Early Optimization Stages of Agave lechuguilla Bagasse Processing toward Biorefinement: Drying Procedure and Enzymatic Hydrolysis for Flavonoid Extraction.

Agave lechuguilla agro-waste is a promising renewable material for biorefining purposes. The procurement of added-value co-products, such as bioactive phytochemicals, is required to improve bioprocesses and promote the bio-based economy of the productive areas of Mexico. In this study, we aimed to evaluate the effect of post-harvest management and enzymatic pretreatment as the first stages of the A. lechuguilla valorization process. Four drying methods were compared, and enzymatic hydrolysis was optimized to obtain a flavonoid-enriched extract applying ultrasound-assisted extraction. In both experiments, the total phenolic (TPC) and flavonoid (TFC) contents, HPLC-UV flavonoid profiles, and radical scavenging capacity (DPPH) were considered as response variables. The results demonstrated that light exposure during the drying process particularly affected the flavonoid content, whereas oven-dehydration at 40 °C in the dark preserved the flavonoid diversity and antioxidant functionality of the extracts. Flavonoid glycoside recovery, particularly anthocyanidins, was 1.5-1.4-fold enhanced by enzymatic hydrolysis using the commercial mix Ultraflo© under optimized conditions (pH 4, 40 °C, 180 rpm, and 2.5 h) compared to the unpretreated biomass. The extraction of flavonoids from A. lechuguilla bagasse can be carried out using a scalable drying method and enzymatic pretreatment. This study confirmed the potential of this agro-waste as a source of marketable natural products.

Transcriptome-based metabolic profiling of flavonoids in Agave lechuguilla waste biomass.

Agave lechuguilla is one of the most abundant species in arid and semiarid regions of Mexico, and is used to extract fiber. However, 85 % of the harvested plant material is discarded. Previous bioprospecting studies of the waste biomass suggest the presence of bioactive compounds, although the extraction process limited metabolite characterization. This work achieved flavonoid profiling of A. lechuguilla in both processed and non-processed leaf tissues using transcriptomic analysis. Functional annotation of the first de novo transcriptome of A. lechuguilla (255.7 Mbp) allowed identifying genes coding for 33 enzymes and 8 transcription factors involved in flavonoid biosynthesis. The flavonoid metabolic pathway was mostly elucidated by HPLC-MS/MS screening of alcoholic extracts. Key genes of flavonoid synthesis were higher expressed in processed leaf tissues than in non-processed leaves, suggesting a high content of flavonoids and glycoside derivatives in the waste biomass. Targeted HPLC-UV-MS analyses confirmed the concentration of isorhamnetin (1251.96 µg), flavanone (291.51 µg), hesperidin (34.23 µg), delphinidin (24.23 µg), quercetin (15.57 µg), kaempferol (13.71 µg), cyanidin (12.32 µg), apigenin (9.70 µg) and catechin (7.91 µg) per gram of dry residue. Transcriptomic and biochemical profiling concur in the potential of lechuguilla by-products with a wide range of applications in agriculture, feed, food, cosmetics, and pharmaceutical industries.

Antioxidant, anti-inflammatory and antinociceptive potential of Ternstroemia sylvatica Schltdl. & Cham.

OBJECTIVE: To evaluate the anti-inflammatory, analgesic, antioxidant and acute toxicity of extracts obtained from a successive extraction with solvents of ascending polarity [hexane, hex; chloroform, CHCl3 and ethanol (EtOH)] of Ternstroemia sylvatica Schltdl. & Cham. METHODS: The antioxidant potential was evaluated by 2,2 diphenyl-1-picrylhydrazyl, the ferric reducing/antioxidant power assays and by determining the total phenolic content. The anti-inflammatory and antinociceptive effects were evaluated using the in vivo croton oil-induced ear edema, phorbol 12-myristate 13-acetate induced ear edema, carrageenan-induced paw edema, acetic acid-induced writhing and formalin murine models. The acute toxicity was tested using the Lorke's method in mice. RESULTS: The EtOH extract was the most active for the antioxidant potential tests diphenyl-1-picrylhydrazyl (68.70% inhibition), ferric reducing/antioxidant power [(2431.30 ± 102.10) mmol Fe2+ and total polyphenols content (215.80 ± 8.50) meqAG/g]. The anti-inflammatory activity was evaluated by topical application of croton oil (2 mg/ear dose) where the EtOH extract showed the strongest activity compared to the control group (45.13% inhibition), whereas in the phorbol 12-myristate 13-acetate model, at the same dose, the CHCl3 extract showed the highest inhibition (42.88%). In the carrageenan induced edema model, the EtOH extract showed a stronger inhibition compared to indomethacin (56.34% and 50.70% at doses of 250 and 500 mg/kg of extract, respectively) during the first hour. Similarly, the same extract showed the highest analgesic activity (30.60% inhibition) in the acetic acid contortion assay, and in the formalin test it showed a greater effect with respect to the control group in both phases. CONCLUSIONS: Our work confirms the value of Ternstroemia sylvatica as an important anti-inflammatory and analgesic plant, whose mechanism seems to be associated to its antioxidant effects, and supports its uses in the Mexican traditional medicine.

Ribosome-inactivating proteins with an emphasis on bacterial RIPs and their potential medical applications.

Ribosome-inactivating proteins (RIPs) are toxic due to their N-glycosidase activity catalyzing depurination at the universally conserved α-sarcin loop of the 60S ribosomal subunit. In addition, RIPs have been shown to also have other enzymatic activities, including polynucleotide:adenosine glycosidase activity. RIPs are mainly produced by different plant species, but are additionally found in a number of bacteria, fungi, algae and some mammalian tissues. This review describes the occurrence of RIPs, with special emphasis on bacterial RIPs, including the Shiga toxin and RIP in Streptomyces coelicolor recently identified in S. coelicolor. The properties of RIPs, such as enzymatic activity and targeting specificity, and how their unique biological activity could be potentially turned into medical or agricultural tools to combat tumors, viruses and fungi, are highlighted.