Lack of fitness costs in dsRNA-resistant Leptinotarsa decemlineata ([Coleoptera]: [Chrysomelidae]).

The Colorado potato beetle, Leptinotarsa decemlineata (Say) ([Coleoptera]: [Chrysomelidae]), is the most important defoliator of solanaceous plants worldwide. This insect displays a notorious ability in adapting to biological and synthetic insecticides, although in some cases this adaptation carries relevant fitness costs. Insecticidal gene silencing by RNA interference is a novel mode of action pesticide against L. decemlineata that is activated by ingestion of a double stranded RNA (dsRNA) targeting a vital L. decemlineata gene. We previously reported laboratory selection of a > 11,000-fold resistant strain of L. decemlineata to a dsRNA delivered topically to potato leaves. In this work, we tested the existence of fitness costs in this dsRNA-resistant colony by comparing biological parameters to the parental strain and an additional susceptible reference strain. Biological parameters included length of egg incubation period, number of eggs per clutch, egg viability, larval viability, length of larval and pupal periods, adult emergence, number of eggs laid per day, sex ratio, and adult longevity. Comparisons between the 3 beetle strains detected no fitness costs associated with resistance to dsRNA. This information is important to guide effective insect resistance management plans for dsRNA insecticides against L. decemlineata applied topically to potato leaves.

Nickel in terrestrial biota: Comprehensive review on contamination, toxicity, tolerance and its remediation approaches.

Nickel (Ni) has been a subject of interest for environmental, physiological, biological scientists due to its dual effect (toxicity and essentiality) in terrestrial biota. In general, the safer limit of Ni is 1.5 µg g-1 in plants and 75-150 µg g-1 in soil. Litreature review indicates that Ni concentrations have been estimated up to 26 g kg-1 in terrestrial, and 0.2 mg L-1 in aquatic resources. In case of vegetables and fruits, mean Ni content has been reported in the range of 0.08-0.26 and 0.03-0.16 mg kg-1. Considering, Ni toxicity and its potential health hazards, there is an urgent need to find out the suitable remedial approaches. Plant vascular (>80%) and cortical (<20%) tissues are the major sequestration site (cation exchange) of absorbed Ni. Deciphering molecular mechanisms in transgenic plants have immense potential for enhancing Ni phytoremediation and microbial remediation efficiency. Further, it has been suggested that integrated bioremediation approaches have a potential futuristic path for Ni decontamination in natural resources. This systematic review provides insight on Ni effects on terrestrial biota including human and further explores its transportation, bioaccumulation through food chain contamination, human health hazards, and possible Ni remediation approaches.

Xanthones for melanogenesis inhibition: Molecular docking and QSAR studies to understand their anti-tyrosinase activity.

The human skin is constantly exposed to external factors that affect its integrity, UV radiation being one of the main stress factors. The repeated exposure to this radiation leads to increased production of Reactive Oxygen Species (ROS) which activate a series of processes involved in photoaging. Excessive UV exposure also exacerbates melanin production leading to a variety of pigmentation disorders. Xanthones are reported to exhibit properties that prevent deleterious effects of UV exposure and high levels of ROS in the organism, so in this work a wide library of xanthones with different patterns of substitution was synthesized and tested for their inhibitory activity against the skin enzymes tyrosinase, elastase, collagenase and hyaluronidase, many of which were evaluated for the first time. Most of the compounds were tyrosinase inhibitors, with the best one (xanthone 27) presenting an IC50 of 1.9 µM, which is approximately 6 times lower than the IC50 of the positive control kojic acid. Concerning the other enzymes, only one compound presented IC50 lower than 150 µM in elastase inhibition (xanthone 14 = 91.8 µM) and none in collagenase and hyaluronidase inhibition. A QSAR model for tyrosinase inhibitory activity was built using six molecular descriptors, with a partial negative surface area descriptor and the relative number of oxygen atoms being positively contributing to the tyrosinase inhibitory activity. Docking using AutoDock Vina shows that all the tested compounds have more affinity to mushroom tyrosinase than kojic acid. Docking results implied that the tyrosinase inhibitory mechanisms of xanthonic derivatives are attributed to an allosteric interaction. Taken together, these data suggest that xanthones might be useful scaffolds for the development of new and promising candidates for the treatment of pigmentation-related disorders and for skin whitening cosmetic products.

Bio-remediation approaches for alleviation of cadmium contamination in natural resources.

