Staphylococcal and streptococcal species trigger a wide variety of infections involving epithelial tissues. Virginian witch hazel (WH;
Hamamelis virginiana
L.; family: Hamamelidaceae) is a plant that has been used traditionally by Native Americans to treat a variety of skin conditions. Extracts from the leaves were examined for their inhibitory effects on these bacterial species. Solvents of different polarity (water, methanol, ethyl acetate, hexane and chloroform) were used to prepare extracts from WH leaves, and the aqueous resuspensions were screened for antibacterial activities using disc diffusion and liquid dilution assays. Extract phytochemical profiles and toxicities were also examined, and combinations of extracts with conventional antibiotics were tested against each bacterial strain. The methanolic and aqueous extracts inhibited the growth of
S. oralis
,
S. pyogenes
,
S. epidermidis
and
S. aureus
, but not
S. mutans
. The extracts were especially active against staphylococcal species, with MIC values between 200 and 500 μg/ml. Combinations of active extracts with conventional antibiotics failed to yield beneficial interactions, except for two cases where additive interactions were observed (aqueous WH extract combined with chloramphenicol against
S. oralis
, and methanolic WH extract combined with ciprofloxacin against
S. aureus
). Phytochemical assays indicated an abundance of tannins, triterpenoids and phenolics in the water and methanol extracts, with trace amounts of these components in the ethyl acetate extract. Phytochemicals were not detected in hexane and chloroform extracts. Thus, phytochemical abundance in extracts was concordant with antibacterial activities. All extracts were found to be non-toxic in
Artemia nauplii
assays. These findings indicate the potential for WH leaf extracts for clinical use in treating staphylococcal and streptococcal infections, while substantiating their traditional Native American uses.
This Article presents removal of
ibuprofen from aqueous solution
using commercially available silk sericin as an adsorbent in an integrated
adsorbent-membrane process. The adsorption study was performed at
different physiological conditions, such as adsorbent concentration
(1–10g), ibuprofen concentration (10–70 mg/L), temperatures
(20, 30, and 40 °C), and pH (5, 6, 7, and 8). The occurrence
of adsorption before membrane separation was confirmed by performing
analysis of sericin–ibuprofen interaction and complex formation.
Sericin–ibuprofen interaction and complex formation was investigated
using FTIR, FESEM, fluorescence spectroscopy, XRD, and ITC. Sericin
and ibuprofen interaction is spontaneous and endothermic in nature,
while random coil transition of Sericin governed the adsorption system.
ITC analysis exhibited a binding affinity (K
b) value of 2.51 × 104 ± 1.4 and one binding
site (n ≈ 1) per molecule at 27 °C, revealing
moderate binding of ibuprofen to the sericin protein. Complete removal
of ibuprofen (at 10 mg/L, pH 8) was achieved using 10 g of sericin
(pH 4) and at a temperature of 40 °C in reverse osmosis membrane
process. The results established in this work concludes that sericin
may be used as an adsorbent for the removal of micropollutants, such
as ibuprofen from drinking water.
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