A mechanistic approach to anti-nociceptive potential of Artemisia macrocephala Jacquem.

BACKGROUND: Artemisia macrocephala Jacquem (A. macrocephala), locally known as "Tarkha", is a perennial plant found abundantly in northern areas of Pakistan. It is widely used in traditional medicine to treat fever, pain, gastrointestinal disorders and diabetes. Till date, no published studies are available regarding the in-vivo antinociceptive potential of the crude extract and sub-fractions from the aerial parts of A. macrocephala. METHODS: Antinociceptive effects of the crude methanolic extract and its sub-fractions were assessed using experimental pain models, including chemical nociception induced by intraperitoneal acetic acid or subplantar formalin injection and thermal nociception like tail immersion test in-vivo. RESULTS: The administration of various doses of crude extract and its fractions showed a dose-dependent indomethacin like antinociceptive effect in acetic acid induced writhing, subplantar formalin injection animal model suggesting the involvement of central mechanism of pain inhibition. Moreover, the crude extract and sub-fractions, on tail flick model (thermal nociception) demonstrated the involvement of central mechanism and significantly increased the latency time to 66.54, 82.94 and 70.53 %. The antagonistic study proposed the possible involvement of opioid receptor using naloxone as non-selective antagonist. The pharmacologically active chloroform and ethyl acetate fractions were further subjected to column chromatography that lead to the isolation four compounds. These isolated compounds were then subjected to various spectroscopic techniques upon which they were confirmed to be one sterol and three flavonoid derivatives. These findings suggest that Artemisia macrocephala possesses peripheral and central analgesic potentials partially associated with opioid system that support its folkloric use for the management of pain. The isolated compounds are currently under investigation in our laboratory for analgesic activity and its possible mechanism of action. CONCLUSION: The results in this study provide evidences that A. macrocrphala has anticonciceptive effects and can be used for treatment of pain in traditional therapies. This study opens a new channel for isolation of analgesic compounds from the specie that is used traditionally for the management of pain.

Dihydroartemisinin promotes angiogenesis during the early embryonic development of zebrafish.

AIM: To investigate the embryotoxicity of dihydroartemisinin (DHA), the main active metabolite of artemisinin, in zebrafish, and explore the corresponding mechanisms. METHODS: The embryos of wild type and TG (flk1:GFP) transgenic zebrafish were exposed to DHA. Developmental phenotypes of the embryos were observed. Development of blood vessels was directly observed in living embryos of TG (flk1:GFP) transgenic zebrafish under fluorescence microscope. The expression of angiogenesis marker genes vegfa, flk1, and flt1 in the embryos was detected using real-time PCR and RNA in situ hybridization assays. RESULTS: Exposure to DHA (1-10 mg/L) dose-dependently caused abnormal zebrafish embryonic phenotypes in the early developmental stage. Furthermore, exposure to DHA (10 mg/L) resulted in more pronounced embryonic angiogenesis in TG (flk1:GFP) zebrafish line. Exposure to DHA (10 mg/L) significantly increased the mRNA expression of vegfa, flk1, and flt1 in the embryos. Knockdown of the flk1 protein partially blocked the effects of DHA on embryogenesis. CONCLUSION: DHA causes abnormal embryonic phenotypes and promotes angiogenesis in zebrafish early embryonic development, demonstrating the potential embryotoxicity of DHA.

Risk assessment of thujone in foods and medicines containing sage and wormwood--evidence for a need of regulatory changes?

Thujone is a natural substance found in plants commonly used in foods and beverages, such as wormwood and sage, as well as in herbal medicines. The current limits for thujone in food products are based on short-term animal studies from the 1960s, which provided evidence for a threshold-based mechanism, yet only allowed for the derivation of preliminary values for acceptable daily intakes (ADI) based on the no-observed effect level (NOEL). While the 2008 European Union Regulation on flavourings deregulated the food use of thujone, the European Medicines Agency introduced limits for the substance in 2009. The present study re-evaluates the available evidence using the benchmark dose (BMD) approach instead of NOEL, and for the first time includes data from a long-term chronic toxicity study of the National Toxicology Program (NTP). The NTP data provide similar results to the previous short-term studies. Using dose-response modelling, a BMD lower confidence limit for a benchmark response of 10% (BMDL10) was calculated as being 11 mg/kg bw/day for clonic seizures in male rats. Based on this, we propose an ADI of 0.11 mg/kg bw/day, which would not be reachable even for consumers of high-levels of thujone-containing foods (including absinthe). While fewer data are available concerning thujone exposure from medicines, we estimate that between 2 and 20 cups of wormwood or sage tea would be required to reach this ADI, and view that the short-term medicinal use of these herbs can also be regarded as safe. In conclusion, the evidence does not point to any need for changes in regulations but confirms the current limits as sufficiently protective for consumers.

