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PubMed2004

In vitro and in vivo properties of usnic acid encapsulated into PLGA-microspheres.

Microparticles will probably play a promising role in the future of chemotherapy. These polymeric delivery systems are capable of maximizing the therapeutic activity while reducing side effects of anti-cancer agents. Usnic acid (UA) is a secondary metabolite produced by lichens, which exhibits an anti-tumour activity. In this study, PLGA-microspheres containing usnic acid from Cladonia substellata were prepared by the double emulsion method, with or without PEG as stabilizer. The morphology of the microspheres was examined by optical and scanning electron microscopy. The in vitro kinetic profile of usnic acid loaded-microspheres was carried out by dissolution testing. The usnic acid content was analysed by HPLC. The cytotoxicity of free and encapsulated usnic acid was evaluated against HEp-2 cells using the MTT method. The anti-tumour assay was performed in mice against Sarcoma-180 tumour (UA 15 mg kg(-1) weight body/day) during 7 days. Animals were then sacrificed and tumour and organs were excised for histopathological analysis. Microspheres presented a smooth spherical surface with a mean diameter of 7.02 +/- 2.72 microm. The usnic acid encapsulation efficiency was approximately 100% (UA 10 mg 460 mg(-1) microspheres). A maximum release of 92% was achieved at the fifth day. The IC50 values for free and encapsulated usnic acid were 12 and 14 microg ml(-1), respectively. The encapsulation of usnic acid into microspheres promoted an increase of 21% in the tumour inhibition as compared with the free usnic acid treatment. In summary, usnic acid was efficiently encapsulated into PLGA-microspheres and the microencapsulation improved its anti-tumour activity.

Animals↗

PubMed2006

[Plasmid elimination effect of usnic acid on antibiotic-resistant Staphylococcus aureus].

OBJECTIVE: To observe the influence of Usnic acid on the antibiotic-resistant plasmid in Staphylococcus aureus (Sa). METHODS: The antibiotic-resistant plasmid was abstracted from the clinical divided strain of Sa and plasmid elimination test was performed in vitro. RESULTS: Plasmid elimination test showed that Usnic acid could eliminate the resistant plasmid in Sa effectively. At 24th and 48th hour after the treatment of Usnic acid, the elimination rate of resistant plasmid was 5.2% and 16.4% respectively. CONCLUSION: Usnic acid can eliminate the antibiotic-resistant plasmid in Sa. It is possible to use Usnic acid to treat the infection of antibiotic-resistant Sa in clinic.

Anti-Bacterial Agents↗

PubMedDate not supplied

Quantitative determination of usnic acid in Usnea lichen and its products by reversed-phase liquid chromatography with photodiode array detector.

Usnic acid, a lichen substance, has a wide range of pharmaceutical applications, including antibiotic, antimycotic, antifeedant, antitubercular, antitumor, and analgesic activities. Some products containing usnic acid are marketed as weight control supplements; however, hepatotoxicity and acute liver failures were reported as severe side effects. The usnic acid content present in the plant materials and market products was analyzed by reversed-phase high-pressure liquid chromatography with a photodiode array detector at 233 nm. A Waters XTerra RP18 (150 x 4.6 mm; 5 microm particle size) column was the stationary phase; mobile phase was aqueous 0.1% acetic acid and acetonitrile gradient at flow rate of 1.0 mL/min. The temperature was held constant at 30 degrees C. The retention time of usnic acid was approximately 13.3 min. Acetone extraction of the samples took place with sonication. The precision of the method was confirmed by a standard deviation below 3.0% (n=3) and usnic acid recovery was 99.0%. Limit of detection was 0.4 microg/mL and the response was linear from 1.4 to 570.0 microg/mL with a correlation coefficient (R2) of 0.9991. The content of usnic acid in 4 raw materials and 22 finished products was analyzed.

Animals↗

PubMedDate not supplied

Pharmacokinetics of D(+)-usnic acid in rabbits after intravenous and oral administration.

