Chemical Constituents of Cymodocea rotundata Asch. and Schweinf

Abstract

Introduction:Cymodocea rotundata Asch. and Schweinf, a widespread seagrass with reported antimicrobial activity, was investigated for its chemical constituents. Methods: The compounds were isolated by silica gel chromatography and identified by NMR spectroscopy. Results: This study has led to the isolation of β-sitosteryl-3β-glucopyranoside-6′-O-fatty acid esters (1), chlorophyll a (2) and a mixture of β-sitosterol (3a) and stigmasterol (3b) in about 1:1 ratio from the dichloromethane extract of C. rotundata. Conclusion: This is the first report on the isolation of 1-3b from C. rotundata. Compounds 2-3b were reported to exhibit antibacterial activity and may be partly responsible for the reported antimicrobial activity of the C. rotundata extract. Key words: Cymodocea rotundata, Cymodoceaceae, β-sitosteryl-3β-glucopyranoside-6′-Ofatty acid esters, Chlorophyll , β-sitosterol, Stigmasterol. Thin layer chromatography was performed with plastic backed plates coated with silica gel F 254 and the plates were visualized by spraying with vanillin/ H 2 SO 4 solution followed by warming. Sample CollectionSamples of the leaves of Cymodocea rotundata Asch. and Schweinf. were collected from the seagrass meadow of Caramoan, Camarines Sur Philippines in September 2016. The samples were authenticated at the Botany Division, Philippine National Museum. General Isolation ProcedureA glass column 6 inches in height and 0.25 inch internal diameter was used for the chromatography. The crude extracts were fractionated by silica gel chromatography using increasing proportions of acetone in CH 2 Cl 2 at 10% increment by volume as eluents. Five milliliter fractions were collected. All fractions were monitored by thin layer chromatography. Fractions with spots of the same Rf values were combined and rechromatographed in appropriate solvent systems until TLC pure isolates were obtained. Final purifications were conducted using Pasteur pipettes as columns. One milliliter fractions were collected. Isolation of the Chemical Constituents from the Leaves of C. rotundataThe air-dried C. rotundata (50 g) leaves were ground in a blender, soaked in CH 2 Cl 2 for 3 days and then filtered. The solvent was evaporated under vacuum to afford a crude extract (0.3 g) which was chromato- Ragasa et al.: Cymodocea rotundataPharmacognosy Journal, Vol 10, Issue 4, Jul-Aug, 2018 621 graphed using increasing proportions of acetone in CH 2 Cl 2 at 10% increment by volume. The 10% acetone in CH 2 Cl 2 fraction was rechromatographed using 10% EtOAc in petroleum ether. The less polar fractions were combined and rechromatographed using 10% EtOAc in petroleum ether to afford 2 (4 mg) after washing with petroleum ether, followed by Et 2 O. The more polar fractions were combined and rechromatographed (2 ×) using 15% EtOAc in petroleum ether to yield a mixture of 3a and 3b (6 mg) after washing with petroleum ether. The 60% acetone in CH 2 Cl 2 fraction was rechromatographed using CH 3 CN:Et 2 O:CH 2 Cl 2 (1:1:8, v/v) to afford 1 (3 mg) after washing with petrole...

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“…18 Another aspect of our research showed the presence of fatty acids derivatives besides phenolics derivatives, which was detected from GC-MS chromatogram. In a study of 19 has led to the isolation of fatty acid esters, chlorophyll in about 1:1 ratio from the dichloromethane extract of C. rotundata. Fatty acid esters obtained from the extract of C. rotundata exhibited antibacterial activity and partly showed antimicrobial activity B.…”