Concomitant Effect of Quercetin- and Magnesium-Doped Calcium Silicate on the Osteogenic and Antibacterial Activity of Scaffolds for Bone Regeneration

Quercetin is a bioflavonoid which has a broad spectrum of biological activity. Due to its lower chemical stability, it is usually encapsulated, or a metal–quercetin complex is formed to enhance its biological activity at a lower concentration. Here, our novel approach was to form a quercetin complex to magnesium-doped calcium silicate (CMS) ceramics through a coprecipitation technique so as to take advantage of quercetin’s antibacterial activity within the antibacterial and osteogenic potential of the silicate. Due to quercetin’s inherent metal-chelating ability, (Ca+Mg)/Si increased with quercetin concentration. Quercetin in magnesium-doped calcium silicate ceramic showed concentration-dependent pro-oxidant and antioxidant activity in SaOS-2 with respect to quercetin concentration. By optimizing the relative concentration, we were able to achieve 3-fold higher proliferation and 1.6-fold higher total collagen at day 14, and a 1.7-fold higher alkaline phosphatase production at day 7 with respect to polycaprolactone/polyvinylpyrrolidone (PCL/PVP) scaffold. Quercetin is effective against Gram-positive bacteria such as S. aureus. Quercetin is coupled with CMS provided similar effect with lower quercetin concentration than quercetin alone. Quercetin reduced bacterial adhesion, proliferation and biofilm formation. Therefore, quercetin-coupled magnesium-doped calcium silicate not only enhanced osteogenic potential, but also reduced bacterial adhesion and proliferation.

Control of Gene Expression With Quercetin-Responsive Modular Circuits

Control of gene expression is crucial for several biotechnological applications, especially for implementing predictable and controllable genetic circuits. Such circuits are often implemented with a transcriptional regulator activated by a specific signal. These regulators should work independently of the host machinery, with low gratuitous induction or crosstalk with host components. Moreover, the signal should also be orthogonal, recognized only by the regulator with minimal interference with the host operation. In this context, transcriptional regulators activated by plant metabolites as flavonoids emerge as candidates to control gene expression in bacteria. However, engineering novel circuits requires the characterization of the genetic parts (e.g., genes, promoters, ribosome binding sites, and terminators) in the host of interest. Therefore, we decomposed the QdoR regulatory system of B. subtilis, responsive to the flavonoid quercetin, and reassembled its parts into genetic circuits programmed to have different levels of gene expression and noise dependent on the concentration of quercetin. We showed that only one of the promoters regulated by QdoR worked well in E. coli, enabling the construction of other circuits induced by quercetin. The QdoR expression was modulated with constitutive promoters of different transcriptional strengths, leading to low expression levels when QdoR was highly expressed and vice versa. E. coli strains expressing high and low levels of QdoR were mixed and induced with the same quercetin concentration, resulting in two stable populations expressing different levels of their gene reporters. Besides, we demonstrated that the level of QdoR repression generated different noise levels in gene expression dependent on the concentration of quercetin. The circuits presented here can be exploited in applications requiring adjustment of gene expression and noise using a highly available and natural inducer as quercetin.

EVALUATION OF ANTIOXIDANT AND ANTIFUNGAL PROPERTIES OF PALU SHALLOT (Allium ascalonicum L VAR. Aggregatum)

Shallot is one of the typical plants at Palu, Central Sulawesi, Indonesia, famous by local people as fried Shallot. It is used as a cooking spice and traditional medicine for treating various diseases. This study was carried out to assess the phytochemical constituent including total phenolics, total flavonoids, and quercetin content of the Palu shallot (Allium ascalonicum L var. aggregatum), and to determine the antifungal and antioxidant properties of this plant ethanolic extract. Total phenolics/ flavonoids and quercetin concentration were determined by spectrophotometry UV-Vis and Reverse Phase - High-Performance Liquid Chromatography (RP-HPLC) methods. Antifungal activity and antioxidant capacity of the ethanolic extract was assayed by using diffusion agar and 2,2-diphenyl-1-picrylhydrazyl (DPPH) methods. Results of the study revealed that the total flavonoids content of the ethanolic extract was 0.3634 ± 0.018 mg QE/100 mg while total phenolics content was 0.4834 ± 0.003 mg GAE/100 mg. Meanwhile, the quercetin content was 65.46±0.0002 mg/kg. Further, ethanolic extract of Palu shallot also showed the radical scavenging activity with IC50 of 0.1398 mg/mL and growth inhibition on Candida albicans with inhibitory zone diameter range from 7.57 to 16.51 mm. This study confirms the high quality of Palu shallot as it has high total flavonoids, represented by the high quercetin concentration, and it is proposed to be a source for an antioxidant and antifungal medicinal herb.

