Antibacterial activities of lactic acid bacteria isolated from selected vegetables grown in nigeria: a preliminary report

Members of lactic acid bacteria (LAB) are known probiotics and have been reported to have antimicrobial properties. Although various researchers have documented the isolation of these bacteria from fruits and vegetables; studies on LAB associated with lettuce; cucumber and cabbage are limited and non-existing in Nigeria. This study was designed to assess lettuce; cucumber and cabbage as potential sources of LAB and investigate the actions of their bacterial cell supernatants (BCS) on some pathogenic bacteria. Using standard microbiological methods; isolated LAB were identified to species level with API 50 CH kits (Biomerieux; France). Cell free supernatants (CFS) from de Man Rogosa Sharpe (MRS) broth cultures of the LAB strains were used to challenge Pseudomonas aeruginosa ATCC 27853; Enterococcus faecalis ATCC 29212; Escherichia coli ATCC 12900 and Proteus penneri ATCC 13315 by agar well diffusion method. The control consisted of the sterile MRS broth subjected to the same growth conditions as LAB broth cultures. A total of four lactic acid bacteria were isolated as follows: Pediococcus pentosaceus 2 from cucumber; Lactobacillus cellobiosus from cabbage; Lactobacillus salivarius and Lactobacillus plantarum 1 from lettuce. Pediococcus pentosaceus 2 and L. salivarius showed inhibitory effects on all the standard strains tested while L. plantarum 1 showed no inhibitory activity against E. faecalis and E. coli. Lactobacillus cellobiosus showed inhibition against all except P. penneri. Although; the molecular characterisation and probiotic potentials of these LAB strains are being investigated in an on-going study; we presumed these vegetables are prospective sources of the bacteria in Nigeria and therefore the need to extensively investigate the vegetables and other related vegetables becomes imperative

Essential oil composition of Piper guineense and its antimicrobial activity. Another chemotype from Nigeria.

The analysis of the essential oil of Piper guineense from Nigeria presents a new chemotype of constituents different from earlier reports with the absence of the usual myristicin. Ishwarane, a common constituent of Aristolochia indica and Bixa orellana, was also isolated from the essential oil of the fruit. The essential oil inhibited the growth of Pseudomonas aeruginosa UCH 655 strain at 5 mg/mL on which standard antibiotic drugs were ineffective.

In vitro anti-mycobacterial activities of three species of Cola plant extracts (Sterculiaceae).

Extracts obtained from three Nigerian Sterculiaceae plants: Cola accuminata, C. nitida and C. milleni were screened for anti-mycobacterium properties using a slow growing Mycobacterium bovis ATCC 35738 (designated BCG Mexican and known to have some virulence in mouse and guinea pig) at 1000 microg/ml using the radiometric (BACTEC) method. The extracts were also tested against six fast growing ATCC strains of M. vaccae using the broth microdilution method. The methanol extracts from both leaves, stem bark and root bark of Cola accuminata and from the leaves and stem bark of C. nitida and C. milleni were not active at the highest concentration of 1000 microg/ml. Only the methanol extract of root bark for both C. nitida and C. milleni were found to be potent against both M. bovis and strains of M. vaccae. The minimum inhibitory concentration (MIC) of C. nitida against M. bovis is 125 microg/ml while the MIC of C. milleni against M. bovis is 62.5 microg/ml after at least 6 days of inhibition with growth index (GI) units lesser than or equal to the change in GI units inoculated with a 1/100 of the BACTEC inoculum for a control vial. The minimum inhibitory concentration of C. milleni against the six ATCC strain of M. vaccae ranged from 62.5 microg/ml to 250 microg/ml while for C. nitida ranged from 500 microg/ml to above 1000microg/ml. Evidently, C. milleni has the highest inhibitory activity against both M. bovis and strains of M. vaccae used. Rifampicin, the positive control used has strong activity against M. bovis at the tested concentration of 5 microg and 10 microg/ml and 4 to 8 microg/ml against the six strains of M. vaccae.

Antimicrobial and cytotoxic activities of the fruit essential oil of Xylopia aethiopica from Nigeria.

The fruits essential oil of Xylopia aethiopica showed activity against four microorganisms and cytotoxicity to carcinoma cells (Hep-2 cell line) at 5 mg/ml concentration.

Do Aloe vera and Ageratum conyzoides enhance the anti-microbial activity of traditional medicinal soft soaps (Osedudu)?

