Hydroponic technologies have increased the cultivated area under greenhouses covered with UV filter polyethylene film. However, there is a concern about the antioxidant contents of lettuces produced under these systems. In this study, it was compared to the antioxidant contents of green and red leaf lettuces produced in two hydroponic systems in a greenhouse, against the ones produced with the conventional cultivation system by Colombian farmers. The antioxidant analysis revealed significant statistical differences for DPPH and Anthocyanin analyses (P=0) versus all other culture systems. The best results were obtained in the conventional cultivation. Red lettuce obtained the highest value of FRAP (655.3±82.6 mgAAE 100g-1), ABTS (17.8±6.9 mmolTE 100g-1), total phenols (680.2±69.3 mgGAE 100g-1) and anthocyanin (126.2±6.9 mgC3G 100g-1). Green lettuce exhibited the most antioxidant activity of DPPH (20.7±5.6 mmolTE 100g-1). These results suggest a detrimental effect of the greenhouse covered with UV filter polyethylene film in the antioxidant production of lettuce. Finally, red leaf lettuce showed better antioxidant capacity independent of the cultivation system.

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Somatic embryogenesis in the wild rice species (Oryza perennis) was induced from cultured mature seeds and young inflorescences. Murashige and Skoog's (MS) medium supplemented with 2 mg/l 2,4-D and 0.2 mg/l BAP was used for induction of a compact, white nodular callus and somatic embryos. Plant regeneration occurred with the tranfer of the nodular callus to MS basal medium containing 0.5 mg/l IAA, 0.5 mg/l NAA, 4 mg/l BAP and 500 mg/l casein hydrolysate. The embryogenic nature of the callus from both explants was maintained over 10 subcultures for about 12 months. Plant regeneration with respect to the number of calli plated from the 6th to 10th passage varied from 80% to 60% for young inflorescence derived callus and from 75% to 69.8% for seed-derived callus.

Tea is a beverage made from leaves with high contents of polyphenolic substances that vary based on the process they are subjected to. In this study, the apical and young leaves from Vaccinium meridionale (named mortiño) were processed to obtain two kinds of tea: green and black tea. This was done in order to compare their antioxidant activity, content of secondary metabolites at different temperatures of extraction and their antiproliferative effect against SW480 colon cancer cells. Results showed that at 40°C, the green tea infusion presented higher antioxidant activity than the black tea infusion, based on their evaluation using Trolox equivalent antioxidant capacity (TEAC)-diphenylpicrylhydrazyl (DPPH) and oxygen radical absorbance capacity (ORAC) techniques. The green tea also had maximum contents of epicatechin, caffeine, ferulic, chlorogenic and ascorbic acid than the black tea. The total contents of phenols, including hydroxycinnamic acids (caffeic and p-coumaric acid) presented similar results, in both types of tea at the same temperature, as well as the total contents of flavonoids and catechin. When temperatures increased, the extraction of bioactive compounds was more efficient in the black tea infusion than the green tea. This situation led to the increased growth rate per the temperature of the total content of phenols, among which chlorogenic, caffeic and p-coumaric acid were prominent, as well as the corresponding non-polyphenolic substances such as ascorbic acid. The latter may be responsible for the increased antioxidant activity as the temperature increased in the extraction. This antioxidant activity was observed in the black tea from mortiño leaves, using TEAC-DPPH, fluorescence recovery after photobleaching (FRAP) and ORAC assays. Both types of teas had a dose-dependent antiproliferative effect against SW480 colon adenocarcinoma cells. The IC 50 of the green and black tea was 26.3 and 36 µg/ml, respectively. These findings suggest that a tea prepared from mortiño leaves may be a promising source of antioxidant and bioactive compounds against colon cancer cells.

In the present study, the effect of biotization of Mentha spicata microplants with Trichoderma asperellum and Bacillus subtilis on growth, Rhizoctonia sp., incidence, and specialized metabolites content was evaluated. Analyses of root tissues of the microplants showed 100% endophytism with both microorganisms. During the acclimatization phase, plants with the endophytes T. asperellum and B. subtilis had a survival rate of 95% and 93%, respectively, compared to 75% for control plants. Then, under greenhouse conditions, a trial was carried out with biotized plants with or without Rhizoctonia sp. inoculation, plants inoculated with Rhizoctonia sp., and endophyte- and pathogen-free control. Biotized plants with the endophytes showed higher dry biomass and the incidence of Rhizoctonia was lower (8% for T. asperellum and 10% for B. subtilis) compared to plants inoculated with the pathogen (82%). In addition, plants with T. asperellum had the highest contents of total polyphenols (280 GAE/100 mg sample) and rosmarinic acid (28 mg RA/100 g sample). Thus, this study shows the potential of the technique of using the endophytes T. asperellum and B. subtilis on M. spicata microplants to improve plant survival and growth, decrease the incidence of Rhizoctonia sp., and improve the contents of specialized metabolites, which can contribute to the sustainable management of this crop.