Cytoprotective effects of geraniin against peroxynitrite- and peroxyl radical-induced cell death via free radical scavenging activity

Byrsonima sericea Ethanol Extract Protected PC12 Cells from the Oxidative Stress and Apoptosis Induced by 6-Hydroxydopamine

Parkinson's disease is characterized by the progressive loss of dopaminergic neurons in the nigrostriatal pathway and oxidative stress is one of the main mechanisms that lead to neuronal death in this disease. Previous studies have shown antioxidant activity from the leaves of Byrsonima sericea, a plant of the Malpighiaceae family. This study aimed to evaluate the cytoprotective activity of the B. sericea ethanolic extract (BSEE) against the cytotoxicity induced by 6-hydroxydopamine (6-OHDA) in PC12 cells, an in vitro model of parkinsonism. The identification of phenolic compounds in the extract by HPLC-DAD revealed the presence of geraniin, rutin, isoquercetin, kaempferol 3-O-β-rutinoside, and quercetin. The BSEE (75-300 µg/mL) protected PC12 cells from toxicity induced by 6-OHDA (25 µg/mL), protected cell membrane integrity and showed antioxidant activity. BSEE was able to decrease nitrite levels, glutathione depletion, and protect cells from 6-OHDA-induced apoptosis. Thus, we suggest that the BSEE can be explored as a possible cytoprotective agent for Parkinson's disease due to its high antioxidant capacity and anti-apoptotic action.

Nutritional, pharmaceutical, and functional aspects of rambutan in industrial perspective: An updated review

Numerous researchers have been motivated to investigate new plant sources as a result of the continued advancement of functional foods and herbal medicines. The rambutan fruit (Nephelium lappaceum L.) with its significant nutritional and bioactive compositions offers therapeutic properties such as anticancer, antiallergic, antiobesity, antidiabetic, antimicrobial, antihypercholesterolemic, and antihyperglycemic. Rambutan is high in antioxidants, dietary fibers, and vitamins and minerals. Its parts including fruit peel, pulp, and seed are a great source of bioactive compounds. Rambutan fruit extracts have been found to have cardioprotective and hepatoprotective properties. This review provides an insight into the nutritional as well as therapeutic value, health potential, and utilization of rambutan fruit along with its nonedible parts (seeds and peels). Advanced research and phytochemical screening would also encourage the rambutan fruit as a viable choice for the preparation of medications and functional foods. However, it is necessary to further analyze the functional aspects and nutritional potential of this fruit along with the therapeutic mechanisms and to improve its industrial use as a nutraceutical and functional food product.

Functional and nutritional properties of selected Amazon fruits: A review

This review reports the nutritional, phytochemical compounds and biological properties of 4 fruits commonly consumed by people living in Amazon region, namely Biribá (Rollinia mucosa Jacq.), Rambutan (Nephelium lappaceum L.), Pupunha (Bactris gasipaes Kunth) and Tucumã (Astrocaryum aculeatum Meyer). These fruits have been high held nutritional, functional and economic potential and contribute to the daily intake of nutrients, energy and bioactive compounds by people living in Amazon rainforest region. Phytochemical compounds with biological properties were detected in these fruits, for instance (but not limited to), annonaceous acetogenins in Biribá, geraniin and corilagin in Rambutan, rutin and catechin in Pupunha, and β-carotene and flavonoids in Tucumã. The biological properties of Biribá, Rambutan, Pupunha and Tucumã have been evaluated by in vitro and in vivo assays, especially antioxidant and antimicrobial activities. Therefore, these Amazonian fruits can be exploited by the food industry as a food and therapeutic plant-material to develop valuable products, such as medicine products and can be used as sources for obtaining compounds for the food, cosmetics and pharmaceutical applications.

Cytoprotective effect exerted by geraniin in HepG2 cells is through microRNA mediated regulation of BACH-1 and HO-1

Geraniin, a hydrolysable tannin, used in traditional medicine in Southeast Asia, is known to exhibit various biological activities. As an antioxidant it is known to up-regulate phase II enzyme Heme oxygenase-1 (HO-1). However its mechanism is not clearly understood. Nuclear factor erythroid-derived 2 related factor 2 (Nrf-2) is transcriptionally up-regulated by Extracellular signal-regulated kinase (ERK) 1/2 and retained in nucleus due to inactivated Glycogen synthase kinase 3 beta (GSK-3β). Geraniin additionally down-regulates expression of microRNA 217 and 377 (miR-217 and miR-377) which target HO-1 mRNA. Expression of BTB and CNC homolog 1 (BACH-1), another regulator of HO-1, is also down-regulated by up-regulating microRNA 98 (miR-98), a negative regulator of BACH-1. Thus, geraniin up-regulates HO-1 expression both through activating its positive regulator Nrf-2 and by down-regulating its negative regulator BACH-1. Up-regulation of HO-1 also confers protection to HepG2 cells from tertiary butyl hydroperoxide (TBH) induced cytotoxicity.

