Investigations on physiochemical and biomedical properties of Aloe vera - Sterculia gum copolymeric dressings impregnated with antibiotic-anesthetic drugs to enhance wound healing

Recently, various innovative advancements have been made in carbohydrate research to design versatile materials for biomedical applications. The current research focuses on the development of copolymeric hydrogel wound dressings (HWD) using a combination of aloe vera (AV) - sterculia gum (SG) - poly (vinylsulfonic acid) (VSA)-based with the aim to enhancing their efficacy in drug delivery (DD) applications. These hydrogel dressings were encapsulated with levofloxacin and lidocaine to address both microbial infection and pain. Copolymers were characterized by FESEM, SEM, EDS, AFM, 13C NMR, FTIR, XRD, and TGA-DTG analysis. Hydrogel exhibited a fluid absorption capacity of 4.52 ± 0.12 g per gram of polymeric dressing in simulated wound conditions. The hydrogels displayed a sustained release of drugs, demonstrating a non-Fickian diffusion mechanism. Polymer dressings revealed antibacterial, mucoadhesive, antioxidant, biocompatible and non-cytotoxic properties. Additionally, HWD displayed permeability to O2 and water vapour, yet was impermeable to microbial penetration. Overall, the findings of physiological, biochemical and drug delivery properties demonstrated the suitability of materials for wound dressing applications.

Functionalization of sterculia gum for making platform hydrogels via network formation for use in drug delivery

Recently, various advancements have been made in the development of functional polymeric materials for innovative applications. Herein this work, functionalization of sterculia gum (SG) was carried out via grafting of poly(2-(methacryloyloxy) ethyltrimethylammonium chloride) (METAC)-polyvinyl pyrrolidone (PVP) to develop hydrogel dressings as a platform for use in drug delivery (DD). The innovation of the present work is the exploration of inherent antioxidant and antimicrobial properties of the SG along with antimicrobial characteristic of poly(METAC) and PVP, to design the doxycycline encapsulated hydrogel dressings for better wound healing. FESEM, EDS and AFM analyzed the surface morphology of hydrogels. FTIR, 13C NMR and XRD inferred inclusion of poly(METAC)-PVP into polymers. 13C NMR confirmed the incorporation of poly(METAC) and PVP onto gum by the presence of a peak at 54.74 ppm because of methyl carbon attached to quaternary nitrogen of poly(METAC) and at 45.48 ppm due to the ring carbon of PVP along with FTIR peak at 949 cm-1 because of CN bending of quaternary nitrogen of poy (METAC). Thermal characterization of copolymers has been performed using TGA analysis. One gram of copolymeric hydrogel dressing absorbed 6.51 ± 0.03 g simulated salivary fluid (SSF) and 7.65 ± 0.03 g simulated wound fluid (SWF). Release of doxycycline drug occurred in a sustained manner and followed the Non-Fickian diffusion mechanism from hydrogels. The release profile was most effectively described by Hixon-Crowell kinetic model. Hydrogel demonstrated biocompatibility and expressed thrombogenicity 79.7 ± 4.9 % during its polymer-blood interactions. Copolymer revealed mucoadhesive property, requiring a force of 77.00 ± 0.01 mN to detach from bio-membrane. Additionally, it exhibited antioxidant features, showing 43.81 ± 0.286 % free radical scavenging. Hydrogel dressings were mechanically stable and revealed 0.76 ± 0.09 N mm-2 tensile strength and 9.18 ± 0.01 N burst strength. Polymer films were permeable to oxygen and water vapor and were impermeable to microorganisms. Hydrogel dressings exhibited antimicrobial properties against Pseudomonas aeruginosa and Staphylococcus aureus bacteria. Overall, these properties displayed the suitability of hydrogels for wound dressing (WD) applications which may actively enhance wound healing.

Detailed approach toward the anti-hyperglycemic potential of Sterculia diversifolia G. Don against alloxan-induced in vivo hyperglycemia model

OBJECTIVE

To investigate Sterculia diversifolia G. Don for potential anti-diabetic activity in the in vivo mouse model of alloxan-induced hyperglycemia.

METHODS

Sterculia diversifolia (S. diversifolia) was subjected to extraction and isolation techniques and structural characterization of the isolated compounds were performed using spectroscopic methods. The acute toxicity test was performed by orally administering S. diversifolia in doses of 500-2000 mg/kg. For the assessment of anti-hyperglycemic activity, S. diversifolia bark and leaves extracts were administered orally in doses of 50, 100, and 200 mg/kg, along with metformin (150 mg/kg, i.p) as positive control, after confirmation of alloxan (150 mg/kg, i.p.) induced hyperglycemia in BALB/c mice. Serum biochemical parameters were monitored for the period of study.

