Background/Aims: Previously we described insulinotropic effects of Leonurus sibiricus L. plant extracts used for diabetes mellitus treatment in Traditional Mongolian Medicine. The flavonoid quercetin and its glycoside rutin, which exert anti-diabetic properties in vivo by interfering with insulin signaling in peripheral target tissues, are constituents of these extracts. This study was performed to better understand short- and long-term effects of quercetin and rutin on beta-cells. Methods: Cell viability, apoptosis, phospho-protein abundance and insulin release were determined using resazurin, annexin-V binding assays, Western blot and ELISA, respectively. Membrane potentials (V_mem), whole-cell Ca²⁺ (ICa)- and ATP-sensitive K⁺ (IK_ATP) currents were measured by patch clamp. Intracellular Ca²⁺ (Ca_i) levels were measured by time-lapse imaging using the ratiometric Ca²⁺ indicator Fura-2. Results: Rutin, quercetin and the phosphoinositide-3-kinase (PI3K) inhibitor LY294002 caused a dose-dependent reduction in cell viability with IC₅₀ values of ∼75 µM, ∼25 µM and ∼3.5 µM, respectively. Quercetin (50 µM) significantly increased the percentage of Annexin-V+ cells within 48 hrs. The mean cell volume (MCV) of quercetin-treated cells was significantly lower. Within 2 hrs, quercetin significantly decreased basal- and insulin-stimulated Akt(T308) phosphorylation and increased Erk1/2 phosphorylation, without affecting P-Akt(S473) abundance. Basal- and glucose-stimulated insulin release were significantly stimulated by quercetin. Quercetin significantly depolarized V_mem by ∼25 mV which was prevented by the K_ATP-channel opener diazoxide, but not by the L-type ICa inhibitor nifedipine. Quercetin significantly stimulated ICa and caused a 50% inhibition of IK_ATP. The effects on V_mem, ICa and IK_ATP rapidly reached peak values and then gradually diminished to control values within ∼1 minute. With a similar time-response quercetin induced an elevation in Ca_i which was completely abolished in the absence of Ca²⁺ in the bath solution. Rutin (50 µM) did not significantly alter the percentage of Annexin-V+ cells, MCV, Akt or Erk1/2 phosphorylation, insulin secretion, or the electrophysiological behavior of INS-1 cells. Conclusion: We conclude that quercetin acutely stimulates insulin release, presumably by transient K_ATP channel inhibition and ICa stimulation. Long term application of quercetin inhibits cell proliferation and induces apoptosis, most likely by inhibition of PI3K/Akt signaling.

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The finding that extracts from Leonurus sibiricus L. enhance insulin secretion and/or foster cell proliferation may provide possible explanations for the underlying therapeutic principles in the empirical use of LS-containing formulations in DM and DM-related disorders as applied in TMM.

Zinc, an essential trace element, plays a critical role in cell signaling, and defect(s) in zinc homeostasis may contribute to adverse physiological and pathological conditions, including cancer. Zinc is present in healthy prostate at a very high concentration, where it is required for important prostatic functions. However, zinc levels are significantly diminished in cancerous tissue, and intracellular zinc level is inversely correlated with prostate cancer progression. During neoplastic transformation, zinc-accumulating, citrate-producing normal prostate cells are metabolically transformed to citrate oxidizing cells that lose the ability to accumulate zinc. Interestingly, zinc has been shown to function as chemopreventive agent against prostate cancer, albeit at high doses, which may lead to many adverse effects. Therefore, novel means to enhance bioaccumulation of sufficient zinc in prostate cells via increasing zinc transport could be useful against prostate cancer. On the basis of available evidence, we present a possibility that the grape antioxidant resveratrol, when given with zinc, may lead to retuning the zinc homeostasis in prostate, thereby abolishing or reversing malignancy. If experimentally verified in in vivo model(s) of prostate cancer, such as transgenic mouse models, this may lead to novel means toward management of prostate cancer and other conditions with compromised zinc homeostasis.

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HPLC-CAD analysis allowed sensitive quantitation of the selected marker compounds in Leonurus sibiricus, thereby providing a reliable tool for its quality control.

At least three species,, and , are used in various traditional medicinal systems for different therapeutic purposes. The plant names "" and "" are often used as synonyms, which causes confusion in literature and implies that several studies may be based on improperly identified plant material. To avoid further confusion, the current status of the identification of these three species is illustrated. Characteristics for their unequivocal identification are presented using stereo and light microscopy as well as HPTLC.The establishment of the species-specific anatomical, morphological, and phytochemical characters was based on reference specimens in comparison with wild collected or commercially obtained material. Morphologically, the species differed in shape and length ratio of the upper and lower lip of the corolla. Differentiating anatomical characters involve the presence, density, and dimension of trichomes on different organs. Detailed anatomical descriptions of the leaves and corollae of and are given and compared to . These three sets of characters facilitate fast and reliable identification. Complementary HPTLC fingerprints show type-specific patterns that allow the differentiation of from the other two species. For the distinction of and, flower morphology has to be considered.The presented data contribute to the quality control of the three species and additionally meet a definite and timely need regarding the introduction of to the European Pharmacopoeia in addition to the already existing monograph of .

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