Inhibitory effect of Piper betel leaf extracts on copper-mediated LDL oxidation and oxLDL-induced lipid accumulation via inducing reverse cholesterol transport in macrophages

Sitosterol-rich Digera muricata against 7-ketocholesterol and lipopolysaccharide-mediated atherogenic responses by modulating NF-ΚB/iNOS signalling pathway in macrophages

Digera muricata L., commonly known as Tartara, is an edible herb used as traditional medicine in many countries of Africa and Asia. This study aimed to elucidate the effect of a phytosterol-rich extract of D. muricata on 7-ketocholesterol-mediated atherosclerosis in macrophages. The extract was examined by phytochemical analyses, GC-MS, TLC, DPPH scavenging and hRBC membrane stabilization assays. Macrophage polarization was studied with experimental groups framed based on alamar blue cell viability and griess assays. Regulations of arginase enzyme activity, ROS generation, mitochondrial membrane potential, cell membrane integrity, pinocytosis, lipid uptake and peroxidation, as well as, intracellular calcium deposition were determined. In addition, expressions of atherogenic mediators were analysed using PCR, ELISA and immunocytochemistry techniques. Diverse phytochemicals with higher free radical scavenging activity and anti-inflammatory potential have been detected in the D. muricata. Co-treatment with D. muricata markedly reduced the atherogenic responses induced by 7KCh in the presence of LPS such as ROS, especially, NO and O2- along with lipid peroxidation. Furthermore, D. muricata significantly normalized mitochondrial membrane potential, cell membrane integrity, pinocytic activity, intracellular lipid accumulation and calcium deposition. These results provided us with the potentiality of D. muricata in ameliorating atherogenesis. Additionally, it decreased the expression of pro-atherogenic mediators (iNOS, COX-2, MMP9, IL-6, IL-1β, CD36, CD163 and TGFβ1) and increased anti-atherogenic mediators (MRC1 and PPARγ) with high cellular expressions of NF-κB and iNOS. Results showed the potential of sitosterol-rich D. muricata as a versatile biomedical therapeutic agent against abnormal macrophage polarization and its associated pathologies.

Attenuating lipid metabolism in atherosclerosis: The potential role of Anti-oxidative effects on low-density lipoprotein of herbal medicines

Atherosclerosis (AS) is a multifactorial chronic disease with great harm to the health of human being, which is a basic pathogenesis of many cardiovascular diseases and ultimately threatens human life. Abnormal blood lipid level is one of the most common diagnostic indicators of AS in clinic, and lipid metabolism disorder is often observed in patients with AS. Cholesterol is an important lipid in the human body, which is of great significance for maintaining normal life activities. Generally, cholesterol is transported to peripheral tissues by low-density lipoprotein (LDL), and then transported to the liver by high-density lipoprotein (HDL) via its cholesterol reverse transport function, and finally discharged. Under oxidative stress condition, LDL is commonly oxidized to the form ox-LDL, which is ingested by macrophages in large quantities and further forms foam cells, disrupting the normal metabolic process of cholesterol. Importantly, the foam cells are involved in forming atherosclerotic plaques, whose rupture may lead to ischemic heart disease or stroke. Furthermore, ox-LDL could also promote the development of AS by damaging vascular endothelium, promoting the migration and proliferation of smooth muscle cells, and activating platelets. Therefore, inhibiting LDL oxidation may be an effective way to improve lipid metabolism and prevent AS. In recent years, increasing studies have shown that herbal medicines have great potentiality in inhibiting LDL oxidation and reducing ox-LDL induced foam cell formation. Accordingly, this paper summarized current research on the inhibitory effects of herbal medicines against LDL oxidation and foam cell formation, and made a brief description of the role of cholesterol and LDL in lipid metabolism disorder and AS pathogenesis. Importantly, it is suggested that herbal medicines could inhibit LDL oxidation and regulate cholesterol homeostasis via downregulation of CD36 and SR-A, whereas upregulation of ABCA1 and ABCG1.

A Review of Bioactive Compounds and Antioxidant Activity Properties of Piper Species

Antioxidants are compounds that are able to inhibit the negative effects that come from free radicals. The phenomenon of imbalanced antioxidant production and the accumulation of free radicals in cells and tissues can cause oxidative stress. Excessive free radicals that enter the body cannot be warded off by endogenous antioxidant compounds so that the required antioxidant compounds can come from the outside, which helps in the performance of endogenous antioxidants. Antioxidants that come from outside consist of synthetic and natural antioxidants; however, synthetic antioxidants are not an option because they have toxic and carcinogenic effects. Therefore, the use of natural ingredients is an alternative method that is needed to create a new natural antioxidant compound. Piper species are being considered as possible medicinal plants for the development of new sources of antioxidants. Several studies have been carried out starting from the extract levels, fractions, and compounds of the Piper species, which showed good antioxidant activity. Currently, some of these plants are being used as ingredients in traditional medicines to treat allergies, toothaches, and coughs. This review examines the distribution, botanical data, pharmacology, especially antioxidant activity, and the compounds contained in five Piper species, namely Piper amalago L., Piper betle L., Piper hispidum Sw., Piper longum L., and Piper umbellatum L.

