Medicinal plants: Traditions of yesterday and drugs of tomorrow

The essential oil of black cumin seeds, Nigella sativa L., was tested for a possible antioxidant activity. A rapid evaluation for antioxidants, using two TLC screening methods, showed that thymoquinone and the components carvacrol, t-anethole and 4-terpineol demonstrated respectable radical scavenging property. These four constituents and the essential oil possessed variable antioxidant activity when tested in the diphenylpicrylhydracyl assay for non-specific hydrogen atom or electron donating activity. They were also effective.OH radical scavenging agents in the assay for non-enzymatic lipid peroxidation in liposomes and the deoxyribose degradation assay. GC-MS analysis of the essential oil obtained from six different samples of Nigella sativa seeds and from a commercial fixed oil showed that the qualitative composition of the volatile compounds was almost identical. Differences were mainly restricted to the quantitative composition.

Antioxidant activity of Nigella sativa essential oil

Phenolics and polyphenolics in foods, beverages and spices: Antioxidant activity and health effects – A review

https://www.eolss.net/Sample-Chapters/C03/E6-79-10.pdf

Plants as a source of anti-cancer agents.

Dietary phenolics: chemistry, bioavailability and effects on health.

Four new iridoid glucosides 1–4, named blumeosides A–D, were isolated from the methanolic stem-bark extract of Fagraea blumei G. DON. (Loganiaceae). They were accompanied by the benzyl-alcohol derivative di-O-methylcrenatin (5) and the flavone C-glucoside swertisin (6). The structures of 1–4 were established by spectroscopic methods, including FAB-MS, and 1H- and 13C-NMR, and by alkaline hydrolysis. Blumeosides A (1) and C (3) are 10-O-(2,5-dihydroxytercphthalo) adoxosidic acid and 10-O-(2-hydroxyterephthalo)adoxosidic acid, respectively. In blumeosides B (4) and D (2), both carboxylic groups of the terephthalic-acid moiety are esterified by adoxosidic-acid units, Blumeosides A–D (1–4) inhibited bleaching of crocin induced by alkoxyl radicals. Blumeosides A (1) and D (2) also demonstrated scavenging properties towards the 2,2-diphenyl-1-picryl-hvdrazvl (CDPPH) radical in TLC autographic and spectrophotometric assays.

Iridoid Glucosides with Free Radical Scavenging Properties from Fagraea blumei

Pterostilbene, a natural methoxylated analogue of resveratrol, was evaluated for antioxidative potential. The peroxyl-radical scavenging activity of pterostilbene was the same as that of resveratrol, having total reactive antioxidant potentials of 237 +/- 58 and 253 +/- 53 microM, respectively. Both compounds were found to be more effective than Trolox as free radical scavengers. Using a plant system, pterostilbene also was shown to be as effective as resveratrol in inhibiting electrolyte leakage caused by herbicide-induced oxidative damage, and both compounds had the same activity as alpha-tocopherol. Pterostilbene showed moderate inhibition (IC50 = 19.8 microM) of cyclooxygenase (COX)-1, and was weakly active (IC50 = 83.9 microM) against COX-2, whereas resveratrol strongly inhibited both isoforms of the enzyme with IC50 values of approximately 1 microM. Using a mouse mammary organ culture model, carcinogen-induced preneoplastic lesions were, similarly to resveratrol, significantly inhibited by pterostilbene (ED50 = 4.8 microM), suggesting antioxidant activity plays an important role in this process.

Cancer chemopreventive and antioxidant activities of pterostilbene, a naturally occurring analogue of resveratrol.