Cadmium (Cd) is a harmful heavy metal that can cause potent environmental and health hazards at different trophic levels through food chain. Cd is relatively non-biodegradable and persists for a long time in the environment. Considering the potential toxicity and non-biodegradability of Cd in the environment as well as its health hazards, this is an urgent issue of international concern that needs to be addressed by implicating suitable remedial approaches. The current article specifically attempts to review the different biological approaches for remediation of Cd contamination in natural resources. Further, bioremediation mechanisms of Cd by microbes such as bacteria, fungi, algae are comprehensively discussed. Studies indicate that heavy metal resistant microbes can be used as suitable biosorbents for the removal of Cd (up to 90%) in the natural resources. Soil-to-plant transfer coefficient (TC) of Cd ranges from 3.9 to 3340 depending on the availability of metal to plants and also on the type of plant species. The potential phytoremediation strategies for Cd removal and the key factors influencing bioremediation process are also emphasized. Studies on molecular mechanisms of transgenic plants for Cd bioremediation show immense potential for enhancing Cd phytoremediation efficiency. Thus, it is suggested that nano-technological based integrated bioremediation approaches could be a potential futuristic path for Cd decontamination in natural resources. This review would be highly useful for the biologists, chemists, biotechnologists and environmentalists to understand the long-term impacts of Cd on ecology and human health so that potential remedial measures could be taken in advance.

In vitro evaluation of the antimicrobial effects of different intracanal medications in necrotic immature teeth.

AIM: This was to assess the antimicrobial effectiveness of pastes used as intracanal medicaments against Enterococcus faecalis in necrotic immature teeth. METHOD: An agar-disc diffusion method over a period of 30 days was used. The following medications were analysed: triple antibiotic paste (TAP) I; double antibiotic paste (DAP) I; DAP I with calcium hydroxide; calcium hydroxide paste with saline solution 0.9 %; calcium hydroxide paste with chlorhexidine 2 % gel; DAP II; DAP II with zinc oxide; DAP II with calcium hydroxide; and saline solution 0.9 % as control. The diameters of the halos of inhibition (in mm) of tested medicaments were determined and analysed with one-way analysis of variance and Tukey's post hoc tests. RESULTS: TAP I (G1) was significantly more effective against E. faecalis, and showed the largest halo of inhibition during all the experiments. DAP groups (G2 and G6) also showed inhibiting bacterial growth with said inhibition remaining stable throughout the 30-day period. In contrast, G4 and G5 groups, in which Ca(OH)2 was added to saline and chlorhexidine, had no antibacterial effect. CONCLUSIONS: TAP and DAP showed better antibacterial efficacy and remained active for 30 days. Combination of Ca(OH)2 with antibiotics should be avoided, due to the possibility of antibiotic hydrolysis.

A dose-response curve for biodosimetry from a 6 MV electron linear accelerator.

Biological dosimetry (biodosimetry) is based on the investigation of radiation-induced biological effects (biomarkers), mainly dicentric chromosomes, in order to correlate them with radiation dose. To interpret the dicentric score in terms of absorbed dose, a calibration curve is needed. Each curve should be constructed with respect to basic physical parameters, such as the type of ionizing radiation characterized by low or high linear energy transfer (LET) and dose rate. This study was designed to obtain dose calibration curves by scoring of dicentric chromosomes in peripheral blood lymphocytes irradiated in vitro with a 6 MV electron linear accelerator (Mevatron M, Siemens, USA). Two software programs, CABAS (Chromosomal Aberration Calculation Software) and Dose Estimate, were used to generate the curve. The two software programs are discussed; the results obtained were compared with each other and with other published low LET radiation curves. Both software programs resulted in identical linear and quadratic terms for the curve presented here, which was in good agreement with published curves for similar radiation quality and dose rates.

A dose-response curve for biodosimetry from a 6 MV electron linear accelerator

Biological dosimetry (biodosimetry) is based on the investigation of radiation-induced biological effects (biomarkers), mainly dicentric chromosomes, in order to correlate them with radiation dose. To interpret the dicentric score in terms of absorbed dose, a calibration curve is needed. Each curve should be constructed with respect to basic physical parameters, such as the type of ionizing radiation characterized by low or high linear energy transfer (LET) and dose rate. This study was designed to obtain dose calibration curves by scoring of dicentric chromosomes in peripheral blood lymphocytes irradiated in vitro with a 6 MV electron linear accelerator (Mevatron M, Siemens, USA). Two software programs, CABAS (Chromosomal Aberration Calculation Software) and Dose Estimate, were used to generate the curve. The two software programs are discussed; the results obtained were compared with each other and with other published low LET radiation curves. Both software programs resulted in identical linear and quadratic terms for the curve presented here, which was in good agreement with published curves for similar radiation quality and dose rates.

