Planta Med 2007; 73 - P_548
DOI: 10.1055/s-2007-987328

Chromatographic separation, characterization and bioactivity guided assays of the aqueous root extract fractions of Dalbergia saxatilis HOOK. F. (Papilionaceae)

OK Yemitan 1, OO Adeyemi 1
  • 1Department of Pharmacology, College of Medicine of the University of Lagos, Idi-Araba, P.M.B. 12003 Lagos, Lagos, Nigeria

The aqueous root decoction of Dalbergia saxatilis (DS), is used to treat convulsive and anxiety disorders, pain and muscle tension in traditional African medicine. Separation of phytochemical constituents was conducted on DS using Sephadex G-50 packed chromatography into thirty 5ml fractions. Preliminary chemical characterization was conducted on fractions employing the Agilent 8453 UV-Visible spectrophotometer between 200 and 600 nm; and phytochemicals present in fractions were confirmed by simple chemical tests on determination of phytochemicals in medicinal plants [1]. Based on the distribution of the phytochemicals, fractions 9 & 10; 11 & 12; 15 & 16; 17 & 18 (labelled as „A“, „B“, „C“, „D“, respectively), were pooled for biological tests. Bioactivity guided assays were done by investigating the CNS depressant effects of fractions on strychnine induced seizures [2], pentobarbitone hypnosis [2] and exploratory behavioural test [3] models. Results as depicted by the chemical tests method [1] showed chromatographic separation of DS into fractions of saponins (7–26), reducing sugar (5–21), soluble carbohydrates (5–27), tannins (5–19), phenols (5–19) and C-glycosides (15–18). Bioactivity guided assays showed that fraction „C“ (200mg/kg, p.o.), like phenobarbitone (40mg/kg, i.p.) produced significant (P<0.01) antiseizure effect; fraction „D“ (200mg/kg, p.o.) produced prolongation of pentobarbitone (40mg/kg, i.p.) sleeping time, while fraction „A“ (200mg/kg, p.o.) produced suppression of exploratory behaviour, like chlorpromazine (4mg/kg, i.m.). The unfractionated extract (200mg/kg, p.o.), however, showed significantly (P<0.05, ANOVA) higher effects than the fractions in these three models. The results suggest that the active CNS depressant phytochemicals may have been fractionated, but their effects are synergistic in the unfractionated extract.

References: [1] Odebiyi and Sofowora (1978) Lloydia 41: 234. [2] Yemitan et al. (2001) Nig. J. Neurosci. 4: 33–40. [3] Dhara et al. (2002) Psychopharmacologia 44: 53–59.