Pharmaco-Chemical Studies on the Aqueous Methanolic Extract of Diospyros lotus Leaves

Antioxidant and Anticholinesterase Activities of Extracts and Phytochemicals of Syzygium antisepticum Leaves

Bioassay-guided separation of young leaves extracts of Syzygium antisepticum (Blume) Merr. & L.M. Perry led to the isolation of four triterpenoids (betulinic acid, ursolic acid, jacoumaric acid, corosolic acid) and one sterol glucoside (daucosterol) from the ethyl acetate extract, and three polyphenols (gallic acid, myricitrin, and quercitrin) from the methanol (MeOH) extract. The MeOH extract of S. antisepticum and some isolated compounds, ursolic acid and gallic acid potentially exhibited acetylcholinesterase activity evaluated by Ellman’s method. The MeOH extract and its isolated compounds, gallic acid, myricitrin, and quercitrin, also strongly elicited DPPH radical scavenging activity. In HEK-293 cells, the MeOH extract possessed cellular antioxidant effects by attenuating hydrogen peroxide (H₂O₂)-induced ROS production and increasing catalase, glutathione peroxidase-1 (GPx-1), and glutathione reductase (GRe). Furthermore, myricitrin and quercitrin also suppressed ROS production induced by H₂O₂ and induced GPx-1 and catalase production in HEK-293 cells. These results indicated that the young leaves of S. antisepticum are the potential sources of antioxidant and anticholinesterase agents. Consequently, S. antisepticum leaves are one of indigenous vegetables which advantage to promote the health and prevent diseases related to oxidative stress.

Quantitative Analysis of 7 Compounds in Diospyros lotus Leaf Extract and Its Biological Effects on Neuroprotection and Antineuroinflammation

Diospyros lotus L. (Ebenaceae) is a deciduous plant that was traditionally used to treat various diseases such as sedation, constipation, and hypertension. However, its effects on Alzheimer’s diseases (AD) have not been reported. We investigated the potent biological effects of D. lotus on AD and performed quantitative analysis of 7 standard compounds in D. lotus leaves. First, two parts leaf and branch of D. lotus were compared to examine the effects on amyloid-β (Aβ) aggregation and oxidative stress. Ethanol extract of D. lotus leaves (EDLL) had higher activities on the Aβ disaggregation and antioxidation compared with ethanol extract of D. lotus branches (EDLB). Second, we have focused on the biological activities of EDLL for neurocellular analyses. In HT22 neuronal cells, EDLL reversed hydrogen peroxide (H2O2)-damaged cell death. In BV-2 microglia, EDLL suppressed lipopolysaccharide-stimulated productions of nitric oxide (NO) and prostaglandin E2. Third, we performed quantitative analyses of 7 standard compounds in D. lotus using high-performance liquid chromatography. Among 7 compounds, myricitrin (44.189 mg/g) was the most abundant compound in EDLL. Myricetin presented the marked inhibitory effect on Aβ aggregation, indicating its potential as a bioactive compound to control Aβ aggregation. Overall, this study suggests that EDLL may be a promising therapeutic agent for AD via Aβ disaggregation, and inhibition of neuronal cell damage and inflammation.

Chemical characterisation of the constituents of Eugenia protenta McVaugh and leishmanicidal activity of dimethylxanthoxylin

The chemical study of Eugenia protenta McVaugh extracts performed by classical and high-performance liquid chromatography techniques and spectral methods has led to the identification of known triterpenoids, flavonoids and an acetophenone derivative (dimethylxanthoxylin). The effect of dimethylxanthoxylin on Leishmania (Leishmania) amazonensis was evaluated against the promastigotes forms after 96 h of treatment. Dimethylxanthoxylin reduced 57 and 59% of the promastigotes growth when treated with 50 and 100 μg/mL solutions, respectively (IC₅₀ 117.35 μg/mL or 52.3 μM). Cytotoxicity experiments using MTT assays showed that this substance did not promote cell death after 24 h of treatment. Dimethylxanthoxylin was active on the promastigotes and could be a promising agent for treating leishmaniasis.

Anti-inflammatory activity of myricetin from Diospyros lotus through suppression of NF-κB and STAT1 activation and Nrf2-mediated HO-1 induction in lipopolysaccharide-stimulated RAW264.7 macrophages

Diospyros lotus is traditionally used for the treatment of diabetes, diarrhea, tumor, and hypertension. The purpose of this study was to investigate the anti-inflammatory effect and underlying molecular mechanisms of myricetin in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. Myricetin dose-dependently suppressed the production of pro-inflammatory mediators (NO, iNOS, PGE2, and COX-2) in LPS-stimulated RAW264.7 macrophages. Myricetin administration decreased the production of NO, iNOS, TNF-α, IL-6, and IL-12 in mice. Myricetin decreased NF-κB activation by suppressing the degradation of IκBα, nuclear translocation of p65 subunit of NF-κB, and NF-κB DNA binding activity in LPS-stimulated RAW264.7 macrophages. Moreover, myricetin attenuated the phosphorylation of STAT1 and the production of IFN-β in LPS-stimulated RAW264.7 macrophages. Furthermore, myricetin induced the expression of HO-1 through Nrf2 translocation. In conclusion, these results suggest that myricetin inhibits the production of pro-inflammatory mediators through the suppression of NF-κB and STAT1 activation and induction of Nrf2-mediated HO-1 expression in LPS-stimulated RAW264.7 macrophages.

Polyphenolic Compounds and Antioxidant Activities of the Leaves of Glochidion hypoleucum

Bioassay-guided fractionation of the methanol extract of Glochidion hypoleucum (Miq.) Boerl leaves led to the isolation of five polyphenol compounds, methyl gallate, gallic acid, apigenin-8- C-β-D-glucopyranoside (vitexin), luteolin-8- C-β-D-glucopyranoside (orientin), and luteolin-6- C-β-D-glucopyranoside (isoorientin). The chemical structures of the isolated compounds were determined using spectroscopic (NMR, UV-Vis, IR) and mass spectrometric techniques. The antioxidative properties of the methanol extract and isolated polyphenols were evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH) for radical scavenging activity and 2′,7′-dichlorodihydrofluorescein diacetate (DCFH-DA) to measure the level of reactive oxygen species (ROS). With the exception of vitexin, the crude methanol extract and the polyphenol compounds inhibited DPPH radicals with IC50 values ranging from 2.46 ± 0.05 to 40.0 ± 0.3 μg/mL. In addition, the crude methanol extract attenuated H2O2-induced intracellular ROS production in a dose-dependent manner in HEK-293 cells. Gallic acid and isoorientin significantly reduced the ROS level in HEK-293 cells at a concentration of 20 μM.

Antipyretic and antinociceptive activity of Diospyros lotus L. in animals

OBJECTIVE

To evaluate pharmacologically the traditional use of Diospyros lotus as antipyretic and antinociceptive in various animal models.

METHODS

In vivo experimental models were used in this study. Antipyretic activity of extract/fractions was evaluated in brewer's yeast induced hyperthermic mice while antinociceptive activity was studied in acetic acid induced writhing test at 50 and 100 mg/kg i.p.

RESULTS

The crude extract strongly ameliorated the induced pyrexia during various assessment times. Upon fractionation, the antipyretic effects were strongly augmented by the chloroform and ethyl acetate fractions of the plant. However, hexane and butanol fractions were insignificant in their effect as antipyretic. The extract showed marked inhibition on the noxious simulation induced by post acetic acid injection. The effect was strongly supported by other fraction expect hexane.

CONCLUSIONS

In short, our study scientifically validated the traditional use of the plant as antipyretic.