Anti-Inflammatory Effect of Charantadiol A, Isolated from Wild Bitter Melon Leaf, on Heat-Inactivated Porphyromonas gingivalis-Stimulated THP-1 Monocytes and a Periodontitis Mouse Model.

Porphyromonas gingivalis has been identified as one of the major periodontal pathogens. Activity-directed fractionation and purification processes were employed to identify bioactive compounds from bitter melon leaf. Ethanolic extract of bitter melon leaf was separated into five subfractions by open column chromatography. Subfraction-5-3 significantly inhibited P. gingivalis-induced interleukin (IL)-8 and IL-6 productions in human monocytic THP-1 cells and then was subjected to separation and purification by using different chromatographic methods. Consequently, 5ß,19-epoxycucurbita-6,23(E),25(26)-triene-3ß,19(R)-diol (charantadiol A) was identified and isolated from the subfraction-5-3. Charantadiol A effectively reduced P. gingivalis-induced IL-6 and IL-8 productions and triggered receptors expressed on myeloid cells (TREM)-1 mRNA level of THP-1 cells. In a separate study, charantadiol A significantly suppressed P. gingivalis-stimulated IL-6 and tumor necrosis factor-α mRNA levels in gingival tissues of mice, confirming the inhibitory effect against P. gingivalis-induced periodontal inflammation. Thus, charantadiol A is a potential anti-inflammatory agent for modulating P. gingivalis-induced inflammation.

Protective Effect of Caffeic Acid Derivatives on tert-Butyl Hydroperoxide-Induced Oxidative Hepato-Toxicity and Mitochondrial Dysfunction in HepG2 Cells.

Oxidative stress results in structural and functional abnormalities in the liver and is thought to be a crucial factor in liver diseases. The aim of this study was to investigate the cytoprotective and antioxidant effects of caffeic acid (CA) derivatives on tert-butyl hydroperoxide (t-BHP)-induced oxidative stress in HepG2 cells. Nine CA derivatives were synthesized, including N-phenylethyl caffeamide (PECA), N-(3-florophen)methyl caffeamide (FMCA), N-(4-methoxy-phen)methyl caffeamide (MPMCA), N-heptyl caffeamide (HCA), N-octyl caffeamide (OCA), octyl caffeate (CAOE), phenpropyl caffeate (CAPPE), phenethyl caffeate (CAPE), and phenmethyl caffeate (CAPME). The results showed that CA and its derivatives significantly inhibited t-BHP-induced cell death of HepG2 cells. The rank order of potency of the CA derivatives for cytoprotection was CAOE > HCA > OCA > FMCA > CAPPE > CAPME > CAPE > PECA > MPMCA > CA. Their cytoprotective activity was associated with lipophilicity. The antioxidant effect of these compounds was supported by the reduction in the levels of thiobarbituric acid reactive substrates, a biomarker of lipid peroxidation, in HepG2 cells. Pre-treatment of CA derivatives significantly prevented the depletion of glutathione, the most important water-soluble antioxidant in hepatocytes. Pre-treatment of CA derivatives before t-BHP exposure maintained mitochondrial oxygen consumption rate and ATP content in the injured HepG2 cells. CA derivatives except OCA and HCA significantly suppressed t-BHP-induced hypoxia-inducible factor-1α (HIF-1α) protein level. In addition, all of these CA derivatives markedly increased the nuclear factor erythroid 2-related factor 2 (Nrf2) accumulation in the nucleus, indicating that their cytoprotection may be mediated by the activation of Nrf2. Our results suggest that CA derivatives might be a hepatoprotective agent against oxidative stress.

Wild Bitter Melon Leaf Extract Inhibits Porphyromonas gingivalis-Induced Inflammation: Identification of Active Compounds through Bioassay-Guided Isolation.

Porphyromonas gingivalis has been identified as one of the major periodontal pathogens. Activity-directed fractionation and purification processes were employed to identify the anti-inflammatory active compounds using heat-killed P. gingivalis-stimulated human monocytic THP-1 cells in vitro. Five major fractions were collected from the ethanol/ethyl acetate extract of wild bitter melon (Momordica charantia Linn. var. abbreviata Ser.) leaves and evaluated for their anti-inflammatory activity against P. gingivalis. Among the test fractions, Fraction 5 effectively decreased heat-killed P. gingivalis-induced interleukin (IL)-8 and was subjected to separation and purification by using chromatographic techniques. Two cucurbitane triterpenoids were isolated from the active fraction and identified as 5ß,19-epoxycucurbita-6,23-diene-3ß,19,25-triol (1) and 3ß,7ß,25-trihydroxycucurbita-5,23-dien-19-al (2) by comparing spectral data. Treatments of both compounds in vitro potently suppressed P. gingivalis-induced IL-8, IL-6, and IL-1ß levels and the activation of mitogen-activated protein kinase (MAPK) in THP-1 cells. Both compounds effectively inhibited the mRNA levels of IL-6, tumor necrosis factor (TNF)-α, and cyclooxygenase (COX)-2 in P. gingivalis-stimulated gingival tissue of mice. These findings imply that 5ß,19-epoxycucurbita-6,23-diene-3ß,19,25-triol and 3ß,7ß,25-trihydroxycucurbita-5,23-dien-19-al could be used for the development of novel therapeutic approaches against P. gingivalis infections.

