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Selenium (Se) concentrations in plasma, urine, and feces were determined by PIXE analysis before and after intravenous (iv) / oral (po) administration of sodium selenite (a dose equivalent to 2 mg/kg of selenium) to rats. The concentration-time profiles of Se were analyzed by a pharmacokinetic approach. The plasma Se profile after iv injection was biphasic and well-fit to a 2-compartment open model, showing two half lives (t1/2). The first t1/2 was about 0.3 hr and the second t1/2 was 6.9 hrs. The plasma concentration reached almost basal level after about 80 hrs of injection. On the other hand, plasma profiles after po administration showed absorption rate-limiting elimination. The bioavailability of oral sodium selenite (about 49%) and significantly higher amount of fecal Se excretion indicated relatively poor intestinal absorption of sodium selenite, compared to the previously published data. Urinary Se excretion was almost comparable between iv and po groups. The total recovery of the dose excreted in urine and feces was 30 ± 10 % in iv and 56 ± 15 % in po group. The renal excretion was considered to be a major route of Se excretion after absorption. Significant amount of Se that was not fully excreted was noted, suggesting Se distribution or accumulation in organs, together with volatile excretion.

Selenium (Se) concentration-time profiles in plasma and organs including liver, kidney, heart, lung, spleen and brain of rats (Jcl Wister, 9 wks old, n = 32) were investigated after a single intravenous (iv) / oral (po) administration of sodium selenite (dose is equivalent to 2 mg/kg b.w. of Se), The Se concentration was determined by PIXE analysis. Among the investigated biological samples, Se concentration was the highest in the kidney or liver, followed by the heart, lung or spleen, then plasma, and the brain. Se concentrations in these organs were 0.5 to 5 times of plasma Se. The distribution profiles of Se in the organs were dependent on the route of administration. Furthermore, their profiles appeared almost parallel to the plasma Se-concentration in a logarithmic scale. Compared to the Se concentration-time profiles in plasma and organs by the route of administration, po group showed about 1/4-1/2 of the Se concentration in iv group except for kidney. Kidney kept relatively higher concentration of Se, which was similar in the both groups. This may explain our recently published data that urinary excretion was similar in the both groups. The relative oral bioavailability of plasma and each organ was calculated by the ratio of area under the concentration-time curve after oral administration (AUCpo) to AUCiv. Each organ appeared to have their own bioavailability (i.e., liver 39%, kidney 97%, heart 37%, lung 18%, spleen 10%, and brain 72%), where plasma was 46%. These results highly suggested that different Se distribution in organs by the different route of administration was due to the different metabolic profile.

In clinical acupuncture, when acupuncture points are stimulated, several types of reflex responses can be evoked. Consequently, different categories of physiological responses are induced, which include changes in the activities of internal organs and tissues. The acupuncture point Sanyinjiao (SP6) has been used successfully to treat different human gastrointestinal conditions. The aim of this work was to investigate the effects of end-organ response induced by acupuncture point SP6 on the bioavailability of the radiopharmaceutical sodium pertechnetate (Na^99mTcO₄) in Wistar rats. Healthy rats were allocated into 2 groups, control-CG and treated-TG. TG was bilaterally stimulated at acupuncture point SP6 with stainless steel needles. Ocular plexus administration of Na^99mTcO₄ (3.7MBq) was carried out 10 min after every needle insertion in all animals. Ten minutes later, the animals were killed, the organs were isolated, the radioactivity was determined in a well gamma counter, and the percentage of injected dose per gram of tissue (%ID/g) was determined for each organ. The %ID/g was significantly altered (p < 0.05) in the small intestine of TG (0.56 ± 0.09) when compared to CG (0.82 ± 0.18). These results may suggest that this stimulation might induce physiological responses capable of altering the bioavailability of the radiopharmaceutical sodium pertechnetate. These findings aid in providing a better understanding of acupuncture and its effects on various organs and tissues.

Tanshinone IIA (TSNIIA) is the major active component of Salvia miltorrhiza, which is used in treatment of cardiovascular and cerebrovascular diseases traditionally in China. However, the low bioavailability of TSNIIA limits its clinical usage. To reveal the mechanism relating the absorption of TSNIIA, we detected the expression of efflux transporters in Caco-2 cells under the stimulation of TSNIIA. TSNIIA was purified and above 98% purity was confirmed by high-performance liquid chromatography. The expression of nine efflux transporters including BCRP, hPepT1, MCT and MRP1-6 in Caco-2 were verified by reverse transcription polymerase chain reaction, and the up-regulation of TSNIIA on the expression of these transporters was found by reverse transcription real-time polymerase chain reaction. These results indicate that the low bioavailability of TSNIIA is partially due to its up-regulation on efflux transporters.

