Volatile Profile of the Baccharis Genus: A Narrative Review

1. Introduction

Plants synthesize a broad range of compounds during their biochemical processes, among which secondary metabolites, particularly phenolic compounds and terpenoids, stand out. Within the terpenoid class, monoterpenes and sesquiterpenes are volatile substances associated with diverse ecological functions, especially the attraction of pollinators and natural enemies, in addition to their relevance for agro-industrial applications [1,2].

The genus Baccharis is one of the 196 genera of the family Asteraceae occurring in Brazil and is widely recognized in traditional communities for its medicinal properties. Although distributed across all American continents, approximately 90% of its species occur naturally in South America, a concentration that supports the idea that its center of origin lies within the Neotropical region [3,4,5].

Species of Baccharis are generally described as perennial shrubs ranging from 50 cm to 4 m in height, characterized by leaves and stems covered with a tufted indumentum composed of trichomes with adjacent basal cells, and by their dioecious nature. They exhibit substantial morphological diversity, with stems typically lacking a xylopodium, winged or striated branches, and leaves ranging from scale-like to fully developed, showing varied venation patterns and dentate margins. Their inflorescences are capitulescences of multiple forms, with homogamous and sexually distinct capitula (staminate or pistillate), reflecting broad ecological adaptability [6].

These species are frequently cited for their distinctive phytochemical composition, including phenolic compounds and volatile constituents, which confer a range of bioactive properties, such as antifungal [7], anticariogenic [8], antibacterial [9], antidiabetic [10], antitumoral [11], antioxidant, anti-inflammatory [12], and hepatoprotective effects [13]. These bioactivities have been widely exploited through the incorporation of oils extracted from these plants into food, pharmaceutical, and cosmetic formulations [14,15,16,17].

Considering the above, the main objective of this study was to compile a database of volatile compounds occurring in species of the genus Baccharis, with the purpose of supporting the identification of these metabolites.

2. Materials and Methods

This narrative review aimed to answer the following guiding question: “What is the profile of volatile compounds reported in species of the genus Baccharis?”. Based on this inquiry, search strategies were defined for the databases ScienceDirect, PubMed, Periódicos CAPES, Web of Science, and Scopus.

The search was conducted using the descriptors “Chemical profile,” “Volatile compounds,” and “Baccharis,” combined with the logical operator “AND,” according to the structure of each platform. A 10-year time window was adopted, covering publications from 2015 to 2025. Another selection criterion concerned the analytical technique: only studies employing gas chromatography coupled with mass spectrometry (GC–MS) for compound identification were included.

To group species of the genus Baccharis, a dendrogram was constructed based on interspecific similarity derived from their volatile compound profiles. The analysis employed hierarchical clustering using the Jaccard dissimilarity coefficient, with binary data indicating the presence or absence of the 162 volatile compounds surveyed. Dendrograms were generated using the unweighted pair group method with arithmetic mean (UPGMA). All analyses were performed using the vegan package implemented in the R programming environment [18].

3. Results and Discussion

3.1. Search and Selection

Study selection was carried out through screening of titles and abstracts, considering their relevance to the research question. A total of 94 studies were identified; after removing duplicates (13) and excluding non-relevant works (69), 12 studies were included, all focused on the chemical profiles and volatile compounds of Baccharis species. Table 1 presents the number of studies retrieved from each database.

Fifteen species of the genus Baccharis were identified across the selected studies, distributed among three distinct subgenera: Oblongifolia, Molina, and Baccharis. B. oblongifolia belongs to the subgenus Oblongifolia, whereas B. anomala and B. salicifolia are classified within the subgenus Molina. The remaining species, B. dracunculifolia, B. milleflora, B. trimera, B. tridentata, B. uncinella, B. dentata, B. calvescens, B. axillaris, B. articulata, B. mesoneura, B. myriocephala, and B. retusa, belong to the subgenus Baccharis, which exhibited the highest species diversity in this survey.

The species with the greatest number of publications addressing volatile compound profiles was B. dracunculifolia, with six studies. Following this, B. trimera and B. uncinella each appeared in three studies, and B. milleflora was represented in two.

Among the studies focused on B. dracunculifolia, five were published after 2019, indicating a growing interest in the bioactive properties of its metabolites and in its close association with green propolis.

3.2. Volatile Compounds

A total of 158 volatile compounds were identified as constituents of the volatile profiles reported for the surveyed species. The monoterpenes p-cymene, myrcene, β-E-ocimene, α-pinene, β-pinene, sabinene, γ-terpinene, and α-thujene, along with the sesquiterpenes copaene, α-humulene, and γ-muurolene, were detected in 75% of the species analyzed. This recurrent composition suggests that these volatiles serve as strong indicators of the presence of plant parts and/or extracts belonging to the genus (Figure 1).

The occurrence of compounds such as α-pinene, β-pinene, α-thujene, sabinene, and α-humulene in the chemical profiles of plants belonging to the class Magnoliopsida, which includes families such as Asteraceae, Myrtaceae, and Lamiaceae [19,20], suggests a group of metabolites associated with conserved metabolic patterns maintained throughout evolutionary processes.

