminuria test. Such loss is due to the rapid albumin fragmentation by urinary proteases. Some fragments were suggested to be bioactive biomarkers of diabetes and renal disease, but no structural and dynamical properties of albumin fragments are available. Thus, in this work, the structural and dynamical properties of reported albumin fragments are revealed using molecular dynamics simulations. The properties of nine fragments (F1–F9) discovered recently were studied at the real pH conditions of urine samples (pH 4.5, 7 and 8). The complete loss of secondary structure is found in short fragments (F1–F6), while large-sized polypeptides (F7–F9) can somehow maintain their folds. Especially, F8 (subdomain IIIB) is the most stable fragment. The difference in histidine protonation states has no impact on the structural stability of albumin fragments. The ability of F8 (subdomain IIIB) to maintain its stability and folds suggests it as an alternative albumin biomarker in urine. An insight obtained here will become the fundamental importance for understanding clinical assays for albumin detection, sample stability and peptidomics analysis of urine.Communicated by Ramaswamy H. Sarma

Human serum albumin (HSA) is a protein carrier that transports a wide range of drugs and nutrients. The amount of glycated HSA (GHSA) is used as a diabetes biomarker. To quantify the GHSA amount, the fluorescent graphene-based aptasensor has been a successful method. In aptasensors, the key mechanism is the adsorption/desorption of albumin from the aptamer–graphene complex. Recently, the graphene quantum dot (GQD) has been reported to be an aptamer sorbent. Due to its comparable size to aptamers, it is attractive enough to explore the possibility of GQD as a part of an albumin aptasensor. Therefore, molecular dynamics (MD) simulations were performed here to reveal the binding mechanism of albumin to an aptamer–GQD complex in molecular detail. GQD saturated by albumin-selective aptamers (GQDA) is studied, and GHSA and HSA are studied in comparison to understand the effect of glycation. Fast and spontaneous albumin–GQDA binding was observed. While no specific GQDA-binding site on both albumins was found, the residues used for binding were confined to domains I and III for HSA and domains II and III for GHSA. Albumins were found to bind preferably to aptamers rather than to GQD. Lysines and arginines were the main contributors to binding. We also found the dissociation of GLC from all GHSA trajectories, which highlights the role of GQDA in interfering with the ligand binding affinity in Sudlow site I. The binding of GQDA appears to impair albumin structure and function. The insights obtained here will be useful for the future design of diabetes aptasensors.

AbstractRhipicephalus (Boophilus) microplusis tick parasite that affects the cattle industry worldwide. In R. (B.) microplus, acaricide resistance develops rapidly against many commercial acaricides. One of main resistance strategies is to enhance the metabolic detoxification mediated by R. (B.) microplusglutathione-S-transferase (RmGST). RmGST detoxifies acaricides by catalyzing the conjugation of glutathione to acaricides. Although structural and dynamic details of RmGST are expected to elucidate the biologic activity of this molecule, these data have not been available to date. Thus, Molecular Dynamics simulations were employed to study ligand-free RmGST at an atomic level. Like other m-class GSTs, the flexible m loop (m1) of RmGST was observed. M1 seems to shield the active sites from the bulk. A RmGST dimer is stabilized by the lock-and-key motif (F57 as “key”) and hydrogen bonds of R82-E91 and R82-D98 at the dimer interface. Without substrates, conserved catalytic Y116 and N209 can interact with V112, G210 (for Y116) and F215 (for N209). Overall, most residues involving in RmGST function and stability are similar to other m-class GSTs. This implies similar structural stability and catalytic activity of RmGST to other GSTs. An insight obtained here will be useful for management of acaricide resistance and tick control.Communicated by Ramaswamy H. Sarma

