Macroalgae are increasingly viewed as a source of secondary metabolites with great potential for the development of new drugs. In this development, in vitro studies are only the first step in a long process, while in vivo studies and clinical trials are the most revealing stages of the true potential and limitations that a given metabolite may have as a new drug. This literature review aims to give a critical overview of the secondary metabolites that reveal the most interesting results in these two steps. Phlorotannins show great pharmaceutical potential in in vivo models and, among the several examples, the anti-dyslipidemia activity of dieckol must be highlighted because it was more effective than lovastatin in an in vivo model. The IRLIIVLMPILMA tridecapeptide that exhibits an in vivo level of activity similar to the hypotensive clinical drug captopril should still be stressed, as well as griffithsin which showed such stunning results over a variety of animal models and which will probably move onto clinical trials soon. Regarding clinical trials, studies with pure algal metabolites are scarce, limited to those carried out with kahalalide F and fucoxanthin. The majority of clinical trials currently aim to ascertain the effect of algae consumption, as extracts or fractions, on obesity and diabetes.

Global demand for food production is causing pressure to produce faster and bigger crop yields, leading to a rampant use of synthetical pesticides. To combat the nefarious consequences of its uses, a search for effective alternatives began in the last decades and is currently ongoing. Nature is seen as the main source of answers to crop protection problems, supported by several examples of plants/extracts used for this purpose in traditional agriculture. The literature reviewed allowed the identification of 95 plants whose extracts exhibit insecticide activity and can be used as bio-pesticides contributing to sustainable agriculture. The option for ethanol and/or water extracts is more environmentally friendly and resorts to easily accessible solvents, which can be reproduced by farmers themselves. This enables a bridge to be established between raw scientific data and a more practical reality. Azadirachta indica, Capsicum annuum, Nicotiana tabacum and Tagetes erecta are the most researched plants and have the potential to be viable options in the pest management approach. Azadirachta indica showed the most promising results and Brevicoryne brassicae was the most targeted pest species, being tested against the aqueous and/or ethanolic extracts of 23 different plants. Maceration using dried material (usually leaves) is the extraction method preferred by the majority of authors.

An imbalance in the production of reactive oxygen species in the body can cause an increase of oxidative stress that leads to oxidative damage to cells and tissues, which culminates in the development or aggravation of some chronic diseases, such as inflammation, diabetes mellitus, cancer, cardiovascular disease, and obesity. Secondary metabolites from Inula species can play an important role in the prevention and treatment of the oxidative stress-related diseases mentioned above. The databases Scopus, PubMed, and Web of Science and the combining terms Inula, antioxidant and secondary metabolites were used in the research for this review. More than 120 articles are reviewed, highlighting the most active compounds with special emphasis on the elucidation of their antioxidative-stress mechanism of action, which increases the knowledge about their potential in the fight against inflammation, cancer, neurodegeneration, and diabetes. Alantolactone is the most polyvalent compound, reporting interesting EC₅₀ values for several bioactivities, while 1-O-acetylbritannilactone can be pointed out as a promising lead compound for the development of analogues with interesting properties. The Inula genus is a good bet as source of structurally diverse compounds with antioxidant activity that can act via different mechanisms to fight several oxidative stress-related human diseases, being useful for development of new drugs.

Background: Plants and their derived natural compounds possess various biological and therapeutic properties, which turns them into an increasing topic of interest and research. Juniperus genus is diverse in species, with several traditional medicines reported, and rich in natural compounds with potential for development of new drugs. Methods: The research for this review were based in the Scopus and Web of Science databases using terms combining Juniperus, secondary metabolites names, and biological activities. This is not an exhaustive review of Juniperus compounds with biological activities, but rather a critical selection taking into account the following criteria: (i) studies involving the most recent methodologies for quantitative evaluation of biological activities; and (ii) the compounds with the highest number of studies published in the last four years. Results: From Juniperus species, several diterpenes, flavonoids, and one lignan were emphasized taking into account their level of activity against several targets. Antitumor activity is by far the most studied, being followed by antibacterial and antiviral activities. Deoxypodophyllotoxin and one dehydroabietic acid derivative appears to be the most promising lead compounds. Conclusions: This review demonstrates the Juniperus species value as a source of secondary metabolites with relevant pharmaceutical potential.

A current research topic of great interest is the study of the therapeutic properties of plants and of their bioactive secondary metabolites. Plants have been used to treat all types of health problems from allergies to cancer, in addition to their use in the perfumery industry and as food. Hedychium species are among those plants used in folk medicine in several countries and several works have been reported to verify if and how effectively these plants exert the effects reported in folk medicine, studying their essential oils, extracts and pure secondary metabolites. Hedychium coronarium and Hedychium spicatum are the most studied species. Interesting compounds have been identified like coronarin D, which possesses antibacterial, antifungal and antitumor activities, as well as isocoronarin D, linalool and villosin that exhibit better cytotoxicity towards tumor cell lines than the reference compounds used, with villosin not affecting the non-tumor cell line. Linalool and α-pinene are the most active compounds found in Hedychium essential oils, while β-pinene is identified as the most widespread compound, being reported in 12 different Hedychium species. Since only some Hedychium species have been investigated, this review hopes to shed some light on the uncharted territory that is the Hedychium genus.

Metabolic syndrome, a cluster of metabolic disorders comprising dyslipidemia, insulin resistance, elevated blood pressure, and abdominal obesity, is a silent epidemic that may lead to outcomes such as cardiovascular disease, diabetes, and cancer. Due to the increase in the prevalence of these pathologies, the search for better treatments and more efficient drugs is imperative. Species of Artemisia and Salvia genera are excellent examples of noteworthy sources of bioactive products with health applications, their therapeutic properties being well known both in popular medicine and in the scientific community. There are reports of plant extracts or compounds from species belonging to either of these genera, which were able to combat cancer, diabetes, and cardiovascular pathologies. For instance, dihydroartemisinin (analog of artemisin extracted from Artemisia annua L.) can reduce tumor markers p53 and Ki-67 expression levels, leading to a reduction in tumor proliferation. Salvia officinalis L. has antihyperglycemic and lipid profile-improving effects since it decreases total cholesterol, glycosylated hemoglobin, fasting glucose, low-density lipoprotein cholesterol, and triglyceride levels while increasing high-density lipoprotein cholesterol levels. Clinical trials using mixtures (dried powdered plants or extracts) of known medicinal plants are recurrent in published works, in contrast with the scarce clinical trial studies with isolated compounds. Salvia miltiorrhiza Bunge. was by far the most targeted plant in the clinical trials analyzed here. Regarding clinical trials concerning Artemisia, there are more studies aiming to see its effect on diabetes, but the studies about cancer are more advanced. This review aims to give a critical summary of the most interesting and promising results from clinical trials. The abundance of studies with limited statistically significant clinical evidence hinders progress in clinical therapy. This situation demands far greater rigor from the scientific community, researchers, regulatory agencies, editors, and reviewers in conducting and publishing clinical studies.