Anti-Salmonella activity of metabolites from African soldier termites, Macrotermes bellicosus

Background: The global emergence and rapid dissemination of multidrug resistant Salmonella strains necessitate research to find new antimicrobials that will effectively be used against these pathogens. In the present study, anti-Salmonella activity of metabolites from African Soldier Termites, Macrotermes bellicosus was demonstrated and subsequently compared with a potent antibiotic, ciprofloxacin. Materials and Methods: N-hexane, ethylacetate, methanol and aqueous extracts of metabolites from the M. bellicosus were assayed for anti-Salmonella activity using the agar dilution method in the determination of the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The inhibitory activities of the extracts were compared to ciprofloxacin (256µg/ml). Also, the bioactive components of the extracts were determined using standard techniques. Results: At 4000 µg/ml, N-hexane extract inhibited the growth of Salmonella Typhi, S. Paratyphi A, B and C while ethylacetate extract was able to inhibit S. Paratyphi A and C. Methanolic and aqueous extracts at the same concentration were unable to inhibit these strains of Salmonella. Furthermore, our findings revealed that the MIC of ethylacetate extract was 2000µg/ml for S. Paratyphi A and B, 250µg/ml for S. Typhi, and 125µg/ml for S. Paratyphi C. Also, the MIC of hexane extract was 4000µg/ml for S. Paratyphi B, 2000 µg/ml for S. Paratyphi C, 500µg/ml for S. Typhi and 250µg/ml for S. Paratyphi A respectively. The screening of bioactive components revealed the presence of cardiac glycosides and alkaloids. Conclusion: Our results provide evidence of anti-Salmonella action of metabolites from African Soldier Termites, M. bellicosus. N-hexane and ethylacetate extracts of M. bellicosus may be explored as novel antimicrobials for the treatment of typhoid and paratyphoid fevers thereby reducing the pressure exerted on available antibiotics

Pharmaceutical potentials of the oils of some popular insects consumed in southern Nigeria

Macrotermes bellicosus (MB), Imbrasia belina larva (IBL), Oryctes rhinoceros larva (OR) andRhynchophorus pheonicis (RP) larva oils were extracted, and the oils were physically and chemically characterized. The lipid content recorded for the insects were 31.46 ± 0.57%, 15.16 ± 0.18%, 14.87 ± 0.33% and 23.30 ± 0.33% (wet weight) for MB, IBL, OR and RP respectively. RP and OR insect oils were golden yellow, odourless and fluid at room temperature (26 ± 2oC), while that extracted from IBL and MB were of a lighter yellow colour. The insect lipids all gave a low solidification temperature and high iodine number indicating a relatively high level of unsaturation of the insect/larval oils. Their saponification values were high suggesting the presence of a fair amount of fatty acids but their acid values were low pointing to the fact that these fatty acids were not free but esterified acids. The cholesterol values were also low but highest in MB with a value of 41.8 ± 0.15 mg/100 g lipid. For all the insects, the neutral lipid fraction was the major fraction in the insect oils. RP had the highest neutral lipid fraction of 88.40 while MB had the least value of 69.87. At the same time MB had the highest phospholipids and glycolipid fractions with values of 19.14 and 10.81 respectively while RP had the least phospholipids and glycolipid fractions with values of 8.20 and 2.60 respectively. For IBL, RP and OR (which are insect larvae) the major fatty acids in the oils were palmitic and oleic acids while for MB (mature insect) the major fatty acids were palmitic and linoleic acids. The insect/larval oils contained more unsaturated fatty acids which explained the high iodine number, low solidification values and the liquid nature of the oils at room temperature. OR recorded the highest level of unsaturation of 65.61 while MB had the least level of unsaturation of 50.02%. Further analysis revealed a refractive index ranging from 1.1 ± 0.01 to 1.3 ± 0.05, specific gravity of 0.84 ± 0.02 to 0.90 ± 0.01, solidification value of 10 - 14°C, total lipid phosphorus ranging from 31.0 ± 0.25 to 47.18 ± 0.03 mmmmg/gm lipid, acid value of 3.12 ± 0.55 to 3.6 ± 0.06, iodine value of 108 ± 0.15 to 140 ± 0.51, saponification value of 187.17 ± 0.55 to 198.9 ± 0.25 and unsaponifiable matter of 8.11 ± 0.02 to 12.04 ± 0.11. These values when compared with that observed in oils which have been considered to be of high quality and of much use in pharmaceutical industries suggest that these insect oils may have pharmaceutical potential