Rapid Isolation of Ricinine, a Pyridone Alkaloid from Ricinus communis (L.) with Antifungal Properties

Abstract The present study introduces an effective and rapid method for isolation of antifungal compound ricinine from Ricinus communis (L.). In this respect, the tender leaves of R. communis were extracted using methanol and tested for antifungal activity against a panel of dermatophytes and plant pathogenic fungi. Primarily, the total extract exhibited broad-spectrum antifungal activity with the zones of inhibition ranging from 12 ± 1.00 to 18.66 ± 1.52 mm. Further, investigation of chemical constituents led to the isolation of a cyano-pyridone alkaloid, ricinine using acid-base extraction. The compound exhibited significant antifungal activity with MIC values ranging from 6.25-250 µg/mL against the tested pathogenic fungi. Particularly, antifungal activity was recorded against A. flavus with the MIC value of 7.81 µg/mL followed by B. cinerea and A. niger with 15.62 µg/mL, respectively; T. mentagrophytes and T. rubrum with 62.5 µg/mL, respectively and it showed weak activity against Scopulariopsis sp. with 250 µg/mL. This efficient result provide new insights on large-scale isolation and identification of 4-methoxy-1-methyl-2-oxo-1,2-dihydropyridine-3-carbonitrile (Ricinine) which possess potent antifungal activity. In conclusion, the compound ricinine can be used as potential antifungal agent for controlling plant pathogenic fungi as well dermatophytes. Further, this potentially useful technique is operationally simple, safe, time-saving and inexpensive, and can be applied by medicinal, pharmaceutical and scientific research for the isolation of other potentially useful alkaloids in the drug discovery programs. Graphical abstract