Within the subgenus Oblongifolia, 17 volatile compounds were identified, with a clear predominance of monoterpenes such as α-pinene, sabinene, myrcene, γ-terpinene, and α-terpineol (Table 2). No compound was found to be exclusive to this species when compared with the other species included in this review [21].

Within the subgenus Molina, represented by B. anomala and B. salicifolia, 34 volatile compounds were identified. Although both species belong to the same subgenus, where a certain degree of chemical similarity would be expected, only α-pinene and β-pinene were shared between them. This low overlap may be attributed to several factors, including chromatographic conditions, extraction methodologies, and the season or phenological stage at which plant material was collected.

Among the compounds reported for species of the Molina subgenus, sesquiterpenes were particularly diverse, followed by monoterpenes, especially in B. anomala (Table 3) [21,22].

The most extensively studied subgenus in terms of volatile compounds was the subgenus Baccharis, comprising 12 of the surveyed species and totaling 148 compounds, with a predominance of terpenoids—particularly monoterpenes and sesquiterpenes (Table 4). Among the compounds identified, β-pinene, α-thujene, sabinene, α-humulene, and γ-muurolene were detected in all species of this group.

In B. calvescens, guaiol was the only compound reported as exclusive among the species of the subgenus [21]. B. trimera exhibited exclusivity for β-isophorone, carquejol acetate, and trans-pinocarvyl acetate [21]. B. mesoneura showed the singular presence of salviol-4(14)-en-1-one, whereas B. milleflora was distinguished by the exclusive occurrence of α-acorenol [21,23].

In B. uncinella, the following compounds were identified as exclusive constituents: α-felandrene, (Z)-β-ocimene, nopinone, pinocarvone, safranal, (E)-sabinol, (Z)-carveol, (E)-tagetone, (E)-β-ionone, cadalene, (E)-calamen-10-ol, iso-italicene epoxide, and cubene [23,24,25].

In B. dracunculifolia, the exclusive constituents identified were acetophenone, δ-isopulegol, dihydrotagetone, methyl eugenol, α-curcumene, α-elemene, α-bourbonene, ylangene, δ-elemene, dauca-5,8-diene, isobicyclogermacrenal, ledene oxide, cedrene-13-en-8-ol, germacran-8-4-ol, cabreuva oxide B, β-copaen-4α-ol, khusimol, trans-nerolidol, junenol, α-muurolol, β-oplopenone, phytol, and heptacosane. The high diversity of exclusive constituents reported for B. dracunculifolia can be explained by the large number of studies focusing on this species [25,26,27,28,29,30,31].

In B. retusa, the exclusive constituents identified were 2-hexenal, hexanal, (E)-3-hexen-1-ol, 1-hexanol, n-cymene, 3-carene, α-ocimene, β-damascenone, β-eudesmene, and β-cadinene [32]. In B. dentata, the exclusive compounds were n-nonanal, carvone, α-campholenal, (E)-pinocarveol, (E)-verbenol, geranial, α-calacorene, (E)-muurola-4(14),5-diene, and δ-amorphene [23].

3.3. Cluster Analysis

All volatile compounds identified in the selected studies were subjected to hierarchical clustering analysis (UPGMA) to investigate patterns of similarity among Baccharis species (Figure 2). The dendrogram was constructed using the Jaccard dissimilarity coefficient, based on the presence or absence of 159 volatile compounds. The clustering results revealed the formation of at least five distinct chemical profiles among the evaluated species.

The first group consisted exclusively of B. salicifolia, indicating a unique chemical profile. The second cluster brought together B. dentata, B. dracunculifolia, and B. uncinella. The third group consisted of B. retusa, which exhibited a volatile composition distinct from the remaining species. The fourth cluster encompassed a larger set of species, B. calvescens, B. axillaris, B. articulata, B. oblongifolia, B. myriocephala, B. mesoneura, and B. anomala, suggesting close chemical similarity among them. Finally, the fifth group included B. tridentata, B. milleflora, and B. trimera, which displayed similar volatile profiles.

Although organisms classified as closely related often exhibit similar chemical characteristics due to shared evolutionary ancestry, the available data are not sufficiently comprehensive to conclusively confirm taxonomic proximity. Nonetheless, the findings suggest a probable evolutionary relationship among the groups observed [33].

5. Conclusions

Given the number of studies identified, species belonging to the subgenus Baccharis, particularly B. dracunculifolia and B. trimera, stand out in comparison with the others surveyed. The presence of α-pinene, β-pinene, α-thujene, sabinene, myrcene, γ-terpinene, copaene, α-humulene, γ-muurolene, p-cymene, and β-E-ocimene in their chemical profiles may serve as potential biomarkers indicating the contribution of Baccharis species to the composition of plant-derived products. Although these volatiles constitute strong indicators, broader and more comprehensive studies are needed to refine and validate these patterns, given the considerable diversity of species classified within the genus.

In the composition of volatile profiles, monoterpenes and sesquiterpenes are the phytochemical classes most frequently reported, with B. dracunculifolia exhibiting the highest number of these compounds in its volatile profile.