Anti-HIV-1 activities of constituents from the rhizomes of Boesenbergia thorelii

A new lignan, thoreliin A (1), and a new bisnorlignan, thoreliin B (2), were isolated from a MeOH extract of the rhizomes of Boesenbergia thorelii. In addition, the known bisnorlignans 3 and 4, neolignan 5, phenylpropanoids 6-15, as well as benzenoids 18-21 were also obtained from the same source. The structures were elucidated based on their spectroscopic data. By single crystal X-ray analysis, the relative stereochemistry of 1 was confirmed. All isolated compounds were evaluated for anti-HIV-1 activities. Among them, thoreliin A (1) exhibited anti-HIV-1 activities on both HIV-1 reverse transcriptase (41.43% inhibition at 200 μg/mL) and syncytium reduction assays (EC₅₀ 20.6 μM, SI 3.7), while compounds 3-6, 9 and 11-21 showed anti-HIV-1 activity only in the anti-syncytium assay (EC₅₀ 6.6-454.1 μM, SI >1.32-7.75).

Euodenine A: a small-molecule agonist of human TLR4

A small-molecule natural product, euodenine A (1), was identified as an agonist of the human TLR4 receptor. Euodenine A was isolated from the leaves of Euodia asteridula (Rutaceae) found in Papua New Guinea and has an unusual U-shaped structure. It was synthesized along with a series of analogues that exhibit potent and selective agonism of the TLR4 receptor. SAR development around the cyclobutane ring resulted in a 10-fold increase in potency. The natural product demonstrated an extracellular site of action, which requires the extracellular domain of TLR4 to stimulate a NF-κB reporter response. 1 is a human-selective agonist that is CD14-independent, and it requires both TLR4 and MD-2 for full efficacy. Testing for immunomodulation in PBMC cells shows the induction of the cytokines IL-8, IL-10, TNF-α, and IL-12p40 as well as suppression of IL-5 from activated PBMCs, indicating that compounds like 1 could modulate the Th2 immune response without causing lung damage.

Chemical composition and antimicrobial activity of Phyllanthus muellerianus (Kuntze) Excel essential oil

ETHNOPHARMACOLOGICAL RELEVANCE

Phyllanthus muellerianus (Kuntze) Excel (family Euphorbiaceae) stem bark is used in Cameroon by Baka pygmies as a remedy for wound healing and tetanus.

AIM OF THE STUDY

To characterize the chemical composition and to evaluate the antimicrobial properties of the essential oil of the plant.

MATERIALS AND METHODS

The essential oil was extracted from the stem bark by dynamic head space and by hydrodistillation and characterized by GC and GC-MS analyses. The antimicrobial activity was evaluated on the basis of the minimum inhibitory concentration (MIC) and the minimum bactericidal-fungicidal concentration (MBC-MFC) by the micro and macrodilution methods. The following bacteria and fungi were used: Clostridium sporogenes ATCC 3584, Staphylococcus aureus ATCC 6538, Streptococcus mutans ATCC 25175, Streptococcus pyogenes ATCC 19615, Escherichia coli ATCC 10536, Candida albicans ATCC 10231, Candida albicans LM 450, Trichophyton mentagrophytes LM 230, Trichophyton rubrum LM 237, Microsporum canis LM 324.

RESULTS

The hydrodistillation afforded 0.06% (dry weight basis) of pale yellow oil. Thirty-eight compounds representing 90.69% were identified. The major component (36.40%) was found to be (E)-isoelemicin, identified by comparison of its (1)H-NMR experimental data, with literature data. The oil showed good antibacterial activity against Clostridium Sporogenes, Streptococcus mutans and Streptococcus pyogenes with MIC ranging from 13.5 to 126 μg/ml. A weak antifungal activity (MIC 250 μg/ml) was found against Trichophyton rubrum, only.

CONCLUSIONS

The antimicrobial activity and the chemical composition of Phyllanthus muellerianus stem bark essential oil are reported for the first time.