Cell-Based Phenotypic Drug Screening Identifies Luteolin as Candidate Therapeutic for Nephropathic Cystinosis.

BACKGROUND: Mutations in the gene that encodes the lysosomal cystine transporter cystinosin cause the lysosomal storage disease cystinosis. Defective cystine transport leads to intralysosomal accumulation and crystallization of cystine. The most severe phenotype, nephropathic cystinosis, manifests during the first months of life, as renal Fanconi syndrome. The cystine-depleting agent cysteamine significantly delays symptoms, but it cannot prevent progression to ESKD and does not treat Fanconi syndrome. This suggests the involvement of pathways in nephropathic cystinosis that are unrelated to lysosomal cystine accumulation. Recent data indicate that one such potential pathway, lysosome-mediated degradation of autophagy cargoes, is compromised in cystinosis. METHODS: To identify drugs that reduce levels of the autophagy-related protein p62/SQSTM1 in cystinotic proximal tubular epithelial cells, we performed a high-throughput screening on the basis of an in-cell ELISA assay. We then tested a promising candidate in cells derived from patients with, and mouse models of, cystinosis, and in preclinical studies in cystinotic zebrafish. RESULTS: Of 46 compounds identified as reducing p62/SQSTM1 levels in cystinotic cells, we selected luteolin on the basis of its efficacy, safety profile, and similarity to genistein, which we previously showed to ameliorate other lysosomal abnormalities of cystinotic cells. Our data show that luteolin improves the autophagy-lysosome degradative pathway, is a powerful antioxidant, and has antiapoptotic properties. Moreover, luteolin stimulates endocytosis and improves the expression of the endocytic receptor megalin. CONCLUSIONS: Our data show that luteolin improves defective pathways of cystinosis and has a good safety profile, and thus has potential as a treatment for nephropathic cystinosis and other renal lysosomal storage diseases.

Luteolin attenuates doxorubicin-induced cytotoxicity to MCF-7 human breast cancer cells.

Luteolin, a flavone found in some vegetables, has been reported to exhibit antioxidant, antiinflammatory, and anticancer activities. In the present study, we found that luteolin has biphasic effects on the viability of the human breast cancer cell line MCF-7. That is, cell viability increased at relatively low luteolin concentrations and decreased at relatively high concentrations. Focusing on the proliferative effect at low concentrations, we showed that luteolin has a cytoprotective effect on MCF-7 cells when administered with doxorubicin. Moreover, luteolin attenuated doxorubicin-induced cytotoxicity even in the presence of the estrogen receptor (ER) antagonist ICI 182,780 and the ER-negative MDA-MB-453 human breast cancer cell line. Reactive oxygen species (ROS) were generated after doxorubicin treatment of MCF-7 cells. In contrast, luteolin attenuated doxorubicin-induced ROS generation. Levels of the antiapoptotic protein Bcl-2 in luteolin-treated MCF-7 cells were significantly higher than those in doxorubicin-treated MCF-7 cells. Our results suggest that a low concentration of luteolin attenuates doxorubicin-induced cytotoxicity to MCF-7 cells through a combination of antioxidant activity and an increase in levels of Bcl-2 protein.

Endocrine disrupting activities of the flavonoid nutraceuticals luteolin and quercetin.

Dietary plant flavonoids have been proposed to contribute to cancer prevention, neuroprotection, and cardiovascular health through their anti-oxidant, anti-inflammatory, pro-apoptotic, and antiproliferative activities. As a consequence, flavonoid supplements are aggressively marketed by the nutraceutical industry for many purposes, including pediatric applications, despite inadequate understanding of their value and drawbacks. We show that two flavonoids, luteolin and quercetin, are promiscuous endocrine disruptors. These flavonoids display progesterone antagonist activity beneficial in a breast cancer model but deleterious in an endometrial cancer model. Concurrently, luteolin possesses potent estrogen agonist activity while quercetin is considerably less effective. These results highlight the promise and peril of flavonoid nutraceuticals and suggest caution in supplementation beyond levels attained in a healthy, plant-rich diet.

An open-label pilot study of a formulation containing the anti-inflammatory flavonoid luteolin and its effects on behavior in children with autism spectrum disorders.