The pharmacokinetics of D(+)-usnic acid--a lichen antitubercular, antitumor, and enzyme-inhibiting agent--was studied in rabbits following intravenous or oral administration of 5 and 20 mg/kg body weight doses, respectively. Plasma samples were collected at different time intervals, and usnic acid was determined by HPLC. Plasma usnic acid levels following intravenous administration showed a triexponential elimination with a mean +/- SD terminal half-life of 10.7 +/- 4.6 hr. The volume of distribution of the central compartment and systemic clearance were 43.9 +/- 21.3 ml/kg and 12.2 +/- 3.0 ml/hr/kg, respectively. Pharmacokinetic parameters obtained, based on compartmental and noncompartmental approaches, were comparable. Plasma concentration data obtained after oral administration were analyzed using a noncompartmental method. Peak plasma level (Cmax) of 32.5 +/- 6.8 micrograms/ml was achieved in 12.2 +/- 3.8 hr (tmax). Mean absolute bioavailability of usnic acid following oral administration was 77.8%.

Administration, Oral↗

PubMed2006

Determination of usnic acid in lichen toxic to elk by liquid chromatography with ultraviolet and tandem mass spectrometry detection.

Usnic acid is unambiguously confirmed by tandem mass spectrometry (MS/MS) in tumbleweed shield lichen, Xanthoparmelia chlorochroa. The lichen contains 2% usnic acid by liquid chromatography with UV quantification at 282 nm. The UV linear range for usnic acid quantification is from its 4 ng limit of detection to 2 microg injected. UV signal saturation is recognized by distortion of the usnic acid UV spectrum. Positive ion electrospray-tandem mass spectrometry offers no similar means to recognize quantification data recorded above the linear range of electrospray. Electrospray ionization capacity and matrix effects limit the reliability of tandem mass spectrometry quantification. The combination of UV quantification and MS confirmation provides a reliable analytical method for measuring usnic acid levels in plant material.

Acetone↗

PubMed1979

Usnic acid derivatives as potential antineoplastic agents.

Usnic acid, a lichen antibiotic, showed low-level activity in the Lewis lung carcinoma test system. In an effort to produce new agents of potential use in the treatment of lung cancer, derivatives of the natural product were synthesized and evaluated with a cytotoxicity assay. Structure--activity analysis of the cytotoxicity data indicated the importance of the lipophilicity and the beta-triketone moiety of usnic acid on cytotoxicity. No significant increases in survival of test animals over controls were shown by any of the synthetic compounds in the P388 leukemia or the Lewis lung carcinoma test systems.

Animals↗

PubMed1999

[Preparation and antineoplastic activity of acylhydrazones of R- and S-usnic acid].

Hydrazones of R- and S-usnic acid were prepared by condensation of the appropriate enantiomer of usnic acid with hydrazides of aromatic acids. Prepared compounds were characterized by spectral methods. Reaction kinetic was studied with capillary electrokinetic chromatography, enantiomeric purity of products was checked by capillary electrophoresis in the presence of gamma-cyclodextrin. Obtained hydrazones were tested as prospective antimitotic agents. The antitumor activity was screened in vitro on human tumor cell lines. The overall activity of tested compounds was low, however, the R- enantiomers were more active than their opposite stereoisomers.

Antineoplastic Agents↗

PubMed2005

Seasonal trends in usnic acid concentrations of Arctic, alpine and Patagonian populations of the lichen Flavocetraria nivalis.

