Chemical characterization, antioxidant activity and morphological traits in the leaves of guayule (Parthenium argentatum A. Gray) and its hybrids

Polyphenols in Jabuticaba (Plinia spp.) Peel Flours: Extraction and Comparative Evaluation of FTIR and HPLC for Quantification of Individual Compounds

“…The differences in extraction methods employed for HLPC, TMA and TEP have most certainly affected polyphenol yield and composition, so a direct comparison of the methods is not possible [ 36 , 37 ]. However, statistical analysis using Pearson’s correlation is still applicable, given that changes in the type of measurement should affect the agreement between techniques, but not the correlation [ 38 , 39 ]. The fact that high correlations were obtained between distinct methods, for example, in the case of C3G (the anthocyanin quantified in larger amounts) and TMA, indicates that TMA results can provide a reliable estimate of the anthocyanins in jabuticaba peels, regardless of the differences in extraction methodologies.…”

Argentatin Content in Guayule Leaves (Parthenium argentatum A. Gray)

“…The content of the paclitaxel precursor in Taxus baccatta (European Yew) is even lower than that of podophyllotoxin, being around 0.01–0.03% [ 33 ]. It should be noted that the content of argentatins in leaves is much higher than other compounds that have been considered to valorize guayule leaves, including phenolic compounds (0.8%, as reported by Jara et al [ 7 ] or their essential oil content, which were reported to be 1.04% [ 13 ].…”

“…The most abundant argentatins in guayule resin correspond to argentatin A (C 30 H 48 O 4 ) and B (C 30 H 48 O 3 ), as representative of the cycloartenol-type triterpenes, and isoargentatin A (C 30 H 48 O 4 ) and isoargentatin B (C 30 H 48 O 3 ), with lanostane-type triterpenes (Figure 1). apiculate leaves with the petiole delimited based on leaf margin, serrate or lanceolate types [7]. Differences identified within the recent USDA germplasm collection confirm that growth environment has a major influence on leaf morphological characterization [8].…”

“…This process occurs because leaf materials can reduce rubber recovery due to the formation of very fine particles that clog the filtration systems and increase the ash content associated with rubber degradation and quality reduction [ 2 , 6 ]. The complete morphological characterization of guayule leaves was performed within 27 guayule accessions in Spain, grouping them into three main groups depending on their morphological parameters, which, in general, were apiculate leaves with the petiole delimited based on leaf margin, serrate or lanceolate types [ 7 ]. Differences identified within the recent USDA germplasm collection confirm that growth environment has a major influence on leaf morphological characterization [ 8 ].…”

“…Other studies proposed the valorization of different plants from their leaves [ 9 , 10 , 11 , 12 ]. Early studies on the valorization of guayule by-products focused on the extraction of essential and volatile oils from stem resin [ 13 , 14 ], while more recent attention was paid to phenolic compounds [ 7 , 15 , 16 ], particularly hydroxycinnamic and hydroxybenzoic acids, flavones, flavanols and anthraquinones [ 7 , 15 ]. In addition to the stem resin, a significant proportion of total guayulin content is found in leaf tissue, where the four major guayulins (A–D) are observed in a more consistent relationship than in the stem [ 17 ], whereas rubber content in the leaves is discarded [ 18 ].…”