Structure based design, synthesis, and evaluation of potential inhibitors of steroid sulfatase.

The activity of the enzyme steroid sulfatase (STS) is high in breast tumors and elevated levels of STS mRNA expression have been associated with a poor prognosis. Potent STS irreversible inhibitors have been developed, paving the way to use this new type of therapy for the treatment of breast cancer. Several small molecules belonging to a natural products-inspired library of previously obtained inhibitors of tumor cell growth and new molecules planned to be reversible inhibitors of this enzyme were docked into STS. Some of the synthesized xanthone derivatives, which revealed high scores against STS, namely oxo-9H-xanthene-3,6-diyl bis(3-chlorobenzoate) (5), 9-oxo-9H-xanthene-3,6-diyl bis(4-tertbutylbenzoate) (6) and 9-oxo-9H-xanthene-3,6-diyl bis(4-methoxybenzoate) (7) showed poor water solubility. Therefore, formulations of these derivatives with cyclodextrins were prepared and characterized. The compounds were evaluated regarding their effect on the in vitro growth of various human tumor cell lines, as well as the effect in STS inhibition, for the compounds with the most favorable ΔG values. Additionally, the capacity of these derivatives and of some prenyl and acetoxy-benzophenone and xanthones to inhibit the in vitro growth of MCF-7 ER(+) and/or to inhibit STS in a micromolar range was also assessed. Some compounds developed in the present work were shown to be potential STS inhibitors.

A century of thioxanthones: through synthesis and biological applications.

The interest in the synthesis and applications of thioxanthones, dibenzo-gamma-thiopyrones, started in the beginning of the 20th century. Thioxanthones are traditionally synthesized via benzophenone, diarylthioether or diarylthioester intermediates. In recent years, more efficient and cleaner synthetic methodologies are being applied to obtain thioxanthone derivatives, especially for photochemical applications. Considering biological activities, the first thioxanthone introduced in therapy in 1945 was Miracil D, as an antischistosomal agent. Since then, the variety of studies of biological/ pharmacological activities of thioxanthones led to the discovery of new agents and to the disclosure of their mechanisms of action. Moreover, the ability to sensitize cancer cells suggested new and promising applications in chemotherapy. New antitumor derivatives are being developed by molecular modifications such as isosterism (aza-thioxanthones and aminoethylthioxanthones) or hybridation (psorospermine and acronycin analogues). The last generation of antitumor thioxanthones rendered a derivative, SR271425, with an excellent preclinical antitumor efficacy. The last decade has been excited in the research of thioxanthones with important achievements in both synthesis and biochemical applications, especially in order to dissociate the antitumor activity from the toxicity of drug candidates. Recently, thioxanthones emerged as dual inhibitors of P-glycoprotein and tumor cell growth. It is expected that in the following years new analogues with the thioxanthone scaffold emerge in the field of anticancer therapy, with enhanced antitumor activity and without serious side effects.

Three decades of P-gp inhibitors: skimming through several generations and scaffolds.

Many tumor cells become resistant to commonly used cytotoxic drugs due to the overexpression of ATP-binding cassette (ABC) transporters, namely P-glycoprotein (P-gp). The discovery of the reversal of multidrug resistance (MDR) by verapamil occured in 1981, and in 1968 MDR Chinese hamster cell lines were isolated for the first time. Since then, P-gp inhibitors have been intensively studied as potential MDR reversers. Initially, drugs to reverse MDR were not specifically developed for inhibiting P-gp; in fact, they had other pharmacological properties, as well as a relatively low affinity for MDR transporters. An example of this first generation P-gp inhibitors is verapamil. The second generation included more specific with less side-effect inhibitors, such as dexverapamil or dexniguldipine. A third generation of P-gp inhibitors comprised compounds such as tariquidar, with high affinity to P-gp at nanomolar concentrations. These generations of inhibitors of P-gp have been examined in preclinical and clinical studies; however, these trials have largely failed to demonstrate an improvement in therapeutic efficacy. Therefore, new and innovative strategies, such as the fallback to natural products, the design of peptidomimetics and dual activity ligands emerged as a fourth generation of P-gp inhibitors. The chemistry of P-gp inhibitors, as well as their in vitro, in vivo and clinical trials are discussed, and the most recent advances concerning Pgp modulators are reviewed.

