Anti-inflammatory Activity of <i>Etlingera elatior</i> (Jack) R.M. Smith Flower on Gastric Ulceration-induced Wistar Rats

Phytochemical Analysis, Computational Study, and in vitro Assay of Etlingera elatior Inflorescence Extract Towards Inducible Nitric Oxide Synthase

Background

Overproduction of nitric oxide (NO), catalyzed by inducible nitric oxide synthase (iNOS), in the gastric mucosa, contributes to the inflammatory process caused by oxidative stress. Current medications for gastric ulcers, such as proton pump inhibitors and histamine-2 receptor antagonists, have been reported to generate adverse reactions.

Purpose

To obtain the phytochemical profile of Etlingera elatior inflorescence extract, computational studies, and in vitro assay of the extract towards iNOS.

Methods

Fresh E. elatior inflorescence petals collected from West Java, Indonesia, were extracted using ethanol, and their nutritional composition, anthocyanin content, and levels of vitamin C, C3G, and quercetin in the extract were determined. Drug-likeness and ADMET properties were predicted, and the binding affinity and stability of the phytoconstituents towards iNOS were studied using molecular docking and molecular dynamic simulation, and in vitro assay of the extract towards human iNOS.

Results

The extract contains protein 21.81%, fat 0.99%, carbohydrate 38.27%, water 24.56%, and ash 14.37%. The total anthocyanin and vitamin C levels were 47.535 mg/100 g and 985.250 mg/100 g, respectively. The levels of C3G and quercetin were 0.0007% w/w, 0.004% w/w, and 0.0005% w/w, respectively. Drug-likeness and ADMET properties of the constituents showed that most followed Lipinski Rules of Five (Ro5), with few violations. All phytoconstituents occupied the catalytic site by binding to Glu377, and Trp372, similar to S-ethylisothiourea (SEITU) and quinazoline, the iNOS inhibitors. Among these, the flavylium cation of cyanidin, demethoxycurcumin, C3G, cyanidin, and quercetin showed the best binding affinities. Root mean square deviation (RMSD), root mean square fluctuation (RMSF), solvent-accessible surface area (SASA), and radius of gyration (Rg) graphs confirmed the stability of the complexes. E. elatior inflorescence extract inhibited human iNOS with an IC50 value of 24.718 µg/mL.

Conclusion

Etlingera elatior inflorescence may inhibit iNOS activity due to its anthocyanin and flavonoid content. The flavylium cation of cyanidin, demethoxycurcumin, C3G, cyanidin, and quercetin play leading roles in the interaction with iNOS.

Potential of Ageratum conyzoides in Inhibiting Nitric Oxide Synthase

&lt;b&gt;Background and Objective:&lt;/b&gt; Inflammation occurs &lt;i&gt;via&lt;/i&gt; several mechanisms, one of which includes the production of Nitric Oxide (NO) catalyzed by inducible nitric oxide synthase (iNOS), which is inhibited selectively by isothioureas. &lt;i&gt;Ageratum conyzoides&lt;/i&gt; L. has shown activity in reducing pain and inflammation, although the molecular mechanism had not been undertaken. The objectives of this work were (1) to study the mechanism of anti-inflammatory activity of &lt;i&gt;A. conyzoides&lt;/i&gt; through inhibition of iNOS, (2) to correlate the iNOS inhibitory activity of the plant with the total flavonoid content of the plants and (3) to identify the flavonol synthase (FLS), an enzyme that catalyzes the production of quercetin. &lt;b&gt;Materials and Methods:&lt;/b&gt; The inhibitory activity against iNOS was assayed by &lt;i&gt;in vitro&lt;/i&gt; method. The total flavonoids (calculated as quercetin) of &lt;i&gt;A. conyzoides&lt;/i&gt; were determined by fluorometry. The protein extraction of the leaves was carried out by employing Laing and Christeller's (2004) method, followed with SDS-PAGE. &lt;b&gt;Results:&lt;/b&gt; The inhibitory activity (IC&lt;sub&gt;50&lt;/sub&gt;) of ethanol extract and ethyl acetate fraction of &lt;i&gt;A. conyzoides&lt;/i&gt; against iNOS was 92.05 and 4.78 μg mL&lt;sup&gt;&lt;/sup&gt;&lt;sup&gt;1&lt;/sup&gt;, respectively. Pearson correlation analysis resulted in 0.548 (ethanol extract) and 0.696 (ethyl acetate fraction). The total flavonoids (calculated as quercetin) contained in the ethanol extract and ethyl acetate fraction of &lt;i&gt;A. conyzoides&lt;/i&gt; were 0.71 and 7.65%, respectively. The FLS in &lt;i&gt;A. conyzoides&lt;/i&gt; leaves was identified at 31 kDa. &lt;b&gt;Conclusion:&lt;/b&gt; &lt;i&gt;A. &lt;/i&gt;c&lt;i&gt;onyzoides&lt;/i&gt; L. is potential in inhibiting iNOS due to quercetin contained in the leaves. This report will add a scientific insight of &lt;i&gt;A. conyzoides&lt;/i&gt; for biological sciences.