Bioactivity determination of methanol and water extracts for roots and leaves of Kenyan Psidium guajava L landraces against pathogenic bacteria

Abstract

Guava (Psidium guajava L) is native to South America and exists as both wild and cultivated. Guava has been used as a source of food and raw materials for pharmaceuticals. The aim of this study was to determine bioactivity of methanol and water extracts from root and leaves of Kenyan guava landraces against selected pathogenic bacteria. Study samples were collected from Western and South Coast of Kenya. One hundred grams of leaf and root ground powders were used for sequential extraction using methanol and water. Extracts were evaporated and 0.2gms dissolved using the extraction solvent and tested against gram positive (Staphylococcus aureus, Bacillus subtilis) and negative bacteria (Escherichia coli). Data on inhibition zone was taken in mm and analyzed at 95% confidence interval. Extracts from Western region had significant inhibition compared to Coastal region. The two regions have different climatic conditions that result in these plants having different compounds even though they are the same species. Roots had higher inhibition compared to the leaves as they contain high levels of tannins compared to leaves. Water as an extracting solvent had higher inhibition than methanol as it is more polar and it absorbs more bioactive compounds. S. aureus was most inhibited followed by E. coli and B. subtilis respectively. There was no significant difference between the gram positive and negative bacteria. Remarkably, some methanol and water root extracts had significant inhibition against bacteria when compared to some commercial antibiotics used. Results of this study indicate that Kenyan guava roots from Western Kenya extracted with methanol and water have a potential to be used as a source of active compounds in treatment of gram positive and gram negative bacteria pathogens.

Antimicrobial Activity of Psidium guajava Aqueous Extract against Sensitive and Resistant Bacterial Strains

“…In the disk diffusion tests, inhibition halos were found for Gram-positive bacteria, while for Gram-negative bacteria ( Escherichia coli , sensitive and resistant), there was no inhibition at the tested concentrations ( Table 3 and Figure 2 ), corroborating the results reported by Araújo et al [ 33 ] and Kidaha et al [ 12 ], where no inhibition was found for E. coli . Gram-negative bacteria are generally more resistant to antimicrobials than Gram-positive bacteria because they have an additional outer membrane that can protect them from antimicrobial compounds [ 34 ].…”

“…The chemical composition of P. guajava includes tannins such as guavins A-D and flavonoids [ 7 , 8 ], and its extracts have already been widely reported to have antimicrobial potential. Many studies have described the antimicrobial activity of different extracts from the leaves of P. guajava , such as methanolic [ 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 ], ethanolic [ 9 , 16 , 17 , 18 , 19 , 20 ], and aqueous [ 9 , 11 , 12 , 13 , 16 , 19 , 20 , 21 , 22 , 23 ], including the activity of methanolic extracts against methicillin-resistant Staphylococcus aureus (MRSA) strains [ 18 ]. The antimicrobial activity of the root [ 12 ] and fruit extracts [ 24 ] of P. guajava has also been reported.…”

Chemical Characterization and Antifungal Activity of Blue Tansy (Tanacetum annuum) Essential Oil and Crude Extracts against Fusarium oxysporum f. sp. albedinis, an Agent Causing Bayoud Disease of Date Palm

“…Moreover, the results demonstrated that bioactive compound contents were affected by solvent polarity and varied from one part to another. This verified what is described in the literature, the solvent with higher polarity extracted more bioactive compounds that are responsible for several bioactivities [14][15][16].…”

“…The polarity of solvents plays an important role in increasing extraction yield; whereas, the solvent with a higher polarity, such as water, has the ability of solubility and absorbance of bioactive compounds more than solvents with less polarity such as methanol, ethanol, etc. [ 14 , 15 , 16 ]. These confirmed the present results that showed a higher extraction yield using a combination of methanol with water than with methanol alone.…”

Bioactive substances of some herbals and their effectiveness as antioxidant, antibacteria and antifungi

“…Plant bioactives have been reported to have functions as antibiotic, anti fungi, antioxidant and immuno modulator. Some researches have been conducted in order to proof the beneficial effect of plant bioactives to replace AGP such as Aloe vera (Purwadaria et al 2001;Bintang et al 2001;Sinurat et al 2003;Sinurat et al 2004;Sinurat 2013), Curcuma longa and Curcuma xanthorrhiza (Samarasinghe et al 2003;Sinurat et al 2009), and guava leaves (Hoque et al 2007;Kidaha et al 2013). Most of the researches studied the effectivity of the bioactives obtained from single ingredient and the results have not been applied in the livestock industry commercially due to some factors such: variability on the effectivity, high production cost or too expensive when compared to the commercial AGP and when the use of AGP is still allowed in the country.…”