Andropogon is a pantropical grass genus comprising 100–120 species and found mainly in the grasslands of Africa and the Americas. In the new world the genus is represented by approximately sixty (diploids or hexaploids) species grouped in three sections. The hexaploid condition occurs only in the Americas and the full process of this origin is still uncertain, although cytogenetic analysis coupled with taxonomic evidence have provided strong support for new hypothesis. Stebbins proposed the first hypothesis suggesting that the origin of polyploidy in species of Andropogon in North America resulted from duplication of the genome of some diploid species, and then by intergeneric crosses with species of a related genus. Since then, numerous studies were performed to clarify the evolutionary history of the genus in America. In this paper, we present a review of cytogenetic studies in the American Andropogon species during the last four decades.

Valeriana carnosa and V. clarionifolia stand out as principal elements in the indigenous pharmacopeias of Patagonia; however, their phytochemical characterization is unknown. This study constitutes the starting point of a general project that aims to characterize secondary metabolites in these species. The variability of phenolic compounds in root ethanolic extracts was analyzed and compared for thirteen populations of V. carnosa and two of V. clarionifolia from the south of Argentinean Patagonia. Phenolic content was quantified by the Folin-Ciocalteu method and the putative phenolic compound profiles were investigated using HPLC-UV-MS. Antioxidant activity was evaluated through 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assays. Total phenolic content values ranged from 5.6 to 16.6 mg GAE/g in V. carnosa and 7.3 to 9.7 mg GAE/g in V. clarionifolia. Antioxidant evaluation results evidenced that the percentage of neutralized DPPH varied between 26% and 85% in V. carnosa and 39% and 58% in V. clarionifolia. A positive correlation between total phenolic content and antioxidant activity (r = 0.90) was observed. In V. carnosa total phenolic content was not correlated with altitude or latitude (p > 0.05), and chemical variability seems to be associated with genetic variability and/or different growing habitats (microclimatic conditions). However, the presence of some specific phenolic compounds was associated with latitude. In V. carnosa and V. clarionifolia 15 and 10 phenolic compounds were tentatively identified, respectively, and several of these are reported to have beneficial attributes from a phytomedical viewpoint. This study contributes to the phytochemical characterization project of these two medicinal valerians from Patagonia.

The phytochemical variability in Cannabis sativa L. chemovars represents an underexplored factor in environmentally sustainable nanomaterial production. In this study, three distinct chemovars, (i) High-Δ⁹-Tetrahydrocannabinol (THC) (89% THC), (ii) Balanced (60% Cannabidiol (CBD)), and (iii) High-CBD (89% CBD), were comparatively evaluated to determine their suitability for the green synthesis of silver nanoparticles (AgNPs). Ethanolic inflorescence extracts were used to recover bioactive secondary metabolites; among them, the High-CBD extract exhibited the highest total phenolic (3.34 mg gallic acid equivalent/g) and flavonoid (29.49 mg quercetine equivalent/g) contents, together with superior antioxidant capacity (53.16% 2,2-diphenyl-1-picrylhydrazyl free radical (DPPH) inhibition), indicating enhanced redox potential for nanoparticle formation. The terpene profile of High-CBD showed a dominance of myrcene (21.4%), contributing to the stabilization of the system. Using the High-CBD extract, predominantly spherical nanoparticles of 5 ± 0.9 nm were synthesized and confirmed by UV–vis, EDS, and TEM. The biogenic AgNPs demonstrated significant dose-dependent antibacterial activity, with minimum bactericidal concentration (MBC) of 1.0 mg/mL against Staphylococcus aureus and 4.5 mg/mL against Escherichia coli. These findings highlight the critical role of chemovar-dependent phytochemical composition and support a phytochemistry-guided approach for developing silver nanoparticles with potential biomedical applications.