Cereus jamacaru D.C. (mandacaru) is a cactus used as food and in the traditional medicine. In the present study, hydroalcoholic extract of C. jamacaru was evaluated for its chemical composition, antioxidant activity, cytotoxic and anti-cytotoxic effects in human lymphocytes and sarcoma 180 cells in vitro by MTT assay and antitumoral, mutagenic and cytotoxic effects on mice sarcoma-induced in vivo. Phytochemical characterization showed positive reactions for coumarin, flavanol and tyramine and total flavonoid content of 0.51 µg/mL. C. jamacaru showed antioxidant activity following DPPH (EC₅₀ = 427.74 µg/mL), ABTS (EC₅₀ = 270.57 µg/mL) and Fe²⁺ chelating ions assays (EC₅₀ = 41.18 µg/mL). C. jamacaru induced significant decrease of sarcoma 180 viability at 24 h and 48 h of treatment, did not induce cytotoxicity in human lymphocytes and inhibits the cytotoxicity of cisplatin in vitro. Following in vivo assays, C. jamacaru promoted tumor reduction (86.07% of tumor inhibition), without inducing mutagenic or cytotoxic damage on mice blood cells. We propose that phenolic and alkaloid compounds in the extract are related to antioxidant activity, increasing its ability in metal chelating activity and promoting anti-cytotoxic activity against cisplatin, as well as these compounds may act on the cell cycle of the tumor cells in vitro and in vivo, leading to anticancer effects and tumor reduction.

Objective: To evaluate the influence of fruiting phenological stage on total flavonoid content, antioxidant activity, and antiproliferative effects of Cereus jamacaru (C. jamacaru) (mandacaru) cladodes and fruit. Methods: Fruit and cladodes at vegetative and fruiting stage of C. jamacaru were collected. The fruit was dissected and bark, pulp, and seeds were separated. Vegetative and fruiting cladodes, together with bark, pulp, and seeds were used to obtain five hydroalcoholic extracts. The extracts were investigated for total flavonoid content, using AlCl₃ colorimetric method, antioxidant activity by 2,2-diphenyl-1-picrylhydrazyl and 2,2’-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) radical scavenging capacity and Fe²⁺ ion chelating activity, and in vitro antiproliferative effects (sarcoma 180 cells) by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide assay. Results: The extract of C. jamacaru cladodes at the fruiting stage showed higher flavonoid content compared to the other extracts. Seed extracts showed the highest antioxidant activity in 2,2-diphenyl-1-picrylhydrazyl and 2,2’-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) assays, and the extract of cladodes at vegetative stage showed better antioxidant activity in Fe²⁺ ion chelating activity. The extract of fruiting cladodes promoted higher antiproliferative effects compared to the other extracts. Conclusions: These findings suggest that fruiting increases the content of flavonoids and antiproliferative effects of C. jamacaru cladodes. Data reinforce the potential use of C. jamacaru cladodes and fruits as natural antioxidants and potent anticancer agent.

The study was designed to investigate the chemical composition and the biological effects of G. parviflora and V. polyanthes ethanolic extracts in vitro. Total content of phenols, flavonoids and tannins was quantified by spectrophotometry; chemical characterization was permed by mass spectrometry (ESI (-) FT-ICR MS and APCI (+) FT-ICR MS analysis). Antioxidant activities were determined by FRAP and Fe2+ chelating methods. Extracts cytotoxicity was evaluated in human lymphocytes, sarcoma-180 (S-180) and human gastric adenocarcinoma (AGS) cells, by MTT assay. V. polyanthes presented higher total content of tannins and G. parviflora presented higher amount of phenols and flavonoids. Chemical characterization showed the presence of flavonoids, phenolic acids and sesquiterpene lactones in V. polyanthes extract, and steroids, phenolic acids and fatty acids (Poly Unsaturated Fatty Acids - PUFA) in G. parviflora extract. V. polyanthes extract stood out in the Fe2+ chelation test. G. parviflora extract did not present outstanding antioxidant results in the tested protocols. Both species showed a tendency to promote cytotoxicity in human lymphocyte cells. Regarding the antiproliferative effect, both species were able to reduce S-180 cell viability and G. parviflora extract showed high antiproliferative potential in the assay with AGS cells. These findings reinforce the medicinal use of these plants, as well as suggest their potential use for the development of new drugs and for the treatment of cancers.

Sticky disease, which is caused by Papaya meleira virus (PMeV), is a significant papaya disease in Brazil and Mexico, where it has caused severe economic losses, and it seems to have spread to Central and South America. Studies assessing the pathogen-host interaction at the nano-histological level are needed to better understand the mechanisms that underlie natural resistance. In this study, the topography and mechanical properties of the leaf midribs and latex of healthy and PMeV-infected papaya plants were observed by atomic force microscopy and scanning electron microscopy. Healthy plants displayed a smooth surface with practically no roughness of the leaf midribs and the latex and a higher adhesion force than infected plants. PMeV promotes changes in the leaf midribs and latex, making them more fragile and susceptible to breakage. These changes, which are associated with increased water uptake and internal pressure in laticifers, causes cell disruption that leads to spontaneous exudation of the latex and facilitates the spread of PMeV to other laticifers. These results provide new insights into the papaya-PMeV interaction that could be helpful for controlling papaya sticky disease.