Penetapan Kadar Flavonoid Total Ekstrak Etanol Biji Pinang (Areca catechu L.) Menggunakan Metode AlCl3

Pinang merupakan tanaman yang banyak tersedia di Indonesia dan memiliki berbagai manfaat. Pemanfaatan air rebusan biji pinang digunakan masyarakat dalam membersihkan dan menyembuhkan luka infeksi. Biji pinang mengandung senyawa fenolik seperti flavonoid, tannin, asam galat, katekin, beta-sitosterol, gum dan asam amino. Biji pinang dilakukan purifikasi untuk mengilangkan zat ballast yang tidak dibutuhkan. Penelitian ini bertujuan untuk menetapkan kadar flavonoid total ekstrak kasar dan ekstrak terpurifikasi. Metode yang digunakan dalam penetapan kadar adalah metode kolorimetri AlCl3. Penetapan kadar flavonoid dilakukan pada panjang gelombang 413,5 nm dengan standar baku pembanding kuersetin. Plot hubungan antara konsentrasi kuersetin versus absorbansi diperoleh persamaan kurva baku sebesar y = 0,0088x – 0,17 dengan nilai R2 sebesar 0,9998. Uji kualitatif menunjukkan ekstrak biji pinang tanpa purifikasi, dengan perlakuan purifikasi n-heksan dan etil asetat mengandung metabolit sekunder diantaranya flavonoid, saponin, tannin dan fenol. Purifikasi pelarut n-heksan didapatkan hasil rendemen lebih banyak dibandingkan ekstrak yang dipurifikasi dengan pelarut etil asetat. Kadar flavonoid ekstrak tanpa purifikasi, ekstrak purifikasi pelarut n-heksan dan etil asetat berturut – turut sebesar 69,13 ; 130,3 ; dan 94,73 mgQE/g. Hal tersebut sebanding dengan perolehan % rendemen tertinggi diperoleh dari ekstrak terpurifikasi n-heksan. Purifikasi pada ekstrak akan menyebabkan hilangnya zat ballast dalam ekstrak sehingga kandungan flavonoid pada ekstrak akan lebih tinggi.Kata kunci : flavonoid, metode AlCl3, ekstrak, purifikasiAreca nut is a plant that is widely available in Indonesia and has various benefits. Utilization of boiled betel nut water is used by the community to clean and heal infected wounds. Betel nuts contain phenolic compounds such as flavonoids, tannins, gallic acid, catechins, beta-sitosterol, gum, and amino acids. Areca seeds are purified to remove unnecessary ballast substances. This study aims to determine the total flavonoid levels of crude extract and purified extract. The method used in the assay is the AlCl3 colorimetric method. Determination of flavonoid levels was carried out at a wavelength of 413.5 nm with a quercetin standard. The plot of the relationship between quercetin concentration versus absorbance obtained a standard curve equation of y = 0.0088x - 0.17 with an R2 value of 0.9998. The qualitative test showed that betel nut extract without purification, with purification treatment of n-hexane and ethyl acetate, contained secondary metabolites including flavonoids, saponins, tannins, and phenols. The purification of the n-hexane solvent obtained more yields than the extract purified with ethyl acetate solvent. The flavonoid levels of the extract without purification, the purified extract of n-hexane and ethyl acetate were 69.13; 130.3; and 94.73 mg QE / g. This is comparable to the highest% yield obtained from purified extracts of n-hexane. Purification of the extract will cause the loss of ballast substances in the extract so that the flavonoid content in the extract will be higher.Keywords: flavonoids, AlCl3 method, extract, purification