RESULTS

The phytochemical studies showed the presence of quercetin and kaempferol in S. diversifolia. The IC50 values in the in vivo acute toxicity study revealed the safety margin of S. diversifolia bark (1166.66 mg/kg) and leaves (683.34 mg/kg) extracts. A significant attenuation of alloxan induced hyperglycemia was produced by S. diversifolia extracts at 50 mg/kg (P < 0.05), 100 mg/kg (P < 0.05, < 0.01), and 150 mg/kg (P < 0.05, < 0.01, < 0.001) during 1-4 h, which was comparable to metformin (P < 0.001). Significant (P < 0.001) improvement appeared in blood hemoglobin, protein, cholesterol, triglycerides, urea, creatinine, HDL, and LDL of the stem bark and leaves extracts treated diabetic mice.

CONCLUSION

These findings connote the usefulness of S. diversifolia as an anti-diabetic in traditional medicine and this might be attributed to the presence of quercetin and kaempferol, among other phytochemicals.

In vivo laxative, anti-diarrheal, hepatoprotective and diuretic investigations of Sterculia diversifolia and its isolated compound

OBJECTIVE

To investigated the laxative, anti-diarrheal, hepatoprotective and diuretic activity of Sterculia diversifolia and its isolated compounds.

METHODS

The laxative activity was studied by counting wet stools while anti-diarrheal activity was performed by measuring gastrointestinal tract motility. Hepatoprotective activity was studied by biochemical and histo-pathological analysis while diuretic activity was performed by urine collection protocol.

RESULTS

Doses of 30 and 100 mg/kg of crude methanolic extract of Sterculia diversifolia (MESD) stem bark and leaves, significantly (P < 0.05, P < 0.01) produced wet feces in subjects pretreated with atropine while 8-hydroxyquercetin and dihydroquercetin showed highly significant (P < 0.001) results by increasing fecal weight and water contents without producing diarrhea. MESD stem bark and leaves also dose-dependently lowered diarrhea while 8-hydroxyquercetin and dihydroquercetin showed highly significant (P < 0.001) results by producing shaped stools in mice. MESD, 8-hydroxyquercetin and dihydroquercetin offered significant protection against histopathological changes in the liver. Diuretic activity of Crude MESD stem bark and leaves extracts shows highly significant diuretic effect while dihydroquercetin showed better results than 8-hydroxyquercetin.

CONCLUSION

It is concluded that Sterculia diversifolia and its isolated compounds bears laxative, anti-diarrheal, hepatoprotective and diuretic effects.

Sterculia tragacantha Lindl Aqueous Leaf Extract Ameliorate Cardiomyopathy in Streptozotocin-induced Diabetic Rats via Urotensin II and FABP3 Expressions

Sterculia tragacantha (ST) Lindl leaf is commonly used locally in the management of diabetes mellitus (DM) and its complications. This study was aimed at assessing the valuable effects of ST leaf on streptozotocin-diabetic cardiomyopathy (DCM). Streptozotocin was administered intraperitoneally to the experimental animals to induce DM, and hence, placed on different doses of ST for 14 days. Thereafter, on the 15th day of the experiment, the animals were euthanized, and a number of cardiomyopathy indices were investigated. The diabetic rats exhibited a momentous increase in hyperlipidemia, lipid peroxidation as well as a significant (p < 0.05) decline in antioxidant enzyme activities. The serum creatine kinase MB (CK-MB), C-reactive protein (CRP), cardiac troponin I, tumour necrosis factor-alpha (TNF-α) and urotensin II expression revealed a significant (p < 0.05) upsurge in diabetic rats. Also, the expression of GLUT4 and fatty acid-binding protein 3 (FABP3) were significantly (p < 0.05) reduced in diabetic rats. However, at the conclusion of the experimental trial ST significantly (p < 0.05) attenuated hyperlipidemia, oxidative stress biomarkers by augmenting the antioxidant enzyme activities and decrease in lipid peroxidation, ameliorated CK-MB, CRP, cardiac troponin I, TNF-α, and urotensin-II levels, and improved GLUT4 and FABP3 expressions. Similarly, the administration of ST prevented histological alterations in the heart of diabetic animals. Therefore, the obtained results suggest that ST could mitigate DCM in streptozotocin-induced diabetic rats.

Phthalic anhydride esterified chicha gum: characterization and antibacterial activity

The objective of this research was to modify chicha gum with phthalic anhydride to obtain a new biologically active material. The chemical modification of the gum structure was proven through FTIR, elemental analysis, XRD, TG, and DSC. The derived materials demonstrated excellent inhibitory effect against P. aeruginosa and K. pneumoniae species (rating 100% inhibition) and could also inhibit Escherichia coli growth. The best antimicrobial activity observed for the derivatives suggests that chicha gum hydrophobization due to the addition of phthalic groups improved the interaction of these derivatives with bacterial cell wall components. On the other hand, the derivatives increased CC₅₀ in macrophages but did not present acute toxicity or hemolytic activity, indicating that they are promising for use in prophylaxis or treatment of infections caused by Gram-negative bacteria.

