Effects on mice locomotor activity of a narcotic-like principle from Psidium guajava leaves

Studies were carried out on the suppression of both exploratory and spontaneous locomotor activities in the mouse by a non-polar fraction from a methanol extract of the dried leaves of Psidium guajava. Shortly after intraperitoneal administration of this fraction, typical narcotic-like effects were observed, including catalepsy, analgesia, Straub tail, shallow respiratory movements and exophthalmos. The dose for 90% suppression of exploratory activity was between 3.3 and 6.6 mg/kg intraperitoneally and the onset of action was 6-8 min. The duration of activity was dose-dependent and, for a dose of 13.2 mg/kg given intraperitoneally, it was found to be more than 6 h. Qualitatively similar results on exploratory activity were obtained when the extract was administered orally. Doses of 3.3-6.6 mg/kg i.p. depressed spontaneous locomotor activity and tunnel running was curtailed. Higher doses abolished the spontaneous locomotor reflex action. A flavonoid compound or compounds appear to account for the activity seen.     

Antidiabetic effects of extracts from Psidium guajava

During a screening of medicinal plants for inhibition of protein tyrosine phosphatase1B (PTP1B), an extract from Psidium guajava (Myrtaceae) leaves exhibited significant inhibitory effect on PTP1B. Thus, its antidiabetic effect on Lepr(db)/Lepr(db) mice was evaluated. Significant blood glucose lowering effects of the extract were observed after intraperitoneal injection of the extract at a dose of 10mg/kg in both 1- and 3-month-old Lepr(db)/Lepr(db) mice. In addition, histological analysis of the liver from the butanol-soluble fraction treated Lepr(db)/Lepr(db) mice revealed a significant decrease in the number of lipid droplets compared to the control mice. Taken together, it was suggested that the extract from Psidium guajava leaves possesses antidiabetic effect in type 2 diabetic mice model and these effect is, at least in part, mediated via the inhibition of PTP1B.     

The antimicrobial activities of Psidium guajava and Juglans regia leaf extracts to acne-developing organisms

This study aims to present the in vitro inhibitory effect of Psidium guajava and Juglans regia leaf extracts on the main developer of acne lesions, Propionibacterium acnes (P. acnes), and other organisms that are isolated from acne lesions. Thirty-eight subjects (males and females) who had various types of acne were enrolled in the study. The contents of the acne lesions were cultured and the frequency of P. acnes (alone and with Staphylococci spp.) was 47%, whereas the frequencies for Staphylococcus aureus and Staphylococcus epidermidis were 13% and 24%, respectively. The antimicrobial activities of Psidium guajava and Juglans regia leaf extracts, determined by disk diffusion method (zone of inhibition), were compared to tea tree oil (TTO), doxycycline and clindamycin antibiotics. The zones of inhibition due to the Psidium guajava and Juglans regia leaf extracts ranged from 15.8-17.6 mm against P. acnes, 11.3-15.7 mm against S. aureus and 12.9-15.5 mm against S. epidermidis, respectively. These zones of inhibition were significantly higher than those of TTO and equivalent in case of Staphylococci spp., but less in case of P. acnes, to those obtained from doxycycline or clindamycin. It can be concluded that Psidium guajava and Juglans regia leaf extracts may be beneficial in treating acne especially when they are known to have anti-inflammatory activities.     

Anticough and antimicrobial activities of Psidium guajava Linn. leaf extract

The anticough activity of Psidium guajava Linn. (guava) leaf extract was evaluated in rats and guinea pigs. The results showed that water extract of the plant at doses of 2 and 5 g/kg, p.o. decreased the frequency of cough induced by capsaicin aerosol by 35 and 54%, respectively, as compared to the control, within 10 min after injection of the extract, (P < 0.01). However, the anticough activity is less potent than that of 3 mg/kg dextromethorphan which decreased frequency of cough by 78% (P < 0.01). An experiment on isolated rat tracheal muscle showed that the extract directly stimulated muscle contraction and also synergized with the stimulatory effect of pilocarpine. This effect was antagonized by an atropine. Moreover, growth of Staphylococcus aureus and beta-streptococcus group A, as determined by the disc diffusion method, was inhibited by water, methanol and chloroform extract of dry guava leaves (P < 0.001). The LD50 of guava leaf extract was more than 5 g/kg, p.o. These results suggest that guava leaf extract is recommended as a cough remedy.     