Human serum albumin (HSA) is a protein carrier in blood transporting metabolites and drugs. Glycated HSA (GHSA) acts as a potential biomarker for diabetes. Thus, many attempts have been made to detect GHSA. Glycation was reported to damage the structure and ligand binding capability, where no molecular detail is available. Recently, the crystal structure of GHSA has been solved, where two glucose isomers (pyranose/GLC and open-chain/GLO) are located at Sudlow’s site I. GLO was found to covalently bind to K195, while GLC is trapped by noncontact interactions. GHSA exists in two forms (Schiff base (SCH) and Amadori (AMA) adducts), but how both disrupt albumin activity microscopically remains unknown. To this end, molecular dynamics simulations were performed here to explore the nature of SCH and AMA. Both forms are found to alter the main protein dynamics, resulting in (i) the widening of Sudlow’s site I entrance, (ii) the size reduction of nine fatty acid-binding pockets, (iii) the enlargement of Sudlow’s site I and the shrinking of Sudlow’s site II, (iv) the enhancement of C34 reactivity, and (v) the change in the W214 microenvironment. These unique characteristics found here can be useful for understanding the effect of glycation on the albumin function in more detail and designing specific and selective GHSA detection strategies.

AbstractMalaria is a life-threatening disease in humans caused by Plasmodiumparasites. Plasmodium vivax(P. vivax) is one of the prevalent species found worldwide. An increase in an anti-malarial drug resistance suggests the urgent need for new drugs. Zn2+-containing adenosine deaminase (ADA) is a promising drug target because the ADA inhibition is fatal to the parasite. Malarial ADA accepts both adenosine (ADN) and 5′-methylthioadenosine (MTA) as substrates. The understanding of the substrate binding becomes crucial for an anti-malarial drug development. In this work, ADA from P. vivax(pvADA) is of interest due to its prevalence worldwide. The binding of ADN and MTA are studied here using Molecular Dynamics (MD) simulations. Upon binding, the open and closed states of pvADA are captured. The displacement of 7, linking loops of3/12, 4/13,5/15, and/11 is involved in the cavity closure and opening. Also, the inappropriate substrate orientation induces a failure in a complete cavity closure. Interactions with D46, D172, S280, D310, and D311 are important for ADN binding, whereas only hydrogen bonds with D172 and D311 are sufficient to anchor MTA inside the pocket. No Zn2+-coordinated histidine residues is acquired for substrate binding. D172 is found to play a role in ribose moiety recognition, while D311 is crucial for trapping the amine group of an adenine ring towards the Zn2+site. Comparing between ADN and MTA, the additional interaction between D310 and an amine nitrogen on ADN supports a tighter fit that may facilitate the deamination.Communicated by Ramaswamy H. Sarma

Biogenatic nanosilica was synthesized by sol-gel method from rice husk ash. The batch reactor was designed to scaling-up from laboratory scale approximately 5 g to approximately 300 g of the feed raw materials. The synthesized silica products from lab-scale vessel and scaling up designed batch reactor were compared with percent yield and nanoparticle size. The particles of nanosilica from both scale productions were characterized by X-ray Fluorescence (XRF), X-ray Diffraction (XRD) and Scanning Electron Microscope (SEM). The size and size distribution of nanoparticles were estimated by ImageJ software in 100 points from SEM images. The synthesized nanosilica particles from laboratory vessel and designed reactor were the same of % yield production, components, physical structure, silica purity, and nanoparticle size. Moreover, the commercial nanosilica was analyzed for comparison.

The objective of this research is to study the effects of zirconium and silver co-dopants on the photocatalytic reactivity of TiO2. Zirconium and silver co-doped titanium dioxide (Zr-Ag co-doped TiO2) was synthesized by sol-gel method. The molar ratio of silver was fixed at 5% mol, while the molar ratio of zirconium was varied at 5, 10, and 15% mol. The synthesized photocatalysts were calcined at 500 °C for 5 h. The characteristics of the photocatalysts were examined by X-ray diffraction spectroscopy (XRD), ultraviolet-visible spectroscopy (UV-Vis), and field emission scanning electron microscope (FESEM). The XRD results indicated that the anatase phase of TiO2and metal doping did not affect the crystal phase of TiO2, and the FESEM confirmed the presence of silver and zirconium in co-doped TiO2. After doping, the band gap energy of the doped TiO2was significantly reduced due to the red shift effect. The photocatalytic reactivity and kinetics of the photocatalysts were investigated by photocatalytic decolorization of methylene blue (MB) under UV and fluorescent light. Photocatalytic decolorization of MB dramatically improved when TiO2was co-doped with silver and zirconium. The antibacterial efficiency of Zr-Ag co-doped TiO2against Escherichia coli(E. coli) was also investigated under fluorescent light and in the dark. The synergistic effects of zirconium and silver dopants on the photocatalytic and antibacterial activity of TiO2were observed. The 5% mol of silver and 10% mol of zirconium co-doped TiO2exhibited the highest decolorization efficiency at 98.07% under fluorescent light and could completely inhibit E. coliunder fluorescent light within 20 min.