Towards a standardised surveillance for Trichinella in the European Union.

Each year, more than 167 million pigs in the European Union (EU) are tested for Trichinella spp. under the current meat hygiene regulations. This imposes large economic costs on countries, yet the vast majority of these pigs test negative and the public health risk in many countries is therefore considered very low. This work reviewed the current Trichinella status across the EU as well as the national level of monitoring and reporting. It also reviewed which animal species were affected by Trichinella and in which species it should be surveyed. This information was used to design a cost-effective surveillance programme that enables a standardised monitoring approach within the EU. The proposed surveillance programme relies on identifying sub-populations of animals with a distinct risk. Low-risk pigs are finisher pigs that originate from so-called controlled housing. All other pigs are considered high-risk pigs. Controlled housing is identified by the application of a specific list of management and husbandry practices. We suggest that member states (MS) be categorised into three classes based on the confidence that Trichinella can be considered absent, in the specified sub-population of pigs above a specified design prevalence which we set to 1 per million pigs. A simple and transparent method is proposed to estimate this confidence, based on the sensitivity of the surveillance system, taking into account the sensitivity of testing and the design prevalence. The probability of detecting a positive case, if present, must be high (>95 or >99%) to ensure that there is a low or negligible risk of transmission to humans through the food chain. In MS where the probability of a positive pig is demonstrated to be negligible, testing of fattening pigs from a sub-population consisting of pigs from controlled housing can be considered unnecessary. Furthermore, reduced testing of finishers from the sub-population consisting of pigs from non-controlled housing might even be considered, if conducted in conjunction with a proportionate sampling scheme and a risk-based wildlife surveillance programme where applicable. The proposed surveillance programme specifies the required number of samples to be taken and found negative, in a MS. A MS with no data or positive findings will initially be allocated to class 1, in which all pigs should be tested. When a MS is able to demonstrate a 95% or 99% confidence that Trichinella is absent, the MS will be allocated to class 2 or 3, in which the testing requirement is lower than in class 1.

Screening of Jatropha curcas genotypes to anthracnose caused by Colletotrichum gloeosporioides.

Anthracnose caused by Colletotrichum gloeosporioides is an important physic nut (Jatropha curcas) disease causing damages on leaves, stems and fruits and consequently a decrease in seed quantity and quality. Physic nut is a native plant of Central America that has gained international attention due to its potential as biodiesel crop. However despite its highest relevance, studies concerning the response of different Jatropha genotypes to infection with this disease are very limited. The main objective of this study is the evaluation of susceptibility of 38 Jatropha curcas genotypes from a worldwide germplasm collection to Colletotrichum gloeosporioides. A simple method using wounded detached leaves inoculated with a 5-mm mycelia plug was used. Observations (lesion diameter and % of infection) were made after 3 and 7 days under controlled conditions (25 degrees C and 85% RH). Results showed significantly differences (P < or = 0.001) in both percentage of infection and lesion diameter among the tested accessions. Two genotypes from Brazil and Cape Verde, presented no lesions after 7 days of treatment, while the others presented between 67 and 100% of infection. Lesion diameter showed an increase with time of incubation and proved to be a useful tool for evaluation of plant susceptibility.

Cognitive impairment of prefrontal-dependent decision-making in rats after the onset of chronic pain.

Forced choice between alternative options of unpredictable outcome is a complex task that requires continual update of the value associated with each option. Prefrontal areas such as the orbitofrontal cortex (OFC) have been shown to play a major role in performance on ambiguous decision-making tasks with substantial risk component, broadly named as "gambling tasks." We have recently demonstrated that rats display complex decision-making behavior in a rodent gambling task based on serial choices between rewards of different value and probability. This rodent task retains many of the key characteristics of the human Iowa Gambling Task (IGT), and performance in this novel task is also disrupted by OFC or amygdalar lesioning. In the present study we addressed if rat models of chronic pain would have impaired performance in this gambling task, since it is already known that the IGT response patterns of human pain patients are comparable to individuals with OFC lesions. We found that animals with a monoarthritic inflammatory model of chronic pain systematically preferred the lever associated with larger but infrequent rewards. In addition, we measured the neurochemical content of the OFC, amygdala and nucleus accumbens using HPLC, and found that in prolonged chronic pain animals there was a decrease in the tonic levels of dopamine, DOPAC (3,4-hydroxyphenyl-acetic acid) and 5-HIAA (5-hydroxyindole-3-acetic acid) in the OFC. This is the first report of the effect of chronic pain in rat decision-making processes and supports the notion that pain may have profound effects on the functioning of the reward-aversion circuitry relevant to strategic planning.