Acute and chronic toxicity of the aqueous extract of Artemisia afra in rodents.

Artemisia afra (Jacq. Ex. Willd), "African Wormwood" is widely used traditionally in South Africa with no literature evidence substantiating its safety. The aim of this study was to investigate the safety of the aqueous extract of Artemisia afra by determining its pharmaco-toxicological effects after acute and chronic administration in mice and rats, respectively. The aqueous extract mimicked the traditional decoction dosage form of Artemisia afra. In mice, single intraperitoneal injections of Artemisia afra-extract (1.5-5.5g/kg) induced a regular dose-dependent increase in the death rate and incidence of general behaviour adverse effects, while with single oral doses (2-24g/kg) the increases in incidence of general behaviour adverse effects and mortality rate were dose-independent. The LD(50s) after acute intraperitoneal and oral doses were 2.45 and 8.96g/kg, respectively. Rats given oral doses of Artemisia afra-extract (0.1 or 1g/kg/day) survived the 3 months of dosing (i.e. LD(50) much higher than 1g/kg), experienced no significant changes in general behaviour and haematological and biochemical parameters, except for transient decrease in AST activity. No significant changes were observed in organ weights, and histopathological results showed normal profile suggesting no morphological alterations. Collectively, the results indicate that Artemisia afra-extract is non-toxic when given acutely, has low chronic toxicity potential and, in high doses, may have a hepatoprotective effect.

Effects of various levels of dietary Artemisia abyssinica leaves on rats.

Artemisia abyssinica leaves, a traditional medicine for the treatment of various disorders, were fed to male Wistar rats at 2% and 10% of the standard diet for 6 weeks. A 2% A. abyssinica leaf diet was not toxic to rats. Depression in growth, hepatopathy and nephropathy were observed in rats fed a diet containing 10% of A. abyssinica leaves. These findings were accompanied by leukopenia, anaemia and alterations of serum aspartate aminotransferase (AST), alanine aminotransferase (ALT) and gamma glutamyl transferase (GGT) activities with changes in concentrations of total protein, albumin, cholesterol and urea.

Mitigating effects of antioxidant properties of Artemisia campestris leaf extract on hyperlipidemia, advanced glycation end products and oxidative stress in alloxan-induced diabetic rats.

Artemisia campestris is used as antivenom and anti-inflammatory Tunisian folk medicine. Recently, increased oxidative stress was shown to play an important role in the etiology and pathogenesis of diabetes mellitus and its complications. This study was designed to examine the effects of A. campestris leaf aqueous extract (Ac) on alloxan-induced diabetic rats by measuring glycemia, lipid profile, lipid peroxidation (MDA), protein carbonyl content (PCO), advanced oxidation protein products (AOPP), activities of both non-enzymatic and enzymatic antioxidants. Results of our study showed an increase in blood glucose levels, total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-c), a decrease in high-density lipoprotein cholesterol (HDL-c) level and disturbed antioxidant enzyme activities (CAT, SOD, GPx) in the pancreatic tissue of diabetic rats. Furthermore, MDA, PCO and AOPP were elevated in the pancreas of the diabetic rats. The administration of Ac to diabetic rats at a dose of 200mgkg(-1)bw resulted in a significant reduction in glycemia, TC, TG, LDL-c, pancreas LPO, PCO and AOPP levels, CAT and GPx activities associated with an elevation of GSH content and SOD activity in comparison with diabetic group. We conclude that A. campestris aqueous extract may be effective for correcting hyperglycemia and preventing diabetic complications.

Assessment of the toxicity of Artemisia inculta extract on the bone marrow of mice infected with schistosomiasis.

UNLABELLED: The discovery of the crude extract of Artemisia inculta (an Egyptian species of the Artemisia plant) for the therapy of schistosomiasis has evoked the study of its long-term toxicity produced by antischistosomal doses. Hence, an assessment of the noxious effects on bone marrow was attempted in this study. Transmission electron microscopy of the bone marrow was conducted on infected mice receiving a crude ethanolic extract from Artemisia inculta by newly designed dose regimens (500 or 800 mg/kg body weight in the 7th, 14th and 21st weeks post infection). This regimen was found to produce an efficient therapeutic effect in decreasing worm load and causing tegumental damage of juvenile and adult worms. The ultrastructural features of all cell lines in the bone marrow were comparable in both treated (500 and 800 mg/kg body weight dose levels) and untreated groups showing normal cellularity, maturation and morphology. This denotes that the drug is non-toxic to the hemopoietic tissue. IN CONCLUSION: Electron microscopy has provided a direct and accurate evidence of the nontoxic property of the plant extract on bone marrow using therapeutic doses. However, this study should be extended to other vital organs such as the liver or brain to establish the safety of this drug.