The Nigerian traditional soft soaps prepared using varied locally sourced raw materials such as cocoa pod ash (Theobroma cacao) palm kernel shaft ash (Elaies guineensis) have been evaluated for their physico-chemical properties and anti-microbial activities using standard pharmacopoeia protocols and an in-vitro agar diffusion bioassay method. The anti-microbial evaluation was done with and without incorporation of Aloe vera and Ageratum conyzoides extractives into the soap samples. Results showed that the physico-chemical properties of the soaps are dependent on the raw materials utilised. The incorporated medicinal plants used in this study, however, did not show any significant effect on the anti-microbial activities exhibited by the various soaps against the bacterial and fungal test organisms.

In vitro cytotoxicity activity of Diosquinone, a naphthoquinone epoxide.

Diosquinone [1], a naphthoquinone epoxide previously isolated from the root bark of Diospyros mespiliformis (Hostch) and D. tricolor [Ebenaceae] is been assessed for cytotoxicity activity against ten cancer cell lines by standard NIH method. The ethno-pharmacological claim of this plant and the previously observed good antibacterial activity of this compound among the others isolated from this plant suggest its probable cytotoxicity activity. Diosquinone was observed to be very active against most of the cancer cell lines. It shows very good activity against all the cell lines tested with ED50 value ranging between 0.18 microg/ml. against Human Glioblastoma (U373) to 4.5 microg/ml. against Hormone dependent human prostrate cancer( LNCaP).

Antibacterial activity of diospyrin, isodiospyrin and bisisodiospyrin from the root of Diospyros piscatoria (Gurke) (Ebenaceae).

Two dimeric naphthoquinones, diospyrin and isodiospyrin, isolated from the root of Diospyros piscatoria (Gurke), a common ingredient in several folk medicines, have been shown to have a broad spectrum of antibacterial activity. The minimum inhibitory concentrations (MICs) of diospyrin against Streptococcus pyogenes ATCC 12344 and Streptococcus pneumoniae ATCC 33400 ranged from 1.56 to 50 microg/mL. While those against Salmonella choleraesuis serotype typhi (S. typhi), ATCC 6539 and Mycobacterium chelonae ATCC 19977 were between 25 and 100 microg/mL. Isodiospyrin was more active than its racemic isomer diospyrin. The MICs against Gram-positive bacteria ranged from 0.78 to 50 microg/mL. While those against Pseudomonas aeruginosa ATCC 15443 and S. typhi ranged from 50 to 100 microg/mL. The MIC for M. chelonae was between 6.25 and 25 microg/mL. MICs were found to increase with the concentration of cells used for the inoculum. The MICs for Bacillus subtilis ATCC 6633 increased up to the highest concentration of cells tested. The same phenomenon was observed on M. chelonae, but with better effect in the latter. The kinetics of bacteria studies against both B. subtilis and M. chelonae increases with increasing concentration of isodiospyrin tested. Two tetrameric forms of plumbagin were isolated. The naphthoquinone bisisodiospyrin, gave MIC values between 300 and 400 micro g/mL. The second, as yet unidentified tetramer, was not active at 500 micro g/mL.

The antimicrobial activity of roots of Jatropha podagrica (Hook).

Hexane, chloroform and methanol extracts of the rootwood and rootbarks of Jatropha podagrica were studied for their antimicrobial activity against 18 organisms. All the extracts exhibited some broad spectrum antibacterial activity, at a concentration of 20 mg/mL. The hexane extracts were generally more active than the chloroform and methanol extracts. The hexane extract of the yellow rootbark was the most active of all the extracts and its activity was comparable to that of gentamycin but better with regard to the control of S. aureus and B. cereus. Three of the extracts, hexane extract of the yellow rootbark and hexane and methanol extracts of the rootwood showed moderate antifungal activity against the yeast fungus, Candida albicans.

Antimicrobial potentials of Diospyros mespiliformis (Ebenaceae).

The petroleum ether, chloroform, methanol, and water extracts of the leaves, stem bark, and root of Diospyros mespiliformis were studied for their antimicrobial activities. The crude extracts showed broad spectrum antimicrobial activities against 9 Gram-positive bacteria, 8 Gram-negative bacteria, and 6 fungal strains. Of the four extracting solvents, chloroform produced extracts with the best antimicrobial activities, while the chloroform extract of the root exhibited the highest antimicrobial activity. Some tetracycline resistant strains of Staphylococcus aureus and gentamicin resistant strains of Pseudomonas aeruginosa were sensitive to some of the extracts tested. Preliminary phytochemical screening revealed the presence of the following metabolites: anthraquinones, tannins, triterpene, saponins, steroids, and sugars and the absence of alkaloids. The antimicrobial activities observed are discussed in relation to the chemical constituents reportedly isolated from several species of this plant and their traditional uses.