Advances in the phytochemical screening and biological potential of propolis

Natural antibiotics against antimicrobial resistance: sources and bioinspired delivery systems

The current burden associated to multidrug resistance, and the emerging superbugs, result in a decreased and even loss of antibiotic efficacy, which poses significant challenges in the treatment of infectious diseases. This situation has created a high demand for the discovery of novel antibiotics that are both effective and safe. However, while antibiotics play a crucial role in preventing and treating diseases, they are also associated with adverse effects. The emergence of multidrug-resistant and the extensive appearance of drug-resistant microorganisms, has become one of the major hurdles in healthcare. Addressing this problem will require the development of at least 20 new antibiotics by 2060. However, the process of designing new antibiotics is time-consuming. To overcome the spread of drug-resistant microbes and infections, constant evaluation of innovative methods and new molecules is essential. Research is actively exploring alternative strategies, such as combination therapies, new drug delivery systems, and the repurposing of existing drugs. In addition, advancements in genomic and proteomic technologies are aiding in the identification of potential new drug targets and the discovery of new antibiotic compounds. In this review, we explore new sources of natural antibiotics from plants, algae other sources, and propose innovative bioinspired delivery systems for their use as an approach to promoting responsible antibiotic use and mitigate the spread of drug-resistant microbes and infections.

3,3'-O-dimethylquercetin: A bi-functional vasodilator isolated from green propolis of the Caatinga Mimosa tenuiflora

In the search for novel, bi-functional compounds acting as CaV1.2 channel blockers and K+ channel stimulators, which represent an effective therapy for hypertension, 3,3'-O-dimethylquercetin was isolated for the first time from Brazilian Caatinga green propolis. Its effects were investigated through electrophysiological, functional, and computational approaches. In rat tail artery myocytes, 3,3'-O-dimethylquercetin blocked Ba2+ currents through CaV1.2 channels (IBa1.2) in a concentration-dependent manner, with the inhibition being reversed upon washout. The compound also shifted the voltage dependence of the steady-state inactivation curve to more negative potentials without affecting the slope of the inactivation and activation curves. Furthermore, the flavonoid stimulated KCa1.1 channel currents (IKCa1.1). In silico simulations provided additional evidence for the binding of 3,3'-O-dimethylquercetin to KCa1.1 and CaV1.2 channels and elucidated its mechanism of action. In depolarized rat tail artery rings, the flavonoid induced a concentration-dependent relaxation. Moreover, in rat aorta rings its antispasmodic effect was inversely related to the transmembrane K+ gradient. In conclusion, 3,3'-O-dimethylquercetin demonstrates effective in vitro vasodilatory properties, encouraging the exploration of its scaffold to develop novel derivatives for potential use in the treatment of hypertension.

Opportunities and challenges in using NIH's Dietary Supplement Label Database for research on non-nutrient ingredients: Use case for ingredients in honeybee products

Background

Non-nutrient bioactive ingredients of foods such as bee products are often of interest in preclinical and clinical research to explore their possible beneficial effects. The National Institute of Health's Dietary Supplement Label Database (DSLD) contains over 165,000 labels of dietary supplements marketed in the United States of America (US), including declarations on labels for many of these ingredients, including those in honeybee products which have been used in foods and traditional medicines for centuries worldwide and are now also appearing in dietary supplements.

Methods

This article presents a use case for honeybee products that describes and tests the utility of the DSLD and other databases available in the US as research tools for identifying and quantifying the prevalence of such ingredients.. It focuses on the limitations to the information on product composition in these databases and describes how to code the ingredients using the LanguaL™ or FoodEx2 description and classification systems and the strengths and limitations of information on honeybee product ingredients, including propolis, bee pollen, royal jelly, beeswax, and bee venom.

Results and Conclusions

Codes for the ingredients are provided for identifying their presence in LanguaL™ or FoodEx2 ontologies used in Europe and elsewhere. The prevalence of dietary supplement products containing these ingredients in DSLD and on the US market is low compared to some other products and ingredients. Unfortunately label declarations in DSLD do not provide quantitative information and so the data can be used only to screen for their presence, but cannot be used for quantitative exposure estimates by researchers and regulators .

Effects of caatinga propolis from Mimosa tenuiflora and its constituents (santin, sakuranetin and kaempferide) on human immune cells

ETHNOPHARMACOLOGICAL RELEVANCE

Propolis is a bee product used in folk medicine to treat inflammatory diseases. Diverse types of propolis are produced worldwide depending on the local flora. Recently, research has been focused on a propolis sample produced in the northeast Brazilian "caatinga" from Mimosa tenuiflora, popularly known as "jurema-preta".

AIM OF THE STUDY

A possible immunomodulatory/anti-inflammatory action was analyzed to verify the potential of M. tenuiflora propolis (MP) and its constituents (santin, sakuranetin and kaempferide) in human immune cells under baseline conditions or in LPS-stimulated cells.

METHODS

Cell viability, cytokine (TNF-α, IL-1β, IL-6, IL-8, IL-10) production and intracellular pathways (NF-kB and p38 MAPK) were evaluated.

RESULTS

Under basal conditions, MP and sakuranetin did not affect cytokine production; santin enhanced TNF-α, IL-1β, IL-6, while kaempferide inhibited IL-8 and IL-10. In LPS-stimulated cells, MP and its compounds exerted an inhibitory activity on TNF-α and IL-1β, while no effects were seen on IL-6 and IL-8. Santin and kaempferide inhibited IL-10 production. No significant differences were seen on NF-kB and p38 MAPK intracellular pathways.

CONCLUSION

Data indicated the immunomodulatory action of caatinga propolis and its constituents at noncytotoxic concentrations, specifically an anti-inflammatory activity in LPS-treated cells by inhibiting cytokine production. Santin, sakuranetin and kaempferide appeared to be involved in MP activities.