<i>In vivo </i>Immunomodulatory Activity of Faloak Bark Extract (<i>Sterculia quadrifida </i>R.Br)

BACKGROUND AND OBJECTIVE

Faloak (Sterculia quadrifida R.Br) is widely used as traditional medicine in Indonesia to improve stamina (reduce tiredness for heavy workers). However, no scientific reports so far on the immunomodulatory effect. The aim of this study was to determine the effect of the bark of faloak as immunomodulatory agents by evaluating their effect on BALB/c mice lymphocytes proliferation, the activity of macrophage, nitric oxide production and the immunoglobulin G titer by in vivo techniques.

MATERIALS AND METHODS

Decoction of the faloak bark was used for the in vivo assay. BALB/c mice were divided into 5 dose groups, each consisting of 5 mice. One group was chosen as the baseline, 3 groups were used for the group treated with the test substance at doses of 7.5, 11.75 and 17.5 g kg-1 of body weight of mice (p.o) and a positive control group was treated with Phyllanthus niruri Linn. (PN) extract (Stimuno®) 0.585 g kg-1 b.wt., (p.o). The test samples were given every day. All mice were induced by hepatitis B vaccine at day 7 and 14. The activity of in vivo assay was determined at day 19. The activity of immunomodulatory effect is expressed in phagocytic capacity, phagocytosis index, nitric oxide, OD of lymphocyte proliferation and IgG titers.

RESULTS

The macrophage phagocytic capacity and phagocytosis index were significantly increased (p<0.05), nitric oxide production were altered significantly (p<0.05), but OD of lymphocyte proliferation and production of IgG titers were unchanged (p>0.05).

CONCLUSION

This study showed that the faloak bark could increase the macrophages phagocytic activity, but no effect on lymphocyte cells and therefore did not influence the adaptive immune response.

Optimisation, experimental validation and thermodynamic study of the sequential oil extraction and biodiesel production processes from seeds of Sterculia foetida

Non-edible seeds are not used in any commercial applications, which implies that they can be used for biofuel applications. The present study aimed to maximise the process conditions for oil extraction and sterculia biodiesel production from Sterculia foetida (poon oil). GC-MS identified the methyl esters of sterculia oil as sterculic acid (32%), palmitic acid (15.88%), oleic acid (10.00%), linoleic acid (9.95%) and malvalic acid (9%). Response surface methodology (RSM) based parametric optimisation of oil extraction was carried out by choosing process variables such as sample weight, volume of solvent to seed ratio and time. The optimum sample amount of 7.5 g and the volume of solvent to seed ratio of 40 mL/g resulted in a maximum oil yield of 45.27% at 3 h. The results were statistically significant (P < 0.05) with a regression coefficient (R²) of 0.9988. Furthermore, the artificial neural network (ANN) resulted in an R² value greater than 0.9, which validates the RSM. Conventional optimisation of the temperature (55 °C), feedstock to methanol ratio (1:12), catalyst proportion (1.5%) and transesterification reaction time (60 min) yield 90.87% biodiesel production. The physicochemical characteristics of oil and biodiesel complied with the requirements of the ASTM standards. The rate constant and thermodynamic variables at the optimum temperature (333 K) were calculated from the experimental data. The activation energy (E_a), activation enthalpy in transition state theory (ΔH⁺⁺), activation entropy in transition state theory (ΔS⁺⁺) and Gibbs free energy in transition state theory (ΔG⁺⁺) were 37.91 kJ mol^-1, 35.14 kJ mol^-1, - 239.58 J mol^-1 K^-1 and 79.81 kJ mol^-1 respectively. Graphical abstract.

Assessment of raw, acid-modified and chelated biomass for sequestration of hexavalent chromium from aqueous solution using Sterculia villosa Roxb. shells

This study reveals the efficient bio-sorption of Cr(VI) species from simulated wastewater using raw (RSV), acid-activated (PSV) and chelated-activated (PSV-C) Sterculia villosa Roxb. shells. Batch optimization experiments were carried out for determining the optimal pH, dosage of bio-sorbent, initial Cr(VI) concentration and incubation temperature. Physico-chemical alterations in the bio-sorbents prior and following bio-sorption of Cr(VI) species were characterized. Equilibrated experimental data at different temperatures was evaluated as a function of time for understanding the isotherm, kinetics and thermodynamics of the bio-sorption process. Sorption rates for all the bio-sorbents (RSV, PSV and PSV-C) alternately fitted to the Langmuir isotherm model and Langmuir maximum adsorption capacity for RSV, PSV and PSV-C were found to be 57.78, 163.51 and 188.68 mg/g, respectively. Cr(VI) sorption by these bio-sorbents followed pseudo-second-order kinetics. Thermodynamic studies suggest endothermic interaction and increased degree of randomness between the bio-sorbents and Cr(VI) species. Regeneration of the bio-sorbents following sorption-desorption revealed that it can be reused and recycled for several times for Cr(VI) removal from wastewater. Graphical abstract.