Geraniin Protects High-Fat Diet-Induced Oxidative Stress in Sprague Dawley Rats

Geraniin, a hydrolysable polyphenol derived from Nephelium lappaceum L. fruit rind, has been shown to possess significant antioxidant activity in vitro and recently been recognized for its therapeutic potential in metabolic syndrome. This study investigated its antioxidative strength and protective effects on organs in high-fat diet (HFD)-induced rodents. Rats were fed HFD for 6 weeks to induce obesity, followed by 10 and 50 mg/kg of geraniin supplementation for 4 weeks to assess its protective potential. The control groups were maintained on standard rat chows and HFD for the same period. At the 10th week, oxidative status was assessed and the pancreas, liver, heart and aorta, kidney, and brain of the Sprague Dawley rats were harvested and subjected to pathological studies. HFD rats demonstrated changes in redox balance; increased protein carbonyl content, decreased levels of superoxide dismutase, glutathione peroxidase, and glutathione reductase with a reduction in the non-enzymatic antioxidant mechanisms and total antioxidant capacity, indicating a higher oxidative stress (OS) index. In addition, HFD rats demonstrated significant diet-induced changes particularly in the pancreas. Four-week oral geraniin supplementation, restored the OS observed in the HFD rats. It was able to restore OS biomarkers, serum antioxidants, and the glutathione redox balance (reduced glutathione/oxidized glutathione ratio) to levels comparable with that of the control group, particularly at dosage of 50 mg geraniin. Geraniin was not toxic to the HFD rats but exhibited protection against glucotoxicity and lipotoxicity particularly in the pancreas of the obese rodents. It is suggested that geraniin has the pharmaceutical potential to be developed as a supplement to primary drugs in the treatment of obesity and its pathophysiological sequels.

Antioxidant effects of Geranium nepalense ethanol extract on H2O2-induced cytotoxicity in H9c2, SH-SY5Y, BEAS-2B, and HEK293

Oxidative damage leads to many diseases. In this study, we evaluated the antioxidant effects of 70% ethanol extract of Geranium nepalense (GNE) on hydrogen peroxide-induced cytotoxicity in cell lines: H9c2, SH-SY5Y, HEK293, and BEAS-2B. We determined the free radical scavenging activity of GNE using 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), and superoxide dismutase-like activities, as well as the polyphenol and flavonoid contents of GNE. The results showed that GNE scavenged DPPH and ABTS radicals in a dose-dependent manner. In addition, it contained abundant contents of total polyphenol and flavonoid contents and strongly suppressed cellular reactive oxygen species, thereby protecting H₂O₂-induced cytotoxicity in H9c2, SH-SY5Y, HEK293, and BEAS-2B cell lines. The powerful antioxidant activity exhibited by GNE, both in vitro and in cell systems, was attributed to its free radical scavenging activity. Therefore, GNE may be useful in preventing oxidative stress-induced diseases including Alzheimer's disease, respiratory inflammatory disease, and chronic kidney diseases.

Geraniin exerts cytoprotective effect against cellular oxidative stress by upregulation of Nrf2-mediated antioxidant enzyme expression via PI3K/AKT and ERK1/2 pathway

BACKGROUND

Geraniin, an active compound with remarkable antioxidant activity, was isolated from Geranium sibiricum. The present study aimed to investigate whether geraniin has the ability to activate Nrf2, induce antioxidant enzyme expression and protect cells from oxidative damage.

METHODS

The cells were pretreated with geraniin for 24h and exposed to hydrogen peroxide (H₂O₂) for 4h. Intracellular reactive oxygen species (ROS) levels, mitochondrial membrane potential and apoptosis were measured. We also investigated intracellular glutathione (GSH) levels and changes in nuclear factor erythroid 2-related factor 2 (Nrf2)-mediated signaling cascade in cells treated with geraniin.

