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This study evaluates the essential oil (EO) composition of Piper rivinoides Kunth, a shrub native to the Brazilian tropical rainforest, across different plant parts and developmental phases. The aim was to explore the chemical diversity of EO and its reflection in the plant's ecological interactions and adaptations. Plant organs (roots, stems, branches, and leaves) at different developmental phases were subjected to hydrodistillation followed by chemical analysis using Gas Chromatography–Mass Spectrometry (GC–MS) and Gas Chromatography–Flame Ionization Detector (GC–FID). The results revealed a relevant variation in EO yield and composition among different plant parts and developmental phases. Leaves showed the highest yield and chemical diversity, with α-pinene and β-pinene as major constituents, while roots and stems were characterized by a predominance of arylpropanoids, particularly apiol. The chemical diversity in leaves increased with plant maturity, indicating a dynamic adaptation to environmental interactions. The study underscores the importance of considering the ontogeny of plant parts in understanding the ecological roles and potential applications of P. rivinoides in medicine and agriculture. The findings contribute to the overall knowledge of Piperaceae chemodiversity and ecological adaptations, offering insights into the plant's interaction with its environment and its potential uses based on chemical composition. [ABSTRACT FROM AUTHOR]

Piper mollicomum Kunth (Piperaceae) plays a vital role in the preservation of the Brazilian Atlantic Forest by contributing to the regeneration of deforested areas. Recent scientific investigations have analyzed the chemical constituents and seasonal dynamics of essential oils (EO) from various Piper L. species, highlighting the need to elucidate their chemical–ecological interactions. This study aims to expand the chemical–ecological knowledge of this important taxon in neotropical forests, using P. mollicomum as a model. The methodologies employed include the collection of plant material, EO extraction by hydrodistillation, analysis of EO by gas chromatography–mass spectrometry (GC–MS) and gas chromatography–flame ionization detector (GC–FID), recording the frequency of visits by potential pollinators and microclimatic variables, and by conducting calculations of chemodiversity and chemophenetic indices. Chemical analyses indicated that the diversity of EO and environmental factors are linked to the activities of potential pollinators. In the Tijuca Forest, P. mollicomum revealed significant interactions between its volatile constituents and microclimatic variables, showing that the chemodiversity of the leaves and reproductive organs correlates with pollinator visitation. Additionally, a notable difference in chemical evenness was observed between these vegetative structures. The chemophenetic indices by Ramos and Moreira also revealed correlations with chemical diversity. [ABSTRACT FROM AUTHOR]

This study investigated the chemical phenotypical variability of Piper lhotzkyanum Kunth (Piperaceae), a shrub found in Brazilian tropical forests, over time (different periods of the day and seasons) and under natural conditions. For this, essential oils (EOs) from the leaves were collected in different seasons and times of the day and analyzed by gas chromatography coupled with mass spectrometry, and gas chromatography coupled with a flame ionization detector. The indices were applied to evaluate the chemical diversity as well as the dynamics of redox of the mixtures. The results showed that the EOs were dominated by non-oxygenated sesquiterpenes, with β-elemene, E-caryophyllene, and α-zingiberene being the main compounds identified in all collections. Temporal and seasonal analyses revealed important fluctuations in the chemical composition, redox, and chemical diversity indices of the species. A correlation between climatic factors and the variation in redox and chemical diversity was observed, highlighting the chemical phenotypic plasticity P. lhotzkyanum. This study resolves a previously unanswered question by confirming that natural light does not produce interconversion of major compounds. The adaptation capacity of this species to the environmental changes suggests new cultivation strategies to maximize the quality of EO and promote a more sustainable future in partnership with nature. [ABSTRACT FROM AUTHOR]

Oral squamous cell carcinoma (OSCC) is the most common type of head and neck malignancy. Research on essential oils (EOs) has shown important cytotoxic and anti-tumor properties, among others. Piperaceae species are rich in EOs and here we highlight Piper rivinoides Kunth. We investigated the crude EOs from P. rivinoides, their pure major constituents and an enriched fraction with the main EO compounds (EF) as cytotoxic and selective OSCC agents. EOs presented as main compounds (-)-α-pinene, (-)-β-pinene and limonene. EOs showed an IC50 lower than all isolated compounds, except for (-)-β-pinene in OSCC cells. The (-)-β-pinene induced cell death with apoptotic characteristics. Commercial standards showed greater selectivity than EOs, and (-)-β-pinene was the most selective among them. EF showed higher selectivity compared to crude EOs and carboplatin, turning it into a good candidate as an anticancer fraction. These results are important for the possible development of new treatments for OSCC. [ABSTRACT FROM AUTHOR]

