Plant-Derived Antioxidants: Significance in Skin Health and the Ageing Process

Natural substances have traditionally been used in skin care for centuries. There is now an ongoing search for new natural bioactives that not only promote skin health but also protect the skin against various harmful factors, including ultraviolet radiation and free radicals. Free radicals, by disrupting defence and restoration mechanisms, significantly contribute to skin damage and accelerate ageing. Natural compounds present in plants exhibit antioxidant properties and the ability to scavenge free radicals. The increased interest in plant chemistry is linked to the growing interest in plant materials as natural antioxidants. This review focuses on aromatic and medicinal plants as a source of antioxidant substances, such as polyphenols, tocopherols, carotenoids, ascorbic acid, and macromolecules (including polysaccharides and peptides) as well as components of essential oils, and their role in skin health and the ageing process.

Southern African Soap Plants and Screening of Selected Phytochemicals and Quantitative Analysis of Saponin Content

In southern Africa, several plants are used ethnobotanically as soap substitutes, however, this information resides in different literature sources. The foaming and cleansing properties of such plants are attributed mainly to the presence of saponins, but other compounds such as alkaloids and terpenoids are also implicated. This study aimed to compile a comprehensive list of plants used traditionally as soap substitutes in southern Africa and to assess the chemical properties of selected species. Qualitative phytochemical analysis was done using five solvents (ethanol, methanol, water, chloroform, and acetone) to determine the presence of saponins, alkaloids, and terpenoids in selected soap plants. Quantitative analysis of the saponin content was done employing spectrophotometric tests of methanol extracts. There are thirty-seven (37) known southern African soap plants from twenty-four (24) different families, with the Fabaceae having the highest number of species (eight). Saponin concentrations of nine previously unstudied selected soap plants are reported for the first time in this study, whereby Calodendrum capense had the highest saponin concentrations are at 107.89 ± 4.89 mg/g, followed by Noltea africana (52.65 ± 6.81 mg/g), Crinum bulbispermum (35.43 ± 4.25 mg/g), and Merwilla plumbea (25.59 ± 0.83 mg/g). The knowledge of plant composition gives a better understanding of plant chemistry and possible use of plants medicinally, industrially and as soap substitutes. Furthermore, this allows the verification and the justification of traditional plant use. Soap plants have been used traditionally for many years, the potential to commercialise the use of these plants has been realised with the increase in the use of organic products by conscious consumers hence, the purpose of this investigation can have bearing on future projects and products.

SCALING UP SAGEBRUSH CHEMISTRY WITH NEAR-INFRARED SPECTROSCOPY AND UAS-ACQUIRED HYPERSPECTRAL IMAGERY

Sagebrush ecosystems (Artemisia spp.) face many threats including large wildfires and conversion to invasive annuals, and thus are the focus of intense restoration efforts across the western United States. Specific attention has been given to restoration of sagebrush systems for threatened herbivores, such as Greater Sage-Grouse (Centrocercus urophasianus) and pygmy rabbits (Brachylagus idahoensis), reliant on sagebrush as forage. Despite this, plant chemistry (e.g., crude protein, monoterpenes and phenolics) is rarely considered during reseeding efforts or when deciding which areas to conserve. Near-infrared spectroscopy (NIRS) has proven effective in predicting plant chemistry under laboratory conditions in a variety of ecosystems, including the sagebrush steppe. Our objectives were to demonstrate the scalability of these models from the laboratory to the field, and in the air with a hyperspectral sensor on an unoccupied aerial system (UAS). Sagebrush leaf samples were collected at a study site in eastern Idaho, USA. Plants were scanned with an ASD FieldSpec 4 spectroradiometer in the field and laboratory, and a subset of the same plants were imaged with a SteadiDrone Hexacopter UAS equipped with a Rikola hyperspectral sensor (HSI). All three sensors generated spectral patterns that were distinct among species and morphotypes of sagebrush at specific wavelengths. Lab-based NIRS was accurate for predicting crude protein and total monoterpenes (R2 = 0.7–0.8), but the same NIRS sensor in the field was unable to predict either crude protein or total monoterpenes (R2 < 0.1). The hyperspectral sensor on the UAS was unable to predict most chemicals (R2 < 0.2), likely due to a combination of too few bands in the Rikola HSI camera (16 bands), the range of wavelengths (500–900 nm), and small sample size of overlapping plants (n = 28–60). These results show both the potential for scaling NIRS from the lab to the field and the challenges in predicting complex plant chemistry with hyperspectral UAS. We conclude with recommendations for next steps in applying UAS to sagebrush ecosystems with a variety of new sensors.

Dose-dependent effects of CeO2 nanomaterials on tomato plant chemistry and insect herbivore resistance

The use of engineered nanomaterials (NMs) for agricultural applications is becoming increasingly interesting because NMs have been shown to promote crop yield, and also to some extent, protection against insect...

Special Issue: Plant Metabolomics

This Special Issue was initiated to collect a handful of studies on plant chemistry, utilizing metabolomics as the main technique, to show the diversity of possible applications of this approach [...]