Chemical Characterization and Antibiofilm Activities of Bulbs and Leaves of Two Aglione (Allium ampeloprasum var. holmense Asch. et Graebn.) Landraces Grown in Southern Italy.

Lucia Caputo,Raffaele Coppola,Filomena Nazzaro,Florinda Fratianni,Giuseppe Amato,Vincenzo Candido,Vincenzo De Feo

doi:10.3390/molecules25235486

Abstract

The present study was carried out to determine some biochemical characteristics, in particular the total polyphenol content and the free radical scavenging activity, of the extracts recovered from bulbs and aerial parts (these last often considered as by-products) of two landraces of A. ampeloprasum var. holmense cultivated in Southern Italy. For the first time, the capacity of the extracts of these landraces to inhibit the formation of biofilm of different Gram-negative and Gram-positive bacteria and to affect the metabolism of the cells present within the bacterial biofilm was evaluated. All extracts exhibited an amount of total polyphenols not lower than 2.86 mg/g of dried product and revealed a noteworthy antioxidant activity, with EC50 values not exceeding 4.95 mg. In both cases, the aerial parts extracts were more effective than the bulb extracts, which also showed a minor amount of total polyphenols. The extracts inhibited mainly the adhesive capability of Pseudomonas aeruginosa and Staphylococcus aureus, by 95.78% and 85.01%, respectively. The extracts demonstrated to inhibit also the metabolism of the bacterial cells reaching levels up to 90%. Finally, as assessed by the assays performed on the 24-h preformed biofilms, all the extracts were also capable to cause a reduction in bacterial biomass and to affect their metabolism.

Highlights

Allium ampeloprasum L. is a species composed of different cytotypes, which are distributed in the countries surrounding the Mediterranean Sea and that expands from North Africa, South-West Asia, to the south of England
The present study was carried out to determine the total polyphenol content of the extracts recovered by bulbs and aerial parts of two landraces of A. ampeloprasum var. holmense grown in Southern Italy and its antioxidant and anti-biofilm activities
This research provides some insight into two landraces of Allium ampeloprasum var. holmense, once used in Southern Italian traditional foods

Summary

Introduction

Allium ampeloprasum L. is a species composed of different cytotypes, which are distributed in the countries surrounding the Mediterranean Sea and that expands from North Africa, South-West Asia, to the south of England. This species consists of four gene-pools, named wild leek, European leek cultivars, Egyptian kurrat, and great headed garlic. Molecules 2020, 25, 5486 called “aglione” in Italy, has large bulblets and a much larger bulb than common garlic; it is considered more closely related to the leek than to ordinary garlic This vegetable is a cultigen, propagated in vegetative manner all over the world, and usually shows sterile large floral umbel

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