Cytoprotective effects of catechin 7-O-β-D glucopyranoside against mitochondrial dysfunction damaged by streptozotocin in RINm5F cells

Chemopreventive effect of Phaleria macrocarpa on colorectal cancer aberrant crypt foci in vivo

ETHNOPHARMACOLOGICAL RELEVANCE

Natural products are important ingredients for pharmaceutical applications specifically new entities for treating cancer and other diseases. Phaleria macrocarpa is native of Indonesia and considered as a prolific source of bioactive substances useful for chemoprevention.

AIM OF THE STUDY

To investigate the chemopreventive properties of Phaleria macrocarpa on azoxymethane (AOM)-induced aberrant crypt foci (ACF) in rats.

METHODS

The biological activities of the ethanol extract of P. macrocarpa fruits were evaluated both in vitro and in vivo. First the extract was investigated for its in vitro antioxidant activity by the total phenolic content and ferric reducing antioxidant power assay. Then the chemopreventive effect of P. macrocarpa was performed on AOM-induced aberrant crypt foci as colorectal carcinoma model in rats.

RESULT

the crude ethanolic extract of P. macrocarpa has high antioxidant activity and modulated the oxidative stress as proved by the up-regulation of glutathione-s-transferase and superoxide dismutase. Immunohistochemical staining of the treated sections showed overexpression of PCNA and Bax, reduced crypt sizes and numbers, indicating the characteristic feature of apoptotic cancer cells. PCNA is a landmark of cell damage and turn-over and can be associated with clinical cancer mutation. The most potent doses were 250mg/kg and 500mg/kg as compared to 35mg/kg 5-fluorouracil.

CONCLUSION

In this sense, the potential modulation of the colorectal pathophysiological pathway by P. macrocarpa natural compounds mostly flavonoids offer a great possibility for the discovery of new leads towards the colorectal cancer.

Parkia biglobosa improves mitochondrial functioning and protects against neurotoxic agents in rat brain hippocampal slices

OBJECTIVE

Methanolic leaf extracts of Parkia biglobosa, PBE, and one of its major polyphenolic constituents, catechin, were investigated for their protective effects against neurotoxicity induced by different agents on rat brain hippocampal slices and isolated mitochondria.

METHODS

Hippocampal slices were preincubated with PBE (25, 50, 100, or 200 µg/mL) or catechin (1, 5, or 10 µg/mL) for 30 min followed by further incubation with 300 µM H2O2, 300 µM SNP, or 200 µM PbCl2 for 1 h. Effects of PBE and catechin on SNP- or CaCl2-induced brain mitochondrial ROS formation and mitochondrial membrane potential (ΔΨm) were also determined.

RESULTS

PBE and catechin decreased basal ROS generation in slices and blunted the prooxidant effects of neurotoxicants on membrane lipid peroxidation and nonprotein thiol contents. PBE rescued hippocampal cellular viability from SNP damage and caused a significant boost in hippocampus Na(+), K(+)-ATPase activity but with no effect on the acetylcholinesterase activity. Both PBE and catechin also mitigated SNP- or CaCl2-dependent mitochondrial ROS generation. Measurement by safranine fluorescence however showed that the mild depolarization of the ΔΨm by PBE was independent of catechin.

CONCLUSION

The results suggest that the neuroprotective effect of PBE is dependent on its constituent antioxidants and mild mitochondrial depolarization propensity.

In vitro antioxidant activity and effect of Parkia biglobosa bark extract on mitochondrial redox status

Aqueous-methanolic extract of Parkia biglobosa bark (PBB) was screened for its polyphenolic constituents, in vitro antioxidant activity, and effect on mitochondria redox status. The in vitro antioxidant activity was assessed by using the scavenging abilities and the reducing powers of 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) diammonium salt radical cation against Fe(3+). Subsequently, the ability of PBB to inhibit lipid peroxidation induced by FeSO(4) (10 μm) and its metal-chelating potential were investigated. The effects of the extract on basal reactive oxygen species (ROS) generation and on the mitochondrial membrane potential (ΔΨm) in isolated mitochondria were determined by using 2', 7'-dichlorodihydrofluorescin (DCFH) oxidation and safranin fluorescence, respectively. PBB mitigated the Fe(II)-induced lipid peroxidation in rat tissues and showed dose-dependent scavenging of DPPH (IC(50): 98.33 ± 10.0 μg/mL) and ABTS. (trolox equivalent antioxidant concentration, TEAC value = 0.05), with considerable ferric-reducing and moderate metal-chelating abilities. PBB caused slight decreases in both the liver and the brain mitochondria potentials and resulted in a significant decrease (p < 0.001) in DCFH oxidation. Screening for polyphenolics using high-performance liquid chromatography coupled to a diode array detector (HPLC-DAD) revealed the presence of caffeic acid, gallic acid, catechin, epigalocatechin, rutin, and quercetin. These results demonstrate for the first time the considerable in vitro antioxidant activity and favorable effect of PBB on mitochondria redox status and provide justification for the use of the plant in ethnomedicine.

Phenylpropanoid and phenylisoprenoid metabolites from Asteraceae species as inhibitors of protein carbonylation

Three phenolic antioxidant and anti-inflammatory compounds: 7-methylaromadendrin, isoprenylhydroquinone glucoside, and 3.5-dicaffeoylquinic acid methyl ester, all isolated from Western Mediterranean Asteraceae species, have been studied for their inhibitory activity against protein carbonylation, a harmful post-translational modification of peptide chains associated with degenerative diseases. All compounds have proven to be effective, with 50% inhibitory concentration (IC₅₀) values in the micromolar range, against bovine serum albumin carbonylation caused by hypochlorite, peroxynitrite, and phorbol ester-induced leukocyte oxidative burst.