Guang Chen Pi (the pericarp of Citrus reticulata Blanco's cultivars 'Chachi') inhibits macrophage-derived foam cell formation

ETHNOPHARMACOLOGICAL RELEVANCE

The dried pericarp of Citrus reticulata Blanco (CP) occupies an important position in the history of clinical applications of traditional Chinese medicine (TCM). In traditional use, CP is used to treat diseases related to the digestive, respiratory, and cardiovascular systems, as well as to regulate Qi and promote blood circulation throughout the body. In China, a special cultivar of CP named Guang Chen Pi (GCP) which is collected exclusively from Citrus reticulata Blanco's cultivars 'Chachi', is considered to be the best CP with high medicinal and dietary value. Modern pharmacology shows that CP has high effect on regulating metabolic disorders and cardiovascular systems diseases. Atherosclerosis (AS) is not only an inflammatory disease but also cardiovascular lipid metabolism disorder. Foam cells formation is the hallmark of AS. Several reports indicated that CP can mitigate the development of AS, but involved signaling pathway and its role in foam cell formation is unclear. Since the main components of GCP has protective effects in cardiovascular diseases, we evaluated its effect of inhibiting foam cell formation to support the traditional usage of GCP.

AIM OF THE STUDY

The objective of this study aims to investigate the effects of GCP on suppressing RAW264.7 foam cell formation and anti-inflammatory in vitro.

MATERIALS AND METHODS

To evaluate the anti-foam cell formation and anti-inflammatory activity of GCP, oxidized low-density lipoprotein (ox-LDL) induced RAW264.7 macrophages model was involved. Meantime, foam cell developing status was also closely monitored. RT-qPCR and Western blot were then applied to further investigate receptors in associated signaling pathways.

RESULTS

GCP shown inhibitory effect on macrophage-derived foam cell formation in Oil Red O staining analysis, which was further confirmed by flow cytometry of Dil-ox-LDL staining and TG and TC analysis. The HDL-mediated cholesterol efflux was also promoted by GCP. Mechanistic studies showed that GCP significantly down-regulate SRA1 and CD36 protein expression, while significantly increasing the expression of PPARγ, LXRα, SRB1 and ABCG1. Also, GCP reduced ox-LDL-induced inflammatory factors level, and inhibited phosphorylation of p38 MAPK, ERK1/2, JNK1/2, NF-κB p65 and IKKα/β.

CONCLUSIONS

GCP exhibited anti-atherogenic ability by interfering RAW264.7 foam cell formation, through inhibiting lipid uptake and promoting HDL-mediated cholesterol. PPARγ-LXRα-ABCG1/SRB1 pathway and its anti-inflammatory effect may involve. This proposed anti-foam cell formation activity is expected to provide new insight on comprehensive utilization of GCP.

Bio-actives of betel leaf (Piper betle L.): A comprehensive review on extraction, isolation, characterization, and biological activity

Piper betle L., belonging to Piperaceae family, known as a traditional herbal medicinal plant and used for several health benefits in Asian countries. Currently, demand for its products such as herbal drugs, medicines, and natural herbal formulations has increased. The beneficial effects of betel leaves and its products have traditionally exploited for the treatment of several diseases like bad breath, cuts, injuries, inflammations, cold cough, indigestion, etc. Till now, a broad range of bioactive compounds including polyphenols, terpenes, etc., has been identified from the extracts and essential oil (EO) of betel leaves. The structural and functional characterization of the extract and EO bio-actives has been derived by various advanced standard methods. Most of the health-related benefits of betel leaves have been associated with their bioactive phenolic compounds. The extract of this highly perishable product can be used in organic synthesis, food, and beverage industry, pharmaceuticals, etc., to the environmental issues. The present review provides information on extraction techniques, identification of bioactive compounds, and their biological activities. That apart, information on processing, preservation, and health benefits along with their mechanisms has also been added.

Protection of natural antioxidants against low-density lipoprotein oxidation

This chapter reports essential information about the protective action of antioxidants against LDL oxidation. The activity of individual compounds (tocopherols, vitamin C, phenolic compounds) as well as extracts obtained from plant material (cereals, fruits, legumes, nuts, mushrooms, by-products of food industry) is reported. The structure-antioxidant activity relationship of phenolic compounds is discussed. This article summarizes the findings to date of both in vitro and in vivo studies using foods or phenolic extracts isolated from foodstuffs at inhibiting the incidence of LDL oxidation. This chapter summarizes also the reportings to date of in vivo studies using foods or beverages at inhibiting the incidence of LDL oxidation.

