Phytochemical Characteristics and Antimicrobial Activity of Australian Grown Garlic (Allium Sativum L.) Cultivars.

Michael Netzel,Anh Phan,Yasmina Sultanbawa,Gabriele Netzel,Panhchapor Chhim

doi:10.3390/foods8090358

Abstract

This study systematically evaluated the main bioactive compounds and associated biological properties of two Australian grown garlic cultivars and commercial non-Australian grown garlic (for comparison purposes only). Additionally, the distribution of bioactive compounds in garlic skin and clove samples was determined to obtain a better understanding of the potential biological functionality of the different garlic parts. The identification and quantification of bioactive compounds was performed by ultra-high performance liquid chromatography with mass spectrometry and photodiode array detection (UHPLC-PDA-MS). A principal component analysis was applied to assess the correlation between the determined bioactive compounds and antioxidant capacity as well as antimicrobial activity. The content of phenolic compounds (free and bound forms) in the garlic skin samples was significantly (p < 0.05) higher than that of the garlic cloves, and was also higher (p < 0.05) in the Australian grown cultivars compared to the commercial non-Australian grown garlic. Anthocyanins were found in the skin samples of the Australian grown garlic cultivars. The organosulfur compounds were higher (p < 0.05) in the cloves compared to the skin samples and higher (p < 0.05) in the Australian grown cultivars compared to the studied commercial sample. As the richer source of bioactive compounds, the Australian grown garlic cultivars exhibited a significantly (p < 0.05) higher antioxidant capacity and stronger (p < 0.05) antimicrobial activity than the commercial non-Australian grown garlic. The potential of garlic cultivars rich in bioactive compounds for domestic and industrial applications, e.g., condiment and natural food preservative, should be explored further.

Highlights

Garlic (Allium sativum L.) has been known as “aroma” vegetable, which is widely used as a food ingredient in many countries and different cultures as a result of its characteristic flavor and potential health benefits
It has been suggested that the biological and health properties of garlic are derived from its polyphenols and organosulfur compounds
Under different physical treatments, the enzyme alliinase, released from the vacuole, lyses the S-alk(en)yl-L-cysteine sulfoxides to liberate the majority of the characteristic aroma thiosulfinate compounds such as allicin, diallyl sulfide, and diallyl disulfides [10,11]

Summary

Introduction

Garlic (Allium sativum L.) has been known as “aroma” vegetable, which is widely used as a food ingredient in many countries and different cultures as a result of its characteristic flavor and potential health benefits. Foods 2019, 8, 358 and S-alk(en)yl-L-cysteine sulfoxides, L-alliin as the major sulfur-containing compound in intact garlic [2]. Under different physical treatments (e.g., cutting, crushing, or chewing), the enzyme alliinase, released from the vacuole, lyses the S-alk(en)yl-L-cysteine sulfoxides to liberate the majority of the characteristic aroma thiosulfinate compounds such as allicin, diallyl sulfide, and diallyl disulfides [10,11]. These volatile compounds are extremely unstable and rapidly decomposed to form other sulfur-containing compounds, which might not be the genuinely active compounds of garlic [12]

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