Inhibition of gastrointestinal release of acetylcholine by quercetin as a possible mode of action of Psidium guajava leaf extracts in the treatment of acute diarrhoeal disease

The electrically stimulated guinea-pig ileum and spontaneously contracting guinea-pig ileum preparations were employed in studies on the effects of an alcoholic extract and two flavonoid compounds, quercetin and quercetin-3-arabinoside, extracted from the leaves of Psidium guajava. The extract showed a morphine-like inhibition of acetylcholine release in the coaxially stimulated ileum, together with an initial increase in muscular tone, followed by a gradual decrease. The morphine-like inhibition was found to be due to quercetin, starting at concentrations of 1.6 micrograms/ml. The glycoside did not show any such action at concentrations of up to 1.28 mg/ml. The extract inhibited spontaneous contractions in the unstimulated ileum with a concentration-response relationship.     

Effect of guava (Psidium guajava Linn.) leaf soluble solids on glucose metabolism in type 2 diabetic rats

This study investigated the effect of aqueous and ethanol soluble solid extracts of guava (Psidium guajava Linn.) leaves on hypoglycemia and glucose metabolism in type 2 diabetic rats. Low-dose streptozotocin (STZ) and nicotinamide were injected into Sprague-Dawley (SD) rats to induce type 2 diabetes. Acute and long-term feeding tests were carried out, and an oral glucose tolerance test (OGTT) to follow the changes in plasma glucose and insulin levels was performed to evaluate the antihyperglycemic effect of guava leaf extracts in diabetic rats.The results of acute and long-term feeding tests showed a significant reduction in the blood sugar level in diabetic rats fed with either the aqueous or ethanol extract of guava leaves (p < 0.05). Long-term administration of guava leaf extracts increased the plasma insulin level and glucose utilization in diabetic rats. The results also indicated that the activities of hepatic hexokinase, phosphofructokinase and glucose-6-phosphate dehydrogenase in diabetic rats fed with aqueous extracts were higher than in the normal diabetic group (p < 0.05). On the other hand, diabetic rats treated with the ethanol extract raised the activities of hepatic hexokinase and glucose-6-phosphate dehydrogenase (p < 0.05) only. The experiments provided evidence to support the antihyperglycemic effect of guava leaf extract and the health function of guava leaves against type 2 diabetes.     

Investigations on the antinociceptive effect of Psidium guajava leaf essential oil and its major constituents

The antinociceptive effect of leaf essential oil from Psidium guajava and its major constituents, β-caryophyllene and α-pinene was assessed using chemical (formalin and acetic acid) and thermal (hot-plate) nociceptive tests in adult male albino mice. Oral administration of 100, 200 and 400 mg/kg of essential oil produced a significant antinociceptive effect in the formalin test and at 200 and 400 mg/kg in the acetic acid- induced writhing test. Of the major components only α-pinene, but not the β-caryophyllene, demonstrated significant antinociception in the formalin test. Neither the essential oil nor the major components could exert any significant effect in the hot-plate test. Pretreatment of mice with caffeine (20 mg/kg, i.p.), significantly inhibited the antinociceptive effect of essential oil in the formalin test. Naloxone (1 mg/kg, s.c.), the opioid antagonist, however, failed to antagonize it. These results suggest that the antinociceptive effect of P. guajava essential oil is probably mediated by endogenously released adenosine. © 1998 John Wiley & Sons, Ltd.     

