Many species of the so-called exotic plants coexist with native species in a balanced way, but others thrive very quickly and escape human control, becoming harmful—these are called invasive alien species. In addition to overcoming geographic barriers, these species can defeat biotic and abiotic barriers, maintaining stable populations. Ailanthus altissima is no exception; it is disseminated worldwide and is considered high risk due to its easy propagation and resistance to external environmental factors. Currently, it has no particular use other than ornamental, even though it is used to treat epilepsy, diarrhea, asthma, ophthalmic diseases, and seborrhoea in Chinese medicine. Considering its rich composition in alkaloids, terpenoids, sterols, and flavonoids, doubtlessly, its use in medicine or other fields can be maximised. This review will focus on the knowledge of the chemical composition and the discovery of the biological properties of A. altissima to understand this plant better and maximise its possible use for purposes such as medicine, pharmacy, or the food industry. Methods for the extraction and detection to know the chemical composition will also be discussed in detail.

Acacia spp. is an invasive species that is widespread throughout the Portuguese territory. Thus, it is pertinent to better understand this species in order to find different applications that will value its use. To evaluate the phenolic profile in Acacia flowers, ethanolic extracts obtained through an energized guided dispersive extraction were analysed, focusing on two species, Acacia retinodes and Acacia mearnsii, at two flowering stages. The phytochemical profile of each extract was determined by ultra-high performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry and high-performance liquid chromatography coupled with diode array detector. The FTIR-ATR technique was used to distinguish the different samples’ compositions. The results showed the presence of high concentrations of phenolic compounds (>300 mg GAE/g extract), among which are flavonoids (>136 mg QE/g extract), for all combinations of species/flowering stages. The phytochemical profile showed a complex composition with 21 compounds identified and quantified (the predominant ones being epicatechin, rutin, vanillin, and catechol). Both species and flowering stages presented significant variations regarding the presence and quantity of phenols and flavonoids, so much so that a principal component analysis performed with FTIR-ATR spectra data of the extracts was able to discriminate between species and flowering stages.

Cytisus spp. is present throughout the Portuguese territory. Although most of these species are considered native in Portugal, at least one species has already been reported as invasive in other parts of the world. Different measures of control have been investigated, and the application of herbicides is the most commonly used. This review gathers information about the biochemical profile and analytical methods used for the evaluation of the potential bioactivities of three species of the genus Cytisus, better known as brooms, which were used in traditional medicine through the production of infusions and decoctions for the treatment of several health problems, mainly due to their high value of phenolic compounds. However, little research has been conducted on its biological activities as a potential antioxidant, anti-inflammatory, and antimicrobial agent. Furthermore, one species (Cytisus striatus) has not been subjected to extensive research in identifying chemical compounds and evaluating their potential bioactivities. This species (known as the Portuguese broom) has a great expression in one of the forest typologies with a considerable percentage in Portugal. This research work is essential to encourage a scientific and sustainable valorisation of Cytisus spp. (namely C. striatus), which will consequently contribute to forest cleaning and management to reduce the risk of wildfires.