Structural Characterization of Mannoglucan Isolated from Ophiocordyceps sobolifera and Its Antioxidant Activities.

A novel polysaccharide structure (PS-T80) was collected from Ophiocordyceps sobolifera biomass and characterized via a combination of chemical and spectral analyses. Employing high-performance gel permeation chromatography (HPGPC), the average molecular weight is proven to be 7.4 × 104 Da. Furthermore, a sugar composition analysis of the obtained polysaccharide suggests two main sugars, ß-d-glucose and α-d-mannose, at a molar ratio of 2:1, respectively, in the backbone. The structure analysis unveils that PS-T80 is a mannoglucan, possessing the repeating unit of [→3)-ß-d-Glcp-(1 → 3)-α-d-Manp-(1 → 3)-ß-d-Glcp-(1→] n . Such a configuration could be considered a novel polysaccharide. Impressively, in vitro antioxidant tests revealed that PS-T80 has a promising antioxidant activity. These results demonstrate that the obtained PS is a potential bioactive material for biomedical applications.

Oleanane-type triterpene saponins from Aralia armata leaves and their cytotoxic activity.

Two new, aramatosides A and B (1 and 2), together with seven known oleanane-type triterpene saponins (3-9) were isolated from the leaves of Aralia armata. Their structures were determined by combination of HR-ESI-MS, 1 D and 2 D NMR spectral data as well as comparison with the previous literature. Compounds 6-9 exhibited cytotoxic effects towards three human cancer cell lines (HT29, A2058, and A549) with IC50 values ranging from 2.01 ± 0.17 to 18.8 ± 1.17 µM. Especially, compound 7 (narcissiflorin) showed significant cytotoxic activity against HT29 and A549 cell lines with IC50 values of 2.02 ± 1.65 and 2.01 ± 0.17 µM, respectively, which are smaller than those of positive control irinotecan hydrochloride (IC50 values of 10.3 ± 1.32 and 9.89 ± 0.19 µM).

New lupane-type and ursane-type triterpene saponins from the leaves of Trevesia palmata.

Three new triterpene saponins including two lupane-types and an ursane-type were isolated from the leaves of Trevesia palmata. Their structures were determined as 2α,3ß,23-trihydroxylup-20(29)-en-28-oic acid 3-O-α-L-arabinopyranoside (1), 2α,3ß,23-trihydroxylup-20(29)-en-28-oic acid 3-O-[α-L-arabinopyranoside]-28-O-[ß-D-glucopyranosyl] ester (2), and 2α,3ß,23-trihydroxyurs-12-en-28-oic acid 3-O-[α-L-arabinopyranoside]-28-O-[ß-D-glucopyranosyl(1→2)-ß-D-glucopyranosyl] ester (3) by analysis of their HR-ESI-MS, 1D and 2D NMR spectra. The 2α,3ß,23-trioxygenated pentacyclic triterpenes were uncommonly found in the nature. At concentration of 100 µM, compounds 1-3 inhibited NO production in LPS activated BV2 cells with inhibitory rates of 17.4 ± 1.8%, 33.1 ± 1.2%, and 11.7 ± 2.2%, respectively. But, they did not significantly inhibit yeast α-glucosidase activity.

Mosquito Larvicidal Activity of the Essential Oils of Erechtites Species Growing Wild in Vietnam.

Mosquito-borne infections are a constant problem in Vietnam, and mosquito vector control is a primary approach to control these infections. Essential oils represent environmentally friendly alternatives to synthetic pesticides for mosquito control. The essential oils of two weedy species in Vietnam, Erechtites hieraciifolius and E. valerianifolius, have been obtained by hydrodistillation and analyzed by gas chromatography⁻mass spectrometry. The essential oils have been screened for mosquito larvicidal activity against Aedes albopictus, Ae. aegypti, and Culex quinquefasciatus. The essential oil from the aerial parts of E. hieraciifolius was rich in α-pinene (14.5%), limonene (21.4%), and caryophyllene oxide (15.1%), while E. valerianifolius essential oil was dominated by myrcene (47.8%) and α-pinene (30.2%). Both essential oils showed good larvicidal activity against Ae. albopictus (24-h LC50 10.5 and 5.8 µg/mL, respectively) and Ae. aegypti (24-h LC50 10.6 and 12.5 µg/mL, respectively). The essential oil of E. valerianifolius also showed good activity against Cx. quinquefasciatus larvae (24-h LC50 = 40.7 µg/mL). Thus, Erechtites essential oils may serve as low-cost vector control agents for mosquito-borne infections.

Chemical composition, Aedes mosquito larvicidal activity, and repellent activity against Triatoma rubrofasciata of Severinia monophylla leaf essential oil.

Aedes aegypti and Ae. albopictus are key vectors in the spread of arboviruses such as dengue, chikungunya, yellow fever, and Zika. Triatoma rubrofasciata is an "assassin bug" whose populations and association with humans have dramatically increased and may represent a serious health concern. Control of insect vectors is a logical course of action to prevent the spread of these insect-borne infections. This work presents the leaf essential oil composition, mosquito larvicidal activities, and insect-repellent activity of Severinia monophylla. The essential oil of S. monophylla from Vietnam was obtained by hydrodistillation and analyzed by gas chromatography and mass spectrometry. The major components were sabinene, ß-caryophyllene, bicyclogermacrene, germacrene D, (E)-nerolidol, globulol, and linalool. The leaf essential oil showed remarkable larvicidal activity against Ae. aegypti with LC50 (48 h) of 7.1 µg/mL and Ae. albopictus with LC50 (48 h) of 36 µg/mL. The essential oil also showed repellent activity on T. rubrofasciata at a concentration of 0.5%.