Histone deacetylase (HDAC) inhibitors have been demonstrated to be beneficial in animal models of neurodegenerative diseases. Such results were mainly associated with the epigenetic modulation caused by HDACs, especially those from class I, via chromatin deacetylation. However, other mechanisms may contribute to the neuroprotective effect of HDAC inhibitors, since each HDAC may present distinct specific functions within the neurodegenerative cascades. Such an example is HDAC6 for which the role in neurodegeneration has been partially elucidated so far. The strategy to be adopted in promising therapeutics targeting HDAC6 is still controversial. Specific inhibitors exert neuroprotection by increasing the acetylation levels of α-tubulin with subsequent improvement of the axonal transport, which is usually impaired in neurodegenerative disorders. On the other hand, an induction of HDAC6 would theoretically contribute to the degradation of protein aggregates which characterize various neurodegenerative disorders, including Alzheimer’s, Parkinson’s and Hutington’s diseases. This review describes the specific role of HDAC6 compared to the other HDACs in the context of neurodegeneration, by collecting in silico, in vitro and in vivo results regarding the inhibition and/or knockdown of HDAC6 and other HDACs. Moreover, structure, function, subcellular localization, as well as the level of HDAC6 expression within brain regions are reviewed and compared to the other HDAC isoforms. In various neurodegenerative diseases, the mechanisms underlying HDAC6 interaction with other proteins seem to be a promising approach in understanding the modulation of HDAC6 activity.

/pdf/hdac6-as-a-target-for-neurodegenerative-diseases-what-makes-1n6qcjn2i2.pdf

HDAC6 as a target for neurodegenerative diseases: what makes it different from the other HDACs?

Chemoprevention involves the use of natural or synthetic substances to reduce the risk of developing cancer. Strategies for protecting cells from initiation events include decreasing metabolic enzymes responsible for generating reactive species (phase I enzymes) while increasing phase II enzymes that can deactivate radicals and electrophiles known to intercede in normal cellular processes. Reduction of electrophilic quinones by quinone reductase is an important detoxification pathway. Following evaluation of approximately 3000 plant and marine organism extracts, the number characterized as “active” was established in the range of 12% of the total, and over 60 active compounds have been isolated as quinone reductase inducers. One of them, isoliquiritigenin (1), isolated from tonka bean, was shown to be a monofunctional inducer by having similar quinone reductase inducing ability in wild-type Hepa 1c1c7 cells and two mutant cell lines. To further investigate the mechanism of induction, HepG2 human hepatoma ...

/pdf/quinone-reductase-induction-as-a-biomarker-for-cancer-4w86g9jef4.pdf

Quinone reductase induction as a biomarker for cancer chemoprevention.

The involvement of prostaglandins (PGs) and other eicosanoids in the development of human cancer has been known for over two decades. Importantly, an increase in PG synthesis may influence tumor growth in human beings and experimental animals, and numerous studies have illustrated the effect of PG synthesis on carcinogen metabolism, tumor cell proliferation and metastatic potential. PGs produced by cyclooxygenases (COXs) are represented by a large series of compounds that mainly enhance cancer development and progression, acting as carcinogens or tumor promoters, with profound effects on carcinogenesis. Further investigations suggest that arachidonic acid (AA) metabolites derived from lipoxygenase (LOX) pathways play an important role in growth-related signal transduction, implying that intervention through these pathways should be useful for arresting cancer progression. We discuss here the implications of COX and LOX in colon, pancreatic, breast, prostate, lung, skin, urinary bladder and liver cancers. Select inhibitors of COX and LOX are described, including nonsteroidal antiinflammatory drugs (NSAIDs), selective COX-2 inhibitors, curcumin, tea, silymarin and resveratrol, as well as a method useful for evaluating inhibitors of COX. Although a substantial amount of additional work is required to yield a better understanding of the role of COX and LOX in cancer chemoprevention, it is clear that beneficial therapeutic effects can be realized through drug-mediated modulation of these metabolic pathways.

Muriel Cuendet

Papers

Iridoid Glucosides with Free Radical Scavenging Properties from Fagraea blumei

Cancer chemopreventive and antioxidant activities of pterostilbene, a naturally occurring analogue of resveratrol.

HDAC6 as a target for neurodegenerative diseases: what makes it different from the other HDACs?

Quinone reductase induction as a biomarker for cancer chemoprevention.

The role of cyclooxygenase and lipoxygenase in cancer chemoprevention.