Sayid Mahdi Mirghazanfari1,2, Mansoor Keshavarz1, Fatemeh Nabavizadeh1, Nepton Soltani3, Mohammad Kamalinejad4. 1. Dept. of Physiology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran. mkeshavarz@tums.ac.ir 2. Dept. of Physiology, School of Medicine, AJA University of Medical Sciences, Tehran, Iran. 3. Dept. of Physiology, School of Medicine, Hormozgan University of Medical Sciences, Bandar Abbas, Iran. 4. Dept. of Pharmacognosy, School of Pharmacy, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
Abstract
BACKGROUND: "Teucrium polium L." (TP) has been long recommended in Iranian folk medicine for its anti-diabetic activities. We attempt here to evaluate the effect of TP extract on insulin secretion in rat pancreas. METHODS: Rat pancreas was isolated in situ and perfused with Krebs solution containing low glucose (LG, 2.8 mM) or high glucose (HG, 16.7 mM) as perfusate. The aqueous extract (Aq. E) and methanolic extract (Met. E) of TP aerial parts and two partition fractions of Met. E were added to perfusate to evaluate insulin release. Diazoxide (DZX) and verapamil (VPM) were also used for assessing the probable mechanism of the effects. In each experimental group, the peak and baseline of insulin levels in effluent samples were compared. The GC/MS analysis was carried out to detect active ingredients in the extracts. RESULTS: Adding Met. E to the LG caused a significant increase (P<0.05) in insulin release from the basal level of 0.17 ± 0.05 µg/l to a peak value of 3.94 ± 1.29 µg/l. when Met. E was introduced to the HG, there was a further protracted stimulation of insulin release from 2.15 ± 1.35 µg/l to 6.16 ± 0.52 µg/l. Both DZX and VPM when added separately to the LG, led to inhibition of Met. E induced insulin secretion. The Aq. E and fractions had no significant effect on insulin secretion. Only in the Met. E, the component 5-hydroxy-4',7-dimethoxyflavone (apigenin-4',7-dimethylether) was detected. CONCLUSION: It can be concluded that the insulinotropic properties of TP extracts can be attributed to the presence of apigenin existing only in Met. E, but not in Aq. E and fractions. Moreover, certain types of K+ and Ca2+ channels take part in this effect.
BACKGROUND: "Teucrium polium L." (TP) has been long recommended in Iranian folk medicine for its anti-diabetic activities. We attempt here to evaluate the effect of TP extract on insulin secretion in rat pancreas. METHODS:Rat pancreas was isolated in situ and perfused with Krebs solution containing low glucose (LG, 2.8 mM) or high glucose (HG, 16.7 mM) as perfusate. The aqueous extract (Aq. E) and methanolic extract (Met. E) of TP aerial parts and two partition fractions of Met. E were added to perfusate to evaluate insulin release. Diazoxide (DZX) and verapamil (VPM) were also used for assessing the probable mechanism of the effects. In each experimental group, the peak and baseline of insulin levels in effluent samples were compared. The GC/MS analysis was carried out to detect active ingredients in the extracts. RESULTS: Adding Met. E to the LG caused a significant increase (P<0.05) in insulin release from the basal level of 0.17 ± 0.05 µg/l to a peak value of 3.94 ± 1.29 µg/l. when Met. E was introduced to the HG, there was a further protracted stimulation of insulin release from 2.15 ± 1.35 µg/l to 6.16 ± 0.52 µg/l. Both DZX and VPM when added separately to the LG, led to inhibition of Met. E induced insulin secretion. The Aq. E and fractions had no significant effect on insulin secretion. Only in the Met. E, the component 5-hydroxy-4',7-dimethoxyflavone (apigenin-4',7-dimethylether) was detected. CONCLUSION: It can be concluded that the insulinotropic properties of TP extracts can be attributed to the presence of apigenin existing only in Met. E, but not in Aq. E and fractions. Moreover, certain types of K+ and Ca2+ channels take part in this effect.
Authors: James Herrington; Yun-Ping Zhou; Randal M Bugianesi; Paula M Dulski; Yue Feng; Vivien A Warren; McHardy M Smith; Martin G Kohler; Victor M Garsky; Manuel Sanchez; Michael Wagner; Kristin Raphaelli; Priya Banerjee; Chinweze Ahaghotu; Denise Wunderler; Birgit T Priest; John T Mehl; Maria L Garcia; Owen B McManus; Gregory J Kaczorowski; Robert S Slaughter Journal: Diabetes Date: 2006-04 Impact factor: 9.461
Authors: M Prashanth; H K Ganesh; M V Vima; M John; T Bandgar; Shashank R Joshi; S R Shah; P M Rathi; A S Joshi; Hemangini Thakkar; P S Menon; N S Shah Journal: J Assoc Physicians India Date: 2009-03