AbstractIxodid ticks have a crucial impact on people and domestic animals worldwide. These parasites also pose a serious threat to livestock. To date, vaccination of hosts against ticks is a safer, more sustainable alternative to chemical control of ticks and the disease agents they transmit. Because of their roles in tick physiology, serpins (serine protease inhibitors) from tick saliva are among the candidates for anti-tick vaccines. Inhibitory serpins employ a suicide inhibition mechanism to inhibit proteases, where the serpin reactive centre loop (RCL) is cleaved, by the targeted protease, and then inserted into the main β-sheet of the serpin. This causes a massive conformational change called the ‘stressed to relaxed’ (S→R) transition, leading to the breakdown of serpin into two regions (core domain and cleaved polypeptide). Recently, the first tick serpin crystal structure from Ixodes ricinusin R-state was reported. We thus employed molecular dynamics simulations to better understand serpin structure and dynamics in atomic detail. Overall, R-state serpin showed high rigidity, especially the core domain. The most flexible region is the terminal of the cleaved polypeptide, due to its high-water exposure, while the rest of the cleaved polypeptide is stably trapped behind the core domain. T363, D367 and N375 are found to play a vital role in protein–protein attachment. This finding can be used to explain the high stability of the R-state serpin at the atomic level and provides insight into this tick serpin which will be useful for rational anti-tick vaccine development.AbbreviationsMDMolecular DynamicsRCLReactive centre loopCommunicated by Ramaswamy H. Sarma

β-TCP was successfully synthesized using cuttlebone as a raw material, which was considered to be a calcium source. The calcium source from cuttlebone and phosphoric acid were hydrothermally prepared for 2 h at ambient temperatures. The effect of the sodium dodecyl sulfate (SDS) concentration (ranging from 0 to 6 critical micelle concentrations (CMC)) was assessed. Fourier-transform infrared spectroscopy and X-ray diffraction were employed to investigate the structural properties of the β-TCP. The particles presented irregularly shaped morphologies with variations in size. Brunauer–Emmett–Teller and dynamic light scattering were employed to evaluate the surface properties. No significant change was observed with variations in the CMC. We carried out preliminary investigations of the cell cytotoxicity against mouse fibroblasts. None of the conditions presented cell cytotoxicity. We can conclude that β-TCP prepared from cuttlebone can be used as a medical material.

Graphene nanopore has been widely employed in nanofilter or nanopore devices due to its outstanding properties. The understanding of its mechanical properties at nanoscale is crucial for device improvement. In this work, the mechanical properties of graphene nanopore is thus investigated using atomistic finite element method (AFEM). Four graphene models with different pore shapes (circular (CR), horizontal rectangle (RH), and vertical rectangle (RV)) in sub-nm size which could be successfully fabricated experimentally have been studied here. The force normal to a pore surface is applied to mimic the impact force due to a fluid flow. Increasing pore size results in the reduction in its strength. Comparing among different pore shapes with comparable sizes, the order of pore strength is CR>RH>RV>SQ. In addition, we observe that the direction of pore alignment and geometries of pore edge also play a key role in mechanical strength of nanopores.

Carbon nanotubes (CNTs) were modified by grafting polymerization with copolymer of polyaniline and poly (vinyl acetate) for improving their electrical conductivity and water dispersion. After surface modification of CNTs, they were used to fabricate as the photoelectrode or working electrode for the dye-sensitized solar cell (DSSC). The characterizations of the modified CNTs were done by FTIR, TEM and SEM. Lastly, the efficiency of DSSC prepared from the modified CNT was evaluated by photovoltaic test. The results showed the high performance of the grafting CNTs-added working electrode.