Continuous or Batch Solid-Liquid Extraction of Antioxidant Compounds from Seeds of Sterculia apetala Plant and Kinetic Release Study

This work has been intended to investigate the antioxidant properties of compounds extracted from seeds of Sterculia apetala (a plant from Central America) in order to add further results to the relatively poor existing literature on the beneficial properties of this plant. Different extraction methodologies were used such as batch or continuous extraction conditions using water or ethanol 50% as solvents. The kinetic study has allowed estimation of the effective diffusion coefficients in a continuous solid-liquid extraction, highlighting the strict dependence of the diffusion rate and temperature and kind of solvent, showing the highest diffusion rate with ethanol 50% at 60 °C. The comparison between different techniques and two solvents led to the selection of water as the best extraction solvent while batch mechanically-agitated extraction was the most efficient mode, with the benefits of use of an environmental-friendly solvent and reduction in process time to achieve a high amount of extracted phenolic compounds. The analysis techniques used were ABTS and Folin-Ciocalteau methods to investigate the antioxidant activity and quantify the Total Phenolic Content (TPC) respectively. Also, different fatty acids were extracted from Sterculia apetala seeds and analysed by Gas Chromatography in order to quantify other interesting chemical species besides antioxidants.

Green Extraction of Natural Antioxidants from the Sterculia nobilis Fruit Waste and Analysis of Phenolic Profile

The waste of Sterculia nobilis fruit was massively produced during food processing, which contains lots of natural antioxidants. In this study, antioxidants in the Sterculia nobilis fruit waste were extracted using the green microwave-assisted extraction (MAE) technique. The effects of five independent variables (ethanol concentration, solvent/material ratio, extraction time, temperature, and microwave power) on extraction efficiency were explored, and three major factors (ethanol concentration, extraction time, and temperature) showing great influences were chosen to study their interactions by response surface methodology. The optimal conditions were as follows: 40.96% ethanol concentration, 30 mL/g solvent/material ratio, 37.37 min extraction time at 66.76 °C, and 700 W microwave power. The Trolox equivalent antioxidant capacity value obtained in optimal conditions was in agreement with the predicted value. Besides, MAE improved the extraction efficiency compared with maceration and Soxhlet extraction methods. Additionally, the phenolic profile in the extract was analyzed by UPLC-MS/MS, and eight kinds of phenolic compounds were identified and quantified, including epicatechin, protocatechuic acid, ferulic acid, gallic acid, p-coumaric acid, caffeic acid, quercetin, and p-hydroxycinnamic acid. This study could contribute to the value-added utilization of the waste from Sterculia nobilis fruit, and the extract could be developed as food additive or functional food.

Antimicrobial effect of novel hydrogel matrix based on natural polysaccharide Sterculia urens

INTRODUCTION

Materials for modern wound-management are a very broad and heterogeneous group. One of the most important representatives is natural materials, or more precisely polysaccharides isolated from various plants and animals. With the increasing resistance of pathogens to established antimicrobial agents, there is also an attempt to discover new mechanisms of the effects of these materials. Gum karaya (GK) is a very promising representative of the natural polysaccharides group and, since it is obtained from Sterculia urens as resin, it is also possible to assume its certain antimicrobial activity.

MATERIAL AND METHODOLOGY

The antimicrobial potential of GK and chitosan (Ch) has been tested on several preselected strains to match the real epidemiological situation of the agents of infectious complications in the field of burned wounds. Tested strains included representatives of gram-positive and gram-negative bacteria as well as selected yeasts. Methicillin susceptible Staphylococcus aureus CCM 4223 (ATCC 29213), methicillin resistant Staphylococcus aureus CCM 4750 (ATCC 43300), Klebsiella pneumoniae CCM 4985 (ATCC 700603), Candida albicans CCM 8261 (ATCC 90028), Pseudomonas aeruginosa CCM 3955 (ATCC 27853) were obtained from the Czech Collection of Microorganisms. Pseudomonas aeruginosa FF 1, Pseudomonas aeruginosa FF 2 and Pseudomonas aeruginosa FF 3 (all multi-resistant clinical strains), Staphylococcus epidermidis A 013, Staphylococcus epidermidis A 117, and Candida parapsilosis BC 11 were obtained from the Collection of Microorganisms at the St. Annes University Hospital, Brno. Antimicrobial tests were performed using the disk diffusion test methodology. Another set of antimicrobial tests was obtained by measuring the growth curves.

RESULTS

Bacteriostatic activity testing showed 1% GK concentration and both 1% and 0.5% chitosan concentration effective against all pathogens tested. The combination of GK50/Ch50 in concentrations of 1% and 0.5% had similar or better effect. Lower concentrations of the combined material are poorly effective against tested strains. Bactericidal activity testing has not produced positive results, except for Candida spp., where only a partial effect of GK50/Ch50 was observed at 1% concentration. In the growth curve test, the efficiency of both GK alone and chitosan was found to be significantly higher in gram-positive bacteria compared to gram-negative ones. In the case of this experiment, only a one-tenth concentration was used compared to the disk diffusion test concentration. This results correspond with the data from the bacteriostatic activity testing.