Visual attention in children with migraine: a controlled comparative study.

The aim of this study was to evaluate the visual attention of children with migraine and compare it with a control group. Thirty migrainous children and 30 controls without headache were subjected to a visual attention assessment with Trail Making Tests (TMT) A/B, Letter Cancellation Test, and the Brazilian computerized test Visual Attention Test, third edition. The migraine group was evaluated after 2 days without headache. The migraine group had an inferior performance compared with the control group on TMT A (P = 0.03) and B (P = 0.001), and more errors on tasks 1 (P = 0.032) and 2 (P = 0.015) of the Visual Attention Test, presenting difficulty with selective and alternate attention. Attention is a neurological function that depends on structures such as the brainstem, cerebral cortex and the limbic system and on neurotransmitters such as dopamine and noradrenaline. The neurochemical aspects involved in the physiopathology of migraine and attention mechanisms probably predispose these children to visual attention deficits.

Serotonin levels in aqueous humor of patients with primary open-angle glaucoma.

PURPOSE: Glaucoma is an optic neuropathy characterized by a high intraocular pressure (IOP), alterations in optic nerve head, and loss of visual field that could lead to bilateral blindness. Serotonin (5-HT) is a biogenic monoamine that is synthesized from hydroxylation of tryptophan and acts by three ways, dissemination, metabolism, and reuptake in synaptic cleft through specific systems of the membrane. The purpose of this study is to evaluate the 5-HT and 5-HIAA (5-hydroxiindolacetic acid) levels in the aqueous humor of patients with primary open-angle glaucoma (POAG). METHODS: We performed a case-control study, and the patients recruited were classified into two groups, 1) 30 patients with POAG (GG) and 2) 30 patients with cataracts (CG), who acted as the controls. Aqueous humor samples of each patient were obtained by paracentesis at the beginning of the surgical procedures. 5-HT and 5-HIAA levels were determined by high performance liquid chromatography (HPLC) with electrochemical detection. RESULTS: There were no statistical differences between age (71.3 +/- 7.2 years in GG, 73.5 +/- 9.0 years in CG; p=0.2581) or gender (sex ratio 0.765 in GG and 0.667 in CG). 5-HT levels were lower in GG, but this difference was not significant (p=0.820). We observed a statistically significant higher level of 5-HIAA in GG (p=0.001). The 5-HT turnover (5-HIAA/5-HT) were higher in GG than in CG (p<0.05), but the difference was not significant (p=0.598). CONCLUSIONS: The level of 5-HT was lower in GG patients, and the level of 5-HIAA was higher in GG patients than in CG patients.

Resistance to white rust in pak choi and Chinese cabbage at the cotyledon stage.

The biothrofic pathogen Albugo candida (Pers.) attacks all the cultivated Brassica species and several wild crucifers causing the disease known as white rust. The symptoms consist on the initial appearance of more or less conspicuous white sori on the plant leaves and stems, followed by severe distortions of the affected organs, especially flowers and siliqua. On delicate vegetable types of Brassica rapa L., like pak choi (B. rapa var. chinensis L.) and chinese cabbages (B. rapa var. pekinensis L.) even a slight white rust infection can render all the production unmarketable. Development of resistant cultivars is the best way to control the disease and to insure low pesticide spraying and residues in vegetables. The objective of this work were: i) the screening of a collection of B. rapa accessions from several seed banks for sources of resistance to white rust; and ii) the study of the inheritance of resistance in the most resistant accessions. Forty three accessions of B. rapa chinensis and 19 accessions of B. rapapekinensis were screened at the cotyledon stage following the methods of Santos and Dias (2004) with a Portuguese A. candida isolate Ac506 (Br) collected from turnip leaves. Four accessions of B. rapa chinensis presented more than 50% of resistant plants: the pak choi (BRA 117) was the most resistant accession with 85% of resistant plants, followed by pak choi (BRA227) with 73%, pai tsai 'Ex China 1' (B00083) with 60% and pak choi 'Ai Jiao Huang' (BRA 225) with 53%. On the opposite, B. rapa pekinensis accessions were all consider as susceptible presenting only 0-11% of resistant plants. The inheritance of resistance was studied in two crosses between pak choi BRA 117 and the rapid cycling B. rapa plant line CrGC 1.19. Selfed parents and F1 and F2 generations were produced, and screened at the cotyledon stage as previously described. Analysis of the results suggests that inheritance of resistance to Ac506 in pak choi BRA 117 is controlled by two nuclear genes with dominant recessive interaction.

