PHYTOCHEMICAL ANALYSIS TO VALIDATE POTENTIAL MEDICINAL PROPERTIES OF FOUR PLANTS FROM THE DOMINICAN REPUBLIC
I. DELGADO, J. SALAZAR, E. JOVEL, E. RODRIGUEZ

Preliminary biological and chemical analyses were conducted in La Altagracia, Dominican Republic on four plants known to contain medicinal properties. Stachytarpheta jamaicensis (Verbenaceae), is know to have anti-ulcer properties, to alleviate diarrhea, and to work as a sedative for nervous disorders. Rawoulfia tetraphylla (Apocynaceae) is known to have tranquilizing effects in people with mental illnesses and is used as an antivenin for snake and scorpion bites. Cissus trifoliata (Vitacaeae) is also known to have anti-ulcer as well as anti-inflammatory properties. Lastly, Argusia gnaphalodes (Boraginaceae) is used to treat gonorrhea, fevers, colds, and liver problems. The root, bark, leaf, flower, fruit and/or latex of each plant was extracted with 95% ethanol and tested for anti-microbial activity against the gram-positive bacteria Bacillus cereus, Bacillus subtilis, and Staphylococcus aureus, the gram-negative Pseudomonas aeruginosa, and three strains of Candida albicans, to validate ethnomedical research. Despite their known anti-bacterial properties, C. trifoliata and S. jamaicensis only inhibited one strain of C. albicans and B. subtilis, respectively. A. gnaphalodes showed weak inhibition against B. cereus and a different strain of C. albicans, while R. tetraphylla showed strong inhibition against all the bacteria and fungi. These active extracts were then separated into their polar and non-polar components and tested for anti-microbial activity. Greater inhibition by the combination of both polar and non-polar compounds suggested synergism between compounds within the active extracts. Phototoxicity tests of the R. tetraphylla extracts showed that exposure to long-wave UV light increased inhibition of B. cereus and S. aureus by the bark extract and of P. aeruginosa by the root extract. Chemical analysis on crude extracts with thin-layer chromatography (TLC) and Dragendorff , vanillin, and 2,2-diphenyl-1-picrylhydrazyl (DPPH) spray reagents demonstrated the presence of alkaloids in S. jamaicensis and R. tetraphylla, phenols in C. trifoliata and A. gnaphalode, terpenoids in S. jamaicensis and R. tetraphylla, and antioxidants in R. tetraphylla. Further research is recommended to isolate these compounds and determine which are responsible for the observed anti-microbial activities.