Among natural substances widespread in fruits, vegetables, spices, and medicinal plants, flavonoids and organic acids belong to the promising groups of bioactive compounds with strong antioxidant and anti-inflammatory properties. The aim of the present work was to evaluate the antibacterial activity of 13 common flavonoids (flavones, flavonols, flavanones) and 6 organic acids (aliphatic and aromatic acids). The minimal inhibitory concentrations (MICs) of selected plant substances were determined by the micro-dilution method using clinical strains of four species of pathogenic bacteria. All tested compounds showed antimicrobial properties, but their biological activity was moderate or relatively low. Bacterial growth was most strongly inhibited by salicylic acid (MIC = 250–500 μg/mL). These compounds were generally more active against Gram-negative bacteria: Escherichia coli and Pseudomonas aeruginosa than Gram-positive ones: Enterococcus faecalis and Staphylococcus aureus. An analysis of the antibacterial effect of flavone, chrysin, apigenin, and luteolin showed that the presence of hydroxyl groups in the phenyl rings A and B usually did not influence on the level of their activity. A significant increase in the activity of the hydroxy derivatives of flavone was observed only for S. aureus. Similarly, the presence and position of the sugar group in the flavone glycosides generally had no effect on the MIC values.

https://www.mdpi.com/2077-0383/9/1/109/pdf

Antibacterial Activity of Some Flavonoids and Organic Acids Widely Distributed in Plants.

Cancer is the second leading cause of death in the world. Chemotherapy and radiotherapy are the common cancer treatments. However, the development of adverse effects resulting from chemotherapy and radiotherapy hinders the clinical use, and negatively reduces the quality of life in cancer patients. Natural products including crude extracts, bioactive components-enriched fractions and pure compounds prepared from herbs as well as herbal formulas have been proved to prevent and treat cancer. Of significant interest, some natural products can reduce chemotherapy and radiotherapy-induced oral mucositis, gastrointestinal toxicity, hepatotoxicity, nephrotoxicity, hematopoietic system injury, cardiotoxicity, and neurotoxicity. This review focuses in detail on the effectiveness of these natural products, and describes the possible mechanisms of the actions in reducing chemotherapy and radiotherapy-induced side effects. Recent advances in the efficacy of natural dietary supplements to counteract these side effects are highlighted. In addition, we draw particular attention to gut microbiotan in the context of prebiotic potential of natural products for the protection against cancer therapy-induced toxicities. We conclude that some natural products are potential therapeutic perspective for the prevention and treatment of chemotherapy and radiotherapy-induced side effects. Further studies are required to validate the efficacy of natural products in cancer patients, and elucidate potential underlying mechanisms.

/pdf/natural-product-interventions-for-chemotherapy-and-553ddawoje.pdf

Natural Product Interventions for Chemotherapy and Radiotherapy-Induced Side Effects.

In this review, the concept of phenolic antioxidants, mechanisms of action, and applications have been reviewed. Phenolic compounds (PCs) acts as an antioxidant by reacting with a variety of free radicals. The mechanism of antioxidant actions involved either by hydrogen atom transfer, transfer of a single electron, sequential proton loss electron transfer, and chelation of transition metals. In foods, the PCs act as antioxidants which are measured with several in vitro spectroscopic methods. The PCs have been found in milk and a wide range of dairy products with sole purposes of color, taste, storage stability, and quality enhancement. The role of PCs in three types of food additives, that is, antimicrobial, antioxidant, and flavoring agents have been critically reviewed. The literature revealed that PCs present in a variety of foods possess several health benefits such as antibacterial, antihyperlipidemic, anticancer, antioxidants, cardioprotective, neuroprotective, and antidiabetic properties. PRACTICAL APPLICATIONS: Phenolic compounds are strong antioxidants and are safer than synthetic antioxidants. The wide occurrence in plant foods warranted continuous review applications. This review, therefore, presented an updated comprehensive overview of the concept, mechanism, and applications of phenolic antioxidants in foods.

Concept, mechanism, and applications of phenolic antioxidants in foods.

Extraction of bioactive compounds and essential oils from mediterranean herbs by conventional and green innovative techniques: A review.

Spice plants have a great influence on world history. For centuries, different civilizations have used them to condiment the foods of kings and nobles and applied them as embalming preservatives, perfumes, cosmetics, and medicines in different regions of the world. In general, these plants have formed the basis of traditional medicine and some of their derived substances have been utilized to treat different human diseases. Essential oils (EOs) obtained from these plants have been also used as therapeutic agents and have shown supportive uses in remedial practices. The discovery and development of bioactive compounds from these natural products, based on their traditional uses, play an important role in developing the scientific evidence of their potential pharmaceutical, cosmetic, and food applications. In the present review, using recent studies, we exhibit a general overview of the main aspects related to the importance of spice plants widely used in traditional medicine: Cinnamomum zeylanicum (true cinnamon), Mentha piperita (peppermint), Ocimum basilicum (basil), Origanum vulgare (oregano), Piper nigrum (black pepper), Rosmarinus officinalis (rosemary), and Thymus vulgaris (thyme); and we discuss new findings of the bioactive compounds obtained from their EOs, their potential applications, as well as their molecular mechanisms of action, focusing on their antioxidant activity. We also exhibit the main in vitro methods applied to determine the antioxidant activities of these natural products.

Bioactive Natural Compounds and Antioxidant Activity of Essential Oils from Spice Plants: New Findings and Potential Applications.

