Bioactive compounds from vegetal sources are a potential source of natural antifungic. An ethanol extraction was used to obtain bioactive compounds from Carica papaya L. cv. Maradol leaves and seeds of discarded ripe and unripe fruit. Both, extraction time and the papaya tissue flour:organic solvent ratio significantly affected yield, with the longest time and highest flour:solvent ratio producing the highest yield. The effect of time on extraction efficiency was confirmed by qualitative identification of the compounds present in the lowest and highest yield extracts. Analysis of the leaf extract with phytochemical tests showed the presence of alkaloids, flavonoids and terpenes. Antifungal effectiveness was determined by challenging the extracts (LE, SRE, SUE) from the best extraction treatment against three phytopathogenic fungi: Rhizopus stolonifer, Fusarium spp. and Colletotrichum gloeosporioides. The leaf extract exhibited the broadest action spectrum. The MIC(50) for the leaf extract was 0.625 mg ml(-1) for Fusarium spp. and >10 mg ml(-1) for C. gloeosporioides, both equal to approximately 20% mycelial growth inhibition. Ethanolic extracts from Carica papaya L. cv. Maradol leaves are a potential source of secondary metabolites with antifungal properties.

Capsicum chinense Jacq. obtained the designation of origin in 2010 due to the unique organoleptic properties given by the characteristics of soils in the Peninsula of Yucatán. So, the aim of this work was to investigate the effect of soil composition on the profile and concentration of polyphenols, antioxidant activity, and its relationship with the degree of maturity in habanero pepper (Capsicum chinense Jacq.). Pepper plants were grown in three soils named according to the Maya classification as: K’ankab lu’um (red soil); Box lu’um (black soil); and Chich lu’um (brown soil). The crops were cultivated in four different dates. The peppers were analyzed for antioxidant activity, profile and content of polyphenols. The results indicated that peppers grown in black soil had the highest concentration of total polyphenols (122.78 ± 12.60 mg of gallic acid 100 g−1), catechin (61.64 ± 7.55 mg 100 g−1) and antioxidant activity by DPPH (86.51 ± 0.82%). Physicochemical characterization indicated that black soil has the highest concentration of organic matter (10.93 ± 0.23%), nitrogen (52.01 ± 7.05 mg kg−1), manganese (5.24 ± 0.45 mg kg−1) and electric conductivity (2.32 ± 0.16 d Sm−1) compared to the other soils evaluated. These results demonstrate that the physicochemical composition of soils could be related to the biosynthesis of polyphenols in the habanero pepper.

We established a Chelex 100-Microwave method for the purification of bacterial genomic DNA (gDNA) in less than 20 min with high yield and good quality, useful for multiple purposes. It combines Chelex 100, proteinase K, RNase A and heating in a microwave oven. The resulting gDNA was used directly to identify bacterial species of the Order Lactobacillales by means of PCR amplification of their 16S rDNA gene, isolated from sediments on the Yucatan Peninsula, Mexico. This method produced gDNA free of phenolic and protein residual contaminants from 100 of these isolated bacteria. 16S rDNA amplification and sequencing showed Pediococcus acidilactici to prevail in inland lagoons, and Pediococcus pentosaceus, Lactobacillus plantarum, Lactobacillus sp., and Lactobacillus fermentum to be most abundant in the soils of livestock farms. The combination of Chelex 100, enzymes and microwave heating used in the Chelex 100-Microwave method produced large amounts of highly pure gDNA from Gram-positive and Gram-negative bacteria, in less than 20 min.

The aim of this work was to investigate the changes of the content of polyphenols in fruits of Capsicum chinense Jacq. at different harvest times and their correlation with the antioxidant activity. Habanero pepper plants grown in black soil (Mayan name: Box lu’um) and harvested at 160, 209, 223, 237 and 252 post-transplant days (PTD) were analyzed. The results indicated that subsequent harvesting cycles decreased the content of total polyphenols, catechin, chlorogenic acid and ellagic acid, while the content of gallic and protocatechuic acid increased. The antioxidant activity determined by DPPH (2,2-Diphenyl-1-picrylhydrazyl) radical scavenging and ABTS (2,2′-azino-di-3-ethylbenzthiazoline sulfonic acid) assay decreased through the harvest days. Linear correlation analysis between total polyphenol content and antioxidant activity in peppers resulted in a correlation of r2DPPH = 0.8999 and r2ABTS = 0.8922. Additionally, a good correlation of the antioxidant activity was found with catechin (r2DPPH = 0.8661 and r2ABTS = 0.8989), chlorogenic acid (r2DPPH = 0.8794 and r2ABTS = 0.8934) and ellagic acid (r2DPPH = 0.8979 and r2ABTS = 0.9474), indicating that these polyphenols highly contributed to the antioxidant activity in Habanero peppers. This work contributes to understanding the changes that take place during the development of Capsicum chinense, indicating that fruit harvested at earlier PTD showed the highest concentrations of total polyphenols and antioxidant activity, obtaining the best results at 160 PTD.

This study presents a sensitive electroanalytical method for the determination of capsaicinoids in chili extracts using flow injection with coulometric array detector. Flow injection method was developed based on the coulometric signal of capsaicinoids obtained by high performance liquid chromatography with coulometric detector (HPLC‐ECD). Capsaicinoids concentration in 18 chili samples from Yucatán México cultivated in different types of soils was quantified using UHPLC‐DAD and HPLC‐ECD and expressed in Scoville units. The plants were cultivated in a greenhouse on three types of limestone soils, namely, red, black and brown. Chili peppers were harvested in two stages of maturity: immature (green), and mature (orange). HPLC‐ECD method showed ten times higher sensitivity compared to the UHPLC‐DAD. Capsaicinoid content in 18 chili samples was measured by flow injection method. The best correlation with the Scoville units was obtained by the analysis of the current signal of the sensor poised at +450 mV (R2=94). ANOVA analysis showed that the soil type and the harvest date were significant for the capsaicinoid content. Chili plants cultivated in red soil had higher capsaicinoid content. In addition, the capsaicinoid content was increasing at later harvest dates. In summary, the suggested flow injection method with coulometric array detector decreased the time of analysis from 15 min to 30 s. Therefore it can be successfully applied for the routine capsaicinoid analysis in chili.