Protective Effect of Pitao (Pitavia punctata (R. & P.) Molina) Polyphenols against the Red Blood Cells Lipoperoxidation and the In Vitro LDL Oxidation

The oxidative stress is characterized by an imbalance between the oxidizing agents and antioxidants; meanwhile, the consumption of antioxidants has been considered as an important tool in the prevention of oxidative stress and its consequences. Pitavia punctata (R. & P.) Molina is an endemic arboreal species from the Chilean Coast Range, in which a large amount of flavonoids has been described. This work focused on characterizing and evaluating, in human erythrocytes, the antioxidant capacity and membrane protection of P. punctata extracts and the in vitro protection of the oxidation of the Low Density Lipoprotein (LDL). The phytochemical screening revealed the presence of Quercetin derivatives and flavonoids, such as (-)-Epicatechin, Kaempferol, and derivatives. The methanolic extract presented an important antioxidant activity, protecting the membrane integrity of the red blood cells against the oxidative damage caused by Hypochlorous acid and inhibiting the oxidation of the LDL lipoprotein.

The Potential Protective Effects of Phenolic Compounds against Low-density Lipoprotein Oxidation

BACKGROUND

The exact mechanism(s) of atherosclerosis in humans remains elusive, but one theory hypothesizes that this deleterious process results from the oxidative modification of low-density lipoprotein (LDL). Research suggests that foods rich in dietary phenolic compounds with antioxidant activity can mitigate the extent of LDL oxidation in vivo. With regard to the different classes of flavonoids, there appears to be a structurefunction relationship between the various moieties/constituents attached to the flavonoids' three ring system and their impact at retarding LDL oxidation.

METHODS

This article summarizes the findings to date of both in vitro and in vivo studies using foods or phenolic extracts isolated from foodstuffs at inhibiting the incidence of LDL oxidation. Three bases: SCOPUS, Web Science, and PubMed were used for search.

RESULTS

An often used method for the determination of antioxidant properties of natural phenolic compounds is the LDL oxidation assay. LDLs are isolated from human plasma and their oxidation is induced by Cu2+ ions or 2,2'-azobis(2-methylpropionamidine) dihydrochloride (AAPH). The sample is incubated with a phenolic extract or individual/isolated phenolic compounds. LDL oxidation is then monitored by various chemical methods (e.g., measurement of the generation of conjugated dienes and trienes). This technique confirmed the antioxidant properties of several extracts as obtained from plant material (e.g., grapes, berries, orange, grapefruit, coffee, tea, chocolate, olives, nuts) as well as the individual phenolic compounds (e.g., luteolinidin, apigenidin, caffeic acid, chlorogenic acid, catechin, quercetin, rutin). Several studies in vivo confirmed protective effects of phenolic compounds against LDL oxidation. They covered the healthy subjects with hyperlipidaemia, overweight, obesity, metabolic syndrome, heavy smokers, patients receiving haemodialysis, patients with peripheral vascular disease, and subjects at high cardiovascular risk. The studies comprise individuals of all ages, and the number of participants in the different experiments varied widely.

CONCLUSION

Properly designed double-blind, placebo-controlled randomised clinical trials offer stronger evidence as to the impact of dietary phenolics consumption at retarding LDL oxidation. More such clinical trials are needed to strengthen the hypothesis that foods rich in dietary phenolic compounds with antioxidant activity can mitigate the extent of LDL oxidation in vivo.

Piper betle leaf extracts induced human hepatocellular carcinoma Hep3B cell death via MAPKs regulating the p73 pathway in vitro and in vivo

Extracts of Piper betle leaf (PBLs) are rich in bioactive compounds with potential chemopreventive ability. In this study, Hep3B cells which are p53 null were used to investigate the anti-tumor effect of PBLs in the cell and in the xenograft model. The results revealed that PBLs (0.1 to 1 mg mL(-1)) induced a dose- and time-dependent increase of cell toxicity. The underlying mechanisms as evidenced by flow cytometry and western blot analysis showed that PBLs triggered ATM, cAbl, and p73 expressions and activated JNK and p38 pathways that subsequently led to cell cycle arrest and mitochondria-dependent apoptosis. PBLs also inhibited tumor growth in Hep3B-bearing mice via inducing the MAPK-p73 pathway. Our results demonstrated the in vitro and in vivo anti-tumor potential of PBLs, supporting their application as a novel chemopreventive agent for the treatment of human hepatocellular carcinoma (HCC) in the future via targeting the p73 pathway.