Fungicidal Activity and Mechanism of Action of Glabridin from Glycyrrhiza glabra L.

Glycyrrhiza glabra (Licorice) belongs to the Fabaceae family and its extracts have exhibited significant fungicidal activity against phytopathogenic fungi, which has mainly been attributed to the presence of phenolic compounds such as flavonoids, isoflavonoids and chalcones. In this study, a series of licorice flavonoids, isoflavonoids and chalcones were evaluated for their fungicidal activity against phytopathogenic fungi. Among them, glabridin exhibited significant fungicidal activity against ten kinds of phytopathogenic fungi. Notably, glabridin displayed the most active against Sclerotinia sclerotiorum with an EC50 value of 6.78 µg/mL and was 8-fold more potent than azoxystrobin (EC50, 57.39 µg/mL). Moreover, the in vivo bioassay also demonstrated that glabridin could effectively control S. sclerotiorum. The mechanism studies revealed that glabridin could induce reactive oxygen species accumulation, the loss of mitochondrial membrane potential and cell membrane destruction through effecting the expression levels of phosphatidylserine decarboxylase that exerted its fungicidal activity. These findings indicated that glabridin exhibited pronounced fungicidal activities against S. sclerotiorum and could be served as a potential fungicidal candidate.

Design, Synthesis, and Antifungal Evaluation of Neocryptolepine Derivatives against Phytopathogenic Fungi.

Neocryptolepine is an alkaloid isolated from traditional African herbal medicine Cryptolepis sanguinolenta, and its broad spectrum of biological activities has been illuminated in past decades. In this study, neocryptolepine and its derivatives (1-49) were designed and synthesized from economical and readily available starting materials. Their structures were confirmed by proton nuclear magnetic resonance, carbon nuclear magnetic resonance, and mass spectrometry. The synthesized compounds were screened for their antifungal profile against six agriculturally important fungi Rhizoctonia solani, Botrytis cinerea (B. cinerea), Fusarium graminearum, Mycosphaerella melonis, Sclerotinia sclerotiorum, and Magnaporthe oryzae. The results of in vitro assay revealed that compounds 5, 21, 24, 35, 40, 45, and 47 presented remarkable antifungal activity against the fungi tested with EC50 values lower than 1 µg/mL. Significantly, compound 24 displayed the most effective inhibitory potency against B. cinerea (EC50 = 0.07 µg/mL), and the data from in vivo experiments revealed that compound 24 demonstrated comparable protective activity with the positive control boscalid. Preliminary mechanism studies indicated that compound 24 showed impressive spore germination inhibitory effectiveness and lower cytotoxicity than azoxystrobin, imparted on normal function of the cell membrane and cell wall, and arrested the normal function of the nucleus. Besides the excellent inhibitory activity against agriculturally important phytopathogenic fungi tested, the designed assemblage possesses several benefits with a high profile of variation in synthesized molecules, the ease of synthesis, and good cost-effectiveness of commercially available synthetic reagents, all of these have highlighted the potential worth of compound 24 as a new and highly efficient agricultural fungicide.

Acaricidal activity and enzyme inhibitory activity of active compounds of essential oils against Psoroptes cuniculi.

Plant essential oils and its chemical compositions are commonly applied in medicinal and other industries due to their broad advanced pharmacological activities. In the present study, we systematically evaluated the acaricidal activities of twelve compounds of essential oils against Psoroptes cuniculi in vitro and in vivo. In addition, to support the clinic uses, their toxicities against immortalized human keratinocytes (HaCaT) and human liver cells (HL-7702) and skin irritation were studied for evaluating the liver and skin safety. The possible mechanism of action of certain chemical were investigated by determining the inhibitory activities against cytochrome P450 (P450) acetylcholinesterase (AChE) and glutathione-S-transferase (GST). Among all tested compounds, eugenol exhibited the best acaricidal activity with LC50 value of 56.61 µg/ml in vitro. Meanwhile, after the treatment of eugenol for five times within 10 days, the P. cuniculi were eliminated in the naturally infested rabbits, no skin irritation was found in rabbits treated by eugenol. Moreover, eugenol presented no or weak cytotoxicity against HaCaT cells and HL-7702 cells with IC50 values of greater than 100 µg/ml. Furthermore, the moderate inhibitory activities of eugenol against mites P450 and AChE were demonstrated. Above results indicated that eugenol presented the promising acaricidal activity against P. cuniculi in vitro and in vivo, is safe for both humans and animals at the given doses. This work lays the foundation for the development of eugenol as an environmentally friendly acaricide agent.

[The influence of rotary manipulation on the internal pressure of cervical nucleus pulposus].

OBJECTIVE: To measure the pressure changes inside the cervical nucleus pulposus in fresh human cervical specimen by imitating different rotary manipulations. METHODS: The load of 100 N was applied for 5 second on the six fresh male cervical samples by using material test system, which imitated the human head weigh and the strength of cervical extensor muscle. After that, traction, rotation and pulling on the samples were performed in different sequence under the force of 150, 200, 300 N respectively. Three states were included in adding the load state A: samples were loaded with traction and then rotation to the biggest angle, pulling backward for 15 degrees; state B: samples were loaded with rotary stress to the biggest angle and then loaded with traction, pulling backward for 15 degrees; state C: samples were loaded simultaneously with traction and rotary stress to the biggest angle, pulling backward for 15 degrees. The internal pressure of cervical nucleus pulposus at segment of C(3,4), C(4,5), C(5,6), and C7 was measurred by micro-pressure sensors for state A, B, C and for the imitation of head weight and the strength of cervical extensor muscle. RESULTS: The pressure inside the cervical nucleus pulposus at segments C(5,6), C(6,7) was higher than that at segments C(3,4) and C(4,5) (P < 0.05) by loading stress with 100 N for 5 seconds. The internal pressure of the nucleus pulposus decreased with the increase of traction (P < 0.05), and increased when traction and rotary force were loaded. State A, the value of increased pressure within the nucleus pulposus became smaller and smaller while increasing of the traction force loaded (P < 0.05). State B, the increase of internal pressure in nucleus pulposus became obvious as loading pressure increased (P < 0.05). State C, the internal pressure in nucleus pulposus was not increased obviously (P > 0.05). There was a transitional pressure raise inside all cervical nucleus pulposus when pulling added after different sepuence traction and rotary strength was applied, however, the internal pressure of state A was significantly higher than that of state B or C (P < 0.05). There was also a transitional pressure raise inside all cervical nucleus pulposus when pulling added in different strength (P < 0.05),the internal pressure by pulling with 150 N was obviously higher than that with 200 N and 300 N (P < 0.05). CONCLUSION: The order of rotation first and traction second should be avoided when practice of rotary manupuplation in case protrusion of the nucleus pulposus. Meanwhile, proper traction should be applied along with rotary manipulation in order to increase its safety.