Evaluating the efficacy of commercial Sela tea- high blood and Sela tea-blood sugar in combination with antihypertensive and anti-diabetic drugs: an in vitro study

Abstract Background Sela Tea - High Blood (SHB) and Sela Tea - Blood Sugar (SBS) are brands made from traditional herbal medicine for lowering blood pressure and blood sugar, respectively. However, there are no reports supporting the therapeutic claims or concerning the efficacy when concomitantly use with prescription antihypertensive and antidiabetic drugs. The study aimed to evaluate the in vitro antihypertensive and antidiabetic potential of these teas and their combined effects with prescription drugs. Method Human embryonic kidney and Chang liver cells were used to assess the cytotoxicity effects of tea extracts. SHB was tested on angiotensin-converting enzyme (ACE) and renin inhibition while SBS was tested on α-amylase and α-glucosidase inhibition. A fixed dose combination design was used to evaluate the combined effects of teas and standard drugs namely, aliskiren for renin inhibition, lisinopril for ACE inhibition, and acarbose for α-amylase and α-glucosidase inhibition. The IC₅₀ concentration of the tea extract was used as fixed extract concentration and was then combined with varying concentrations of the drug. Conversely, the IC₅₀ concentration of the drug was used as the fixed drug concentration and was then combined with varying concentrations of the tea extract. Results SHB and SBS showed no cytotoxicity effects. SHB inhibited ACE and renin activities with IC 50 values of 247.60 and 28.38 µg/mL respectively. SBS inhibited α-amylase and α-glucosidase with IC 50 values of 1974.00 and 4.59 µg/mL respectively. The combination of the IC₅₀ values of SHB or SBS with varying concentrations of lisinopril, aliskiren, or acarbose, as well as the combination of the IC₅₀ values of these drugs with varying concentrations of SHB or SBS, resulted in significantly greater enzyme inhibition than that observed with the corresponding drug or Sela tea extract alone. Conclusion The study highlights the potential of SHB and SBS to inhibit the targeted enzymes (ACE, renin, α-amylase, and α-glucosidase) and to enhance the inhibitory effects of the selected drugs. Sela tea may therefore provide complementary effects when used alongside these drugs. However, further studies are needed to confirm this hypothesis.