Abstract

LEAF VOLATILES AND STEM BARK EXUDATES OF TWO SWIETENIA SPECIES: COMPOSITION AND BIOACTIVITY

Ola Mohamed Mousa*, Marwa Yousry Moustafa Issa, Hesham Ibrahim El-Askaryand Soheir Mohamed El Zalabani

Abstract

This study comprises a comparative physico-chemical investigation of the hydrodistilled leaf volatiles and stem bark exudates of two Swietenia species grown in Egypt viz., Swietenia mahogani (L.) Jacq. and Swietenia macrophylla King. The physical characters were described, and chemical composition determined via chromatographic analyses (PC, GLC and GC/MS). Moreover, the antimicrobial potential of all samples was assessed and the long-term antihyperglycemic activity of gum exudates evaluated. Hydrodistilled leaf volatiles (0.15 vs. 0.10% v/dry wt. in S. mahogani and S. macrophylla, respectively) were dominated by sesquiterpenoids among which hydrocarbons prevailed (75.51 vs. 80.95%), as evidenced by GC/MS analysis. Transcaryophyllene (33.89%) dominated the S. mahogani sample and α- humulene (39.64%) that of S. macrophylla. Oxygenated constituents were minor in both, being mainly represented by sesquiterpenoids, with elemol (6.13%) as major in S. mahogani and E-nerolidol (10.18%) in S. macrophylla. Analytical parameters (moisture content and total ash) of the exudates and mineral composition of ashes were determined. GLC analysis of the sylilated exudate hydrolysates revealed that galactose dominated the sugar composition of the samples (57.99 vs. 59.57%) followed by xylose (8.24 vs. 8.37%). In addition, traces of glucuronic acid were detected in both samples. The volatiles were found effective against all tested Gram-positive bacteria meanwhile stem bark exudates inhibited mycobacterial growth only, and yeast was not affected by any of the samples. Minimum inhibitory concentrations were determined. A significant reduction in blood glucose level was recorded in Alloxandiabetic rats treated with the aqueous solutions of the stem bark exudates of both species.

Keywords: Swietenia species, leaf volatiles, stem bark exudates, antimicrobial, antihyperglycemic.