Leishmanicidal activity of the alkaloid-rich fraction from Guatteria latifolia.

Leishmaniasis is caused by protozoan parasites belonging to the genus Leishmania and includes cutaneous, mucocutaneous and visceral clinical forms. The drugs currently available for leishmaniasis treatment are pentavalent antimonials, amphotericin B and miltefosine, which present high toxicity, elevated cost and development of parasite resistance. The natural products constitute an important source of substances with leishmanicidal potential. Here we evaluated in vitro the anti-Leishmania amazonensis activity of crude extracts of branches, leaves and fruits of Guatteria latifolia. The branch extract (GCE) exhibited promising leishmanicidal activity against promastigotes (IC50 51.7 µg/ml), and was submitted to fractionation guided by in vitro assays. Among the seven subfractions obtained, GF1 and GF2 were the most actives against promastigotes with IC50 25.6 and 16 µg/ml, respectively. Since GCE, GF1 and GF2 were not toxic for macrophages, next, we tested their effect on intracellular amastigotes, and the IC50 values obtained were, respectively 30.5, 10.4 and 7.4 µg/ml, after 24 h treatment. The selectivity index for GCE, GF1 and GF2 were >6.5, >19.2 and > 27, respectively. Additionally, GCE, GF1 and GF2 affected the division pattern of the promastigotes by increasing 6.7, 9.4 and 7-fold the cells in Sub-G0/G1 phase, and decreasing 1.6, 2.5 and 1.8-fold the cells in G0/G1 phase, respectively. To assess the GCE and GFs capacity to modulate microbicidal mechanisms of macrophages, nitric oxide (NO) and TNF-α production were tested. Our results indicated that at the IC50s GCE, GF1 and GF2 decreased NO production of infected macrophages stimulated with IFN-γ and LPS, besides, only GF1 decreased the production of TNF-α. Our data warrant further studies of GCE, GF1 and GF2 to identify active compounds against Leishmania parasites.

Effects of lycopene from guava (Psidium guajava L.) derived products on breast cancer cells.

Polyphenols, condensed tannins, total flavonoids, total carotenoids, lycopene and ascorbic acid were determined besides verifying antioxidant capacity of peel, pulp and desserts (with and without sugar) of red guava (Psidium guajava L.) as well as the effects of lycopene on cytotoxicity, cell cycle and apoptosis on breast cancer cell line MCF-7. Guava peel contains 90% of the total ascorbic acid and heat treatment does not modify bioactive compounds content and antioxidant capacity. Sugar addition decreased guava pulp functional capacity. After heat treatment, lycopene content was stable, but sugar addition reduced its concentration by 57%. Lycopene (10 µM) extracted from guava and standard presented the same cytotoxic effect on MCF-7 cells. Lycopene influenced over G2-M transition check-point of the cell cycle and increased apoptotic cells percentages compared to untreated cells. The consumption of in natura guava, especially with peel can be considered an important source of bioactive compounds.