CONCLUSION

This is the first publication that attempts to comprehensively define the potential for GK antimicrobial activity and also the possible potentiation of this activity with the use of chitosan. Further experiments are needed to extend the antimicrobial efficiency to gram-negative bacteria.

Evaluation of the antileishmanial potency, toxicity and phytochemical constituents of methanol bark extract of Sterculia villosa

CONTEXT

Visceral leishmaniasis is a protozoan disease caused by Leishmania donovani parasite. The genus Sterculia (Malvaceae) possesses ethnobotanical potential against this protozoan infection.

OBJECTIVE

Determining the potential role of methanol bark extracts from Sterculia villosa Roxb (SVE) and its phytoconstituents against Leishmania donovani promastigotes.

MATERIALS AND METHODS

SVE was analysed by TLC, UV-Vis, IR spectroscopy and biochemical assays. Antileishmanial potential of SVE (0.5-130 μg/mL for 72 h) was characterized by MTT assay. Fluorescent microscopy was performed to validate the IC₅₀ dose. To determine the effect of SVE on promastigotes, reactive oxygen species (ROS) and superoxide generation, lipid peroxidation and DNA fragmentation assays were performed. Molecular aggregation of compounds was determined by atomic force microscopy (AFM). Extent of cytotoxicity of SVE at IC₅₀ dose was determined against RAW 264.7 macrophages, peritoneal macrophages and murine RBCs. In vivo cytotoxicity of SVE was evaluated in BALB/c mice.

RESULT

SVE exhibited reverse dose dependent antileishmanial activity when 130-0 μg/mL doses were tested against promastigotes. The IC₅₀ and IC₇₀ values were found to be 17.5 and 10 μg/mL, respectively. SVE at IC₅₀ dose demonstrated elevated level of ROS, superoxide, lipid peroxidation and DNA fragmentation against promastigotes with no cytotoxicity. AFM analysis suggested increasing size of molecular aggregation (31.3 nm < 35.2 nm < 2.93 μm) with increase in concentration (10 μg < 17.5 μg < 130 μg).

DISCUSSION AND CONCLUSIONS

The study elucidates the antileishmanial potential of SVE against Leishmania donovani promastigotes by exerting oxidative stress and DNA damage. In sum, SVE can be explored as an immunotherapeutic candidate against leishmaniasis and other infectious diseases.

Phytochemical screening, safety evaluation, anti-inflammatory and analgesic studies of the leaf extracts of Sterculia tragacantha

BACKGROUND

Sterculia tragacantha (Sterculiaceae) is used in the treatment of boils, diarrhea, dyspepsia, fever, gonorrhea, snake bite, syphilis, and tapeworm in some West African nations. This study is to investigate its anti-inflammatory and analgesic activities since the plant is being used to treat fever.

METHODS

Fresh leaves of the plant were collected and dried at room temperature and pulverized into powder form and 200 g of this powder was dissolved first in hexane for 72 h and the extract was filtered and the filtrate was concentrated while the substrate was further dissolved in chloroform, ethyl acetate and methanol at different times and similar procedure adopted as for the hexane. The organic solvents were used based on order of increasing polarity. Graded concentrations of the solvent extracts were prepared and used for the study. Pilot toxicity test was carried out to determine safety dose using hematology and serum chemistry as indices of toxicity. Thereafter anti-inflammatory and analgesic studies were conducted using standard tests such as carrageenan, histamine-induced-edema, tail flick test and acetic writhing test. Phytochemical screening of the plant was also conducted.

RESULTS

Phytochemical screening of the powdered material showed that alkaloid, flavonoid and reducing sugar were present while tannin, cardiac glycosides, saponins and anthraquinones were absent. Pilot toxicity test using aqueous extract at 100 mg/mL concentration showed that no mortality was recorded although the animals that received 3,000 mg/kg dose exhibited slight dullness after 48 h. No significant changes were also observed for the packed cell volume, hemoglobin, white blood cell counts, platelet counts, alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, blood urea nitrogen, albumin, globulin except for the 200 and 3,000 mg/kg doses that caused significant increase in the level of total protein. The n-hexane, chloroform, ethyl acetate, and methanol extracts of S. tragacantha and indomethacin produced significant (p<0.05) inhibition of paw edema compared with the control using histamine and carrageenan methods of paw edema induction. There was significant (p<0.05) reduction in writhing movements at 100 mg/kg and 200 mg/kg of n-hexane, chloroform, and ethyl acetate leaf extracts of S. tragacantha and indomethacin (10 mg/kg) when compared to the control. This effect using tail flick test was not as effective when compared to the writhing test.

CONCLUSIONS

The different leaf extracts of S. tragacantha exhibited anti-inflammatory and analgesic properties and they are also safe for medicinal use.