The aromatic species Piper gaudichaudianum Kunth (Piperaceae) is widely used in Brazil for medicinal and ritualistic applications. In the current study, chemophenetic patterns were realized across season and circadian rhythm based on the chemical profile of essential oils (EOs) from leaves. Hydrodistilled essential oils were analyzed by GC-MS and GC-FID, and a new calculation of metabolite oxidation level, averaged for each individual molecule component of the EO, was used to explore the patterns of metabolism/biosynthesis. This new index used an intermediate calculation, the 'weighted average redox standard' (SRO), to enable a value for mixtures of metabolites to be generated, the 'general mixture redox index' (GMOR). The indices were subjected to a proof-of-concept approach by making comparison to outcomes from multivariate analyses, i.e., PCA and HCA. Chemical analysis demonstrated that the essential oils were dominated by sesquiterpenes, constructed of 15 classes of compound (C-skeletons), and 4 C-skeletons were recognized in the monoterpene group, giving a total of 19. The variation of chemical profiles was distinct at different phenological stages, but stronger chemical variation was evident between day and night as compared to season. Furthermore, due to comprehensive sampling across different regions, nine chemotypes were recognized, including those previously reported. The SRO and GMRO indices demonstrate that phenological variation of chemistry is mainly an outcome of redox fluctuations in terpene biosynthesis, changing from day to night. These indices also corroborate that chemical diversity is increased with oxidative metabolism. Lastly, the current study demonstrates pronounced phenotypic plasticity in P. gaudichaudianum, which makes it a suitable candidate to help further our understanding of chemophenetics and chemical ecology. [ABSTRACT FROM AUTHOR]

Piper aduncum L. is a species known for its medicinal and pharmacological properties, cultivated due to commercial and industrial interest, especially in the production of essential oils (EOs). To explore its potential, the present study aimed to evaluate the post-harvest impact of UV-C irradiation on the metabolic profile of EOs from fresh leaves of P. aduncum cultivated in Southeastern Brazil, during different storage periods. Fresh leaves were exposed to controlled UV-C light irradiation in a chamber for 60, 120, 240, and 360 min. Subsequently, the EOs were extracted by hydrodistillation in a modified Clevenger apparatus and analyzed using GC. A non-irradiated sample was included as a control for comparison. The results revealed alterations in the relative percentage of specific chemical constituents, including arylpropanoids and sesquiterpenes, after UV-C irradiation. Remarkably, the relative percentage of the arylpropanoid dillapiole, a compound of high commercial value, increased significantly by threefold after exposure to UV-C radiation, ranging from 26.81 % (not irradiated) to 95.60 % (360 min of irradiation). This study indicates that exposure to UV-C radiation in freshly harvested P. aduncum leaves may be a promising technique for enriching the dillapiole content in the EO, with potential commercial applications and large-scale industry use. • Piper aduncum is a medicinal plant and rich in essential oil. • The application of post-harvest UV-C irradiation modifies the metabolic profile of P. aduncum essential oil. • Post-harvest treatment with UV-C triples the relative percentage of dillapiole, a compound with industrial significance. [ABSTRACT FROM AUTHOR]

In this study, the chemical composition of essential oils (EOs) from different vegetative parts from P. mollicomum was evaluated. In addition, the EOs from leaves collected every 3 h in a period of 24 h, in the dry and rainy seasons were also analyzed to establish the circadian rhythm of P. mollicomum from a natural population in the Atlantic Forest. The EOs were obtained by hydrodistillation and the chemical composition and quantification were achieved by GC-MS and GC-FID, respectively. The main compounds identified in the main stems and branches were α-phellandrene, linalool and β-phellandrene. Arylpropanoids myristicin, dillapiole and apiole were identified as main compounds in the roots. Inflorescences and infructescences showed to be rich in linalool, eupatoriocromene and E -nerolidol. In the circardian rhythm study, EOs showed to be rich in 1,8-cienol and/or linalool in accordance with season and phenology. The chemometric analyzes made it possible to register sample variations in the EOs compositions, being linalool as major compound attributed to the rainy and vegetative phase periods. Monoterpene 1,8-cineole was characterized as the main compound in the dry and reproductive phase periods. The same chemometric features allowed to stablished differences considering vegetative parts as a clear grouping of the EOs by biosynthetic pathway. In summary, there are great differences in the EOs composition, considering phenology, seasonality and vegetative parts. These results are very important since P. mollicomum has been used as medicinal plant for many years. Image 1 • The circadian study of the essential oils from leaves of Piper mollicomum Kunth. • PCA and HCA analysis showed quantitative variation in the essential oils constituents. • Significant variation in the essential oils constituents in the seasons. • Significant variation in the essential oils constituents in different vegetative parts. [ABSTRACT FROM AUTHOR]