High-nitrogen fertilizer alleviated adverse effects of drought stress on the growth and photosynthetic characteristics of Hosta 'Guacamole'

BACKGROUND

Several plants are facing drought stress due to climate change in recent years. In this study, we aimed to explore the effect of varying watering frequency on the growth and photosynthetic characteristics of Hosta 'Guacamole'. Moreover, we investigated the effect of high-nitrogen and -potassium fertilizers on alleviating the impacts of drought stress on the morphology, photosynthetic characteristics, chlorophyll fluorescence, fast chlorophyll a fluorescence transient, JIP-test parameters, and enzymatic and non-enzymatic scavenging system for reactive oxygen species (ROS) in this species.

RESULTS

Leaf senescence, decreased chlorophyll contents, limited leaf area, and reduced photosynthetic characteristics and oxygen-evolving complex (OEC) activity were observed in Hosta 'Guacamole' under drought stress. However, high-nitrogen fertilizer (30-10-10) could efficiently alleviate and prevent the adverse effects of drought stress. High-nitrogen fertilizer significantly increased chlorophyll contents, which was higher by 106% than drought stress. Additionally, high-nitrogen fertilizer significantly improved net photosynthetic rate and water use efficiency, which were higher by 467% and 2900% than those under drought stress. It attributes that high-nitrogen fertilizer could reduce transpiration rate of leaf cells and stomatal opening size in drought stress. On the other hand, high-nitrogen fertilizer enhanced actual photochemical efficiency of PS II and photochemical quenching coefficient, and actual photochemical efficiency of PS II significantly higher by 177% than that under drought stress. Furthermore, high-nitrogen fertilizer significantly activated OEC and ascorbate peroxidase activities, and enhanced the performance of photosystem II and photosynthetic capacity compared with high-potassium fertilizers (15-10-30).

CONCLUSIONS

High-nitrogen fertilizer (30-10-10) could efficiently alleviate the adverse effects of drought stress in Hosta 'Guacamole' via enhancing OEC activity and photosynthetic performance and stimulating enzymatic ROS scavenging system.

blocked NF-κB/iNOS/COX-2/MAPKs/Akt signaling pathways in LPS-induced RAW 264.7 macrophages

ETHNOPHARMACOLOGICAL RELEVANCE

Hostaflavone A (HA) is a new flavonoid component isolated from the flower of Hosta plantaginea (Lam.) Asch., which is commonly used as a folk herbal to treat inflammatory diseases in China. Nevertheless, the anti-inflammatory effect of HA remains unknown.

AIM OF THE STUDY

This work aimed to evaluate the HA with anti-inflammatory activity and mechanism in RAW 264.7 macrophages activated by lipopolysaccharide (LPS).

MATERIALS AND METHODS

Anti-inflammatory effect of HA was evaluated by measuring of cell viability, nitric oxide (NO), prostaglandin E2 (PGE2), tumor necrosis factor α (TNF-α), interleukin 1β (IL-1β) and IL-6 levels in RAW 264.7 cells. In parallel, the HA action mechanism of nuclear factor kappa B (NF-κB) p65, inhibitor of NF-κB (IκB), inducible nitric oxide synthase (iNOS), cyclooxygenase 2 (COX-2), c-Jun N-terminal kinases (JNK), extracellular signal-regulated kinase (Erk), p38, and protein kinase B (Akt) were detected by Western blot analysis.

RESULTS

HA has no cytotoxicity at concentrations as high as 40 μM. Besides, HA concentration-dependently clearly suppressed the overproduction of NO, PGE2, TNF-α, IL-1β and IL-6 in RAW 264.7 cells induced by LPS. In addition, HA remarkably reduced the upregulation of phosphorylated NF-κB p65, phosphorylated IκB, phosphorylated JNK, phosphorylated Erk and phosphorylated p38, together with iNOS and COX-2 protein expressions in a concentration-dependent manner.

CONCLUSION

HA blocked the LPS activated inflammation via suppressing NF-κB, iNOS, COX-2, mitogen-activated protein kinases (MAPKs) and Akt pathways in RAW 264.7 cells, and might be a new anti-inflammatory agent.

Cytotoxic steroidal glycosides from the underground parts of Hosta ventricosa

A phytochemical study on the underground parts of Hosta ventricosa yielded one new spirostanol saponin (1), two new furostanol saponins (2 and 3), and one new pregnane glycoside (4), along with three known compounds (5‒7). Their structures were elucidated on the basis of chemical and spectroscopic analysis. All isolated compounds were evaluated for their cytotoxic effects against five human cancer cell lines (HL-60, A-549, SMMC-7721, MCF-7, and SW-480). Compounds 1, 2, and 5‒7 showed cytotoxic activities with IC₅₀ values of 3.21-17.06 μM.

Isolation and characterization of flavonoid derivatives with anti-prostate cancer and hepatoprotective activities from the flowers of Hosta plantaginea (Lam.) Aschers

ETHNOPHARMACOLOGICAL RELEVANCE

The flower of Hosta plantaginea (Lam.) Aschers (Liliaceae) is a traditional medicinal material in Mongolian medicine for treating sore throat, hoarseness, pulmonary fever, and toxic fever in folk. The present work investigated anti-prostate cancer and hepatoprotective activities of flavonoid derivatives from H. plantaginea (Lam.) Aschers.

AIM OF THE STUDY

To isolate and identify the chemicals of H. plantaginea (Lam.) Aschers for anti-prostate cancer and hepatoprotective activities.

MATERIALS AND METHODS

Active chemicals were isolated and purified from H. plantaginea (Lam.) Aschers by chromatographic methods, and their structures were established on spectroscopic analysis and references. These compounds were evaluated for their anti-prostate cancer activities using the LNCaP prostate cancer cells, and assayed for their hepatoprotective activities on CCl₄-induced injury of human L-O2 cells, respectively.

RESULTS

Four new flavonol-lignan heterodimers (1-4), together with nine known flavonoid derivatives (5-13) were isolated from this plant for the first time. Among them, some compounds exhibited moderate anti-prostate cancer and hepatoprotective activities.

CONCLUSION

Compounds 1, 2, 5, and 6 showed anti-prostate cancer activities using the LNCaP prostate cancer cells with IC₅₀ values of 17.84, 33.26, 54.13, and 81.55 μg/mL, and compounds 3, 4, 8, and 9 exhibited moderate hepatoprotective activities, respectively. A preliminary structure-activity relation was summarized in this paper.