Therapeutic Plants with Immunoregulatory Activity and Their Applications: A Scientific Vision of Traditional Medicine in Times of COVID-19

The progression of SARS-CoV-2 (COVID-19) in humans heavily depends on the patient's overall health status, especially on its immunoregulatory capacity. Different plants and plant-derived preparations (infusions, encapsulated, etc.) have been used as immunoregulators, several of them with scientific support. Nevertheless, due to the composition complexity of such plant-derived preparations, the molecular and physiological mechanisms involved in their beneficial effects remain, in some cases, unclear. In this review article, the most reported plants used in traditional medicine to enhance immunoregulatory capacity are presented, and their effect on the innate immune response is discussed and correlated with their respective phytochemical profile. Understanding how the plant phytochemical profile relates to the observed impact on the innate and adaptative immune response is fundamental to designing plant-derived co-treatments to lessen the symptoms and favor the recovery of COVID-19 patients. In this regard, we propose a prospective guideline for using plants and plant-derived preparations as co-treatments for COVID-19 (and similar viral infections), which could be helpful in the context of the worldwide effort to end the current SARS-CoV-2 pandemic.

Edible Flower Species as a Promising Source of Specialized Metabolites

Eating habits are changing over time and new innovative nutrient-rich foods will play a great role in the future. Awareness of the importance of a healthy diet is growing, so consumers are looking for new creative food products rich in phytochemicals, i.e., specialized metabolites (SM). The consumption of fruits, vegetables and aromatic species occupies an important place in the daily diet, but different edible flower species are still neglected and unexplored. Flowers are rich in SM, have strong antioxidant capacities and also possess significant functional and biological values with favorable impacts on human health. The main aim of this study was to evaluate the content of SM and the antioxidant capacities of the edible flower species: Calendula officinalis L. (common marigold), Tagetes erecta L. (African marigold), Tropaeolum majus L. (nasturtium), Cucurbita pepo L. convar. giromontiina (zucchini) and Centaurea cyanus L. (cornflower). The obtained results showed the highest content of ascorbic acid (129.70 mg/100 g fw) and anthocyanins (1012.09 mg/kg) recorded for cornflower, phenolic compounds (898.19 mg GAE/100 g fw) and carotenoids (0.58 mg/g) for African marigold and total chlorophylls (0.75 mg/g) for common marigold. In addition to the esthetic impression of the food, they represent an important source of SM and thus can have a significant impact if incorporated in the daily diet.

HPLC-UV, Metabarcoding and Genome Skims of Botanical Dietary Supplements: A Case Study in Echinacea

The use of DNA-based methods to authenticate botanical dietary supplements has been vigorously debated for a variety of reasons. More comparisons of DNA-based and chemical methods are needed, and concordant evaluation of orthogonal approaches on the same products will provide data to better understand the strengths and weaknesses of both approaches. The overall application of DNA-based methods is already firmly integrated into a wide array of continually modernizing stand alone and complementary authentication protocols. Recently, the use of full-length chloroplast genome sequences provided enhanced discriminatory capacity for closely related species of Echinacea compared to traditional DNA barcoding approaches (matK and rbcL). Here, two next-generation sequencing approaches were used: (1) genome skimming and (2) PCR amplicon (metabarcoding). The two genetic approaches were then combined with HPLC-UV to evaluate 20 commercially available dietary supplements of Echinacea representing "finished" products. The trade-offs involved in different DNA approaches were discussed, with a focus on how DNA methods support existing, accepted chemical methods. In most of the products (19/20), HPLC-UV suggested the presence of Echinacea spp. While metabarcoding was not useful with this genus and instead only resolved 7 products to the family level, genome skimming was able to resolve to species (9) or genus (1) with the 10/20 products where it was successful. Additional ingredients that HPLC-UV was unable to identify were also found in four products along with the relative sequence proportion of the constituents. Additionally, genome skimming was able to identify one product that was a different Echinacea species entirely.