Mucoadhesive-floating zinc-pectinate-sterculia gum interpenetrating polymer network beads encapsulating ziprasidone HCl

A novel dual crosslinked low-methoxyl (LM) pectinate-sterculia gum (SG) interpenetrating polymer network (IPN) beads was developed for intragastric ziprasidone delivery. The IPN beads were accomplished by simultaneous ionotropic gelation with zinc acetate and covalent crosslinking with glutaraldehyde. The effects of pectin and SG contents on drug entrapment efficiency (DEE, %), and cumulative drug release after 8h (Q8, %) were studied to optimize the IPN beads using a 3(2) factorial design. The optimized beads encapsulating ziprasidone HCl (F-O) displayed DEE of 87.98±1.15% and Q8 of 58.81±1.50% with excellent buoyancy (floating lag time <2min, % buoyancy at 8h >63%) and good mucoadhesivity with the goat gastric mucosa. In most cases, the drug release behaviour obeyed Higuchi kinetics with anomalous transport mechanism. The Zn-pectinate-SG IPN beads were also characterized by SEM, FTIR, DSC and P-XRD analyses.

Dodecenylsuccinic anhydride derivatives of gum karaya (Sterculia urens): preparation, characterization, and their antibacterial properties

Esterifications of the tree-based gum, gum karaya (GK), using dodecenylsuccinic anhydride (DDSA) were carried out in aqueous solutions. GK was deacetylated using alkali treatment to obtain deacetylated gum karaya (DGK). The DGK and its DDSA derivative were characterized using gel permeation chromatography/multiangle laser light scattering (GPC/MALLS), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), proton nuclear magnetic resonance spectroscopy ((1)H NMR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) analysis, and rheological studies. The degree of substitution was found to be 10.25% for DGK using (1)H NMR spectroscopy. The critical aggregation concentration of DDSA-DGK was determined using dye solubilization and surface tension methods. The antibacterial activity of the DDSA-DGK derivative was then investigated against Gram-negative Escherichia coli and Pseudomonas aeruginosa and Gram-positive Staphylococcus aureus. The DDSA-DGK derivative has the potential for use as a stabilizing agent in food and nonfood applications. It can also be developed as an antibacterial agent.

Sterculic oil, a natural inhibitor of SCD1, improves the metabolic state of obese OLETF rats

OBJECTIVE

Abnormal lipid metabolism and excess accumulation of lipid in non-adipose tissues are defining characteristics of obesity and its comorbidities. Expression and/or activity of stearoyl-CoA desaturase-1 (SCD1), a major regulator of lipid metabolism, is increased with obesity and the reduction/ablation of this enzyme is associated with an improved metabolic profile. Sterculic oil (SO), obtained from the seeds of the Sterculia feotida tree, contains a high concentration of cyclopropenoic fatty acids which are known inhibitors of SCD1. The purpose of this study was to determine the effects of SO supplementation on the development of obesity and insulin resistance in hyperphagic, obese Otsuka Long-Evans Tokushima Fatty (OLETF) rats.

DESIGN & METHODS

Rats received either an AIN-93G diet (control) or an AIN-93G diet containing 0.5% SO for 10 weeks.

RESULTS

SO did not alter body weight or body composition. Importantly, the desaturase indices, a proxy for the activity of SCD1, were reduced in the liver and adipose tissue of SO supplemented animals. This reduction in SCD1 activity was associated with a reduction in fasting blood glucose concentrations and improved glucose tolerance. In addition, SO reduced intra-abdominal fat mass and adipocyte size and resulted in a ∼3-fold increase in GLUT1 gene expression in intra-abdominal fat. Liver triglyceride content and lipogenic gene expression were reduced by SO. Consistent with an improved metabolic phenotype, SO also improved plasma cholesterol, LDL-cholesterol, and triglyceride concentrations.

CONCLUSION

Overall, our data demonstrate an improved metabolic phenotype with SO supplementation and suggest further studies are required to better understand the therapeutic potential of SO.

Two cerebrosides isolated from the seeds of Sterculia lychnophora and their neuroprotective effect

Two cerebrosides named 1-O-b-D-glucopyranosyl-(2S,3R,4E,8Z)-2-[(2-hydroxyoctadecanoyl)amido]-4,8-octadecadiene-1,3-diol (1) and soya-cerebroside I (2) were isolated from the seeds of Sterculia lychnophora for the first time. Their structures were completely characterized by spectroscopic methods including IR, MS and NMR. Compound 1 exhibited moderate neuroprotective effect against SH-SY5Y cell damage induced by hydrogen peroxide.

Isolation and synthesis of two antiproliferative calamenene-type sesquiterpenoids from Sterculia tavia from the Madagascar rain forest

Investigation of the endemic Madagascan plant Sterculia taiva Baill. (Malvaceae) for antiproliferative activity against the A2780 ovarian cancer cell line led to the isolation of two new bioactive calamenene-type sesquiterpenoids, named tavinin A (2) and epi-tavinin A (3) together with the known sesquiterpenoid mansonone G (1). The structures of the two new compounds were elucidated based on analysis of their 1D and 2D NMR spectra and mass spectrometric data, and were confirmed by de novo synthesis. The three isolated sesquiterpenoids (1-3) had modest antiproliferative activities against the A2780 ovarian cancer cell line, with IC(50) values of 10.2, 5.5 and 6.7 μM, respectively.