大孔吸附树脂纯化番石榴叶总黄酮工艺研究

目的建立大孔吸附树脂富集、纯化番石榴叶总黄酮的最佳工艺。方法通过比较8种树脂的静态吸附量、静态解吸率,确定最佳吸附树脂;考察最佳吸附树脂对番石榴叶总黄酮的动态吸附、洗脱性能,从而优化工艺参数。结果 HPD826型树脂具有最佳的纯化效果,其最佳工艺为上样生药浓度0.1g·ml-1,吸附流速3 ml·min-1,用3 BV水洗除杂,用4 BV 70%乙醇溶液,洗脱流速4 ml·min-1,在此条件下总黄酮的纯度达26.1%。结论 HPD826型大孔吸附树脂可用于番石榴叶总黄酮的分离纯化。     

番石榴叶治疗小儿轮状病毒肠炎的临床研究

目的：观察番石榴叶治疗小儿轮状病毒（HRV）肠炎的临床疗效。方法：62例HRV肠炎患儿随机分为治疗组和对照组，治疗组服用用番石榴叶，对照组服用葛根芩连汤。观察止泻时间：血清Na^+、粪Na^+、粪糖和HRV抗原转阴率。结果：治疗组3天治愈率为87.1%，对照组为58.1%，治疗组显著优于对照组（P<0.05）。治疗组止泻时间为(25.1±9.5)h,对照组为(38.7±15.2)h，治疗组止泻时间显著短于对照组（P<0.01）。治疗组粪Na^+、粪糖较治疗前明显下降，对照组下降不明显，治疗组优于对照组（ P<0.05）。治疗组粪HRV转阴率为87.1%，对照组为58.1%，治疗组显著优于对照组（P<0.05）。结论：番石榴叶治疗小儿HRV肠炎有比较好的疗效。     

番石榴叶总三萜对2型糖尿病大鼠肾损伤的保护作用

目的:探讨番石榴叶总三萜(TTPGL)对2型糖尿病大鼠肾脏病变的影响。方法:采用高糖高脂饮食加腹腔注射小剂量链脲佐菌素(STZ,35 mg/kg)方法建立2型糖尿病大鼠模型。将造模成功的糖尿病大鼠随机分为5组:糖尿病模型组,番石榴叶总三萜低、中、高剂量组,罗格列酮阳性对照组;另取12只正常大鼠作为正常对照组。给药组灌胃给药1次/d,连续给药6 w。取血清测定大鼠空腹血糖(FPG)、空腹血清胰岛素(FINS)、血清肌酐(Cr)、血清尿素氮(BUN)。另取肾组织,进行常规HE染色进行病理组织学切片。结果:与正常对照组比较,糖尿病模型组空腹血糖显著升高、胰岛素水平及胰岛素敏感指数下降;血清肌酐及尿素氮水平升高;肾脏病理形态学显示:肾小球内皮及系膜细胞增生,毛细血管腔变窄,基底膜增厚,肾小球肿大、肾小囊变窄,肾小管水肿等。与糖尿病模型组比较,TTPGL中、高剂量组大鼠的空腹血糖显著降低,血清胰岛素水平及胰岛素敏感指数显著升高(P0.01或P0.05);同时,TTPGL给药组大鼠血清肌酐、尿素氮含量显著降低,肾脏病理形态学损伤明显改善(P0.01或P0.05)。结论:番石榴叶总三萜能显著降低2型糖尿病大鼠的血糖水平,提高胰岛素敏感指数,并对糖尿病肾损伤具有明显的保护作用。     

番石榴叶化学成分研究

目的:研究番石榴Psidium guajava叶的化学成分.方法:利用葡聚糖凝胶Sephadex LH-20、硅胶和MPLC等色谱方法进行化合物的分离纯化,根据化合物的理化性质、波谱数据进行结构鉴定.结果:从番石榴叶中分离得到9个单体化合物,分别为:乌苏酸(ursolic acid,1),2α-羟基乌苏酸(2α-hydroxyursolic acid,2),2α-羟基齐墩果酸(2α-hydroxyoleanolic acid,3),番石榴苷(morin-3-O-α-L-arabopyranoside,4),槲皮素(quercetin,5),金丝桃苷(hyperin,6),杨梅素-3-O-β-D-葡萄糖(myricetin-3-O-β-D-glucopyranosid,7),quercetin-3-O-β-D-glucuronopyranoside(8),1-O-没食子酰基-β-D-葡萄糖(1-O-galloyl-β-D-glucose,9).结论:化合物3,7～9为首次从该植物中分离得到.     

