Ethnopharmacological relevance: Boesenbergia rotunda Linn. (Zingiberaceae) is traditionally used in many
Asian countries as medicine for stomach pain and discomfort, viral and bacterial infection, inflammation,
and as diuretic agent.
Aim of the study: The study aimed to identify adenosine A1 receptor binding compounds from Boesenbergia
rotunda rhizome extract by using comprehensive extraction coupled to the NMR metabolomics method.
Materials and methods: Dried and powdered Boesenbergia rotunda rhizomes were extracted with the
comprehensive extraction method to obtain several fractions with different polarity. Each fraction was
divided into two: for NMR analysis and for adenosine A1 receptor binding test. Orthogonal projection to the
least square analysis (OPLS) was used to study the correlation between metabolites profile and adenosine A1
receptor binding activity of the plant extracts. Based on Y-related coefficient and variable of important (VIP)
value, signals in active area of OPLS loading plot were studied and the respective compounds were then
elucidated
Results and discussions: Based on OPLS Y-related coefficient plot and variable of importance value plot,
several characteristic signals were found to positively correlate to the binding activity. By using 1D and 2D
NMR spectra of one of the most active fraction, pinocembrine and hydroxy-panduratin were identified as the
possible active compounds. Two signals from ring C of pinocembrine flavanone skeleton with negative
coefficient correlations possibly overlapped with those of non-active methoxylated flavanones which were
also presence in the extract. NMR based metabolomics applied in this study was able to quickly identify
bioactive compounds from plant extract without necessity to purify them. Further confirmation by isolating
pinocembrine and hydroxy-panduratin and testing their adenosine A1 receptor binding activity to chemically
validate the method are required.
Conclusion: Two flavonoid derivatives, pinocembrine and hydroxy-panduratin, have been elucidated as
possible active compounds bind to adenosine A1 receptor. Flavonoid was reported to be one of natural
antagonist ligand for adenosine A1 receptor while antagonistic activity to the receptor is known to associate
with diuretic activity. Thus, the result of this research supports the traditional use of Boesenbergia rotunda
rhizome extract as diuretic agent.