molecules Review Guayule (Parthenium argentatum A. Gray), a Renewable Resource for Natural Polyisoprene and Resin: Composition, Processes and Applications Amandine Rousset 1,2, Ali Amor 3,4, Teerasak Punvichai 5, Sandrine Perino 2, Serge Palu 4, Michel Dorget 1,3, Daniel Pioch 4,* and Farid Chemat 2,* 1 GuaTecs, 28 rue Xavier Bichat, 72000 Le Mans, France; [email protected] (A.R.); [email protected] (M.D.) 2 Avignon University, INRAE, UMR408, GREEN Extraction Team, 84000 Avignon, France; [email protected] 3 CTTM, Centre de Transfert de Technologie, 72000 Le Mans, France; [email protected] 4 UR BioWooEB-Biorefinery Team, CIRAD, 34398 Montpellier, France; [email protected] 5 Faculty of Science and Industrial Technology, Prince of Songkla University, Surat Thani Campus 84000, Thailand; [email protected] * Correspondence: [email protected] (D.P.); [email protected] (F.C.) Abstract: Natural rubber is an essential material, especially for plane and truck tyres but also for medical gloves. Asia ranks first in the production of natural rubber, of which the Hevea tree is currently the sole source. However, it is anticipated that this source alone will not be able to fulfill the growing demand. Guayule, a shrub native to northern Mexico and southern United States, may also contribute. This plant not only contains polyisoprene, but also resin, a mixture of lipids and terpenoids. Citation: Rousset, A.; Amor, A.; This review summarizes various aspects of this plant, from the usage history, botanical description, Punvichai, T.; Perino, S.; Palu, S.; geographical distribution and cultivation practices, down to polyisoprene and resin biosynthesis Dorget, M.; Pioch, D.; Chemat, F. Guayule (Parthenium argentatum A. including their distribution within the plant and molecular composition. Finally, the main processes Gray), a Renewable Resource for yielding dry rubber or latex are depicted, as well as the properties of the various extracts along with Natural Polyisoprene and Resin: economic considerations. The aim is to provide a wide picture of current knowledge available about Composition, Processes and this promising crop, a good feedstock candidate for a multiple-product biorefinery. Applications. Molecules 2021, 26, 664. https://doi.org/10.3390/molecules Keywords: guayule; polyisoprene; rubber; latex; green extraction; green reagents; green chemistry 26030664 Academic Editor: Thomas Rosenau Received: 22 December 2020 1. Introduction Accepted: 25 January 2021 Plant chemistry has been receiving increased interest during the last decades, now Published: 27 January 2021 becoming fully integrated to our economy. Indeed, the petrochemicals found today in most manufactured products, are being gradually replaced by products and materials derived Publisher’s Note: MDPI stays neutral from renewable resources. Elastomers are no exception to this trend, particularly rubber, with regard to jurisdictional claims in published maps and institutional affil- an essential material of the 21st century [1]. iations. Polyisoprene (PI, the polymer taken as a whole whatever its stereoisomeric structure and origin) can be used in two different forms, either as latex (the polymer being dispersed in water, as a white liquid) or dry rubber (obtained by latex coagulation) [in this review, “polyisoprene” applies to the polymer molecule, while “rubber” is used when talking about the material which is a mixture of polyisoprene and of other components like proteins Copyright: © 2021 by the authors. and small molecules]. PI is used in more than 40,000 products, like tyres, medical gloves Licensee MDPI, Basel, Switzerland. or condoms. Synthetic routes provide a large amount of PI and of similar polymers, but This article is an open access article distributed under the terms and natural rubber and latex from Hevea (NR and NL, respectively) remain irreplaceable for conditions of the Creative Commons some applications, like plane and truck tyres or medical gloves thanks to the peculiar cis Attribution (CC BY) license (https:// chemical structure of the contained PI and to the presence of other molecules [2]. Indeed creativecommons.org/licenses/by/ NR shows better dynamic properties, especially resilience (defined as the ability to undergo 4.0/). Molecules 2021, 26, 664. https://doi.org/10.3390/molecules26030664 https://www.mdpi.com/journal/molecules MoleculesMolecules2021 2020, 26, 25, 664, x; doi: FOR PEER REVIEW 2 of 232 of 22 other molecules [2]. Indeed NR shows better dynamic properties, especially resilience (bigdefined deformations as the ability without to undergo breaking big anddeformations to recover without its initial breaking form when and to the recover constraint its is initialreleased), form as when well the as veryconstraint