The potential antidiabetic activity of ethyl acetate extract of the leaves of Lagerstroemia speciosa (LSL) was investigated by alpha-amylase and alpha-glucosidase inhibition assay. Six pentacyclic triterpenes (oleanolic acid, arjunolic acid, asiatic acid, maslinic acid, corosolic acid and 23-hydroxyursolic acid) were isolated from LSL. Their structures were determined by spectroscopic analysis and their alpha-glycosidase and alpha-amylase inhibitory activities were investigated. They exhibited no or weak inhibitory activity against alpha-amylase and middle alpha-glucosidase inhibitory activities. Corosolic acid, which shows best bioactivity against alpha-glucosidase (IC(50) = 3.53 microg/mL), contributes most to the alpha-glucosidase inhibitory activity of EtOAc extract. The kinetics of inhibition of corosolic acid was also discussed. Results from this study might provide the scientific evidence for LSL for the treatment of diabetes in traditional medicine.

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Twenty-two compounds based on thiazolidine-2,4-dione moiety were synthesized and evaluated for the inhibitory potency on the production of nitric oxide (NO), inducible nitric oxide synthase (iNOS) activity, and the generation of prostaglandin E(2) (PEG(2)). (Z)-N-(3-chlorophenyl)-2-(4-((2,4-dioxothiazolidin-5-ylidene) methyl) phenoxy) acetamide (3I), superior to the commercial anti-inflammatory drug indomethacin, significantly inhibited iNOS activity (IC(50) = 8.66 μM), iNOS-mediated NO, and cyclooxygenase (COX)-2-derived PGE(2) production (IC(50) = 4.16 and 23.55 μM, respectively) on lipopolysaccharide (LPS)-induced RAW 264.7 cells. Docking study revealed that 3I was perfectly docking into the active site of murine iNOS and suppressed the expression of iNOS protein as evidenced by Western blot analysis. At the dose of 50 mg/kg, oral administration of 3I possessed protective properties in both carrageenan-induced paw edema and adjuvant-induced arthritis rat models.

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Black pepper (Piper nigrum L.) has been commonly utilized in food preparation and traditional medicine in several countries. Seven new amide alkaloids, pipernigramides A–G (3, 10, 38, and 41–44), a new piperic ester, pipernigrester A (48), along with 47 known compounds were isolated from the EtOH extract of P. nigrum. The inhibitory effects on nitric oxide (NO) of all compounds were then evaluated. Among the tested compounds, three of them (42–44) significantly inhibited inducible nitric oxide synthase (iNOS)-mediated NO (IC50 = 4.74 ± 0.18, 4.08 ± 0.19, and 3.71 ± 0.32 μM, respectively), and IL-1β, IL-6, TNF-α, and PGE2 release in RAW 264.7 cells stimulated by lipopolysaccharide. Moreover, 42–44 suppressed IκB degradation and further inhibited the cytosol-nucleus translocation of the p65 subunit by targeting IKK-β. In the carrageenan-induced paw edema test, 42–44 demonstrated anti-inflammatory effects as well. These results indicate that all three compounds from P.nigrum have the potential anti-inflammatory effects.