Phytochemical Investigation of Nymphaea pubescens and Study of its Antimicrobial Activities

Abstract

Nymphaea pubescens Wild (Nymphaeaceae) is a fascinating aquatic plant used in Bangladesh for the treatment of diabetes, liver disorders, urinary problems, menorrhagia, blenorragia; also used as tonic and aphrodisiac. The roots used by the traditional healers of the Tripura, Marma and Murong tribes to treat dysuria, urinary tract infections and leucorrhea. Also, used for indigestion, heart diseases, stomachaches, cancer, and as anti-hemorrhagic. Due to its large traditional use, N. pubescens was the plant of choice of our study. Extraction of Nymphaea pubescens leaves (700 g) at room temperature by maceration with methanol yielded 122 g (17.43% of dry weight) extracts respectively. The methanol extract of Nymphaea pubescens was subjected to Vacuum liquid chromatography and five different fractions were collected using five different solvents; Fractions were- n-hexane Fraction- Fraction -1, DCM fraction-Fraction-2, Ethyl-acetate fraction- Fraction-3, Acetone fraction- Fraction-4 and Methanol fraction- Fraction-5. Their weights were Fraction-1=7.38 gm, Fraction-2=3.28 gm, Fraction-3=34.66 gm, Fraction-4=79.3 gm and Fraction-5=14.27 gm. Among the five fractions n-hexane fraction and Ethyl-acetate fraction were subjected to column chromatography. The n-hexane fraction or Fraction-1 and ethyl acetate fraction or Fraction-3 of Nymphaea pubescens were separated by open column chromatography with silica gel and the fractions were collected monitoring the TLC. Fraction-1-40 yielded a colorless crystal, NPH-40. This compound was UV inactive and charring with methanol and H2SO4 (9:1) gave characteristic red color indicating the compound is a fatty acid derivative. 1HNMR report of NPH-40 informs that may be this is a mixture of four fatty acids and those are myristic acid, palmitic acid, lauric acid and 4-methyl-4-tetradecenoic acid. Further analysis such as 13CNMR, Mass spectroscopy etc is required for definite result. Fraction-3-22 yielded another colorless crystal, NPE-22. This compound was also UV inactive and charring with methanol and H2SO4 (9:1) gave characteristic brown color indicating the compound is a triterpenoid derivative. 1HNMR report of NPE-22 informs that may be this compound is oleanolic acid. Further analysis such as 13CNMR, Mass spectroscopy etc is also required here for definite result. According to the literature review done so far in this research paper, this is the first time that Oleanolic acid has been isolated from Nymphaea pubescens.