The widespread secondary metabolite usnic acid, a dibenzofuran derivative, is the principal acetone-soluble compound in the lichen Flavocetraria nivalis. Seasonal variation in concentrations were studied in four populations of this lichen, three from Arctic-alpine habitats in the Northern Hemisphere, and one from Patagonian heathland in the Southern Hemisphere. Usnic acid is produced in large amounts, making up between 4% and 8% of thallus dry weight. Large seasonal variation is seen, with a trend towards peak levels in late spring and early summer, and generally low levels during autumn and winter. However, at an Arctic steppe in Central West Greenland, remarkably high levels were also detected during late autumn and early winter. Comparisons with environmental data using model selection procedures show that usnic acid levels of three of the populations are positively correlated with time of season, as measured by the proximity in time to nearest summer solstice, solar radiation levels, and temperature conditions. All these three variables are intercorrelated, thus indicating the same overall trend. For the three driest sites, precipitation rates are included in the models that best explain the variation in usnic acid. However, the explanatory powers of the models are generally low, partly due to high variation between thalli growing together and sampled at the same time. This is the first attempt to compare statistically seasonal variation in usnic acid concentrations and environmental variables, and thus also the first time it is shown that the concentration in various populations of the same lichen species shows different types of correlation with seasonal climatic changes.

Arctic Regions↗

PubMed1991

Mitodepressive, clastogenic and biochemical effects of (+)-usnic acid in mice.

Mice were treated orally with aqueous suspensions of (+)-usnic acid in a single dose of either 100 or 200 mg/kg. The effects on femur cells and proteins and on nucleic acids of liver cells were studied 24-72 h after treatment. (+)-Usnic acid was found to affect the proliferation of polychromatic erythrocytes possibly by interference with RNA biosynthesis. The slight increase in the micronucleated polychromatic erythrocytes without affecting DNA synthesis suggests an effect of usnic acid on spindle apparatus.

Administration, Oral↗

PubMed1999

[A zinc sulfate and usnic acid preparation used as post-surgical adjuvant therapy in genital lesions by Human Papillomavirus].

BACKGROUND: To evaluate the efficacy and safety of intravaginal administration of a zinc sulphate and usnic acid compound as adjuvant therapy of Human Papillomavirus (HPV) genital infection, after radiosurgical treatment (RS). METHODS: One hundred patients affected by HPV genital infection were enrolled in the study from October 1996 to July 1998. Patients were classified according to colposcopic and cytologic criteria and treated with RS. Patients were randomized into three groups: the first group did not follow any therapy after RS (control group), (n = 50); the second group was pharmacologically treated with intravaginal administration of a usnic acid and zinc sulphate compound (Zeta N, Bergamon Italia) before and after RS (n = 25), the third group was pharmacologically treated only after RS (n = 25). The last two groups were considered together for the statistical analysis. Patients were reevaluated after one, two, three and six months from electrocoagulation. The safety of treatment was also investigated. RESULTS: One month after RS. HPV lesions disappeared in 93% of the patients in the control group and in 100% of patients treated with usnic acid and zinc sulphate. After one month, reepithelization was complete in 65% of cases treated with usnic acid and zinc sulphate and in only 28% of the control group (p = 0.001). Two months later reepithelization was 94% in the patients pharmacologically treated compared to 76% of the control group (p = 0.06). Treatment prior to RS resulted in a reduction of the overall area of lesions in 88% of cases. Three months after RS, there was a significant reduction of recurrence in the group treated with usnic acid and zinc sulphate (p = 0.01). This reduction was still significant at six months (p = 0.005). CONCLUSIONS: Usnic acid and zinc sulphate adjuvant treatment improved time of reepithelization and reduce the recurrence with few side effects and a good compliance.

Adult↗

PubMed2004

Usnic acid, a natural antimicrobial agent able to inhibit bacterial biofilm formation on polymer surfaces.

