Biological Activity of Pumpkin Byproducts: Antimicrobial and Antioxidant Properties.

Pumpkin fruits are widely appreciated and consumed worldwide. In addition to their balanced nutritional profile, pumpkin species also present valuable bioactive compounds that confer biological and pharmacological properties to them. However, the seeds, peels, and fibrous strands resulting from pumpkin processing are still poorly explored by the food industry. The current study used those fruit components from the genotypes of pumpkin that are economically significant in Portugal and Algeria to produce bioactive extracts. In order to support their usage as preservatives, their phenolic content (HPLC-DAD-ESI/MS) and antioxidant (OxHLIA and TBARS) and antimicrobial properties (against eight bacterial and two fungal strains) were assessed. In terms of phenolic profile, the peel of the Portuguese 'Common Pumpkin' showed the most diversified profile and also the highest concentration of total phenolic compounds, with considerable concentrations of (-)-epicatechin. Regarding the antioxidant capacity, the seeds of 'Butternut Squash' from both countries stood out, while the fibrous strands of Portuguese 'Butternut Squash' and the seeds of Algerian 'Gold Nugget Pumpkin' revealed the strongest antimicrobial activity. The bioactive compounds identified in the pumpkin byproducts may validate their enormous potential as a source of bio-based preservatives that may enhance consumers' health and promote a circular economy.

HPLC-DAD-ESI-MS/MS screening of phytochemical compounds and the bioactive properties of different plant parts of Zizyphus lotus (L.) Desf.

Zizyphus lotus L. (Desf.) has been widely used as a homemade ingredient to treat numerous diseases in Algerian folk medicine. In this context, decoction, infusion and hydroethanolic extracts were prepared from the branches, leaves, roots, and stem barks. The extracts were characterized regarding their phytochemical composition by HPLC-DAD-ESI/MSn and were assessed for in vitro bioactivity (cytotoxicity, anti-inflammatory activity, and antibacterial activity). A total of 29 compounds (flavonoid derivatives and secoiridoids) were identified in Z. lotus, 15 being detected in leaves, 10 in branches, 5 in roots and 7 in stem barks. The highest contents of these compounds, especially secoiridoids, were detected in branches followed by leaves, oleuropein being the main compound detected in leaves and oleoside in branches. The aqueous preparations of the leaves and root barks revealed the highest cytotoxicity and anti-inflammatory potential. On the other hand, as for the antibacterial activity, the hydroethanolic extract of the branches showed the highest potential, especially against the MSSA strain. Hence, the chemical diversity found in Z. lotus makes it a source of bioactive ingredients that can be applied in the formulations of different ingredients in the food and pharmaceutical industries.

Profiling polyphenol composition by HPLC-DAD-ESI/MSn and the antibacterial activity of infusion preparations obtained from four medicinal plants.

The infusions of Thymus pallescens Noë, Saccocalyx satureioides Coss. et Dur., Ptychotis verticillata Briq. and Limoniastrum guyonianum Boiss. have been used as medicinal remedies for many diseases in Algerian folk medicine. These species have also been well documented as rich sources of phytochemicals, such as phenolic compounds with wide diversified chemical structures, which exhibit far-ranging biological activities. Thus, the phenolic compound profile of the aqueous extracts, obtained by infusing, of the mentioned species was obtained by HPLC-DAD-ESI/MS, and their antibacterial activity was evaluated against clinical isolates. Several phenolic acids were identified and quantified, particularly caffeic acid derivatives along with glycosylated flavonoids. T. pallescens and S. satureioides contain 13 phenolic compounds, where rosmarinic acid was the most abundant phenolic acid present, while L. guyonianum presented myricetin-3-O-glucoside and myricetin-O-rhamnoside as the main compounds among the eight detected molecules. P. verticillata presented a profile of ten phenolic compounds, where 5-O-caffeoylquinic acid was the most abundant phenolic acid, followed by the flavone luteolin-3-O-glucoside. The antibacterial activity of the infusions ranged between 2.5 and 20 mg mL-1 (MIC values), and L. guyonianum showed the highest activity against all of the tested bacteria, Staphylococcus aureus and Pseudomonas aeruginosa being the most sensitive and resistant strains, respectively. Thus, the studied plant species are sources of natural antibacterial substances that can be used to fight against pathogenic microorganisms.