Abstract:
Herbal plants are considered to be the best natural remedies, as they are rich in
phytochemicals. Drug combinations are widely used to achieve synergistic effects
in therapeutic use. In treating diabetes and its’ associated complications, Gymnema
sylvestre R. Br, Salacia reticulata Wight, Syzygium cumini (L.) Skeel and Camellia
sinensis (L.) Kuntze has been claimed to have strong anti-diabetic properties.
Though, these plants have proven records on anti-diabetic potency as individual
plants, no systematic investigation of their combined behavior. Therefore, first the
inhibitory effect of crude ethanolic extracts of Gymnema sylvestre leaves (GS),
Salacia reticulata bark (SR), Syzygium cumini bark (SC) and Camellia sinensis tender
shoots (CS) against the α-amylase and α-glucosidase enzymes, glycation and
glucose diffusion were tested using in-vitro trials. Highest inhibitory activity for α-
amylase, α-glucosidase, anti-glycation and glucose diffusion were reported from
S.cumini (IC50 = 18.50μg/mL), S.reticulata (IC50 = 7.85μg/mL), S.cumini (IC50 =15.20
μg/mL) and G.sylvesre (GDRI = 68.60% at 200 μg/mL concentration), respectively.
All these values reported to have dose-dependent inhibition (p<0.05). Secondly, it
was designed to investigate the combined effect of two-factor combination series.
Some combinations exhibited strong antagonistic and synergistic effects (Fa>60%)
against the anti-amylase and anti-glucosidase enzyme activity assays. For the antiglycation
assay, combinations having Camellia sinensis and Salacia reticulata as
principle components exhibited strong antagonism, while all the other
combinations were reported to have a synergistic effect against the glycation
activity. All the combinations reported a strong synergistic effect against the
glucose diffusion activity. The combination of Camellia sinensis and Gymnema
sylvestre exhibited the highest glucose diffusion inhibition at 200μg/mL
concentration (GDRI = 69.37%). It was clear that the combinations show
comparatively higher antagonistic effects in enzyme-dependent pathways due to
the molecular masking activity, competitive inhibitions, chemical bond depletions
and any other possible mechanism. This study recommended investigating the
chemical reactions at the preliminary stage of the drug combinations to increase
drug effectiveness.
