Effect of flavonol derivatives on the carrageenin-induced paw edema in the rat and inhibition of cyclooxygenase-1 and 5-lipoxygenase in vitro

Neuroprotective Potential of Flavonoids in Brain Disorders

Flavonoids are a large subgroup of polyphenols known to be sourced from over 6000 natural products, including fruits, vegetables, bark, and herbs. Due to their antioxidant properties, flavonoids have been implicated as a therapy source for many diseases and conditions, including inflammation, vasculitis, venous insufficiency, and hemorrhoids. Currently, some flavonoids are being researched for their antioxidant ability concerning neuroprotection. These flavonoids can penetrate the blood-brain barrier and, depending on the specific flavonoid, retain adequate bioavailability in certain brain regions. Further data suggest that flavonoids could have a strong anti-inflammatory effect in the brain, which not only could be a robust therapeutic source for known neuroinflammatory diseases such as Alzheimer's Disease or Parkinson's Disease but also could be a therapeutic source for ischemic or hemorrhagic conditions such as a stroke. While flavonoid toxicity exists, they are relatively safe and non-invasive drugs from natural origins. As such, exploring the known mechanisms and therapies may highlight and establish flavonoid therapy as a viable source of therapy for stroke patients. As stated, many flavonoids are already being isolated, purified, and implemented in both in vitro and in vivo experiments. As these flavonoids proceed to clinical trials, it will be important to understand how they function as a therapy, primarily as antioxidants, and by other secondary mechanisms. This review aims to elucidate those mechanisms and explore the neuroprotective role of flavonoids.

Potential Benefits of Flavonoids on the Progression of Atherosclerosis by Their Effect on Vascular Smooth Muscle Excitability

Flavonoids are a group of secondary metabolites derived from plant-based foods, and they offer many health benefits in different stages of several diseases. This review will focus on their effects on ion channels expressed in vascular smooth muscle during atherosclerosis. Since ion channels can be regulated by redox potential, it is expected that during the onset of oxidative stress-related diseases, ion channels present changes in their conductive activity, impacting the progression of the disease. A typical oxidative stress-related condition is atherosclerosis, which involves the dysfunction of vascular smooth muscle. We aim to present the state of the art on how redox potential affects vascular smooth muscle ion channel function and summarize if the benefits observed in this disease by using flavonoids involve restoring the ion channel activity.

Anti-inflammatory Activity of Natural Geranylated Flavonoids: Cyclooxygenase and Lipoxygenase Inhibitory Properties and Proteomic Analysis

Geranyl flavones have been studied as compounds that potentially can be developed as anti-inflammatory agents. A series of natural geranylated flavanones was isolated from Paulownia tomentosa fruits, and these compounds were studied for their anti-inflammatory activity and possible mechanism of action. Two new compounds were characterized [paulownione C (17) and tomentodiplacone O (20)], and all of the isolated derivatives were assayed for their ability to inhibit cyclooxygenases (COX-1 and COX-2) and 5-lipoxygenase (5-LOX). The compounds tested showed variable degrees of activity, with several of them showing activity comparable to or greater than the standards used in COX-1, COX-2, and 5-LOX assays. However, only the compound tomentodiplacone O (20) showed more selectivity against COX-2 versus COX-1 when compared with ibuprofen. The ability of the test compounds to interact with the above-mentioned enzymes was supported by docking studies, which revealed the possible incorporation of selected test substances into the active sites of these enzymes. Furthermore, one of the COX/LOX dual inhibitors, diplacone (14) (a major geranylated flavanone of P. tomentosa), was studied in vitro to obtain a proteomic overview of its effect on inflammation in LPS-treated THP-1 macrophages, supporting its previously observed anti-inflammatory activity and revealing the mechanism of its anti-inflammatory effect.

