Neurodegenerative diseases (ND) primarily affect the neurons in the human brain secondary to oxidative stress and neuroinflammation. ND are more common and have a disproportionate impact on countries with longer life expectancies and represent the fourth highest source of overall disease burden in the high-income countries. A large majority of the medicinal plant compounds, such as polyphenols, alkaloids, and terpenes, have therapeutic properties. Polyphenols are the most common active compounds in herbs and vegetables consumed by man. The biological bioactivity of polyphenols against neurodegeneration is mainly due to its antioxidant, anti-inflammatory, and antiamyloidogenic effects. Multiple scientific studies support the use of herbal medicine in the treatment of ND; however, relevant aspects are still pending to explore such as metabolic analysis, pharmacokinetics, and brain bioavailability.

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The protozoan Trypanosoma cruzi is the etiological agent of Chagas disease (American trypanosomiasis), which affects 16-18 million people in Latin America and is responsible for the deaths of more than 45,000 patients per year (WHO 1997). It is transmitted to humans by triatomine bugs or through infected blood transfusions (Pizzolatti et al. 2002). The life cycle of T. cruzi is complex, and it alternates between vertebrate and invertebrate hosts. When the triatomine bug is feeding on human blood, it defecates and releases metacyclic trypomastigotes near the bite wound. This infective agent is capable of reaching intracellular locations and transforming into amastigotes. After reproduction, the amastigotes turn back into trypomastigotes, and the cells burst. The released parasites can either infect other cells or be consumed by other triatomine bugs. In the intestine of an invertebrate host, the blood trypomastigotes transform into epimastigotes, which divide and give rise to infective metacyclic-trypomastigotes (Brener 1973, Contreras et al. 2002.Medication for Chagas disease is usually effective when given during the acute stage of infection. Once the disease has progressed to later stages, no medication has proven to be completely effective. Moreover, synthetic drugs such as nifurtimox, a 5-nitrofuran, and benznidazole, a 2-nitro-imidazole (Lampit®, Bayer, and Rochagan®, Roche, respectively) are used for the treatment of this disease. Unfortunately, both drugs have limited efficacy during the chronic phase of the disease and present several undesirable side effects (Gutteridge 1985, Umezawa et al. 2001, Coura & Castro 2002. Chemoprophylatic measures against Chagas disease are scarce, present variable efficacy, or are not adopted due to their costs. Currently, gentian violet is used to sterilize blood banks in endemic areas (Pizzolatti et al. 2002, Coura & Castro 2002). An urgent need to develop new drugs exists, and natural products can provide useful drug leads as well as the scientific basis for the rational use of medicinal plants.Calophyllum brasiliense Camb. is a large tree, measuring up to 40 m in height, from the tropical rain forest. It is distributed throughout Latin America, from Brazil to Mexico, and is used in folk medicine. In Mexico, its most common name is bari, and the infusion of the cortex is consumed by women over nine days for "cleaning" the womb after child-birth, while the seeds provide an oil used for lighting and for healing skin afflictions (Soto & Sousa 1995). In Colombia, the peasants call this tree ár-bol de aceite (oil tree), and the yellow latex exuded from the cortex is applied topically for healing the navels of newborn children (García-Barriga 1992). In Brazil, it is known as guanandi, and has been used in folk medicine for the treatment of rheumatism, varicose hemorrhoids and chronic ulcers (Corrêa 1978). In the Amazon basin, the bark infusion is used by the Karaja ethnic group for the treatment of diarrhea, and in Guyana, C. brasiliense is mixed with Coutarea hexandra to trea...

Introduction. Catharanthus roseus (L.) is used in some countries to treat diabetes. The aim of this study was to evaluate the hypoglycemic activity of extracts from the flower, leaf, stem, and root in normal and alloxan-induced diabetic mice. Methods. Roots, leaves, flowers, and stems were separated to obtain organic and aqueous extracts. The blood glucose lowering activity of these extracts was determinate in healthy and alloxan-induced (75 mg/Kg) diabetic mice, after intraperitoneal administration (250 mg/Kg body weight). Blood samples were obtained and blood glucose levels were analyzed employing a glucometer. The data were statistically compared by ANOVA. The most active extract was fractioned. Phytochemical screen and chromatographic studies were also done. Results. The aqueous extracts from C. roseus reduced the blood glucose of both healthy and diabetic mice. The aqueous stem extract (250 mg/Kg) and its alkaloid-free fraction (300 mg/Kg) significantly (P < 0.05) reduced blood glucose in diabetic mice by 52.90 and 51.21%. Their hypoglycemic activity was comparable to tolbutamide (58.1%, P < 0.05). Conclusions. The best hypoglycemic activity was presented for the aqueous extracts and by alkaloid-free stem aqueous fraction. This fraction is formed by three polyphenols compounds.

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