In modern medicine, artificial devices are used for repair or replacement of damaged parts of the body, delivery of drugs, and monitoring the status of critically ill patients. However, artificial surfaces are often susceptible to colonization by bacteria and fungi. Once microorganisms have adhered to the surface, they can form biofilms, resulting in highly resistant local or systemic infections. At this time, the evidence suggests that (+)-usnic acid, a secondary lichen metabolite, possesses antimicrobial activity against a number of planktonic gram-positive bacteria, including Staphylococcus aureus, Enterococcus faecalis, and Enterococcus faecium. Since lichens are surface-attached communities that produce antibiotics, including usnic acid, to protect themselves from colonization by other bacteria, we hypothesized that the mode of action of usnic acid may be utilized in the control of medical biofilms. We loaded (+)-usnic acid into modified polyurethane and quantitatively assessed the capacity of (+)-usnic acid to control biofilm formation by either S. aureus or Pseudomonas aeruginosa under laminar flow conditions by using image analysis. (+)-Usnic acid-loaded polymers did not inhibit the initial attachment of S. aureus cells, but killing the attached cells resulted in the inhibition of biofilm. Interestingly, although P. aeruginosa biofilms did form on the surface of (+)-usnic acid-loaded polymer, the morphology of the biofilm was altered, possibly indicating that (+)-usnic acid interfered with signaling pathways.

Anti-Bacterial Agents↗

PubMed2002

Molecular characterization and action of usnic acid: a drug that inhibits proliferation of mouse polyomavirus in vitro and whose main target is RNA transcription.

Usnic acid is a normal component of lichen cells. This natural compound has shown different biological and physiological activities that might have a great relevance in pharmacology and clinics. For instance, usnic acid is known for its antibacterial and antiparasitic action. Also, the drug has a potential interest in cancer therapy because of its antimitotic and antiproliferative action. The molecular structure of usnic acid has been validated and further explored in this investigation. Many biological properties of this drug are known; however its potential antiviral action has not yet been evaluated. In this paper, we demonstrate that usnic acid is a potent inhibitor of the proliferation of mouse polyomavirus. Its action is not exerted at the level of virion entry into the host cell. Moreover, the abolition of viral DNA replication is an indirect consequence of the drastic inhibition of RNA transcription.

Actins↗

PubMed2005

Experimental studies on the growth and usnic acid production in "lichen"Usnea ghattensis in vitro.

The study was aimed to optimize the culture conditions for the production of usnic acid in the cultured cell aggregates composed of symbionts in lichen Usnea ghattensis in vitro. The cultured lichen tissue composed of symbionts appeared after about 2-3 weeks of inoculation in water-agar and malt-yeast extract (MYE) media and shown the production of usnic acid after 2-3 months of inoculation. However, the growth of symbionts was strongly affected by different culture conditions. The addition of excess carbon and nitrogen sources in the media has significantly enhanced the growth as well as usnic acid content. The cultured symbionts in MYE medium having 4% sucrose, 4% polyethyl glycol (PEG) gave 7.63 g dry biomass with 3.9 microg usnic acid/g dry biomass. In water-agar medium having 4% sucrose and 4% PEG gave 3.08 g dry biomass with 1.11 microg usnic acid/g dry biomass. The positive effects of medium on the growth of symbionts and the production of usnic acid are seemed to be due to nutritional factors.

Benzofurans↗

PubMed2005

Usnic acid: a non-genotoxic compound with anti-cancer properties.

The majority of human tumors bear inactive p53 or cellular factors that down-regulate the expression and activity of the p53 network. Therefore, finding therapies that are effective in such tumors is of great interest. Usnic acid, a normal component of lichens, showed activity against the wild-type p53 breast cancer cell line MCF7 as well as the non-functional p53 breast cancer cell line MDA-MB-231 and the lung cancer cell line H1299 (null for p53). In MCF7 cells treated with usnic acid, although there was an accumulation of p53 and p21 proteins, the transcriptional activity of p53 remained unaffected. We also found that there was no phosphorylation of p53 at Ser15 after treatment of MCF7 cells with usnic acid, suggesting that the oxidative stress and disruption of the normal metabolic processes of cells triggered by usnic acid does not involve DNA damage. The property of usnic acid as a non-genotoxic anti-cancer agent that works in a p53-independent manner makes it a potential candidate for novel cancer therapy.