Akebia Saponin D (ASD) or asperosaponin VI is the most abundant constituent of the rhizome of Dipsacus asper, which has been used for the treatment of lower back pain, traumatic hematoma and bone fractures. In recent years, it was reported that ASD was a potential treatment strategy for Alzheimer's disease (AD). However, the low bioavailability of ASD limited its clinical utility. Microcrystalline preparation is one of the effective methods to improve drug absorption. The drugs prepared by different methods can present different solid forms (polymorphs), and different polymorphs have significantly different bioavailabilities. The objective of this study was to prepare ASD polymorphs using the different preparation processes and to evaluate their physicochemical properties and oral absorption. ASD-2 obtained by the antisolvent process was simpler and had higher recovery (78.5%) than that of ASD-1 by a two-step macroporous resin column separation (56.5%). The ASD polymorphs were characterized using differential scanning calorimetry (DSC), thermogravimetry analysis (TGA), powder X-ray diffraction (PXRD) and scanning electron microscopy (SEM). The results revealed that ASD-2 existed in microcrystalline form, while ASD-1 was amorphous. Furthermore, the equilibrium solubility, dissolution in aqueous solution and pharmacokinetic parameters of the samples were determined. ASD-2 showed lower aqueous solubility than that of ASD-1 (p < 0.01). In addition, ASD-2 showed lower dissolution with only 65% of the drug released while ASD-1 had a higher dissolution with 99% of drug released at the end of the 180 min testing period. Although ASD-1 significantly increased solubility and dissolution, the AUC_0-20h of ASD-2 was 4.3 times that of the amorphous ASD-1 in vivo. Data suggest that the microcrystalline preparation of ASD-2 is not only reasonable in economy and suitable for large-scale preparation, but also a promising method to enhance bioavailability of ASD.

The imbalance of bone homeostasis has become a major public medical problem amid the background of an aging population, which is closely related to the occurrence of osteoporosis, osteoarthritis, and fractures. Presently, most drugs used in the clinical treatment of bone homeostasis imbalance are bisphosphonates, calcitonin, estrogen receptor modulators, and biological agents that inhibit bone resorption or parathyroid hormone analogs that promote bone formation. However, there are many adverse reactions. Therefore, it is necessary to explore potential drugs. Quercetin, as a flavonol compound with various biological activities, is widely distributed in plants. Studies have found that quercetin can regulate bone homeostasis through multiple pathways and targets. An in-depth exploration of the pharmacological mechanism of quercetin is of great significance for the development of new drugs. This review discusses the therapeutic mechanisms of quercetin on bone homeostasis, such as regulating the expression of long non-coding RNA, signaling pathways of bone metabolism, various types of programmed cell death, bone nutrients supply pathways, anti-oxidative stress, anti-inflammation, and activation of Sirtuins. We also summarize recent progress in improving quercetin bioavailability and propose some issues worth paying attention to, which may help guide future research efforts.

Protoporphyrin (Pp IX) derivatives were prepared to study the relationship between photosensitizer structure and photoactivity, with an emphasis on understanding the role of membrane interactions in the efficiency of photosensitizers used in photodynamic therapy (PDT). The synthetic strategies described here aimed at changing protoporphyrin periferic groups, varying overall charge and oil/water partition, while maintaining their photochemical properties. Three synthetic routes were used: (1) modification of Pp IX at positions 3¹ and 8¹ by addition of alkyl amine groups of different lengths (compounds 2–5), (2) change of Pp IX at positions 13³ and 17³, generating alkyl amines (compounds 6 and 7, a phosphate amine (compound 8, and quarternary ammonium compounds (compounds 9 and 10), and (3) amine-alkylation of Hematoporphyrin IX (Hp IX) at positions 3¹, 8¹, 13³ and 17³(compound 12). Strategy 1 leads to hydrophobic compounds with low photocytotoxicity. Strategy 2 leads to compounds 6–10 that have high levels of binding/incorporation in vesicles, mitochondria and cells, which are indicative of high bioavailability. Addition of the phosphate group (compound 8), generates an anionic compound that has low liposome and cell incorporation, plus low photocytotoxicity. Compound 12 has intermediate incorporation and photocytotoxic properties. Compound modification is also associated with changes in their sub-cellular localization: 30% of 8 (anionic) is found in mitochondria as compared to 95% of compound 10 (cationic). Photocytotoxicity was shown to be highly correlated with membrane affinity, which depends on the asymmetrical and amphiphilic characters of sens, as well as with sub-cellular localization.

