Xanthine oxidase, α-glucosidase and α-amylase inhibitory activities of the essential oil from Piper lolot: In vitro and in silico studies.

Introduction: Piper lolot is a species of herb used as a popular food in Vietnam. Furthermore, the species has been used as a Vietnamese traditional medicine to treat many diseases. Methods: Chemical constituents in the essential oil from leaves of Piper lolot were determined using GC/MS analysis. The anti-gout and anti-diabetic activities of the essential oil were determined through the inhibitory assays against xanthine oxidase, α-glucosidase and α-amylase enzymes. In addition, molecular docking simulations were used to elucidate the inhibitory mechanism between the main compounds and the enzymes. Results: The dominant constituents of the Piper lolot essential oils were determined as ß-caryophyllene (20.6%), ß-bisabolene (11.6%), ß-selinene (8.4%), ß-elemene (7.7%), trans-muurola-4(14),5-diene (7.4%), and (E)-ß-ocimene (6.7%). The essential oil displayed xanthine oxidase, α-amylase, and α-glucosidase inhibitory activities with IC50 values of 28.4, 130.6, and 59.1 µg/mL, respectively. The anti-gout and anti-diabetic activities of the essential oil from the P. lolot species are reported for the first time. Furthermore, molecular docking simulation was consistent to in vitro experiments. Conclusion: The present study provides initial evidence that the essential oil of P. lolot may be a potential natural source to develop new diabetes preparations.

Zebrafish larvae use stimulus intensity and contrast to estimate distance to prey.

The ability to determine the distance to objects is an important feature of most visual systems, but little is known about the neuronal mechanisms for distance estimation. Larval zebrafish execute different visual behaviors depending on distance; at medium distances, they converge their eyes and approach, but when the prey is close enough, they execute a strike and suck the prey into their mouths. To study distance estimation, we developed a head-fixed strike assay. We found that we could evoke strike behavior in head-fixed larvae and quantify head movements to classify the behavior as a strike. Strikes were dependent on distance to prey, allowing us to use them to study distance estimation. Light intensity is rapidly attenuated as it travels through water, so we hypothesized that larvae could use intensity as a distance cue. We found that increasing stimulus intensity could cause larvae to strike at prey that would normally be out of range, and decreasing the intensity could lower the strike rate even for very proximal stimuli. In addition, stimulus contrast is a key parameter, and this could allow larvae to estimate distance over the range of natural illumination. Finally, we presented prey in the binocular vs. monocular visual field and found that monocular prey did evoke strikes, although the binocular input produced more. These results suggest that strike behavior is optimally evoked by bright UV dots in the binocular zone with minimal UV background light and provide a foundation to study the neuronal mechanisms of distance estimation.

Two new abietane diterpenes huperphlegmarins A and B from Huperzia phlegmaria.

Two new abietane diterpenes, huperphlegmarin A-B (1-2), were isolated from the aerial parts of Huperzia phlegmaria (L.) Rothm. (Lycopodiaceae), in addition to five known compounds including lycoxanthol (3), 21ß-hydroxyserrat-14-en-3ß-yl acetate (4), 21α-hydroxyserrat-14-en-3ß-yl acetate (5), 21α-hydroxyserrat-14-en-3ß-ol (6), and fawcettidine (7). Their structures were determined by the combination analyses of spectroscopy, including 1D-, 2D-NMR, HRESIMS, CD and comparison with the reported data in the literature. Huperphlegmarin B (2) presented the rare 1,11-epoxy group in the molecule. Compounds 3, 4, 5 and 6 were performed for AChE inhibitory activity and compound 3 showed the inhibitory activity against AChE with IC50 of 465.6 µg/mL.

Cycloartane-type triterpene glycosides anopanins A-C with monoacyldigalactosylglycerols from Anodendron paniculatum.

Three cycloartane-type triterpene glycosides (anopanins A-C), together with three known monoacyldigalactosylglycerols gingerglycolipids A-C and (2S)-1-O-palmitoyl-3-O-[α-d-galactopyranosyl-(1→6)-ß-d-galactopyranosyl]-sn-glycerol, were isolated from the aerial parts of Anodendron paniculatum collected in Viet Nam. The chemical structures of the present compounds were elucidated by means of 1D and 2D NMR and HRESIMS spectroscopy, and by comparing to the reported data in the literature. These compounds did not show significant growth inhibitory activities (IC50 > 100 µg/mL) against the tested cancer cell lines LU-1 (lung adenocarcinoma), KB (epidermoid carcinoma), Hep-G2 (hepatoma cancer), MKN-7 (stomach cancer), and SW-480 (colon adenocarcinoma).

A new lignan glycoside from the aerial parts and cytotoxic investigation of Uvaria rufa.

Chemical investigation of the aerial parts of Uvaria rufa (Dunal) Blume collected from Vietnam yielded one new lignan glycoside, ufaside (1), along with six known compounds, oxoanolobine (2), ergosta-4,6,8(14),22-tetraen-3-one (3), catechin (4), epicatechin (5), daucosterol (6) and glutin-5-en-3-one (7). Their chemical structures were determined by using NMR, HR-MS spectroscopic analyses and in comparison with the reported data. A cytotoxic analysis of U. rufa herb extracts was performed for the first time using nine human cancer cell lines (MCF-7, MDA-MB-231, LNCaP, MKN7, SW480, KB, LU-1, HepG2 and HL-60) derived from different tumour types. Of these seven constituents, compounds 2 and 3 displayed moderate cytotoxicity against the human lung adenocarcinoma cell line (LU-1) with IC50 values of 9.22 ± 1.02 µg/mL and 10.21 ± 1.16 µg/mL, respectively.