Essential oils of oregano are widely recognized for their antimicrobial activity, as well as their antiviral and antifungal properties. Nevertheless, recent investigations have demonstrated that these compounds are also potent antioxidant, anti-inflammatory, antidiabetic and cancer suppressor agents. These properties of oregano essential oils are of potential interest to the food, cosmetic and pharmaceutical industries. The aim of this manuscript is to review the latest evidence regarding essential oils of oregano and their beneficial effects on health.

https://www.mdpi.com/1420-3049/22/6/989/pdf

Essential Oils of Oregano: Biological Activity beyond Their Antimicrobial Properties

Several herb species classified as oregano have been widely used in folk medicine to alleviate inflammation-related diseases, respiratory and digestive disorders, headaches, rheumatism, diabetes and others. These potential health benefits are partially attributed to the phytochemical compounds in oregano such as flavonoids (FL) and phenolic acids (PA). Flavonoids and phenolic acids are among the most abundant and most studied phytochemicals in oregano species. Epidemiological, in vitro and in vivo experiments have related long-term consumption of dietary FL and PA with a decreased risk of incidence of chronic diseases. The aim of this manuscript is to summarize the latest studies on the identification and distribution of flavonoids and phenolic compounds from oregano species and their potential antioxidant, anti-inflammatory and anti-cancer health benefits.

Flavonoids and Phenolic Acids from Oregano: Occurrence, Biological Activity and Health Benefits

Corn stover, remaining after maize production, is produced worldwide. Despite being a residue, it contains bioactive compounds. Phenolic acids and lignin from maize plants were quantified to assess the possibility of valorization of this biomass. Extracts of the dry stem, root, cob, husk, leaf and grain of the maize plant were prepared using ethanol and alkaline hydrolysis. These were further subjected to acid hydrolysis to extract lignin and subsequently evaluated for their total phenolic content (TPC) and antioxidant capacity using two methods: measurement of the scavenging capacity against DPPH radical (2,2-diphenyl-1-picryl-hydrazyl) and the oxygen radical absorbance capacity (ORAC). The extracts showed a TPC of 219.67–1420.94 mg EAG 100 g−1. The antioxidant capacity of the extracts by DPPH scavenging was 1.11–11.75 mmol ET g−1, and their ORAC was 15.43–591.41 µmol ET g−1. Two phenolic acids (p-coumaric and ferulic acid) were identified in the samples using UPLC–PDA. The total lignin content (4.88–32.12%), TPC (3.4–16.9 mg EAG 100 g−1) and antioxidant capacity by DPPH scavenging (1.8–2.55 mmol ET g−1), as well as ORAC (0.8–3.9 µmol ET g−1), of the maize organs were assessed. The results suggest that corn stover is a potential source of natural antioxidants.

Antioxidant Capacity of Lignin and Phenolic Compounds from Corn Stover

Mango bark is an important agro-industrial residue from mango pruning. In traditional medicine, the aqueous extract from mango bark (MBE) has been used in ethnomedicine for the treatment of many diseases. However, there is scarce information using cellular models to evaluate the potential use of this plant material for human consumption. In this study, the phenolic content from the MBE from four varieties (Kent, Keitt, Ataulfo and Tommy Atkins) was analyzed by high-performance liquid chromatography coupled to photodiode array detector (HPLC-DAD) and liquid chromatography coupled with time-of-flight mass spectrometry (LC/MS-TOF). Additionally, the cellular antioxidant activity of the MBE from the four mango varieties were compared. Finally, the intestinal permeability of the main polyphenols found in the MBE (mangiferin and gallic acid) was evaluated. RESULTS Mangiferin and gallic acid were the main constituents in the MBE from the four mango varieties. Furthermore, the Ataulfo variety showed the highest cellular antioxidant activity (67%) at the concentration of 100 µg mL?1. The intestinal permeability of mangiferin present in the bark extracts was 3- to 4.8-fold higher than those of mangiferin as standard, whereas the intestinal permeability of gallic acid varied among the tested extracts. CONCLUSION MBE has the potential to exert antioxidant activity at the cellular level and can have an impact on human health. It may also be a good source for the extraction of polyphenols mainly mangiferin. ? 2019 Society of Chemical Industry

Cellular antioxidant activity and in vitro intestinal permeability of phenolic compounds from four varieties of mango bark (Mangifera indica L.)

Prebiotics are nondigestible food components that have an impact on gut microbiota composition and activity, which in turn results in the improvement of health conditions. Nowadays, the production of prebiotics from agro-industrial by-products is under investigation. In this regard, polysaccharides are usually found in these sources and their potential use as prebiotics has been studied recently since these compounds act as substrates for the human gut microbiota, and they have the potential to modulate its composition through many mechanisms. Additionally, the use of agricultural by-products is advantageous because it is a cheap and abundantly available material. This review focuses on the recent scientific literature regarding the prebiotic properties of polysaccharides from agro-industrial by-products. PRACTICAL APPLICATIONS: Currently, the maintenance of gut homeostasis is a target for the improvement of human health. This review can broaden the perspective on the utilization of agro-industrial by-products that can compete in the market with the commercial ones or act as a source for new food ingredients.

Gabriela Vazquez-Olivo

Papers

Essential Oils of Oregano: Biological Activity beyond Their Antimicrobial Properties

Flavonoids and Phenolic Acids from Oregano: Occurrence, Biological Activity and Health Benefits

Antioxidant Capacity of Lignin and Phenolic Compounds from Corn Stover

Cellular antioxidant activity and in vitro intestinal permeability of phenolic compounds from four varieties of mango bark (Mangifera indica L.)

Prebiotic compounds from agro-industrial by-products