Bioactivity-guided Isolation of TRAIL-Resistance-Overcoming Activity Compounds From the Leaves of Murraya exotica

Fractionation of the leaf extract from Murraya exotica led to the successful isolation of 12 compounds (1-12) with TRAIL-resistance-overcoming activity. Xanthinosin (1), 11α, 13-dihydroxanthinin (2), 11β, 13-dihydroxanthinosin (3), 4α, 11α, 13-trihydroxanthuminol (4), desacetylxanthanol (5), and lasidiol p-methoxybenzoate (6) were sesquiterpenes isolated from this plant for the first time, and 3 was isolated from natural sources for the first time. Among them, compounds 1 and 5 showed strong TRAIL-resistance-overcoming activity, but their mechanisms have already been revealed. Furthermore, dihydroxanthinin (2), 1, 5-dicaffeoylquinic acid (7), and (-) loliolide (8), which belong to different phytochemical groups, were investigated for their effects on increasing apoptosis induction to overcome TRAIL resistance using Western blot analysis. The results demonstrated that 2, 7, and 8 promoted TRAIL-induced apoptosis by increasing the expression of several proapoptotic markers, including cleaved caspases −3 and −8, and suppressing anti-apoptotic protein Bcl-2.

Cooling effect and control factors of common shrubs on the urban heat island effect in a southern city in China

Because the heat island effect can make cities warmer than their surroundings, it can make urban dwellers uncomfortable and even affect their health, which is particularly pronounced in developed cities in southern China. To reduce the heat island effect and improve the environment, various types of vegetation have been planted in the urban green belt. Though previous studies have been conducted on the beauty, air purification functions and cooling effect of vegetation, little is concentrated on the different cooling effects and control factors of various common shrubs on the heat island effect in cities. In this study, five of the most regionally common shrubs were selected to study the cooling effect in Guangzhou, southern China. The maximum surface temperatures of five shrubs and pavement were compared using infrared temperature sensors from April 1st 2019 to October 31st 2019. Results show that (1) All five shrubs showed noticeable seasonal variation, and the average surface temperatures of the five shrubs were between 38.0 and 42.2 °C during May–August and 30.7–34.1 °C during the other seasons (April, September and October);. (2) Murraya exotica L. exhibited the best cooling effect on the maximum surface temperature. Its value was 44.7 °C, and the absolute difference values of Murraya exotica L. (10.3 ± 1.7 °C) were higher than any other shrub during the study period; (3) Both the LAI (R2 = 0.57, p < 0.01) and plant height (R2 = 0.13, p < 0.01) are control factors of the cooling effect on vegetation surface temperature for the five shrubs. This study revealed the differences in the cooling effect and influencing factors of five regionally common shrubs on the heat island effect. Research on the functional characteristics of plants and plant selection in urban green belts has both theoretical and practical significance.

Antiplasmodial and Antipyretic Activity and Safety Evaluation of the Methanolic Leaf Extract of Murraya exotica (L.)

Background. The increasing mortality and morbidity of malaria in Africa coupled with the recent reports of antimalarial drug resistance reinforces the need for novel antimalarial agents from natural plant products with folkloric use for the disease. Murraya exotica (L.) (Rutaceae) is widely used as an ornamental plant used indigenously to treat fever, cough, and infectious wounds and eliminate pain from injury and trauma. This study was conducted to evaluate extracts of the leaves of Murraya exotica (L.) (Rutaceae) for its safety and antipyretic and antimalarial activity in rodent models. Method. In this study, the Peters 4-day suppressive and curative test in Plasmodium berghei-infected mice was used to demonstrate the antiplasmodial activity of the methanolic leaf extract of Murraya exotica (L.) (MEE). The study also evaluated the subacute toxicity study and the antipyretic activity of MEE on baker’s yeast-induced hyperthermia in rodent models. Results. Murraya exotica (L.) extract demonstrated curative antimalarial activity, with a percentage suppression of 45.84, 64.32±0.33, 56.74±2.16, and 64.61±0.67 at doses of 50, 100, 300, and 600 mg/kg, respectively. In the Peters 4-day suppressive test, MEE at dose 600 mg/kg had the highest chemosuppression (76.02±1.38%) compared with artesunate (2 mg/kg, p.o.) (82.56±0.97%). Subacute oral toxicity studies in Sprague-Dawley rats documented no deaths, with no significant changes in clinical signs, organ weights, and hematological and biochemical parameters. The LD50 of MEE was estimated to be above 1000 mg/kg in Sprague-Dawley rats. All doses of MEE and paracetamol reduced pyrexia in 1 h and 2 h after their administration. The percentage reduction of rectal temperature (TR) for the positive control (paracetamol, 150 mg/kg, p.o.) was 44.36% while the Murraya exotica extract at doses 50 mg/kg, 100 mg/kg, 300 mg/kg, and 600 mg/kg recorded 67.74%, 40.78%, 66.42%, and 59.42%, respectively. Murraya exotica at dose 100 mg/kg exhibited significant reduction (p<0.05) in baker’s yeast-induced pyrexia. Conclusions. The findings in this study show the antipyretic, curative, and suppressive antiplasmodial activity as well as the safety of the methanolic leaf extract of Murraya exotica (L.) supporting its traditional use for malaria and fever.