Characterization and Pharmacokinetic Assessment of a New Berberine Formulation with Enhanced Absorption In Vitro and in Human Volunteers

Berberine is a plant-origin quaternary isoquinoline alkaloid with a vast array of biological activities, including antioxidant and blood-glucose- and blood-lipid-lowering effects. However, its therapeutic potential is largely limited by its poor oral bioavailability. The aim of this study was to investigate the in vitro solubility and Caco-2 cell permeability followed by pharmacokinetic profiling in healthy volunteers of a new food-grade berberine delivery system (i.e., Berberine LipoMicel®). X-ray diffractometry (XRD), in vitro solubility, and Caco-2 cell permeability indicated higher bioavailability of LipoMicel Berberine (LMB) compared to the standard formulation. Increased aqueous solubility (up to 1.4-fold), as well as improved Caco-2 cell permeability of LMB (7.18 × 10-5 ± 7.89 × 10-6 cm/s), were observed when compared to standard/unformulated berberine (4.93 × 10-6 ± 4.28 × 10-7 cm/s). Demonstrating better uptake, LMB achieved significant increases in AUC0-24 and Cmax compared to the standard formulation (AUC: 78.2 ± 14.4 ng h/mL vs. 13.4 ± 1.97 ng h/mL, respectively; p < 0.05; Cmax: 15.8 ± 2.6 ng/mL vs. 1.67 ± 0.41 ng/mL) in a pilot study of healthy volunteers (n = 10). No adverse reactions were reported during the study period. In conclusion, LMB presents a highly bioavailable formula with superior absorption (up to six-fold) compared to standard berberine formulation and may, therefore, have the potential to improve the therapeutic efficacy of berberine. The study has been registered on ClinicalTrials.gov with Identifier NCT05370261.

A Pharmacokinetic Study of Different Quercetin Formulations in Healthy Participants: A Diet-Controlled, Crossover, Single- and Multiple-Dose Pilot Study

This study aimed to evaluate the blood concentrations of quercetin in healthy participants after the administration of different formulations in single- and multiple-dose phases. Ten healthy adults (males, 5; females, 5; age 37 ± 11 years) participated in a diet-controlled, crossover pilot study. Participants received three different doses (250 mg, 500 mg, or 1000 mg) of quercetin aglycone orally. In the single-dose study, blood concentrations (AUC0-24 and Cmax) of standard quercetin were compared with those of LipoMicel®-a food-grade delivery form of quercetin. In the multiple-dose study, blood concentrations of formulated quercetin were observed over 72 h, after repeated doses of LipoMicel (LM) treatments. The AUC0-24 ranged from 77.3 to 1128.9 ng·h/ml: LM significantly increased blood concentrations of quercetin by 7-fold (LM 500) compared to standard quercetin, when tested at the same dose, over 24 h (p < 0.001); LM administered at a higher dose (LM 1000) achieved 15-fold higher absorption (p < 0.001); LM tested at half a dose of standard quercetin increased concentration by approx. 3-fold (LM 250). Quercetin blood concentrations were attained over 72 h. The major metabolites measured in the blood were methylated, sulfate, and glutathione (GSH) conjugates of quercetin. Significant differences in concentrations between quercetin conjugates (sulfate vs. methyl vs. GSH) were observed (p < 0.001). Data obtained from this study suggest that supplementation with LipoMicel® is a promising strategy to increase the absorption of quercetin and its health-promoting effects in humans. However, due to the low sample size in this pilot study, further research is still warranted to confirm the observations in larger populations. This trial is registered with NCT05611827.

Consideration for Flavonoid-Containing Dietary Supplements to Tackle Deficiency and Optimize Health

Randomized clinical trials (RCT) and observational studies have highlighted the importance of flavonoid consumption for human health. Several studies have associated a high intake of dietary flavonoids with (a) enhanced metabolic and cardiovascular health, (b) enhanced cognitive and vascular endothelial functions, (c) an improved glycemic response in type 2 diabetes mellitus, and (d) a reduced risk of breast cancer in postmenopausal women. Since flavonoids belong to a broad and diverse family of polyphenolic plant molecules-with more than 6000 compounds interspersed in the human diet-researchers are still uncertain whether the intake of single, individual polyphenols or a large combination of them (i.e., synergistic action) can produce the greatest health benefits for humans. Furthermore, studies have reported a poor bioavailability of flavonoid compounds in humans, which presents a major challenge for determining their optimal dosage, recommended intake, and, consequently, their therapeutic value. Especially because of their scarce bioavailability from foods-along with the overall declining food quality and nutrient density in foods-the role of flavonoid supplementation may become increasingly important for human health. Although research shows that dietary supplements can be a highly useful tool to complement diets that lack sufficient amounts of important nutrients, some caution is warranted regarding possible interactions with prescription and non-prescription drugs, especially when taken concurrently. Herein, we discuss the current scientific basis for using flavonoid supplementation to improve health as well as the limitations related to high intakes of dietary flavonoids.

A Multi-Pronged Technique for Identifying Equisetum palustre and Equisetum arvense—Combining HPTLC, HPLC-ESI-MS/MS and Optimized DNA Barcoding Techniques

The most prominent horsetail species, Equisetum arvense, has an array of different medicinal properties, thus the proper authentication and differentiation of the plant from the more toxic Equisetum palustre is important. This study sought to identify different samples of E. arvense and E. palustre using three analytical methods. The first method involved the use of HPTLC analysis, as proposed by the European Pharmacopoeia. The second, HPLC-ESI-MS/MS, is capable of both identification and quantification and was used to determine the Equisetum alkaloid content in each sample. A third method was DNA barcoding, which identifies the samples based on their genetic make-up. Both HPTLC and HPLC-ESI-MS/MS proved to be suitable methods of identification, with HPLC-ESI-MS/MS proving the more sophisticated method for the quantification of alkaloids in the Equisetum samples and for determining the adulteration of E. arvense. For DNA barcoding, optimal primer pairs were elucidated to allow for the combined use of the rbcL and ITS markers to accurately identify each species. As new DNA marker sequences were added to GenBank, the reference library has been enriched for future work with these horsetail species.