Antineoplastic Agents↗

PubMed1987

Equivalence between Pfr and Cyclic AMP in the Induction of d-Usnic Acid Dehydrogenase in the Lichen Evernia prunastri.

d-Usnic acid dehydrogenase is induced in Evernia prunastri thalli by a supply of exogenous d-usnic acid in light. This effect is enhanced by red light pulses through a two step way: a very rapid increase of activity after the first 10 minutes of red light, which is not reversed by far-red light, and a slow enhancement following successive red light pulses at the beginning of each hour of incubation. The last response is completely reversed by far-red following red light. Although induction of the enzyme is not achieved in the dark, 0.1 and 0.5 millimolar cyclic AMP, or 0.1 millimolar dibutyryl cyclic AMP substitutes light action and, then, the enzyme is produced. In addition, phytochrome-far red-absorbing form-increases the amount of endogenously produced cyclic AMP and this effect is shown to be photoreversible when ethylenediaminetetraacetic acid is inhibiting adenylate cyclase.

Journal Article↗

PubMed2000

The phytotoxic lichen metabolite, usnic acid, is a potent inhibitor of plant p-hydroxyphenylpyruvate dioxygenase.

The lichen secondary metabolite usnic acid exists as a (-) and a (+) enantiomer, indicating a alpha or beta projection of the methyl group at position 9b, respectively. (-)-Usnic caused a dose-dependent bleaching of the cotyledonary tissues associated with a decrease of both chlorophylls and carotenoids in treated plants whereas no bleaching was observed with the (+) enantiomer. (-)-Usnic acid inhibited protophorphyrinogen oxidase activity (I50 = 3 microM), but did not lead to protoporphyrin IX accumulation. Bleaching appears to be caused by irreversible inhibition of the enzyme 4-hydroxyphenylpyruvate dioxygenase by (-)-usnic acid (apparent IC50 = 50 nM).

4-Hydroxyphenylpyruvate Dioxygenase↗

PubMed1992

High-performance liquid chromatographic determination of usnic acid in plasma.

A high-performance liquid chromatographic method for the determination of usnic acid in human plasma using diclofenac sodium as internal standard is described. Plasma proteins were precipitated with methanol. A 250 mm x 4 mm I.D. Nucleosil. C18 (5 microns) column with a mobile phase consisting of methanol-phosphate buffer (pH 7.4) (70:30, v/v) was used. Chromatography was performed at ambient temperature with flow-rate of 1 ml min-1 and ultraviolet detection at 280 nm. Each analysis required no longer than 7 min. Quantification was achieved by measurement of the peak-height ratio and the absolute recovery varied from 93.8 to 97.3%. The limit of quantitation of usnic acid in plasma was 0.25 micrograms ml-1. The intra-day relative standard deviation (R.S.D.) ranged from 1.24 to 4.53% and the inter-day R.S.D. from 2.23 to 8.25% at three different concentrations. The method was applied to the determination of plasma levels of usnic acid after intravenous and oral administration to study its disposition in a healthy male rabbit.

Administration, Oral↗

PubMedDate not supplied

Pharmacokinetics of d(+)-usnic acid in rabbits after intravenous administration.

The pharmacokinetics of usnic acid, a lichen antitubercular, antitumor and enzyme inhibiting agent, was studied in normal male rabbits after administration of 5 mg/kg dose by intravenous route. Plasma samples were collected up to 48 h. The plasma usnic acid levels showed a triexponential decay with a terminal half life of 10.69 h. The mean volume of distribution of the central compartment was 43.93 ml/kg. The pharmacokinetic parameters obtained from a three-compartment body model and a noncompartment body model gave close values. The mean steady-state volume of distribution was 167.17 and 163.29 ml/kg, systemic clearance was 12.17 and 12.25 ml/h/kg and AUC was 428.51 and 426.69 micrograms.ml/h following three-compartmental and noncompartmental analyses respectively.

Animals↗