Epidemiological evidence suggests that flavonoids may play an important role in the decreased risk of chronic diseases associated with a diet rich in plant-derived foods. Flavonoids are also common constituents of plants used in traditional medicine to treat a wide range of diseases. The purpose of this article is to summarize the distribution and biological activities of one of the most common flavonoids: luteolin. This flavonoid and its glycosides are widely distributed in the plant kingdom; they are present in many plant families and have been identified in Bryophyta, Pteridophyta, Pinophyta and Magnoliophyta. Dietary sources of luteolin include, for instance, carrots, peppers, celery, olive oil, peppermint, thyme, rosemary and oregano. Preclinical studies have shown that this flavone possesses a variety of pharmacological activities, including antioxidant, anti-inflammatory, antimicrobial and anticancer activities. The ability of luteolin to inhibit angiogenesis, to induce apoptosis, to prevent carcinogenesis in animal models, to reduce tumor growth in vivo and to sensitize tumor cells to the cytotoxic effects of some anticancer drugs suggests that this flavonoid has cancer chemopreventive and chemotherapeutic potential. Modulation of ROS levels, inhibition of topoisomerases I and II, reduction of NF-kappaB and AP-1 activity, stabilization of p53, and inhibition of PI3K, STAT3, IGF1R and HER2 are possible mechanisms involved in the biological activities of luteolin.

Distribution and biological activities of the flavonoid luteolin.

Natural product growth inhibitors of Mycobacterium tuberculosis.

Antimicrobial activity of the crude extracts and compounds from Ficus chlamydocarpa and Ficus cordata (Moraceae)

major and 26 minor compounds were identified in methanol and aqueous extracts of Eupatorium odoratum by GC -MS analysis showing significant antibacterial, antioxidant and other prophylactic activities. Antibacterial properties of aqueous and organic extracts of different parts of E.odoratum against nine different bacterial strains are examined. All fractions of leaf and root have significant inhibitory activity against all bacterial pathogens tested. However, flowers and stem did not show any activity. Significant protective activities against different ailments are found due to the presence of different phenols, flavonoids, alcohol derivatives and unique compounds consist of 2,4-Bis(1-phenylethy)phenol, Monoethylhexyl phthalate, Hoslundin, 2,4,6-Tris-(1-phenylethyl)-phenol; dl-α-Tocopherol, Phytol, 1,2,4-oxadiazol-5-amine, 3-(4-amino-1,2,5-oxadiazol-3-yl)-N-(2- (4-methoxyphenyl), 1-Heptacosanol, Stigmasterol, γ-Sitosterol, Tetra-O-methylscutellarein, Neophytadiene, (35)-7-O-Methoxymethylvestitol, α- Amyrin, Methylcommate D and 4-Acetyl-3-hydroxy-2,6-dimethoxytoluene. Our results revealed that, experiments conducted on different parts of this plant according to the traditional usage and several compounds identified by GC-MS analysis are principal factors for significant antibacterial, antioxidant and other prophylactic activities.

ANTIBACTERIAL, ANTIOXIDANT ACTIVITY AND GC-MS ANALYSIS OF Eupatorium odoratum

When single-cell (or suspended) bacteria switch into the biofilm lifestyle, they become less susceptible to antimicrobials, imposing the need for anti-biofilms research. Flavonoids are among the most extensively studied natural compounds with an unprecedented amount of bioactivity claims. Most studies focus on the antibacterial effects against suspended cells; fewer reports have researched their anti-biofilm properties. Here, a high throughput phenotypic platform was utilized to screen for the inhibitory activity of 500 flavonoids, including natural and synthetic derivatives, against Staphylococcus aureus biofilms. Since discrepancies among results from earlier antibacterial studies on flavonoids had been noted, the current study aimed to minimize sources of variations. After the first screen, flavonoids were classified as inactive (443), moderately active (47) or highly active (10). Further, exclusion criteria combining bioactivity and selectivity identified two synthetic flavans as the most promising. The body of data reported here serves three main purposes. First, it offers an improved methodological workflow for anti-biofilm screens of chemical libraries taking into account the (many times ignored) connections between anti-biofilm and antibacterial properties. This is particularly relevant for the study of flavonoids and other natural products. Second, it provides a large and freely available anti-biofilm bioactivity dataset that expands the knowledge on flavonoids and paves the way for future structure-activity relationship studies and structural optimizations. Finally, it identifies two new flavans that can successfully act on biofilms, as well as on suspended bacteria and represent more feasible antibacterial candidates.

/pdf/systematic-exploration-of-natural-and-synthetic-flavonoids-54o1pnuoo4.pdf

Systematic Exploration of Natural and Synthetic Flavonoids for the Inhibition of Staphylococcus aureus Biofilms

From the flowers ofChromolaena odorata (Eupatorium odoratum) four flavanones, isosakuranetin (5,7-dihydroxy-4′-methoxyflavanone) (1), persicogenin (5,3′-dihydroxy-7,4′-dimethoxyflavanone) (2), 5,6,7,4′-tetramethoxyflavanone (3) and 4′-hydroxy-5,6,7-trimethoxyflavanone (4), two chalcones, 2′-hydroxy-4,4′,5′,6′-tetramethoxychalcone (5) and 4,2′-dihydroxy-4′, 5′,6′-trimethoxychalcone (6), and two flavones, acacetin (5,7-dihydroxy-4′-methoxyflavone) (7) and luteolin (5,7,3′,4′-tetrahydroxyflavone) (8) were isolated and identified. Compound 1 exhibited moderate antimycobacterial activity againstMycobacterium tuberculosis with the MIC value of 174.8 μM, whereas compounds4,7, and8 exhibited weak activity with the MIC values of 606.0, 704.2 and 699.3 μM respectively. Compound7 showed moderate cytotoxicity against human small cell lung cancer (NCI-H187) cells with the MIC value of 24.6 μM, whereas compound8 exhibited moderate toxicity against NCI-H187 cells and week toxicity against human breast cancer (BC) cells with the MIC values of 19.2 and 38.4 μM respectively.

Saovaluk Vimuttipong

Papers

Antimycobacterial activity and cytotoxicity of flavonoids from the flowers of Chromolaena odorata.