Human serum albumin (HSA) is the most abundant protein found in blood serum. It carries essential metabolites and many drugs. The glycation of HSA causes abnormal biological effects. Importantly, glycated HSA (GHSA) is of interest as a biomarker for diabetes. Recently, the first HSA structure with bound pyranose (GLC) and open-chain (GLO) glucose at Sudlow site I has been crystallised. We therefore employed molecular dynamics (MD) simulations and ONIOM calculations to study the dynamic nature of two bound glucose in a pre-glycated HSA (pGHSA) and observe how those sugars alter a protein structure comparing to wild type (Apo) and fatty acid-bound HSA (FA). Our analyses show that the overall structural stability of pGHSA is similar to Apo and FA, except Sudlow site II. Having glucose induces large protein flexibility at Sudlow site II. Besides, the presence of glucose causes W214 to reorient resulting in a change in W214 microenvironment. Considering sugars, both sugars are exposed to water, but GLO is more solvent-accessible. ONIOM results show that glucose binding is favoured for HSA (−115.04 kcal/mol) and GLO (−85.10 kcal/mol) is more preferable for Sudlow site I over GLC (−29.94 kcal/mol). GLO can strongly react with K195 and K199, whereas K195 and K199 provide slightly repulsive forces for GLC. This can confirm that an open-chain GLO is more favourable inside a pocket.

The degree of vulcanization of latex compound was determined by capillary viscometer with controlled temperature to study effect of time and temperature on vulcanization process. The standard equilibrium swelling test was also conducted to assess the degree of vulcanization. A latex compound for medical glove was investigated. The latex viscosity was observed to increase over time at above room temperature condition. On the other hand, the viscosity fluctuated around mean value at room temperature. This is partly consistent with the swell ratio measurement which complete vulcanization was observed at curing temperature of 60 °C.

Natural rubber compound using different silicas, including unmodified silica, admicellar-modified silica and silica with silane coupling agent, were studied. The properties including cure characteristics, mechanical properties and dynamic properties were examined with the comparison of three compounds. The results show that cure characteristics of admicellar silica/rubber compound (Ad-Si/R) was shorter than those of unmodified silica/rubber compound (Un-Si/R) and silane coupling silica/rubber compound (Sil-Si/R). Mechanical properties of Ad-Si/R and Sil-Si/R were better than those of Un-Si/R. In addition, wet grip and rolling resistance analyzed from tan δ (5 Hz) at 0°C and 60°C, respectively, by DMA were found that the wet grip of Ad-Si/R was the best, whereas the rolling resistance of Sil-Si/R was the best, in the comparison.

This research aims to determine the influences of radiation-induced crosslinking on the mechanical properties of polymer blends between poly (lactic acid) (PLA) and thermoplastic starch (TPS). PLA and TPS were mixed at different ratios (90:10, 80:20, 70:30, 60:40) in the presence of a crosslinking agent using a twin screw extruder. The blends were compression molded into films. The film samples were irradiated by gamma radiation at different doses. Gel fraction was used to determine crosslinking efficiency. Results showed that gamma radiation was able to induce crosslinking for PLA/TPS blends. The gel fraction and mechanical properties decreased with increasing TPS content. The optimum ratio of PLA:TPS with the maximum gel fraction and mechanical properties was 90:10 and the optimum dose was 40 kGy by gamma radiation.

Ultrathin film of polyisoprene was formed on silica surface in the two dimensional adsorbed surfactant by gamma-ray induced polymerization. The effect of gamma irradiation total doses on polymeric film formation was investigated. The modified silica and formed film were characterized. The results showed the potential of the surface modification by polymer film-surfactant-silica hybrid.

Ultrathin film of polyisoprene was formed on silica surface in the two dimensional adsorbed surfactant by gamma-ray induced polymerization. The effect of gamma irradiation total doses on polymeric film formation was investigated. The modified silica and formed film were characterized. The results showed the potential of the surface modification by polymer film-surfactant-silica hybrid.