Potential of Quercetin to Reduce Herbivory without Disrupting Natural Enemies and Pollinators

Quercetin is one of the most abundant flavonoids in terrestrial plants and pollen. In living plants, quercetin can function as a secondary metabolite to discourage insect herbivory. Literature on insect-quercetin interactions was searched and data synthesized to test the hypothesis that quercetin can become an effective biocide to reduce herbivory without disrupting natural enemies and pollinators. The USDA, National Agricultural Library, DigiTop Navigator platform was used to search the literature for harmful versus nonharmful effects of quercetin on insect behavior, physiology, and life history parameters. Quercetin effects were evaluated on herbivores in five insect orders, natural enemies in two orders, and pollinators in one order. Quercetin was significantly more harmful to Hemiptera, Diptera, and Lepidoptera but significantly more nonharmful to Coleoptera. Harmful and nonharmful effects to Orthoptera were indistinguishable. Quercetin had significantly more harmful (than nonharmful) effects on herbivores when data from the five insect orders were combined. Quercetin concentration (mg/mL) did not significantly affect these results. Quercetin was significantly more nonharmful to natural enemies (Coleoptera and Hymenoptera, combined) and pollinators (Hymenoptera). This study suggests that quercetin could prevent herbivory without disrupting natural enemies and pollinators, but field experiments are necessary to substantiate these results.

Honeybee Pollen Extracts Reduce Oxidative Stress and Steatosis in Hepatic Cells

Nonalcoholic fatty liver disease (NAFLD) is a major cause of morbidity and mortality worldwide. Additional therapies using functional foods and dietary supplements have been investigated and used in clinical practice, showing them to be beneficial. Honeybee pollen from Chile has shown a large concentration of phenolic compounds and high antioxidant activity. In this work, we characterized twenty-eight bee pollen extracts from the central zone of Chile according to botanical origin, phenolic profile, quercetin concentration, and antioxidant activity (FRAP and ORAC-FL). Our results show a statistically significant positive correlation between total phenolic content and antioxidant capacity. Selected samples were evaluated on the ability to reverse the steatosis in an in vitro cell model using Hepa1-6 cells. The pollen extracts protected Hepa1-6 cells against oxidative damage triggered by 2,2′-azo-bis(2-amidinopropane) dihydrochloride (AAPH)derived free radicals. This effect can be credited to the ability of the phenolic compounds present in the extract to protect the liver cells from chemical-induced injury, which might be correlated to their free radical scavenging potential. Additionally, bee pollen extracts reduce lipid accumulation in a cellular model of steatosis. In summary, our results support the antioxidant, hepatoprotective, and anti-steatosis effect of bee pollen in an in vitro model.

Concentrations of Phenolic Acids, Flavonoids and Carotenoids and the Antioxidant Activity of the Grain, Flour and Bran of Triticum polonicum as Compared with Three Cultivated Wheat Species

