Anti-malarial activity and toxicity assessment of Himatanthus articulatus, a plant used to treat malaria in the Brazilian Amazon.

BACKGROUND: Plasmodium falciparum has become resistant to some of the available drugs. Several plant species are used for the treatment of malaria, such as Himatanthus articulatus in parts of Brazil. The present paper reports the phyto-chemistry, the anti-plasmodial and anti-malarial activity, as well as the toxicity of H. articulatus. METHODS: Ethanol and dichloromethane extracts were obtained from the powder of stem barks of H. articulatus and later fractionated and analysed. The anti-plasmodial activity was assessed against a chloroquine resistant strain P. falciparum (W2) in vitro, whilst in vivo anti-malarial activity against Plasmodium berghei (ANKA strain) was tested in mice, evaluating the role of oxidative stress (total antioxidant capacity--TEAC; lipid peroxidation--TBARS, and nitrites and nitrates--NN). In addition, cytotoxicity was evaluated using the HepG2 A16 cell-line. The acute oral and sub-chronic toxicity of the ethanol extract were evaluated in both male and female mice. RESULTS: Plumieride was isolated from the ethyl acetate fraction of ethanol extract, Only the dichloromethane extract was active against clone W2. Nevertheless, both extracts reduced parasitaemia in P. berghei-infected mice. Besides, a significant reduction in pulmonary and cerebral levels of NN (nitrites and nitrates) was found, as well as in pulmonary TBARS, indicating a reduced oxidative damage to these organs. The ethanol extract showed low cytotoxicity to HepG2 A16 cells in the concentrations used. No significant changes were observed in the in vivo toxicity studies. CONCLUSIONS: The ethanol extract of H. articulatus proved to be promising as anti-malarial medicine and showed low toxicity.

Nutritional supplementation with the mushroom Agaricus sylvaticus reduces oxidative stress in children with HIV.

BACKGROUND: The involvement of free radicals and oxidative stress in HIV infection has been extensively studied, and the benefits of antioxidant supplementation in animal studies have been demonstrated. However, few studies have demonstrated a benefit in clinical studies. OBJECTIVE: To verify the effects of dietary supplementation with Agaricus sylvaticus, a mushroom rich in antioxidants, on the oxidative profile of children born with HIV undergoing antiretroviral therapy. DESIGN: The sample included 24 children (both boys and girls) between two and eight years of age, of whom 10 were HIV positive and received supplementation with Agaricus sylvaticus for a three-month period, and 14 were HIV negative and received no supplementation. At the beginning and conclusion of the study, thiobarbituric acid-reactive substances (TBARS), nitrite and nitrate (NN), Trolox equivalent antioxidant capacity, and the antioxidant capacity of inhibition of diphenyl-picrilhidrazil (DPPH) free radicals were analyzed. RESULTS: Before supplementation, significantly higher values of TBARS and NN, but decreased values of DPPH, were observed in infected subjects when compared with HIV-negative subjects. After supplementation, a reduction of TBARS and NN values and an increase in DPPH and Trolox equivalent antioxidant capacity values were observed in HIV-positive subjects. CONCLUSIONS: The results of the present study suggest the involvement of oxidative stress in HIV infection, with the participation of NN synthesis. Additionally, supplementation reversed oxidative alterations and improved antioxidant defense in infected individuals, and may become a complementary strategy in the treatment of these patients.

HISTORIQUE: L'activité des radicaux libres et du stress oxydatif dans l'infection par le VIH a fait l'objet de nombreuses études, et les bienfaits des suppléments d'antioxydants ont été démontrés dans des études sur des animaux. Cependant, peu d'études en ont confirmé les avantages dans des études cliniques. OBJECTIF: Vérifier les effets de suppléments alimentaires contenant de l'Agaricus sylvaticus, un champignon riche en antioxydants, sur le profil oxydatif des enfants nés avec le VIH sous thérapie antirétrovirale. MÉTHODOLOGIE: L'échantillon se composait de 24 enfants (garçons et filles) de deux à huit ans, dont dix étaient positifs au VIH et ont reçu des suppléments d'Agaricus sylvaticus pendant trois mois, et 14 étaient négatifs au VIH est n'ont pas reçu de suppléments. Au début et à la fin de l'étude, les chercheurs ont analysé les substances réactives à l'acide thio-barbiturique (SRATB), les nitrites et les nitrates (NN), la capacité antioxydante en équivalent Trolox et la capacité antioxydante de l'inhibition des radicaux libres diphényl-picrylhydrazyl (DPPH). RÉSULTATS: Avant la prise de suppléments, les sujets infectés présentaient des valeurs considérablement plus élevées de SRATB et de NN, mais plus faibles de DPPH, que les sujets négatifs au VIH. Après la prise de suppléments, les valeurs de SRATB et de NN diminuaient tandis que celles de DPPH et de la capacité antioxydante en équivalent Trolox augmentaient chez les sujets positifs au VIH. CONCLUSIONS: D'après les résultats de la présente étude, le stress oxydatif est actif dans l'infection par le VIH, avec la participation de la synthèse des NN. De plus, des suppléments renversaient les altérations oxydatives et accroissaient la défense assurée par les antioxydants chez les sujets infectés. De tels suppléments pourraient devenir une stratégie complémentaire au traitement.

Oxidative stress in malaria.

Malaria is a significant public health problem in more than 100 countries and causes an estimated 200 million new infections every year. Despite the significant effort to eradicate this dangerous disease, lack of complete knowledge of its physiopathology compromises the success in this enterprise. In this paper we review oxidative stress mechanisms involved in the disease and discuss the potential benefits of antioxidant supplementation as an adjuvant antimalarial strategy.