番石榴叶中抗氧化活性成分的研究

目的研究番石榴Psidium guajava叶的活性成分,为开发番石榴叶资源提供依据。方法以抗氧化活性为指标,运用多种柱色谱等现代分离手段对番石榴叶60%乙醇提取物进行活性追踪分离;根据理化性质和波谱学分析鉴定了化合物的结构,并评价了其抗氧化活性。结果分离得到12个化合物,分别鉴定为儿茶素(1)、鸢尾酚酮-2-O-β-D-吡喃葡萄糖苷(2)、山柰酚(3)、槲皮素(4)、槲皮素-3-O-α-L-呋喃阿拉伯糖苷(5)、槲皮素-3-O-β-D-吡喃阿拉伯糖苷(6)、槲皮素-3-O-β-D-吡喃半乳糖苷(7)、槲皮素-3-O-β-D-吡喃葡萄糖苷(8)、槲皮素-3-O-(6″-芥子酸)-β-D-吡喃半乳糖苷(番石柳叶苷A,9)、槲皮素-3-O-(6″-阿魏酸)-β-D-吡喃半乳糖苷(10)、顺式对香豆酸-4-O-β-D-吡喃葡萄糖苷(11)、去甲氧基荚果蕨素(12)。结论对分离得到的11个化合物进行抗氧化活性测试,其中化合物4、5、6显示较强活性,1、3、7、8显示中等强度活性。化合物2、10、11、12为首次从番石榴属植物中分离得到,化合物9为新化合物。     

番石榴叶挥发油成分的GC—MS分析

采用气相色谱-质谱联用技术对番石榴叶挥发油的化学成分进行了分析,共分出93个峰,鉴定了60种成分,占挥发油总量的90.56％,该挥发油主成分为倍半萜类与单萜类。     

Terpenoids Isolated from Psidium guajava Hexane Extract with Depressant Activity on Central Nervous System

A bioguided fractionation of the hexane extract obtained from Psidium guajava leaves led to the isolation of sesquiterpenes with depressant activities on the central nervous system. The results demonstrated that the already reported relaxant properties of Psidium guajava hexane extract are largely due to the presence of terpenes, especially caryophyllene-oxide and β-selinene, which were by far the largest single components and potentiated pentobarbital sleeping time and the latency of convulsions induced by leptazol in mice. Calcium concentration-response curves showed a rightward displacement when the active fraction was added to isolated guinea-pig ileum depolarized with K⁺ (60 mm ) and cumulative concentrations of CaCl₂, suggesting that caryophyllene-oxide, a known Ca²⁺ antagonist agent could be responsible for the blockade of extracellular Ca²⁺ observed with the active fraction.     

Euphorbia hirta leaf extracts increase urine output and electrolytes in rats.

Euphorbia hirta is locally used in Africa and Australia to treat numerous diseases, including hypertension and edema. The diuretic effect of the E. hirta leaf extracts were assessed in rats using acetazolamide and furosemide as standard diuretic drugs. The water and ethanol extracts (50 and 100 mg/kg) of the plant produced time-dependent increase in urine output. Electrolyte excretion was also significantly affected by the plant extracts. The water extract increased the urine excretion of Na+, K+ and HCO3-. In contrast, the ethanol extract increased the excretion of HCO3- decreased the loss of K+ and had little effect on renal removal of Na+. Acetazolamide, like the water extract, increased urine output and enhanced the excretion of Na+, K+ and HCO3-. The high-ceiling diuretic, furosemide, increased the renal excretion of Na+ and Cl-; but had no effect on K+ and HCO3- loss. This study suggests that the active component(s) in the water extract of E. hirta leaf had similar diuretic spectrum to that of acetazolamide. These results validate the traditional use of E. hirta as a diuretic agent by the Swahilis and Sukumas.     

Antidiarrhoeal activity of the methanolic fraction of the extract of unripe fruits of Psidium guajava Linn.

