Antimicrobial activity of methanolic extracts of selected marine macroalgae against some pathogenic microorganisms

Objective:To evaluate the antimicrobial activity of methanolic extracts of six marine macroalgae belonging to green algae(Chlorophyceae),brown algae(Phaeophyceae)and the red algae(Rhodophyceae)collected from the intertidal area of the Sudanese Red Sea coast near Port Sudan.Methods:Methanol was used for extracting the active principles of the algae and the disc diffusion method was performed to examine the activity and the minimum inhibitory concentration of the samples against four pathogenic bacteria and two fungi.Results:All tested algal extracts exhibited considerable bioactivity and inhibited the growth of all pathogenic microorganisms under investigation.The green alga Caulerpa racemosa produced the maximum inhibition zone(21 mm)against Candida albicans while the red alga Laurencia papillosa showed low antimicrobial activity with the minimum inhibition zone of 10 mm against Pseudomonas aeruginosa.The tested algal extracts did not show any special antimicrobial influence on the selected microorganisms when they were considered as Grampositive and Gram-negative bacteria and fungi but the most efficient methanolic extracts in inhibiting microbial growth were those of green macroalgae followed by the brown and the red macroalgae respectively.Conclusions:The study demonstrated that the tested marine macroalgae from Sudanese Red Sea coast may represent a potential and alternative source for secondary metabolites with antimicrobial activity.

The content of some selected metabolites of Hypnea valentiae(Turner)Montagne from the Red Sea coast of Sudan

Objective:To investigate some selected metabolic constituents of Hypnea valentiae(Turner)Montagne collected from the Red Sea coast of Sudan to evaluate the economic potential of the alga.Methods:Healthy thalli of the alga under investigation were collected,thoroughly cleaned,air dried and milled.Authentic analytical methods were used to determine moisture,ash,protein lipid and carrageenan contents.Fatty acids profile was revealed with gas chromatography instrumentation.Testing of phytochemical groups of compounds was based on the development of colouration and precipitation upon addition of certain chemical reagents to the extracts.Results:The ash content of the alga[(40.3±0.2)%of dry weight]was comparatively the highest among the parameters tested.The protein,lipid,and carrageenan constituted(9.30±0.70)%,(6.50±0.34)%,and(33.70±0.01)%,respectively of the alga dry matter.Hypnea valentiae(Turner)Montagne from Sudan Red Sea coast composed of 12 fatty acids,8 of which were unsaturated fatty acids and 4 were saturated fatty acids.The major unsaturated fatty acids in the alga was the trans-isomer of linoleic acid and linolelaidic acid(36.32%)followed by palmitoleic acid(13.64%).The major saturated fatty acids was the heptadecanoic acid amounting to 19.10%of the total fatty acids.Phytochemically the alga contained alkaloids,flavonoids and tannins.Conclusions:This alga may represent a promising source of functional food and therapeutic metabolites.Further investigation and critical evaluation of the bioactivity of the phytochemical compounds is required to assure the therapeutic potential of this alga.

A compiled checklist of seaweeds of Sudanese Red Sea coast

Objective:To present an updated and compiled checklist of Sudanese seaweeds as an example for the region for conservational as well as developmental purposes.Methods:The checklist was developed based on both field investigations using line transect method at 4 sites along the Red Sea coast of Sudan and review of available studies done on Sudanese seaweeds.Results:In total 114 macroalgal names were recorded and were found to be distributed in 16 orders,34 families,and 62 genera.The Rhodophyceae macroalgae contained 8 orders,17 families,32 genera and 47 species.The Phaeophyceae macroalgae composed of 4 orders,5 families,17 genera,and 28 species.The 39 species of the Chlorophyceae macroalgae belong to 2 classes,4 orders,12 families,and 14 genera.The present paper proposed the addition of 11 macroalgal taxa to be included in Sudan seaweeds species list.These include 3 red seaweed species,1 brown seaweed species and 7 green seaweed species.Conclusions:This list is not yet inclusive and it only represents the macroalgal species common to the intertidal areas of Sudan Red Sea coast.Further investigation may reveal the presence of more species.While significant levels of diversity and endemism were revealed for other groups of organisms in the Red Sea region,similar work still has to be performed for seaweeds.Considering the impact of climate change on communities’structure and composition and the growing risk of maritime transportation through the Red Sea particularly that may originate from oil tankers as well as that may emanate from oil exploration,baseline data on seaweeds are highly required for management purposes.