Conversion of t11t13 CLA into c9t11 CLA in Caco-2 cells and inhibition by sterculic oil

BACKGROUND

Conjugated linoleic acids (CLA), and principally c9t11 CLA, are suspected to have numerous preventive properties regarding non-infectious pathologies such as inflammatory diseases, atherosclerosis and several types of cancer. C9t11 CLA is produced in the rumen during biohydrogenation of linoleic acid, but can also be synthesized in mammalian tissues from trans-vaccenic acid (C18:1 t11) through the action of delta-9 desaturase (D9D). For several years, it is also known that c9t11 CLA can be synthesized from conjugated linolenic acids (CLnA), i.e. c9t11c13 CLnA and c9t11t13 CLnA. This study aimed at investigating to which extent and by which route c9t11 CLA can be produced from another isomer of CLA, the t11t13 CLA that is structurally very similar to c9t11t13 CLnA, in Caco-2 cells.

METHODOLOGY/PRINCIPAL FINDINGS

Caco-2 cells were incubated for 24 h with 20 µmol/l of t11t13 CLA in the absence or presence of sterculic oil used as an inhibitor of D9D. Caco-2 cells were able to convert t11t13 CLA into c9t11 CLA, and c9t11t13 CLnA was formed as an intermediate compound. In the presence of sterculic oil, the production of this intermediate was decreased by 46% and the formation of c9t11 CLA was decreased by 26%. No other metabolite was detected.

CONCLUSIONS/SIGNIFICANCE

These results not only highlight the conversion of t11t13 CLA into c9t11 CLA but demonstrate also that this conversion involves first a desaturation step catalysed by D9D to produce c9t11t13 CLnA and then the action of another enzyme reducing the double bond on the Δ13 position.

Gastroprotective activity of Sterculia striata A. St. Hil. & Naudin (Malvaceae) in rodents

The Sterculia striata ethanolic extract (Ss-EtOH) inhibited gastric lesions induced by ethanol, HCl/ethanol, and ischemia/reperfusion, but not those induced by indomethacin, and did not alter the gastric secretion. Ss-EtOH restored the catalase activity and content of nonprotein sulfhydryl groups in the stomach of mice treated with ethanol. The gastroprotection induced by Ss-EtOH in the ethanol-induced gastric lesion model was abolished by N(G)-nitroL-arginine methyl ester (L-NAME) pretreatment, suggesting the involvement of nitric oxide and antioxidant compounds, but not prostaglandins, in this activity. Lupeol obtained from Ss-EtOH promoted gastroprotection as well as the extract at the same dose, and it must therefore contribute to the observed effects.

[Chemical constituents from leaves of Sterculia foetida]

OBJECTIVE

To study the chemical constituents from the leaves of Sterculia foetida.

METHOD

Compounds were isolated by chromatographic techniques. Their structures were elucidated by spectroscopic methods.

RESULT

Eight compounds were identified as 5,7,8-tetrahydroxy-4'-methoxyflavone-8-O-beta-D-glucoside (1), 5,7,8-tetrahydroxy-4'-methoxyflavone-7-O-beta-D-glucoside (2), quercetin-3-O-beta-D-glucoside (3), apigenin-6, 8-di-C-beta-D-glucoside (4), puerarin (5), 5,7,8,3'-tetrahydroxy-4'-methoxyflavone (6), 5,7,8-tetrahydroxy-3',4'-dimethoxyflavone (7), 5,7,8-tetrahydroxy-4'-methoxyflavone (8).

CONCLUSION

Compounds 1, 2 and 4-8 were isolated from this plant for the first time.

Two flavonoid glycosides and a phenylpropanoid glucose ester from the leaves of Sterculia foetida

Two new flavonoid glycosides, hypolaetin 4'-methyl ether 8-O-beta-d-glucuronide 2''-sulfate (1) and hypolaetin 4'-methyl ether 3'-O-beta-d-glucoside (2), and a new phenylpropanoid glucose ester, 1,6-diferuloyl glucose (3), were isolated from the leaves of Sterculia foetida L. Their structures were elucidated by spectroscopic analysis and chemical evidence.

Sterculia guttata seeds extractives--an effective mosquito larvicide

The larvicidal activity of ethanol, chloroform and hexane soxhlet extracts obtained from S. guttata seeds was investigated against the IVth instar larvae of Dengue fever vector, Aedes aegypti and filarial vector, Culex quinquefasciatus. All extracts including fractions of ethanol extract exhibited 100% larval kill within 24 hr exposure period at 500 ppm concentration. Fraction A1 of ethanol was found to be most promising; its LC50 was 21.552 and 35.520 ppm against C. quinquefasciatus and A. aegypti respectively. Naturally occurring S. guttata seed derived fractions merit further study as potential mosquito larval control agents or lead compounds.

