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Looking for a biotechnical potential, aqueous extracts of leaves of 12 native species used in the Mayan traditional medicine of the coastal dune and mangrove of Yucatan (Mexico) were selected to evaluate their biological activities. Rhizophora mangle and Manilkara zapota showed the highest free radical scavenging activity (3.94 ± 0.19 and 6.42 ± 0.32 μg/mL, respectively), and the highest antihypertensive activity was obtained from Solanum donianum (0.38 μg/mL). The anti-hyperglycemic activity of these species was also tested; the highest activities were registered with R. mangle. The antimicrobial activity of Malvaviscus arboreus, S. donianum, M. zapota, and R. mangle at 10% (w/v) was positive against six human pathogenic bacteria and Bonellia macrocarpa against one pathogenic fungus. Solanum donianum, M. zapota, B. macrocarpa, and R. mangle were positive against two pathogenic plant fungi. These results show that the aqueous extracts of five native plants of the Yucatan coast have potential as antioxidants, ACE inhibitors, α-amylase and α-glucosidase inhibitors, and as antimicrobials, which make their exploration for utilization in the agricultural and pharmaceutical industries a possibility., Competing Interests: The authors have declared that no competing interests exist.

High polyphenol and polysaccharide levels in plant tissues such as banana fruit and leaves constitute a significant challenge to the extraction of sufficient amounts of high-quality RNA required for cDNA library synthesis and molecular analysis. To determine their comparative effectiveness at eliminating polyphenols, polysaccharides and proteins, three protocols for RNA extraction from in vitro banana plantlet leaves were tested: Concert(TM) Plant RNA isolation kit, a small-scale protocol based on Valderrama-Cháirez, and a modified version of the Valderrama-Cháirez protocol. RNA quantity and purity were evaluated by UV-spectrophotometry using DEPC-treated water and Tris-HCl, pH 7.5. Purity was greater using Tris-HCl. The Concert(TM) Plant protocol produced the poorest quality RNA. Reverse transcription into cDNAs from RNA isolated from in vitro banana plantlet leaves infected with Mycosphaerella fijiensis using the modified Valderrama-Cháirez protocol, followed by PCR using primers designed against gamma-actin from banana and M. fijiensis, yielded products of the anticipated size. In addition, this protocol reduced the processing time, lowered costs, used less expensive equipment, and could be used for other plants that have the same problems with high polyphenol and polysaccharide levels.

High-quality RNA preparations are critical for further applications such as reverse transcriptase-polymerase chain reaction (RT-PCR) transcript amplifications, and elaboration of cDNA and expressed sequence tag libraries. Melanins are phenolic compounds present in many fungi and apparently play key roles in fungi pathogenesis and survival. However, during RNA extraction these compounds constitute a significant challenge to extraction of substantial quantities of high-quality RNA, and consequently to preparation of cDNA libraries. No method currently exists for RNA extraction from Mycosphaerella fijiensis that produces high quantities of melanin-free RNA. This fungus is the most important pathogen of cultivated Musa sp. varieties. A comparison is made between results obtained from the Trizol and RNeasy protocols for RNA extraction, two commercially available methods commonly used to obtain RNA from various sources. An improved methodology is described that allows isolation of intact RNA and elimination of melanins from M. fijiensis mycelium. RNA quality is evaluated by electrophoresis in formaldehyde-agarose gels, RT into cDNAs, and subsequent PCR amplification using primers designed against actin and beta- tubulin from fungi.