The association of biodegradable and biosourced polymers with biomass raw materials is a promising way for the preparation of new drug delivery systems (DDS). Cork as one of the typical biomass raw materials seems to be very interesting in the formulation of effective and reliable DDS. In this study, several formulations of DDS based on microspheres of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and different amounts of microparticles of cork (MPC) powder, containing albendazole, were successfully prepared by microencapsulation, using emulsification/solvent evaporation technique. The prepared formulations showed good production yields and encapsulation efficiencies exceeding 80%. The chemical compatibility between the drug and the DDS matrix was evaluated by Fourier transform infra-red spectroscopy (FTIR). The obtained results proved the lack of interactions. In term of morphology, scanning electron microscopy (SEM) revealed that DDS were composed of non-aggregated spherical shape PHBV microspheres and porous MPC capable of entrapping the drug and the PHBV microspheres. The evaluation of the drug dispersion state in the DDS matrix was conducted using thermogravimetric (TG) analysis, differential scanning calorimetry (DSC) and X-ray diffraction (XRD) suggesting drug amorphization. The in vitro drug release experiments by UV-Visible spectrophotometery showed an initial burst followed by a sustained release. Compared with a commercial albendazole form no significant drug degradation was observed at low pH. Additionally, an improvement in the bioavailability of albendazole was obtained with increasing amounts of MPC in the DDS. In view of these results, the developed DDS appear to have great potential as carrier for a prospective delivery to colon.

The study of soil-to-plant transfer of radionuclides has attracted considerable attention from a large number of researchers because of the continuous pollution of soils and the effects of radionuclides on plants. In addition, it is one of the important routes for radionuclide entry into the food chain, leading to humans’ exposure to radiation. This chapter focuses on the influence of radionuclides on plant growth, with a particular emphasis on the ratio of these substances in soil and plants concerning nutrition. It is shown in this review that physical and chemical processes and biological accumulation influence the uptake and fate of radionuclides in plants. It is reported that soil contamination by radionuclides affects plant survival rates and inhibits their growth. The effects of radionuclides on plant growth depend on the type of plants, soil properties, initial radionuclide concentration in the soil, and the duration of exposure for the plants. However, some plants have developed radionuclide tolerance mechanisms and accumulate a significant amount of radionuclides, making them suitable for soil remediation.

In order to effectively address the optimization of remediating agricultural lands affected by nuclear accidents, thorough research on the parameters of radionuclide accumulation by crops and the factors that influence this process is necessary.

The mobility of radionuclides in soil is affected by a number of factors, including the granulometric composition of soils. Soils with high-dispersed particles are characterized by a high absorption capacity. Differences in the ability to fix radionuclides are associated with the mineralogical composition of the mechanical fractions of the soil. The ability of soils to fix ¹³⁷Cs is largely determined by the content of labile clay minerals in the soil.

The development of remediation techniques for contaminated soils relies on effectively regulating the processes of sorption/fixation of ¹³⁷Cs. These techniques involve the use of agromeliorants (sorbents) to minimize the mobility of the radionuclide in the soil–plant system. The physicochemical processes of the interaction between agromeliorants (sorbents) and soil, as well as the behavior of chemical analogues such as potassium (K), play a crucial role in understanding how these substances influence the transfer of radionuclides, particularly ¹³⁷Cs.

This chapter presents the findings of a series of comprehensive studies that examine how the mineral composition of soil’s clay fraction affects the behavior of ¹³⁷Cs, investigate the migration parameters of the isotopes ¹³⁷Cs and ⁴⁰K from soil to pasture grasses, and analyze the impact of agromeliorants on the biological mobility of ¹³⁷Cs in soil using radiocesium interception potential.

Iron deficiency is the most common micronutrient deficiency in the world, with many adverse health effects on human beings and the animals. The success of an iron fortification program depends largely on the iron compounds. In this work, the various iron fortification compounds were investigated and their advantages and disadvantages were discussed. There are three stages in the development of iron fortification compounds: inorganic iron (e.g. ferrous sulfate), organic iron (e.g. iron fumarate) and chelating iron (e.g. iron-glycine chelate). Among them, the ferric pyrophosphate does not modify organoleptic characteristics of foods, and can have a similar bioavailability with ferrous sulfate through micronization or solubilization, making it a potential and alternative iron fortification compound.