Biosorption and preconcentration of lead and cadmium on waste Chinese herb Pang Da Hai

The biosorption behavior of the solid waste Chinese herb Pang Da Hai (seeds of Sterculia lychnophera Hance) was studied as a sorbent for trace lead and cadmium. The solid waste Chinese herb Pang Da Hai has good sorption and desorption properties for Pb and Cd. The sorbed waste Chinese herb Pang Da Hai was both easily eluted with 0.1 mol l(-1) HNO(3) and easily digested with concentrated HNO(3). The extent of adsorption depends on pH, metal concentration, substrate concentration and the presence of interfering ions. The adsorption capacities were found to be 27.1 and 17.5 mg g(-1) for Pb and Cd. The relative standard deviation of the metal uptake experiment was found to be less than 10% for Pb(II) and Cd(II) using 100 microg l(-1) of metal ions and 20 mg substrate. Based on above, an ecofriend and low cost method for Cd and Pb preconcentration and determination with flame atomic absorption spectrophotometry was developed. The method was validated by the analysis of a standard reference material (GBW 08301). The results agree with those quoted by manufactures. It was used for 90-fold preconcentration of Cd and Pb from tap water and river water samples followed by flame atomic absorption spectroscopic (FAAS) determination with satisfactory results.

Evaluation of a methylation procedure to determine cyclopropenoids fatty acids from Sterculia striata St. Hil. Et Nauds seed oil

Cyclopropenoids fatty acids (CPFA) from Sterculia striata seed oil were characterized by gas chromatography/mass spectrometry (GC/MS) and quantified by gas chromatography-flame ionization detector (GC-FID) after derivation to fatty acid methyl esters using a cold base-catalyzed procedure. 1H nuclear magnetic resonance (NMR) analysis were done in oil and fatty acid methyl esters derivatives to quantify CPFA and verify artifacts formation during the base-catalyzed reaction. Similar quantities of CPFA were found in S. striata and Sterculia foetida seed oils before and after a base-catalyzed methylation by NMR analysis, with no artifact formation. These results were compatible with those obtained by GC-FID analysis. Transmethylation with KOH in methanol was an appropriated method to prepare cyclopropenoids fatty acids methyl esters and quantify them by GC and NMR analysis.

Endogenous Synthesis of cis-9, trans-11 Conjugated Linoleic Acid in Dairy Cows Fed Fresh Pasture

New Zealand Holstein-Friesian cows (n = 4) were used to quantify the importance of endogenous synthesis of cis-9, trans-11 conjugated linoleic acid (CLA) via Delta(9)-desaturase in cows fed a fresh pasture diet. The experiment was a 4 x 4 Latin square design with treatments arranged in a 2 x 2 factorial. Treatments lasted 4 d and were pasture only, pasture plus sterculic oil, pasture plus sunflower oil, and pasture plus sunflower oil plus sterculic oil. Abomasal infusion of sterculic oil inhibited Delta(9)-desaturase and decreased the concentration of cis-9, trans-11 CLA in milk fat by 70%. Using the changes in cis-9 10:1, cis-9 12:1 and cis-9 14:1 to correct for incomplete inhibition of Delta(9)-desaturase, a minimum estimate of 91% of cis-9, trans-11 CLA in milk fat was produced endogenously in cows fed fresh pasture. Dietary supplementation of a pasture diet with sunflower oil increased the proportion of long chain fatty acids in milk fat; however, the increase in vaccenic acid concentration was small (18%) and there was no increase in cis-9, trans-11 CLA concentration. Overall, results show that endogenous synthesis is responsible for more than 91% of the cis-9, trans-11 CLA secreted in milk fat of cows fed fresh pasture. However, the failure of plant oil supplements to increase the concentration of cis-9, trans-11 CLA in milk fat from pasture-fed cows requires further investigation.

Alkaloids from the seeds of Sterculia lychnophora (Pangdahai)

Two alkaloids, named sterculinine I and sterculinine II, together with thirteen known compounds were isolated from the ethanol extract of a well-known Chinese traditional drug, Pangdahai (the seeds of Sterculia lychnophora Hance). Their structures were elucidated by NMR, UV, IR and MS spectroscopic analysis.

[Analysis of fatty acids in the seeds of Sterculia lychnophora by GC-MS]

OBJECTIVE

To analyze and identify fatty acids in the seeds of Sterculia lychnophora.

METHOD

The compositions was isolated and determined by GC-MS technique, and area normalization method was used to make quantitative analyze of the content of compositions.

RESULTS

21 Fatty acids and 5 other compositions were isolated and determined.

CONCLUSION

The major fatty acids are 9,12(Z,Z)-octadecadienoic acid(37.96%), hexadecanoic acid(24.77%), 9-(Z)-octadecenoic acid(19.77%) and octadecanoic acid(5.01%).