In vitro antimicrobial activities against cariogenic streptococci and their antioxidant capacities: A comparative study of green tea versus different herbs.

The antimicrobial activity against cariogenic bacteria, total antioxidant capacity and phenolic constituents of methanolic extracts from 11 herbs were investigated and compared with those of green tea (Camellia sinensis). Among the 12 tested herbs, eight herbal extracts could inhibit the growth of Streptococcus sanguinis. Jasmine, jiaogulan, and lemongrass were the most potent, with minimum inhibitory concentrations (MIC) of 1mg/ml, while green tea was less effective, with a MIC of 4mg/ml. Among them, only rosemary could inhibit the growth of S. mutans at a MIC of 4mg/ml. Total antioxidant capacities of herbal extracts were analyzed by three different assays, including 2,2-diphenyl-1-picrylhydrazyl (DPPH·) radical scavenging activity, trolox equivalent antioxidant capacity (TEAC) and oxygen radical absorbance capacity (ORAC). Regardless of the assays used, green tea exhibited the highest antioxidant capacity, followed by osmanthus. Wide variations in total phenolics and total flavonoids of herbal tea extracts were observed. Chlorogenic acid was detected in high amount in honeysuckle and duzhong. These data suggest that rosemary is a potent inhibitor of oral streptococci, and green tea and osmanthus may be effective potential sources of natural antioxidants.

Protective capacities of certain spices against peroxynitrite-mediated biomolecular damage.

Peroxynitrite, a potent cytotoxic agent, can damage a variety of biomolecules such as proteins, lipids, and DNA, and is considered as one of the major pathological causes of several diseases. Therefore, it would appear likely that interception of peroxynitrite by certain dietary compounds may represent one mechanism by which such foods may exert their beneficial action in vivo. A number of researchers have speculated that certain spices, rich in phenolics, may, conceivably, act as potential protectors against the actions of peroxynitrite. Eight culinary spices including cardamom, cinnamon, cloves, cumin, nutmeg, paprika, rosemary and turmeric were selected for study purposes. Further, the protective effects of methanol extracts of such spices against peroxynitrite-mediated damage to proteins, lipids and DNA were evaluated as determined by these extracts' ability to attenuate the formation of, respectively, nitrotyrosine in albumin, thiobarbiturate acid-reactive substances (TBARS) in liposome and strand breakages for plasmid DNA. All of the tested spices exerted some level of protective ability against peroxynitrite-mediated biomolecular damage. Amongst them, cloves deserve special attention due to their outstanding protective abilities against two of three forms of peroxynitrite-mediated biomolecular damage. Additionally, the phenolic content of certain spices appears to correlate well with such spices' protective effect against peroxynitrite-mediated tyrosine nitration and lipid peroxidation. Such an observation indicates that phenolics present in the spices contributed to such spice-elicited protection against peroxynitrite toxicity.

Evaluation of NO-suppressing activity of several Mediterranean culinary spices.

Excess nitric oxide (NO) produced by inducible nitric oxide synthase (iNOS) is implicated in the development of a number of diseases. Due to the absence of any natural specific enzymatic defense system in vivo, the consumption of certain foods which exhibit selective suppressive ability as regards NO overproduction might boost the host's protective effects against NO-mediated toxicity. Spices, rich in phenolics, are speculated conceivably to act as potential NO-scavengers or iNOS suppressors. The relative NO-suppressing activity of methanol extracts deriving from nine Mediterranean culinary spices was determined by measuring their inhibitory effect upon NO production for lipopolysaccharide (LPS)-activated RAW 264.7 macrophages. In addition, the specifics of the suppressing mechanism were further explored. All of the spices tested, with the exception of clove, displayed a rather linear dose-dependent NO-suppressing effect without there appearing to exist any effect upon cell viability. Furthermore, the NO-suppressing capacity of certain spices was able to be ranked based upon their IC(50) (the concentration of spice extracts is required to cause 50% inhibition of NO production by LPS-activated RAW 264.7 cells), the ranking appearing as: rosemary (0.031%)>tarragon (0.052%)>cinnamon (0.059%)>oregano (0.106%)>basil (0.162%)>marjoram (0.236%)>allspice (0.269%)>and thyme (0.270%). Only cinnamon displayed excellent NO-scavenging ability, whereas all of the other spices demonstrated moderate to poor activities in this regard. Moreover, the inhibitory effect of tested spices upon the iNOS protein level was almost equivalent to their suppressive effect upon NO production. It would appear that inhibition of iNOS expression was the primary mechanism of action of spices as regards their exerting NO-suppressing activity.