3-Hy-droxy-2-(4-meth-oxy-phen-yl)-4H-chromen-4-one

In the title compound, C₁₆H₁₂O₄, the benzene ring is twisted at an angle of 12.3 (1)° relative to the 4H-chromene skeleton, and an intramolecular O—H⋯O hydrogen bond occurs. The meth­oxy group is almost coplanar with the benzene ring [1.5 (1)°]. In the crystal, inversely oriented mol­ecules are arranged in double (A, A′) columns, along the b axis, and are linked by a network of inter­molecular O—H⋯O hydrogen bonds (between A and A′) and C—H⋯π contacts (within A or A′). The 4H-chromene cores are parallel within A or A′, but make a dihedral angle of 88.6 (1)° between A and A′.

3-Hy-droxy-2-(4-hy-droxy-phen-yl)-4H-chromen-4-one

In the title compound, C₁₅H₁₀O₄, the benzene ring is twisted at an angle of 20.7 (1)° relative to the 4H-chromene skeleton. In the crystal, adjacent mol­ecules are linked via a network of O—H⋯O and C—H⋯O hydrogen bonds. The mean planes of adjacent 4H-chromene moieties are parallel or oriented at an angle of 20.9 (1)° in the crystal structure.

Evaluation of antirotavirus activity of flavonoids

Flavonoids are dietary components and the most ubiquitous phenolic compounds found in nature, showing a range of pharmacological activities including antiviral action. This study describes the antiviral screening of 60 different flavones and flavonols against human rotavirus (Wa-1 strain) as well as their cytotoxicity in MA104 cells. Cytotoxicity was investigated by cell morphology assessment and antirotavirus activity by cytopathic effect inhibition. Results were expressed as CC₅₀ and IC₅₀, respectively, in order to calculate the selectivity index (SI = CC₅₀/IC₅₀) of each compound. Structure–activity relationships (SAR) were proposed based on antirotavirus activity.

Quercetin does not alter lipopolysaccharide-induced fever in rats

Fever is considered an important component of the acute phase response of the body in defence against invading organisms such as bacteria. Quercetin, an important representative of the flavonoid class, has been extensively studied as an anti-inflammatory agent. In the present study, we investigated the effect of quercetin, administered orally (5, 25 and 50 mg kg−1) or intraperitoneally (50 mg kg−1), on the febrile response induced by either intraperitoneally (50 μg kg−1) or intravenously (5 μg kg−1) injected lipopolysaccharide (LPS from Escherichia coli) in rats. In contrast with the well known anti-inflammatory activity of quercetin, the results demonstrate that quercetin, at the doses used, did not alter the fever induced by LPS, regardless of the route of administration.

Synthesis of the flavonoid 3',4',5'-trimethoxyflavonol and its determination in plasma and tissues of mice by HPLC with fluorescence detection

3',4',5'-Trimethoxyflavonol (TMFol) was synthesized as a potential colorectal cancer chemopreventive agent. An HPLC method for determination for TMFol in murine plasma and tissues was developed and validated using human plasma. Analyte was separated (C(18) column; fluorescence detection 330nm excitation, 440nm emission) using 69% methanol and 0.1M ammonium acetate buffer (pH 5.1) as mobile phase. The method was linear for 50-2500ng/ml plasma and 0.05-10microg/g tissue (r>0.99). TMFol was recovered from plasma or tissues using solid phase columns or organic solvent protein precipitation, respectively. Recovery at low, medium and high concentrations was 97.6-107.3%, with inter- and intra-day coefficients of variation of <10%. The lower limit of quantitation for plasma was 50ng/ml. The method was applied to measure steady-state TMFol plasma and tissue levels in mice which received dietary TMFol (0.2%).

Passiflora alata and Passiflora edulis spray-dried aqueous extracts inhibit inflammation in mouse model of pleurisy

The aqueous leaves extracts of Passiflora alata (100-300 mg/kg, i.p.) and Passiflora edulis (100-1000 mg/kg, i.p.) possess a significant antiinflammatory activity on carrageenan-induced pleurisy in mice. Treatment with the extracts inhibited leukocyte migration and reduced the formation of exudate. Moreover, a significant inhibition of myeloperoxidase and adenosine-deaminase activities was observed at the doses tested (100 or 250 mg/kg, i.p.). At the same doses, a significant decrease of serum C-reactive protein was observed.