Aureobasidium pullulansas a biocontrol agent of blue mold in "Rocha" pear.

The blue mold of "Rocha" pear caused by Penicillium expansum is an important postharvest disease which is adequately controlled by application of synthetic fungicides. In recent years, strategies like biological control have been considered a desirable alternative to chemicals. Several studies have demonstrated the potential of the yeast-like fungus Aureobasidium pullulans for control of postharvest decay of pear. A Portuguese isolate of Aureobasidium pullulans was characterized and evaluated for its activity in reducing postharvest blue mold decay of "Rocha" pear caused by Penicillium expansum. Study of optimal conditions for antagonist growth was carried out in six different culture media. The effect of four maturity stages of fruits in the development of A. pullulans was also studied. Biocontrol studies were performed with two concentrations of the antagonist (3 x 10(8) and 4 x 10(9) CFU/ml). A. pullulans growth was significantly different (P < or = 0.001) according to the various media and time of incubation. Best results were obtained in Corn Meal Agar (CMA) and Potato Dextrose Agar (PDA) media which contains the higher concentration of glucose (20 mg/l). Medium resulted from fruits of the first harvest date presented lower colony diameter. Inoculation of A. pullulans at 3 x 10(8) and 4 x 10(9) CFU/ml reduced the incidence of the disease by 23 and 63%, and reduced the lesion diameter by 36 and 46%, respectively.

Synthesis of xanthones: an overview.

Among the known synthetic routes to obtain xanthones, the Grover, Shah, and Shah reaction, the cyclodehydration of 2, 2'-dihydroxybenzophenones and electrophilic cycloacylation of 2-aryloxybenzoic acids are the most popular methods. Due to important biological applications of xanthones, some synthetic strategies leading to more complex derivatives have been widely explored in the past years. Thus, the purpose of this review is to report some recent improvements of the classical synthetic methods as well as of some non-classical methods to obtain simple oxygenated xanthones. The strategies for introduction of substituents into the xanthonic nucleus are also summarized. Furthermore, different approaches used to synthesize complex structures, with an emphasis on the total synthesis of bioactive natural products, accomplished in the last twenty years, are also discussed. Besides the synthesis of xanthones, the reactivity of the xanthonic nucleus and its role as a key intermediate for the synthesis of other important classes of compounds are also highlighted.

Xanthone derivatives: new insights in biological activities.

Xanthones or xanthen-9H-ones (dibenzo-gamma-pirone) comprise an important class of oxygenated heterocycles whose role is well-known in Medicinal Chemistry. The biological activities of this class of compounds are associated with their tricyclic scaffold but vary depending on the nature and/or position of the different substituents. In this review, an array of biological/pharmacological effects is presented for both natural and synthetic xanthone derivatives, with an emphasis on some significant studies on structure-activity relationships. The antitumor activity of some xanthones as well as the related targets, particularly PKC modulation studies, is also discussed in detail. Examples of the "hit" compounds involved in cancer therapy, namely DMXAA, psorospermin, mangiferin, norathyriol, mangostins, and AH6809, a prostanoid receptor antagonist, are also mentioned. Finally, a historical perspective of these xanthonic derivatives, their relevance as therapeutic agents and/or their uses as pharmacological tools and as extract components in folk medicine are also highlighted.

Validation of a spectrophotometric method for quantification of xanthone in biodegradable nanoparticles.

Xanthone has been incorporated for the first time in nanoparticles of poly(D,L-lactide-co-glycolide) (PLGA). For this purpose the estimation of xanthone content in the nanoparticles is a crucial tool for guaranteeing the reliability of the results. Thus, a simple spectrophotometric method was validated according to USP25 and ICH guidelines for its specificity, linearity, accuracy and precision. The method was found to be specific for xanthone in the presence of nanoparticle excipients. The calibration curve was linear over the concentration range of 0.5 to 4.0 microg/mL (r > 0.999). Recovery of xanthone from nanoparticles ranged from 86.5 to 95.9%. Repeatability (intra-assay precision) and intermediate precision were found to be acceptable with relative standard deviations values (RSD) ranging from 0.3 to 3.0% and from 1.4 to 3.1%, respectively. The method was found to be suitable for the evaluation of xanthone content in nanoparticles of PLGA.