Enhancement of Vindoline and Catharanthine Accumulation, Antioxidant Enzymes Activities, and Gene Expression Levels in Catharanthus roseus Leaves by Chitooligosaccharides Elicitation.

Wenzhu Tang,Fan Yang,Xiaoqi Liu,Yuning He

doi:10.3390/md20030188

Abstract

Catharanthus roseus (L.) G. Don is a plant belonging to the genus Catharanthus of the Apocynaceae family. It contains more than one hundred alkaloids, of which some exhibit significant pharmacological activities. Chitooligosaccharides are the only basic aminooligosaccharides with positively charged cations in nature, which can regulate plant growth and antioxidant properties. In this study, the leaves of Catharanthus roseus were sprayed with chitooligosaccharides of different molecular weights (1 kDa, 2 kDa, 3 kDa) and different concentrations (0.01 μg/mL, 0.1 μg/mL, 1 μg/mL and 10 μg/mL). The fresh weights of its root, stem and leaf were all improved after chitooligosaccharides treatments. More importantly, the chitooligosaccharides elicitor strongly stimulated the accumulation of vindoline and catharanthine in the leaves, especially with the treatment of 0.1 μg/mL 3 kDa chitooligosaccharides, the contents of them were increased by 60.68% and 141.54%, respectively. Furthermore, as the defensive responses, antioxidant enzymes activities (catalase, glutathione reductase, ascorbate peroxidase, peroxidase and superoxide dismutase) were enhanced under chitooligosaccharides treatments. To further elucidate the underlying mechanism, qRT-PCR was used to investigate the genes expression levels of secologanin synthase (SLS), strictosidine synthase (STR), strictosidine glucosidase (SGD), tabersonine 16-hydroxylase (T16H), desacetoxyvindoline-4-hydroxylase (D4H), deacetylvindoline-4-O-acetyltransferase (DAT), peroxidase 1 (PRX1) and octadecanoid-responsive Catharanthus AP2-domain protein 3 (ORCA3). All the genes were significantly up-regulated after chitooligosaccharides treatments, and the transcription abundance of ORCA3, SLS, STR, DAT and PRX1 reached a maximal level with 0.1 μg/mL 3 kDa chitooligosaccharides treatment. All these results suggest that spraying Catharanthus roseus leaves with chitooligosaccharides, especially 0.1 μg/mL of 3 kDa chitooligosaccharides, may effectively improve the pharmaceutical value of Catharanthus roseus.

Highlights

Catharanthus roseus, a well-known herb with great pharmaceutical value, has been recorded in folklore and traditional medical literature since 50 BC [1]
The root weight, stem weight, leaf weight and plant height of Catharanthus roseus were markedly promoted by chitooligosaccharides treatments
The accumulation of vindoline and catharanthine was significantly increased with 0.1 μg/mL 3 kDa chitooligosaccharides treatment

Summary

Introduction

Catharanthus roseus, a well-known herb with great pharmaceutical value, has been recorded in folklore and traditional medical literature since 50 BC [1]. Catharanthus roseus can be used in the treatments of diabetes, menstrual regulators, hypertension, cancer and antigalactagogue etc. More than 130 terpenoid indole alkaloids (TIAs), including catharanthine, vindoline, vincristine, vinblastine etc., have been isolated and identified from Catharanthus roseus [3]. Two precursors of them, catharanthine and vindoline, are of great significance in the pharmacological functions of Catharanthus roseus. Eltayeb et al have shown that Catharanthus roseus leaf extract can inhibit the invasive ability of two types of breast cancer cells by regulating matrix metalloproteinases activity [5]. According to Mariadi et al, the blood glucose levels in mice reduced quickly after being treated by nanoemulsion of Catharanthus roseus leaf extract [6]. Oguntibeju et al found that vindoline can reduce diabetes and kidney diseases in rats [8]. Many investigations are carried out in order to enhance the production of important TIAs [9]

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Conclusion