Objective To assess the efficacy and safety of first-line treatment with once-daily saquinavir/ritonavir with two nucleoside reverse transcriptase inhibitors (NRTIs), as induction therapy before enrollment in a randomized trial of structured treatment interruption strategies.Design Two-hundred antiretroviral-naive patients with CD4+cell counts between 200–350 at screening were enrolled in this open-label 24week study.Methods Patients were followed up every 8 weeks for CD4+cells, HIV RNA, and clinical and laboratory toxicities. Results: Two-hundred patients were enrolled with median baseline CD4+cell count of 267 cells/µl and HIV RNA 50 118 (4.7 log10) copies/ml. After 24 weeks of treatment, 191 of 200 (96%) patients had below 400 copies/ml HIV RNA, with 177/200 (89%) below 50 copies/ml (intent to treat, missing equals failure method), with a median rise in CD4+cell count of 122 cells/µl. There was no significant correlation between the minimum concentration of saquinavir and HIV RNA reductions at week 8 (P=0.957) or absolute HIV RNA at week 24 (P=0.77).Conclusion First-line highly active antiretroviral therapy (HAART) with once-daily saquinavir/ritonavir plus two NRTIs showed strong antiviral efficacy over 24 weeks, and should be evaluated in larger prospective randomized clinical trials.

The wettability of yarns from plain cotton fabric and from polystrene-coated fabric modified by admicellar polymerization was examined by transient force measurements with a microbalance. Analysis of the observed time scales and forces suggests that water transport in cotton yarn proceeds by an initial rapid, capillary-driven axial flow over the exterior, followed by a radial flow between fibers, and is completed by a slow diffusion of water into the individual fibers. Both the initial and final forces indicated a significant reduction in the affinity of the modified fabric for water. Admicellar polymerization after optimization yielded coated cotton yarn that absorbed only 3% of the water retained by the unmodified yarn.

The Nahua of the Mexican state of Veracruz use Baccharis confertain the treatment of a variety of gastrointestinal illnesses, especially diarrhoea associated with gastrointestinal cramps. The aerial parts of B. confertawere investigated phytochemically and pharmacologically using the guinea pig ileum assay as a model (histamine, KCl and electric stimulation). The crude ethanolic extract showed a dose-dependent antispasmodic effect that was particularly strong in flavonoid-rich fractions (e.g. IC50 value for fraction E.3.1 from the ethyl acetate fraction, in histamine-induced contraction, 10 μg mL−1). Several flavonoids (apigenin-4′,7-dimethylether, naringenin-4,7-dimethylether, pectolinarigenin and cirsimaritin) were isolated, while others were identified in complex fractions by GC-MS. The flavonoids play an important role in the antispasmodic activity of this indigenous drug. Additionally, oleanolic acid and its methyl ester as well as erythrodiol were isolated. Oleanolic acid methyl ester shows weak antibacterial activity against M. luteusand E. coli(20 μg/spot in a TLC assay). The phytochemical as well as the pharmacological data provide some in-vitro evidence for the use of B. confertain the treatment of gastrointestinal cramps.

The Nahua of the Mexican state of Veracruz use Baccharis confertain the treatment of a variety of gastrointestinal illnesses, especially diarrhoea associated with gastrointestinal cramps. The aerial parts of B. confertawere investigated phytochemically and pharmacologically using the guinea pig ileum assay as a model (histamine, KCl and electric stimulation). The crude ethanolic extract showed a dose‐dependent antispasmodic effect that was particularly strong in flavonoid‐rich fractions (e.g. IC50 value for fraction E.3.1 from the ethyl acetate fraction, in histamine‐induced contraction, 10 μg mL−1). Several flavonoids (apigenin‐4′,7‐dimethylether, naringenin‐4,7‐dimethylether, pectolinarigenin and cirsimaritin) were isolated, while others were identified in complex fractions by GC‐MS. The flavonoids play an important role in the antispasmodic activity of this indigenous drug. Additionally, oleanolic acid and its methyl ester as well as erythrodiol were isolated. Oleanolic acid methyl ester shows weak antibacterial activity against M. luteusand E. coli(20 μg/spot in a TLC assay). The phytochemical as well as the pharmacological data provide some in‐vitro evidence for the use of B. confertain the treatment of gastrointestinal cramps.

