Phytochemical Screening, Radical Scavenging and Antimicrobial Activities of the Crude Ethanolic, Methanolic, Ethyl Acetate and Chloroform Leaf Extracts of Arayat Pitogo (Cycas riuminiana Porte ex Regel)

In the Philippines, Cycas spp. are found in Luzon Island particularly in Pampanga, Batangas, Bataan and Isabela provinces.. In this study, the bioactive potentials of the crude methanolic, ethanolic, ethyl acetate and chloroform leaf extracts of Cycas riuminiana Porte ex Regel were investigated. Based on the results of the four solvents used, the best extraction solvent for the phytochemicals is ethanol, followed by methanol, ethyl acetate and chloroform. The ethanolic and methanolic leaf extracts showed comparable antioxidant activity. The chloroform and ethyl acetate extracts also have comparable antioxidant activity but significantly lower than both methanolic and ethanolic extracts. However the greatest antimicrobial activity was exhibited by the ethyl acetate extract, followed by chloroform, methanolic and ethanolic extracts. The variation and similarity in the antioxidant and antimicrobial activities of the different extracts can be attributed to different mechanisms of interactions, namely, independent joint action, additive, synergistic, competitive or antagonistic interactions, among the bioactive compounds present in the crude extracts. Further studies are needed to elucidate the structure of the different phytochemicals present in the leaf extracts of Arayat Pitogo (C. riuminiana Porte ex Regel) and the specific mechanisms of interaction among these phytochemicals. SUMMARYThe extracts were tested for the presence (trace, moderate or abundant amounts) of flavonoids, saponins, tannins, triterpenes, alkaloids, sterols and glycosides. The ethanolic extract was positive for all phytochemicals screened with sterols, flavonoids, glycosides and tannins being abundant, alkaloids being moderate and triterpenes and saponins in trace amounts. The methanolic extract was also positive for all constituents but in trace amounts, except for flavonoids which were abundant. The ethyl acetate extract contained abundant sterols, moderate alkaloids and trace amounts of saponins, glycosides and tannins. Finally, the chloroform extract contained abundant sterols, and trace amounts of alkaloids, saponins and glycosides. The radical scavenging assay revealed that the highest percent inhibition was obtained for the ethanolic leaf extract (60.53{+/-}0.7801%), followed by methanolic extract (59.92{+/-}3.160%), chloroform extract (50.17{+/-}4.779%) and ethyl acetate extract (47.25{+/-}3.759%). In terms of antibacterial activity, the ethyl acetate extract registered the highest inhibition against the three test organisms, namely, Staphylococcus aureus, Bacillus subtilis and Escherichia coli. The chloroform extract inhibited S. aureus and B. subtilis. The methanol extract inhibited S. aureus only. Finally, the ethanolic extract failed to inhibit any of the test organisms despite its abundant phytochemicals and high antioxidant activity. In terms of antifungal activity, the different extracts inhibited Candida albicans with the ethyl acetate and chloroform extracts showing a high degree of inhibition followed by the methanolic and ethanolic extracts. However, none of the extracts showed any bioactivity against Aspergillus niger.