7,7'-Dihydroxy bursehernin inhibits the expression of inducible nitric oxide synthase through NF-kappaB DNA binding suppression

Botany, ethnopharmacology, phytochemistry and pharmacology of Erodii Herba Geranii Herba-An review

ETHNOPHARMACOLOGICAL RELEVANCE

As a commonly used traditional Chinese herbal medicine, Erodii Herba Geranii Herba (Geranium wilfordii Maxim., Geranium carolinianum L. and Erodium stephanianum Willd.), which was known as Laoguancao (Chinese:), has high medicinal value. It has been used to dispel rheumatism, dredge the meridians, activate blood circulation, remove blood stasis, clear heat and detoxify, and stop diarrhea and dysentery. It's also used to treat eczema, sores, carbuncles, boils caused by accumulation of damp toxin.

AIM OF THE REVIEW

This review aimed to provide a systematic and comprehensive analysis of the current research progress in terms of the botany, ethnopharmacology, phytochemistry and pharmacological activities of Erodii Herba Geranii Herba, and discuss expectations for prospective research and implementation about this herb.

MATERIALS AND METHODS

Information on Erodii Herba Geranii Herba was gathered via the Internet (using Google Scholar, Baidu Scholar, Pubmed, Elsevier, ACS, Medline Plus, CNKI and Web of Science) and libraries. Additionally, information was also obtained from local books and brilliant scholars in ethnopharmacology.

RESULTS

More than isolated 240 chemical compounds were recorded, and main compositions are tannins, flavones, organic acids and volatile oil. The pharmacoactives of Erodii Herba Geranii Herba and its active constituents are diverse, including antibacterial, antiviral, antioxidant, liver and kidney protection, anti-inflammatory and analgesic, other activities. Among them, the antibacterial, antiviral, anti-inflammatory, analgesic, antidiarrheal and other pharmacological activities of it are consistent with traditional applications.

CONCLUSIONS

All kinds of research conducted on Erodii Herba Geranii Herba, especially in field of ethnopharmacological use, phytochemicals and pharmacology have been reviewed. There are plenty of active compounds with varied effects in Erodii Herba Geranii Herba. However, some traditional applications and pharmacological activities of Erodii Herba Geranii Herba have not been scientifically evaluated or convincing due to incomplete methods and ambiguous results, as well as the lack of clinical data. In order to verify the pharmacological activity, clinical efficacy and safety of it, a systematic and comprehensive research evaluation is also required. As an important traditional Chinese medicine, Erodii Herba Geranii Herba should be further explored to promote the development of new drugs and therapeutics for various diseases. How to make better use of it should be paid more attention to.

Chemical analysis of amyloid β aggregation inhibitors derived from Geranium thunbergii

Amyloid β (Aβ) aggregates in the brains of patients with Alzheimer's disease (AD) and accumulates via oligomerization and subsequent fiber elongation processes. These toxicity-induced neuronal damage and shedding processes advance AD progression. Therefore, Aβ aggregation-inhibiting substances may contribute to the prevention and treatment of AD. We screened for Aβ42 aggregation inhibitory activity using various plant extracts and compounds, and found high activity for a Geranium thunbergii extract (EC₅₀ = 18 μg/mL). Therefore, we screened for Aβ42 aggregation inhibitors among components of a G. thunbergii extract and investigated their chemical properties in this study. An active substance was isolated from the ethanol extract of G. thunbergii based on the Aβ42 aggregation inhibitory activity as an index, and the compound was identified as geraniin (1) based on spectral data. However, although geraniin showed in vitro aggregation-inhibition activity, no binding to Aβ42 was observed via saturation transfer difference-nuclear magnetic resonance (STD-NMR). In contrast, the hydrolysates gallic acid (2) and corilagin (5) showed aggregation-inhibiting activity and binding was observed via STD-NMR. Therefore, the hydrolysates produced under the conditions of the activity test may contribute to the Aβ42 aggregation-inhibition activity of G. thunbergii extracts. Geraniin derivatives may help prevent and treat AD.