RESULTS

We investigated the protective effects of geraniin against H₂O₂-induced apoptosis in HepG2 cells. Geraniin significantly reduced H₂O₂-induced oxidative damage in a dose dependent manner. Further, geraniin induced the expression of heme oxygenase-1 (HO-1), NAD(P)H quinone oxidoreductase-1 (NQO1) and level of glutathione (GSH) in a concentration- and time-dependent manner, and increased Nrf2 nuclear translocation. The Nrf2-related cytoprotective effects of geraniin were PI3K/AKT and extracellular signal-regulated protein kinase1/2 (ERK1/2) pathway-dependent. However, inhibitors of PI3K/AKT and ERK1/2 (LY294002 or U0126) not only suppressed geraniin-induced nuclear translocation of Nrf2 but also abolished the expression of HO-1, NQO1 and GSH.

CONCLUSIONS

These results demonstrated that geraniin induced Nrf2-mediated expression of antioxidant enzymes HO-1 and NQO1, presumably via PI3K/AKT and ERK1/2 signaling pathways, thereby protecting cells from H₂O₂-induced oxidative cell death.

GENERAL SIGNIFICANCE

Geraniin, at least in part, offers an antioxidant defense capacity to protect cells from the oxidative stress-related diseases.

Geraniin induces apoptotic cell death in human lung adenocarcinoma A549 cells in vitro and in vivo

Geraniin has previously been reported to possess extensive biological activity. In this study, we reported that geraniin is an inhibitor of tumor activity in vitro and in vivo. Geraniin suppressed the proliferation of A549 cells in a dose- and time-dependent manner. Geraniin arrested the cell cycle in the S phase and induced a significant accumulation of reactive oxygen species (ROS), as well as an increased percentage of cells with mitochondrial membrane potential (MMP) disruption. Western blot analysis showed that geraniin inhibited Bcl-2 expression and induced Bax expression to disintegrate the outer mitochondrial membrane and cause cytochrome c release. Mitochondrial cytochrome c release was associated with the activation of caspase-9 and caspase-3 cascades. Additionally, geraniin resulted in tumor growth inhibition in A549 xenografts. Our results indicate cytotoxic activity of geraniin towards cancer cells in vitro and in vivo.

Antioxidant and Cytoprotective Effects of an Ethanol Extract of Acalypha wilkesiana var. macafeana from Malaysia

In the annals of biomedical theory perhaps no single class of natural product has enjoyed more ingenious speculation than antioxidants formally aimed at counteracting oxidative insults which are involved in the pathophysiology of Alzheimer's and Parkinson's disease, cancer, amyotrophic lateral sclerosis, skin ageing and wound healing. In pursuing our study of Malaysian traditional medicines with antioxidant properties, we became interested in Acalypha wilkesiana var. macafeana hort., used traditionally to heal wounds. To examine whether Acalypha wilkesiana var. macafeana hort. could suppress oxidation an ethanol extract was tested by conventional chemical in vitro assays i.e., ferric reducing antioxidant potential assay (FRAP), DPPH scavenging assay and beta-carotene bleaching (BCB) assay. To explore whether Acalypha wilkesiana var. macafeana hort. protected cells against oxidative injuries, we exposed human hepatocellular liver carcinoma (HepG2) cells to tert-butylhydroperoxide ( t-BHP). In all the aforementioned experiments, the ethanol extracts elicited potent antioxidant and cytoprotective activities. To gain a better understanding of the phytochemical nature of the antioxidant principle involved, five fractions (F1-F5) obtained from the ethanol extract were tested using FRAP, DPPH and BCB assays. Our results provided evidence that F5 was the most active fraction with antioxidant potentials equal to 2.090 ± 0.307 μg/mL, 0.532 ± 0.041 μg/mL, 0.032 ± 0.025 μg/mL in FRAP, DPPH and BCB assay, respectively. Interestingly, F5 protected HepG2 against t-BHP oxidative insults. To further define the chemical identity of the antioxidant principle, we first performed a series of phytochemical tests, followed by liquid-chromatography and mass spectrometry (LC/MS) profiling which showed that the major compound contained in F5 was geraniin. To the best of our knowledge, this is the first report showing that the wound healing property of Acalypha wilkesiana var. macafeana hort. is mediated by a geraniin containing extract. Furthermore, our data leads us to conclude that geraniin could be used as a potential pharmaceutical and/or cosmetic topical agent.