Phytochemicals, antioxidant, antimicrobial and phytotoxic activities of Ailanthus altissima (Mill.) Swingle leaves

• Volatile oils of A. altissima leaves were dominated by tetradecanol, heneicosane, tricosane and docosane.
• The main phenolic compounds were gallic acid, chlorogenic acid, HHDP-galloylglucose, epicatechin, rutin and hyperoside.
• Methanolic extracts of leaves and their hydrodistilled residues possess strong antioxidant activities.
• Both extracts were effective against Gram-positive bacteria.
• Leaf extracts exhibited strong phytotoxic activity against wild Daucus carota.

A comprehensive study on the volatile oil and phenolic constituents of Ailanthus altissima Swingle (Simaroubaceae) leaves was performed. Methanolic extracts of leaves and their hydrodistilled residues were screened for their antioxidant, antimicrobial and phytotoxic properties. The results showed that the leaf volatile oils were a complex mixture of more than a hundred components, mainly composed by non-terpenic compounds (tetradecanol, heneicosane, tricosane and docosane) and sesquiterpene hydrocarbons (α-curcumene and α-gurjunene). Methanolic extracts from leaves contain the highest level of total phenolic content, while those from the hydrodistilled residues showed the highest total flavonoid content. The most frequent phenolic compounds identified by HPLC-DAD–MS were gallic acid, chlorogenic acid, HHDP-galloylglucose, epicatechin, rutin, hyperoside and quercetin-3-galloyl hexoside. Evaluation of the antioxidant activities by using four complementary tests (DPPH, ABTS, 2-deoxyribose and FRAP) showed that both extracts exhibited strong concentration-dependent antioxidant activities. These extracts were efficient against Gram-positive bacteria, but not active against Gram-negative bacterial strains and the yeast Candida albicans. They also exhibited strong inhibitory effects on the germination and the radicle growth of the wild Daucus carota. This work provides scientific supports for the high antioxidant and phytotoxic activities of this species and thus, it may find potential applications in the development of natural herbicides and antioxidants for agro-food and pharmaceutical industries.