The methanolic fraction of the extract of unripe fruits of Psidium guajava was found to possess significant antidiarrhoeal activity. The fraction decreased gastric motility in an experimental animal model and inhibited acetylcholine release from isolated guinea-pig ileum. On microbial screening the fraction was found to inhibit significantly the growth of different strains of Shigella spp. and Vibrio cholerae.     

番石榴叶总三萜改善糖尿病周围神经病变

目的观察番石榴叶总三萜(TTPGL)对糖尿病大鼠周围神经病变(DPN)的改善作用,并探讨其作用机制。方法采用高脂饮食加腹腔注射链脲佐菌素(STZ)建立糖尿病大鼠模型。将糖尿病大鼠随机分为6组,石榴叶总三萜低、中、高剂量组[30、60、120 mg/(kg·d)],正常组,模型组和罗格列酮组。测定坐骨神经运动传导速度(MCV)并对组织HE染色;利用RT-PCR检测坐骨神经组织肿瘤坏死因子-α(Tnfa),白细胞介素-6(Il6)和一氧化氮合酶(i NOS)mRNA的表达量;印迹法检测蛋白激酶B(AKT)、核转录因子κB激酶抑制因子IKKα、p65及其各自磷酸化蛋白表达。结果与模型组比较,石榴叶总三萜(120 mg/kg)组显著地改善了坐骨神经的神经病变(P0.05);石榴叶总三萜显著性抑制各炎症因子mRNA的表达(P0.05),并显著下调p-AKT/AKT、p-IKKα/IKKα、p-p65/p65的表达(P0.01或P0.05)。结论石榴叶总三萜具有显著改善DPN的作用,其机制可能通过下调NF-κB介导的信号通路,从而减少炎症介质产生。     

番石榴果实中总黄酮的提取及含量测定

目的:采用正交试验法优选番石榴果实中总黄酮的提取工艺。方法:以提取的总黄酮含量为评价指标,选择醇的体积分数、料液比、提取时间和提取次数为考察因素,用正交试验法确定黄酮的最佳提取工艺。通过分光光度法测定总黄酮的含量,检测波长为508 nm。结果:最佳工艺为醇的体积分数60%,料液比1∶25,提取时间2.5 h,提取3次。芦丁在8.24~50.42 mg·L~(-1)具有良好的线性关系(r=0.999 9),平均回收率为98.23%(RSD=1.36%)。总黄酮含量可达到1.54%。结论:确定的提取工艺简单、易于操作,提取率高。建立的定量方法可用于番石榴总黄酮的测定。     

Effect of Psidium guajava leaves on some aspects of the central nervous system in mice

The present work examines the effects of hexane, ethyl acetate and methanol extracts of Psidium guajava leaves (20,100,500 and 1250 mg/kg) on the central nervous system in mice. The three extracts exhibited mostly dose-dependent antinociceptive effects in chemical and thermal tests of analgesia. The extracts also produced dose-dependent prolongation of pentobarbitone-induced sleeping time. However, they had variable and mostly non-significant effects on locomotor coordination, locomotor activity or exploration. In the pharmacological tests used, the ethyl acetate extract seemed to be the most active, followed by the hexane and then the methanol extracts.     

番石榴叶调节小鼠血糖血脂作用的研究

目的:研究番石榴叶对实验性糖尿病小鼠和高脂血症小鼠的影响。方法:采用链脲佐菌素复制糖尿病小鼠模型,观察番石榴叶对小鼠空腹血糖和糖耐量的影响;采用脂肪乳剂灌胃建立高血脂小鼠模型,观察番石榴叶对小鼠血脂水平及肝脏指数的影响。结果:番石榴叶高、低剂量(10g/kg、5g/kg)均能明显降低糖尿病小鼠空腹血糖,改善其糖耐量,也能明显调节高脂血症小鼠的血脂水平,高剂量还能降低高脂血症小鼠的肝脏指数。结论:番石榴叶有明显的降糖和调脂作用,为其临床应用和研究开发提供实验依据。