Enhancement of alkaloid content (galanthamine and lycorine) and antioxidant activities (enzymatic and non-enzymatic) unders salt stress in summer snowflake (Leucojum aestivum L.)

Abstract

Summer snowflake (Leucojum aestivum L.) is a bulbous plant to the Amaryllidaceae family. L. aestivum is a Euro-Mediterranean region plant and is a well-known source of pharmacologically important alkaloids. Galanthamine is the major bioactive compound that is widely used in the treatment of neurological disorders, including Alzheimer's disease. Another alkaloid lycorine has antitumor, antimalarial, hepatoprotective, antiviral, antifungal and antiparasitic activities. The objective of this study was to determine the effect of different salt stress treatments on galanthamine and lycorine amounts, growth and development, non-enzymatic antioxidant activities (free radical scavenging activity and total phenol-flavonoid content) and enzymatic antioxidant activities [superoxide dismutase (SOD) and catalases (CAT)] in L. aestivum. The plant was cultivated for 3.5 months watering with 3 different concentrations (2, 4 and 8 g/L) of 2 different salt types (NaCl and CaCl2). Salt stress treatments did not change the shoot length, bulb size and water content significantly. Obtained leaves and bulbs were extracted with methanol and analyzed with HPLC-DAD system. Galanthamine and lycorine amounts were enhanced with 4 g/L CaCl2 in the bulbs. Galanthamine in the leaves was also improved with 8 g/L NaCl. Salt stress treatments did not change the lycorine content in the leaves. Antioxidant capacity of the bulbs and leaves of L. aestivum was very low. Salt stress caused by 4 g/L CaCl2 increased the antioxidant activity only in the leaves and total phenol-flavonoid content in the bulbs. All salt stress treatments increased the SOD activity in the bulbs. The highest SOD and CAT activities were observed with 8 g/L CaCl2 and 4 g/L NaCl, respectively in the bulbs. Some CaCl2 treatments (2 g/L and 4 g/L) increased the activity of SOD and CAT, respectively. It was concluded that L. aestivum is a salt tolerant plant, and 4 g/L CaCl2 is a conspicuous treatment in terms of increased galanthamine amount and antioxidant activities (non-enzymatic and enzymatic) in the bulbs.