Cannabis sativa : The Plant of the Thousand and One Molecules

Christelle M. Andre, Jean-Francois Hausman and Gea Guerriero

Frontiers in Plant Science, 2016, Volume 7, Article 19.

doi:10.3389/fpls.2016.00019

 

Cannabis sativa L. is an important herbaceous species originating from Central Asia, which has been used in folk medicine and as a source of textile fiber since the dawn of times. This fast-growing plant has recently seen a resurgence of interest because of its multi-purpose applications : it is indeed a treasure trove of phytochemicals and a rich source of both cellulosic and woody fibers. Equally highly interested in this plant are the pharmaceutical and construction sectors, since its metabolites show potent bioactivities on human health and its outer and inner stem tissues can be used to make bioplastics and concrete-like material, respectively. In this review, the rich spectrum of hemp phytochemicals is discussed by putting a special emphasis on molecules of industrial interest, including cannabinoids, terpenes and phenolic compounds, and their biosynthetic routes. Cannabinoids represent the most studied group of compounds, mainly due to their wide range of pharmaceutical effects in humans, including psychotropic activities. The therapeutic and commercial interests of some terpenes and phenolic compounds, and in particular stilbenoids and lignans, are also highlighted in view of the most recent literature data. Biotechnological avenues to enhance the production and bioactivity of hemp secondary metabolites are proposed by discussing the power of plant genetic engineering and tissue culture. In particular two systems are reviewed, i.e., cell suspension and hairy root cultures. Additionally, an entire section is devoted to hemp trichomes, in the light of their importance as phytochemical factories. Ultimately, prospects on the benefits linked to the use of the -omics technologies, such as metabolomics and transcriptomics to speed up the identification and the large-scale production of lead agents from bioengineered Cannabis cell culture, are presented.

Keywords : fibers, hemp, Cannabis, cellulose, lignin, cannabinoids, terpenes, lignans

 

INTRODUCTION

The current climatic and economic scenario pushes toward the use of sustainable resources to reduce our dependence on petrochemicals and to minimize the impact on the environment. Plants are precious natural resources, because they can supply both phytochemicals and lignocellulosic biomass. In this review, we focus on hemp (Cannabis sativa L.), since it is a source of fibers, oil and molecules and a ssuch it is an emblematic example of a multi-purpose crop. We treat the aspects related to the use of hemp biomass and, more extensively, those linked to its wide variety of phytochemicals.

Known since the ancient times for its medicinal and textileuses (Russo et al.,2008; Skoglund et al.,2013), hemp is currently witnessing a revival, because of its rich repertoire of phytochemicals, its fibers and its agricultural features, namelyquite good resistance to drought and pests, well-developed root system preventing soil erosion, lower water requirement with respect to other crops, e.g., cotton. This shows the great versatility of this fiber crop and encourages future studies focused on both Cannabis (bio)chemistry and genetic engineering. Hemp varieties producing oil, biomass or even both are currently cultivated and the availability of the hemp genome sequence greatly helps molecular studies on this important crop (van Bakel et al., 2011). In addition, the scientific community is very much interested in harnessing Cannabis pharmacological power : for example microorganisms are being engineered to produce 9-tetrahydro-cannabinolic acid (THCA) and cannabidiolic acid (CBDA) (Taura et al., 2007a; Zirpel et al.,2015).

The final scope of this review is to discuss the potential of hemp for industry and to highlight its importance for the bio-economy. More specifically, we : (i) describe the use of hemp biomass (i.e., the fibers), (ii) discuss hemp molecules of industrial interest (namely cannabinoids, terpenes and phenolic compounds), (iii) describe the potential of hemp trichomes as pharma-factories and (iv) discuss the potential of genetic engineering, by describing the use of plant cell suspension and hairy root cultures.

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