good resistanceis released) to, as abrasion, well as very shock good and resistance tearing [3 to,4 ].abrasion, shockMore and tearing than 2000 [3,4]. plants produce PI [5]. The best-known plants for their potential commercialMore than interest 2000 areplants part produc of thee familiesPI [5]]. The of Euphorbiaceae best-known plants(Hevea, for Bentamia, their potential Manihot ), Asteraceaecommercial(Parthenium interest are argentatum, part of the Taraxacumfamilies of kok-saghyz Euphorbiaceae) and (Hevea,Sapotaceae Bentamia,(Gutta Manihot percha,) Arga-, Asteraceaenia spinosa )[(Parth6]. Theenium more argentatum, promising Taraxacum ones are Kazakhkok-saghyz dandelion) and Sapotaceae (Taraxacum (Gutta kok-saghyz) percha, and Arganiaguayule spinosa (Parthenium) [6]. argentatumThe more A.promising Gray) [ 7,ones8]. This are reviewKazakh will dandelion focus on guayule.(Taraxacum As of koktoday,-saghyz a lot) and of scientific guayule ( papersParthenium have argentatum been published A. Gray [)9 ],[7,8] on. differentThis review aspects will focus of the on plant, granginguayule. fromAs of agronomytoday, a lot to of extraction scientific papers process, have focusing been published on PI or even [9], on resin, different a mixture as- of pectcompoundss of the plant, also found ranging in from this plant. agronomy to extraction process, focusing on PI or even resin,Guayule a mixture is of therefore compound ans interestingalso found in species this plant and. it falls within the framework of the 17 UNGuayule Sustainable is therefore Development an interesting Goals species (SDGs) and (Figure it fall1s). within These the SDGs framework were adopted of the by 17all UN United Sustainable Nations Development Member States Goals in 2015 (SDGs and) (Figure represent 1). These shared SDGs guidelines were adopted “for peace by and allprosperity United Nations for people Member and theStates planet, in 2015 now and and represent into the share future”d guidelines [10]. Indeed, “for peace guayule and can prosperitybe grown onfor marginalpeople and land, the andplanet, its PInow can and be into extracted the future” under [10] latex. Indeed, form by guayule a water-based can beprocess grown to on manufacture marginal land, non-allergenic and its PI can medical be extracted gloves under and latex condoms, form by thus a water contributing-based to process to manufacture non-allergenic medical gloves and condoms, thus contributing to people’s health and safety; in addition, a range of co-products can be valorized [11,12]. The people’s health and safety; in addition, a range of co-products can be valorized [11,12]. current interest on guayule leads to large international multi-scope projects, in view of The current interest on guayule leads to large international multi-scope projects, in view setting-up a new production chain, potentially opening new jobs in agriculture, academia of setting-up a new production chain, potentially opening new jobs in agriculture, aca- and industry. demia and industry. Figure 1. UUnitednited Nations Nations SDGs SDGs app appliedlied to toguayule guayule and and their their impacts impacts.. 2. History of Guayule Molecules 2021, 26, 664 3 of 22 2. History of Guayule Guayule, also called “yerba de hule” is native to the desert of Chihuaha, located in Mexico and southern Texas in the United States. The name comes from the Nahuatl language (Aztec): quahu (wood, tree, forest) and olli (rubber). During the pre-Columbian times, it was basic knowledge that guayule contained an elastomer. The Aztecs used it to make rubber balls by mastication of the bark [13,14]. According to Lloyd [13], guayule was first documented by Bigelow, a member of the Mexican Boundary Survey party, in 1852. He submitted specimens he had collected in Texas to Harvard University, where Asa Gray named it botanically [15]. It was first presented to the public at the Centennial Exposition of 1876 in Philadelphia by the Mexican Government. On the same year, the Natural History Society of Mexico investigated the plant and reported the presence of good quality rubber [15] (Figure2). Rediscovery of the plant by J. M. Bigelow Emergency Rubber Project 1852 1942 Centennial Exposition at Philadelphia End of the World War II 1876 1945 Obtention of rubber by the Mecanical Rubber Company in New Jersey 1888 Mexican Revolution Oil Embargo - Project by Firestone and Goodyear 1910 1970 Discovery of America by Christopher Columbus Great Depression Native Latex Act 1492 1929 1978 Conquest of the Aztec Empire by Hernan Cortes Establishment of SAIGA in Italy EPOBIO & EU-PEARLS Projects 1521 1937 2005 1200 1500 1900 2000 [1220......1480] [1530......1850] Research in Europe, Australia, New Zealand, Argentina, Morocco Production