The experiment was performed on 66 breeding lines of Triticum polonicum, four T. durum cultivars, four T. aestivum cultivars, and one T. turanicum cultivar (Kamut® wheat). Wheat grain, bran, and flour were analyzed to determine the concentrations of carotenoids, free and bound phenolic acids, and flavonoids, as well as antioxidant activity in the ABTS+ assay. The total concentrations of lutein, zeaxanthin, and β-carotene in grain and milling fractions were determined at 3.17, 2.49, and 3.16 mg kg−1 in T. polonicum (in grain, flour, and bran, respectively), and at 4.84, 3.56, and 4.30 mg kg−1 in T. durum, respectively. Polish wheat grain was characterized by high concentrations of p-coumaric acid and syringic acid (9.4 and 41.0 mg kg−1, respectively) and a low content of 4-hydroxybenzoic acid (65.2 mg kg−1). Kamut® wheat (T. turanicum) which is closely related to T. polonicum was particularly abundant in 4-hydroxybenzoic, chlorogenic, ferulic, gallic, and t-cinnamic acids. The studied Triticum species did not differ considerably in the concentrations of the eight analyzed flavonoids, and significant differences were noted only in rutin levels. The grain and milling fractions of Kamut® wheat were characterized by very high concentrations of quercetin, naringenin, and vitexin, but significant differences were observed only in vitexin content. Quercetin concentration in Kamut® wheat grain (104.8 mg kg−1) was more than five times higher than in bread wheat (19.6 mg kg−1) and more than twice higher than in Polish wheat (44.1 mg kg−1). Antioxidant activity was highest in bran, followed by grain and flour (4684, 1591, and 813 μM TE g−1, respectively). The grain and flour of the analyzed Triticum species did not differ significantly in terms of antioxidant activity.

Organic and conventional apple fermented by Saccharomyces boulardii – The effect of the antioxidant quercetin on cellular oxidative stress

PurposeThe objective of this study was to evaluate the influence of Saccharomyces boulardii on the kinetics of fermentation for organic and conventional apple pulp and to verify the effect of the antioxidant quercetin on the response to cellular oxidative stress.Design/methodology/approachThe kinetic parameters, the content of phenolic compounds, the quantity of quercetin and the antioxidant activity were determined during the fermentation process. The effect of quercetin on cellular oxidative stress was also investigated.FindingsThe content of phenolic compounds, the antioxidant activity and the quercetin concentration were higher in the organic fermented apple pulp (ORG) than in the conventional fermented apple pulp (CON). However, both apple pulps were considered ideal substrates for the growth of S. boulardii, suggesting that they are potentially probiotic. After fermentation, the quercetin concentration in the ORG treatment and YPDQ treatment (YPD broth with 0.1 mg quercetin rhamnoside/mL) increased viability by 9%, while in the CON treatment generated there was an increase of 6% in viability, compared to the YPD control treatment (YPD broth).Originality/valueThe high concentration of quercetin in the organic apple pulp supports the proposal that quercetin reduces the oxidative stress mediated by reactive oxygen species through its antioxidant action on S. boulardii that have similarities to mammalian eukaryotic cells. These findings suggest that fermented organic apple pulp could be consumed as a potential non-dairy probiotic product.

STANDARDIZATION AND STABILITY EVALUATION OF DRY EXTRACTS OF MYRACRODRUON URUNDEUVA ALLEMÃO OBTAINED BY SPRAY DRIER

<p><strong>Objective</strong>:<strong> </strong>This study aimed to obtain standardised dry extracts of <em>Miracrodruon urundeuva </em>Allemão using spray-dryer and evaluate the stability of the extracts.</p><p><strong>Methods</strong>:<strong> </strong>It evaluated the drying parameters: Proportion of colloidal silicon dioxide (CSD) (10, 15 and 20%), inlet temperature (160, 170 and 180 °C) and feed rate (4, 6 and 8 ml/min). The study of the accelerated stability of dry extract occurred in temperature of 40 °C (±2 °C) and relative humidity of 75% (±5%) for 6 mo. The anti-inflammatory activity of the dry extract was evaluated in Swiss mice by the paw edema method.</p><p><strong>Results</strong>:<strong> </strong>Variations in drying conditions did not represent significant variations in yields of the process. The drying temperature and feed rate significantly influenced the concentration of quercetin (p≤0.05). The increase in inlet temperature and feed flow promoted the increase of quercetin concentration in the extracts. The stability study showed that the concentration of quercetin in dry extract was stable over a period of 6 mo. The dry extract showed anti-inflammatory activity in mice orally.</p><p><strong>Conclusion</strong>:<strong> </strong>A condition of 10% of colloidal silicon dioxide with an 180 °C inlet temperature and a feed rate of 8 ml/min was considered the most adequate for obtaining the extracts and the drying process resulted in stable dry extracts and the quercetin was a suitable biomarker for monitoring the process.</p>