| dc.description.abstract | In ethnomedicine, Terminalia brownii is used to treat and control human illnesses such as
yellow fever, rheumatoid arthritis, hepatitis, diabetes, diarrhea, stomach ulcers, and
abdominal pain. The study sought to determine the antibacterial activity of crude
organic extracts and characterize the components responsible for the action of T. brownii
from commonly used plant bark and easily regenerated flower material. T. brownii plant
was randomly identified. The fresh stem bark and flowers of T. brownii were collected
from Mwingi sub-county, Kitui County in the month of April, 2021. The samples were
air dried under shade at room temperature. The dry stem bark and flowers were
ground into fine powder using electric grinder, weighed and packed in a clean sample
container. The powdered plant materials were sequentially extracted with n-hexane,
dichloromethane, dichloromethane:methanol (1:1), methanol and hot water (to simulate
the conventional preparation process). Phytochemical screening of
dichloromethane:methanol (1:1) and methanol crude extracts indicated the presence of
alkaloids, flavonoids, tannins, terpenoids, saponins, steroids, phenols and glycosides.
Antimicrobial activities of different crude extracts were recorded using agar well
diffusion method and all extracts, except those obtained from n-hexane, demonstrated
variable antibacterial activity against E. coli, S. aureus, and P. aeruginosa with inhibition
zone ranging between 8.0±0.7 mm and 23.6±0.6 mm. Dichloromethane:methanol (1:1)
extract (stem bark) exhibited the highest activity against E. coli with inhibition zone of
23.6±0.6 mm and 17.3±0.4 mm in flower extract while methanol bark extracts displayed
good inhibitory activity against S. aureus (21.0±0.5 mm) and P. aeruginosa (21.7±0.5 mm)
when compared to the other extracts. Only methanol extract exhibited antifungal
activity against C. albicans with zone of inhibition of 15.0±1.5mm (stem bark) and
7.6±0.8mm (flower). The activity of the active crude extracts was comparable to
commonly used over the counter drugs (Amoxicillin, 24.7±1.4, and fluconazole
19.0±0.3). Purification of the more active dichloromethane: methanol (1:1) and methanol
extracts through silica gel column chromatography resulted in isolation of three new
compounds: 1,4,7-tri-O-galloyl hept-6-deoxyheptose, 1,2,4-tri-O-galloyl-8,9-
dideoxynonose,Rhamnetin-3-O-(2,3,6-trigalloyl)-β-D-glucopyranosideand seven known
compounds: termiglaucescin, arjunglucoside – I, sericoside, 23-galloyl arjungenin, 28-O β-D-glucopyranosyl-2,3,6-trihydroxy-23-galloylolean-12-dien-28-oate, 3,3',4',5-
tetrahydroxy-7-methoxyflavone and 3,3',4',5,7-pentahydroxyflavone. The compound
1,4,7-tri-O-galloyl hept-6-deoxyheptose, was highly active against E. coli (16.5±0.7 mm)
while termiglaucescin showed good inhibitory activity against C. albicans (16±5.7 mm).1,4,7-tri-O galloyl hept-6-deoxyheptose, 1,2,4-tri-O-galloyl-8,9 dideoxynonose, Rhamnetin-3-O-
(2,3,6-galloyl)-β-D-glucopyranoside,3,3',4',5-tetrahydroxy-7-methoxyflavone and
3,3',4',5,7-pentahydroxyflavone were isolated and characterized for the first time from
dichloromethane:methanol (1:1) extract of T.brownii flower. Dichloromethane:
methanol (1:1) crude extract of T. brownii flowers yielded three new bioactive
compounds with remarkable antimicrobial activity against E. coli, P. aeruginosa, S. aureus
and C. albicans. In conclusion this study has shown that flower extracts of T. brownii
have antifungal and antibacterial properties associated with stem bark extracts of T.
brownii. Hence the more sustainable flower extracts are recommended for use in the
treatment of bacterial and fungal infections. | en_US |