This study aimed to apply simultaneous grafting induced by radiation to prepare adsorbents for removal of copper ions. Polyethylene/polypropylene nonwoven fabric (PE/PP NWF) was functionalized with bis[2-(methacryloyloxy) ethyl] phosphate (BMEP) via radiation-induced graft polymerization (RIGP) to yield PE/PP NWF-g-PBMEP adsorbent. Effects of parameters such as monomer concentration and radiation dose on degree of grafting and efficiency of adsorption were investigated. Chemical and morphological characterizations of the prepared adsorbents were performed. The optimum condition for the preparation of PE/PP NWF-g-PBMEP adsorbent suitable for the adsorption of copper ions was at 2.5% BMEP concentration and 1 kGy of gamma radiation by simultaneous RIGP. Batch tests were performed to examine the efficiency of copper ions adsorption, in terms of the adsorption kinetics, adsorption isotherm and mechanisms of the adsorption. Effects of initial concentration of copper ions, time and pH on the adsorption were investigated. Results were proved to fit to Freundlich isotherm model and pseudo-second order kinetics. The adsorbent’s maximum adsorption capacity was 35.96 mg g−1at 90 mg/L initial concentration of Cu2+at pH 5. The reusability of the adsorbent was examined at 10 mg/L initial concentration of copper ions. The adsorption/desorption study showed that the adsorbents can be reused for four cycles with effective performance for Cu(II) ions removal from aqueous solution.

A hexane extract of the rhizome of Zingiber cassumunarwas found to exhibit topical antiinflammatory activity, when tested in the model of 12-O-tetradecanoylphorbol-13-acetate-induced ear edema in rats (ID50= 854 μg/ear). Bioassay-guided fractionation (by MPLC on silica gel) of the hexane extract led to the isolation and identification of (E)-4-(3′,4′-dimethoxyphenyl)but-3-enyl acetate (1), cis-3-(3′,4′-dimethoxyphenyl)-4-[(E)-3,‴,4‴- dimethoxystyryl]cyclohex-l-ene (2), cis-3-(3′,4′-dimethoxyphenyl)-4-[(E)-2‴,4‴,5‴- trimethoxystyryl]cyclohex-1-ene (3), cis-3-(2′,4′,5′-trimethoxyphenyl)-4-[(E)-2‴,4‴,5‴- trimethoxystyryl]cyclohex-l-ene (4) and (E)-4-(3′-4′-dime-thoxyphenyl)but-3-en-l-ol (5). Compounds 1–5 exerted potent topical antiinflammatory activities with ID50-values of 62, 21, 20, 2 and 47μg/ear, respectively. The ID50of the reference drug diclofenac was determined to be 61 μg/ear.

The essential oil of the rhizome of Zingiber cassumunarwas found to exhibit a topical antiinflammatory effect, when tested using the model of carrageenan-induced hind paw edema in rats (ID50= 22 mg oil/paw). Individual assessment of topical antiinflammatory activity of the five major components of the oil demonstrated that (E)-1-(3,4-dimethoxyphenyl)butadiene (DMPBD), terpinen-4-ol and α-terpinene significantly inhibited edema formation, whereas sabinene and γ-terpinene were inactive up to 6 mg/paw. The most active compound, DMPBD, was found to be an antiinflammatory agent twice as potent as the reference drug diclofenac (ID50= 3 vs6 mg/paw, respectively).

The topical anti-inflammatory activity of three non-phenolic linear 1,7-diarylheptanoids, previously isolated from a Thai medicinal plant, CURCUMA XANTHORRHIZA (Zingiberaceae) and four new semi-synthetic derivatives of the naturally occurring compounds were assessed in the murine model of ethyl phenylpropiolate-induced ear edema. The naturally occurring compound 1 E,3 E,1,7-diphenylheptadien-5-one ( 6) exerted the most potent anti-inflammatory activity, with an ID 50 value of similar magnitude to that of the reference drug oxyphenbutazone (67 vs. 46 g/ear, respectively). None of the semi-synthetic diarylheptanoids was more active than 6. The chemical structures and pharmacological data of the natural and semi-synthetic derivatives identified a distinct structure-activity relationship. The degree of unsaturation in positions 1 and 3, and the nature of the oxygenated functional group in position 5 of the C 7-chain were found to play significant roles in determining the observed IN VIVO activity. Based on these findings, the non-phenolic linear 1,7-diaryl-heptanoids are proposed to represent a novel class of topical anti-inflammatory agents.