Anticancer activity of synthetic (±)-kusunokinin and its derivative (±)-bursehernin on human cancer cell lines

Kusunokinin is a potent lignan compound with a several biological properties including antitrypanosomal and anticancer. In this study, (±)-kusunokinin and its derivative, (±)-bursehernin, were synthesized and investigated for their anticancer activities on cell viability, cell cycle arrest and apoptosis in cancer cell lines including breast cancer (MCF-7, MDA-MB-468 and MDA-MB-231), colon cancer (HT-29) and cholangiocarcinoma (KKU-K100, KKU-M213 and KKU-M055) cells. The result showed that (±)-kusunokinin and (±)-bursehernin represented the strongest growth inhibition against breast cancer (MCF-7) and cholangiocarcinoma (KKU-M213) cells with the IC₅₀ values of 4.30 ± 0.65 μM and 3.70 ± 0.79 μM, respectively, both of which were lower than IC₅₀ of normal fibroblast cells (L929). Etoposide was used as a positive control since this chemotherapeutic drug is in the lignan group same as (±)-kusunokinin. Surprisingly, etoposide showed less cytotoxicity than (±)-kusunokinin and its derivative on MCF-7, HT-29, KKU-M213 and KKU-K100. Moreover, (±)-bursehernin induced cell cycle arrest at G2/M phase, meanwhile (±)-kusunokinin tended to increased cell population at G2/M phase but did not show the significant difference compared with non-treated cells. Interestingly, protein levels related to cell proliferation pathway (topoisomerase II, STAT3, cyclin D1, and p21) were significantly decreased at 72 h. Both compounds induced apoptotic cell in time-dependent manner as confirmed by MultiCaspase assay. In conclusion, synthetic compound, (±)-kusunokinin and (±)-bursehernin, showed anticancer effects via the reduction of cell proliferation proteins and induction of apoptosis.

Diarctigenin, a lignan constituent from Arctium lappa, down-regulated zymosan-induced transcription of inflammatory genes through suppression of DNA binding ability of nuclear factor-kappaB in macrophages

Diarctigenin was previously isolated as an inhibitor of nitric oxide (NO) production in macrophages from the seeds of Arctium lappa used as an alternative medicine for the treatment of inflammatory disorders. However, little is known about the molecular basis of these effects. Here, we demonstrated that diarctigenin inhibited the production of NO, prostaglandin E(2), tumor necrosis factor-alpha, and interleukin (IL)-1beta and IL-6 with IC(50) values of 6 to 12 miciroM in zymosan- or lipopolysaccharide-(LPS) activated macrophages. Diarctigenin attenuated zymosan-induced mRNA synthesis of inducible NO synthase (iNOS) and also inhibited promoter activities of iNOS and cytokine genes in the cells. Because nuclear factor (NF)-kappaB plays a pivotal role in inflammatory gene transcription, we next investigated the effect of diarctigenin on NF-kappaB activation. Diarctigenin inhibited the transcriptional activity and DNA binding ability of NF-kappaB in zymosan-activated macrophages but did not affect the degradation and phosphorylation of inhibitory kappaB (IkappaB) proteins. Moreover, diarctigenin suppressed expression vector NF-kappaB p65-elicited NF-kappaB activation and also iNOS promoter activity, indicating that the compound could directly target an NF-kappa-activating signal cascade downstream of IkappaB degradation and inhibit NF-kappaB-regulated iNOS expression. Diarctigenin also inhibited the in vitro DNA binding ability of NF-kappaB but did not affect the nuclear import of NF-kappaB p65 in the cells. Taken together, diarctigenin down-regulated zymosan- or LPS-induced inflammatory gene transcription in macrophages, which was due to direct inhibition of the DNA binding ability of NF-kappaB. Finally, this study provides a pharmacological potential of diarctigenin in the NF-kappaB-associated inflammatory disorders.

4-Hydroxykobusin Inhibits the Induction of Nitric Oxide Synthase by Inhibiting NF-.KAPPA.B and AP-1 Activation

We recently isolated a novel lignan, 4-hydroxykobusin from Geranium thunbergii (Liu et al., Arch. Pharm. Res., 29, 1109-1113, 2006). Here, we studied its effect on the expression of inducible nitric oxide synthase (iNOS) gene in RAW264.7 cells. 4-Hydroxykobusin inhibited nitric oxide (NO) production in a concentration-dependent manner and blocked the lipopolysaccharide (LPS)-induced expression of inducible nitric oxide synthase (iNOS). To identify the mechanistic basis for its inhibition of iNOS induction, we examined the effect of 4-hydroxykobusin on the transactivation of iNOS gene by luciferase reporter activity using -1.59 kb flanking region. The lignan suppressed the reporter gene activity and the LPS-induced reporter activations of nuclear factor-kappaB (NF-kappaB) and activator protein-1 (AP-1) were also significantly blocked by 4-hydroxykobusin. These findings suggest that the inhibition of LPS-induced NO formation by 4-hydroxykobusin is due to its inhibition of NF-kappaB and AP-1 activation.