Comprehensive metabolite and biological profile of “Sulmona Red Garlic” ecotype’s aerial bulbils
Annalisa Chiavaroli, Fabrizio Masciulli, Cinzia Ingallina, Luisa Mannina, Maria Loreta Libero, Simonetta Cristina Di Simone, Alessandra Acquaviva, Nilofar Nilofar, Lucia Recinella, Sheila Leone, Luigi Brunetti, Simone Carradori, Luca Cantò, Giustino Orlando, Gökhan Zengin, Abdullahi İbrahim Uba, Uğur Çakılcıoğlu, Muzaffer Mükemre, Ömer Elkıran, Maura Di Vito, Luigi Menghini, Claudio Ferrante
Abstract
“Sulmona Red Garlic” is a well-known Italian traditional product. Bulbs, used in for culinary purposes, have been largely investigated for their medicinal properties whereas aerial bulbils are usually removed as waste material. Here, for the first time, chemical composition and biological properties of the hydroalcoholic extracts from aerial bulbils were investigated. Complementary information on metabolite composition were obtained using both NMR based untargeted and HPLC-DAD targeted methodologies. The NMR analysis revealed the presence of sugars, organic acids, amino acids, organosulphur compounds (methiin, alliin, allicin and cycloalliin), and other secondary metabolites. In particular, methiin and alliin were identified for the first time in the NMR spectra of garlic extracts. Polyphenol content was determined by HPLC-DAD analysis: catechin, chlorogenic acid, and gallic acid turned out to be the most abundant phenolics. Hydroalcoholic extract blocked cell proliferation of colon cancer cell line HCT116 with an IC50 of 352.07 µg/mL, while it was non-toxic to myoblast cell line C2C12. In addition, it caused seedling germination reduction of two edible and herbaceous dicotyledon species, namely Cichorium intybus and C. endivia. Moreover, the same extract reduced the gene expression of TNF-α (tumor necrosis factor), HIF1-α (hypoxia-inducible factor), VEGFA (vascular endothelial growth factor), and transient receptor potential (TRP) M8 (TRPM8) indicating the ability to contrast cancer development through the angiogenic pathway. Final, in silico experiments were also carried out supporting the biological effects of organosulphur compounds, particularly alliin, which may directly interact with TRPM8. The results here reported suggests the potential use of garlic aerial bulbils often considered a waste product as a source in phytotherapeutic remedies.