Quercetin, one of the most abundant flavonoids in nature, has attracted the attention of many researchers due to its chemical and biological properties. A series of metal–quercetin complexes (Cu²⁺, Co²⁺, Zn²⁺, Sn²⁺, Al³⁺, Cd²⁺ and Mg²⁺) were synthesized and systematically characterized by Fourier transform infrared spectroscopy (FTIR), UV-visible spectroscopy (UV–Vis) and nuclear magnetic resonance (NMR). These analyses confirmed that the complexes predominantly form through coordination with the 4-carbonyl group and adjacent phenolic hydroxyls. This induces measurable shifts in the ν(C=O), ν(O–H), and π→π* transition bands relative to free quercetin. The antioxidant capacity of the complexes was evaluated using 2,2-Diphenyl-1-Picrylhydrazyl (DPPH^•) radical scavenging method, 2,2′-Azinobis(3-Ethylbenzothiazoline-6-Sulfonic Acid) (ABTS^•)⁺ radical activity, and Ferric Reducing Antioxidant Power (FRAP) assay. Several complexes exhibited higher radical scavenging efficiency than quercetin, with inhibition percentages exceeding 80% in the DPPH^• and ABTS^•+ assays. Others showed reduced activity due to the masking of redox-active hydroxyl groups during metal coordination. FRAP results corroborated these trends, indicating metal-dependent modulation of reducing power. Antimicrobial evaluation revealed that selected complexes were more active than free quercetin, particularly against Staphylococcus aureus and Candida spp., with minimum inhibitory concentrations (MICs) ranging from 75–250 μg mL⁻¹. Overall, metal complexation significantly alters the electronic structure and biological behavior of quercetin, highlighting the potential of metal–flavonoid complexes as multifunctional antioxidants and antimicrobials.

Diltiazem hydrochloride (DH) is a calcium channel blocker used to modify or restore normal heart rhythm in cardiovascular diseases. The aim of this study was to develop and validate a new innovative method using UV molecular absorption spectrophotometry to evaluate the in vitro dissolution of DH using a factorial design of experiments. Physical and physicochemical tests were performed. The dissolution profiles of DH tablets (30 and 60 mg) available as the reference, generic and similar drugs were compared. The dissolution test was used to obtain and compare dissolution profiles and to determine the similarity of pharmaceutical formulations (USP type 2 apparatus at 75 rpm, with 750 mL of water at 37.0 ± 0.5 oC for 120 minutes). Only samples G30 and G60 showed compliance with the parameters established by the Brazilian Pharmacopoeia in all tests. Drug dissolution percentages are in accordance with the Brazilian and American Pharmacopoeias (>75% dissolution in 180 minutes). Using the proposed new method, it was observed that > 80% of DH was released in approximately 60 minutes. The proposed method was found to be sensitive, rapid and efficient for the quality control of DH tablets.

Plant chemical diversity constitutes an essential dimension of biodiversity, arising from interactions among genetic background, biosynthetic regulation, the environment, ontogeny, ecology, and evolutionary history. Although the term chemotype is widely used for distinguishable chemical patterns within a taxon, its meaning remains inconsistent across plant biology, phytochemistry, pharmacognosy, chemical ecology, and natural-product standardization. This conceptual review examines the historical development, conceptual boundaries, chemical criteria, biological significance, and methodological requirements of plant chemotypes. We define a chemotype as a distinguishable, recurrent, relatively stable, analytically reproducible, and biologically interpretable intraspecific chemical pattern expressed by individuals, populations, or lineages of the same taxon. Assignment should be based primarily on chemical discontinuity, diagnostic markers, recurrence, relative stability, and analytical reproducibility; ecological, functional, biosynthetic, and genetic information should be treated as supporting evidence when available. The framework applies to volatile and non-volatile systems, including essential oils, cannabinoids, alkaloids, phenolics, and glucosinolates, while recognizing that platform coverage, annotation confidence, and taxon-specific biology can alter the inferred groups. We distinguish chemotypes from chemical phenotypes, chemical ecotypes, chemical geotypes, chronotypes, chemovars, and chemophenetic groups and propose three evidence levels: putative, supported, and confirmed chemotypes.

Plant specialized metabolism changes throughout development, but developmental context remains inconsistently incorporated into phytochemical interpretation. This integrative narrative review synthesizes evidence on chemical ontogeny in plants, defined here as the qualitative and quantitative reorganization of specialized metabolism along plant and organ development. We distinguish ontogenetic variation from phenology, seasonality, organ maturation, developmental plasticity, and environmentally induced chemical plasticity, and examine the genetic, hormonal, anatomical, ecological, and analytical processes that generate stage-dependent chemical profiles. Across seeds, seedlings, vegetative organs, reproductive structures, fruits, and senescent tissues, the evidence shows recurrent changes in metabolite abundance, composition, spatial allocation, and bioactivity. These trajectories can alter ecological interactions, marker stability, harvest recommendations, and the reproducibility of botanical raw materials. Analytical strategies should therefore be selected according to the biological question and available resources, ranging from validated targeted or single-omics designs to spatial, single-cell, and multi-omics integration when mechanistically justified. Chemical ontogeny is proposed not as evidence that developmental metabolism is newly discovered, but as an operational framework for stage-aware sampling, reporting, interpretation, quality control, and bioprospecting.