BACKGROUND: Accumulating evidence suggests an association between autism spectrum disorders (ASD) and inflammation in brain regions related to cognitive function. The natural flavonoid luteolin has antioxidant, anti-inflammatory, mast cell-blocking, and neuroprotective effects. It was shown to improve cognitive performance in a mouse model of ASD, but its effect in humans has not been adequately studied. OBJECTIVES: The goal of this study was to assess the effectiveness and tolerability in white children with ASD of a dietary supplement containing 2 flavonoids (>95% pure), luteolin (100 mg/capsule, from chamomile) and quercetin (70 mg/capsule), and the quercetin glycoside rutin (30 mg/capsule) from the Sophora japonica leaf, formulated in olive kernel oil to increase oral absorption. METHODS: Fifty children (4-10 years old; 42 boys and 8 girls) with ASD were enrolled in a 26-week, prospective, open-label trial at the 2nd University Department of Psychiatry at "Attikon" General Hospital, Athens, Greece. Children were referred for the study by their respective physicians or came from the practice of the senior author. ASD diagnosis by clinical assessment was based on the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision, symptom list and corroborated by using the Autism Diagnostic Observation Schedule. The dose of the study formulation used was 1 capsule per 10 kg weight per day with food. The primary outcome measures were the age-equivalent scores in the Vineland Adaptive Behavior Scales domains. Secondary outcomes included the Aberrant Behavior Checklist, the Autism Treatment Evaluation Checklist, and the Clinical Global Impression-Improvement score. Data were measured at baseline, week 18, and week 26. Parents were interviewed for any possible improvements they noticed and instructed to report any unusual adverse events. RESULTS: A total of 40 children completed the protocol. There was a significant improvement in adaptive functioning as measured by using the VABS age-equivalent scores (8.43 months in the communication domain, 7.17 months in daily living skills, and 8 months in the social domain; P < 0.005), as well as in overall behavior as indicated by the reduction (26.6%-34.8%) in Aberrant Behavior Checklist subscale scores. Age, sex, and history of allergies had no effect on the results, whereas the initial level of functioning or difficulty did predict the final outcome in most of the measures used. There was a transient (1-8 weeks) increased irritability in 27 of the 50 participants. CONCLUSIONS: These results are encouraging in that the combination of the flavonoids luteolin and quercetin seemed to be effective in reducing ASD symptoms, with no major adverse effects. ClinicalTrials.gov identifier: NCT01847521.

Wound healing effect of flavonoid rich fraction and luteolin isolated from Martynia annua Linn. on streptozotocin induced diabetic rats.

OBJECTIVE: To evaluate wound healing potential of flavonoid fractions of Martynia annua (M. annua) Linn. leaves in diabetic rats on the basis of folkloric information and preliminary study. METHODS: The flavonoid compound luteolin and apigenin were isolated from dried leaves of plant by column chromatography. The two concentrations (0.2% and 0.5% w/w) of luteolin and flavonoid fraction were selected for topically applied as ointment on diabetic wound. The Povidone Iodine Ointment USP was used as a reference. On 18th days, protein content, hydroxyproline and antioxidants (SOD, CAT and GSH) level in granuloma tissues were determined. RESULTS: The results showed that, percent wound contraction were observed significantly (P<0.01) greater in MAF fraction and 0.5% w/w of luteolin treatment groups. Presence of matured collagen fibres and fibroblasts with better angiogenesis were observed in histopathological studies. CONCLUSIONS: In conclusion, our findings suggest that flavonoid fraction (MAF) and luteolin (0.5% w/w) may have potential benefit in enhancing wound healing in diabetic condition, possibly due to free-radical scavenging activity of plant.

A case series of a luteolin formulation (NeuroProtek®) in children with autism spectrum disorders.

There has been an impressive, little understood increase in cases of autism spectrum disorders (ASD). The lack of any distinctive pathogenetic mechanism has hampered the development of any effective treatments. Increasing evidence indicates oxidative stress, brain inflammation, gastrointestinal (GI) dysfunction and allergic symptoms may be present in ASD patients. The flavone luteolin has anti-oxidant, anti-flammatory, anti-allergy and neuroprotective properties. Given these findings, a dietary supplement was developed with a unique mixture of luteolin with the related flavonoids quercetin and rutin in a liposomal formulation of olive kernel oil (OKO), which increases their absorption. Results are presented for children with ASD (n=37, 4-14 years old) who had not obtained any benefit from multiple other regimens and who used this formulation for at least 4 months. GI and allergy symptoms improved in about 75 percent of children, eye contact and attention in 50 percent, social interaction in 25 percent and resumption of speech in about 10 percent. There were no adverse effects. Even though these results represent an uncontrolled open case series, they are encouraging because they suggest good tolerability and potential effectiveness.