Efflux Pump Inhibition and Resistance Modulation in Mycobacterium smegmatis by Peucedanum ostruthium and Its Coumarins

Antibiotic resistance is a growing problem and may become the next major global health crisis if no timely actions are taken. Mycobacterial infections are widespread and, due to antibiotic resistance, also hard to treat and a major cause of mortality. Natural compounds have the potential to increase antibiotic effectiveness due to their resistance modulatory and antimicrobial effects. In this study, Peucedanum ostruthium extracts, fractions, and isolated compounds were investigated regarding their antimicrobial and resistance-modulatory effects as well as efflux pump inhibition in Mycobacterium smegmatis.&nbsp;P. ostruthium extracts were found to have anti-mycobacterial potential and resistance modulating effects on ethidium bromide activity. The major antibacterial effect was attributed to ostruthin, and we found that the more lipophilic the substrate, the greater the antimicrobial effect. Imperatorin caused potent modulatory effects by interfering with the action of the major LfrA efflux pump in M. smegmatis. The plant P. ostruthuim has a complex effect on M. smegmatis, including antibacterial, efflux pump inhibition, resistance modulation, and membrane permeabilization, and its major constituents, ostruthin and imperatorin, have a distinct role in these effects. This makes P. ostruthium and its coumarins promising therapeutics to consider in the fight against drug-resistant mycobacteria.

Flavonoids: A complementary approach to conventional therapy of COVID-19?

COVID-19, the highly contagious novel disease caused by SARS-CoV-2, has become a major international concern as it has spread quickly all over the globe. However, scientific knowledge and therapeutic treatment options for this new coronavirus remain limited. Although previous outbreaks of human coronaviruses (CoVs) such as SARS and MERS stimulated research, there are, to date, no antiviral therapeutics available that specifically target these kinds of viruses. Natural compounds with a great diversity of chemical structures may provide an alternative approach for the discovery of new antivirals. In fact, numerous flavonoids were found to have antiviral effects against SARS-and MERS-CoV by mainly inhibiting the enzymes 3-chymotrypsin-like protease (3CLpro) and papain-like protease (PLpro). In this review, we specifically focused on the search for flavonoids, polyphenolic compounds, which are proven to be effective against human CoVs. We therefore summarized and analyzed the latest progress in research to identify flavonoids for antiviral therapy and proposed strategies for future work on medicinal plants against coronaviruses such as SARS-CoV-2. We discovered quercetin, herbacetin, and isobavachalcone as the most promising flavonoids with anti-CoV potential.

Palladium-catalysed synthesis of arylnaphthoquinones as antiprotozoal and antimycobacterial agents

Malaria and tuberculosis are still among the leading causes of death in low-income countries. The 1,4-naphthoquinone (NQ) scaffold can be found in a variety of anti-infective agents. Herein, we report an optimised, high yield process for the preparation of various 2-arylnaphthoquinones by a palladium-catalysed Suzuki reaction. All synthesised compounds were evaluated for their in-vitro antiprotozoal and antimycobacterial activity. Antiprotozoal activity was assessed against Plasmodium falciparum (P.f.) NF54 and Trypanosoma brucei rhodesiense (T.b.r.) STIB900, and antimycobacterial activity against Mycobacterium smegmatis (M.s.) mc² 155. Substitution with pyridine and pyrimidine rings significantly increased antiplasmodial potency of our compounds. The 2-aryl-NQs exhibited trypanocidal activity in the nM range with a very favourable selectivity profile. (Pseudo)halogenated aryl-NQs were found to have a pronounced effect indicating inhibition of mycobacterial efflux pumps. Cytotoxicity of all compounds towards L6 cells was evaluated and the respective selectivity indices (SI) were calculated. In addition, the physicochemical parameters of the synthesised compounds were discussed.

Antimicrobial and Efflux Pump Inhibitory Activity of Carvotacetones from Sphaeranthus africanus Against Mycobacteria

Carvotacetones (1-7) isolated from Sphaeranthus africanus were screened for their antimycobacterial and efflux pump (EP) inhibitory potential against the mycobacterial model strains Mycobacterium smegmatis mc2 155, Mycobacterium aurum ATCC 23366, and Mycobacterium bovis BCG ATCC 35734. The minimum inhibitory concentrations (MICs) of the carvotacetones were detected through high-throughput spot culture growth inhibition (HT-SPOTi) and microbroth dilution assays. In order to assess the potential of the compounds 1 and 6 to accumulate ethidium bromide (EtBr) in M. smegmatis and M. aurum, a microtiter plate-based fluorometric assay was used to determine efflux activity. Compounds 1 and 6 were analyzed for their modulating effects on the MIC of EtBr and the antibiotic rifampicin (RIF) against M. smegmatis. Carvotacetones 1 and 6 had potent antibacterial effects on M. aurum and M. bovis BCG (MIC ≤ 31.25 mg/L) and could successfully enhance EtBr activity against M. smegmatis. Compound 1 appeared as the most efficient agent for impairing the efflux mechanism in M. smegmatis. Both compounds 1 and 6 were highly effective against M. aurum and M. bovis BCG. In particular, compound 1 was identified as a valuable candidate for inhibiting mycobacterial efflux mechanisms and as a promising adjuvant in the therapy of tuberculosis or other non-tubercular mycobacterial infections.