Ursane-Type Triterpenes, Phenolics and Phenolic Derivatives from Globimetula braunii Leaf

Globimetula braunii is a hemi-parasitic plant used in African ethnomedicine for the management of microbial infections, rheumatic pain and tumors amongst others. We report the isolation and characterization of eight compounds with their antioxidant and antimicrobial activities. The air-dried powdered leaf was macerated in EtOH/H₂0 (4:1). The extract was solvent-partitioned into n-hexane, EtOAc, n-BuOH and aqueous fractions. The fractions were screened for their antioxidant properties, using DPPH, FRAP, TAC and FIC assays. Antimicrobial analysis was performed using the micro-broth dilution method. The active EtOAc fraction was purified for its putative compounds on a repeated silica gel column chromatography monitored with TLC-bioautography. The isolated compounds were characterized using spectroscopic methods of UV, FT-IR, NMR and MS. Eight compounds (1–8) were isolated and characterized as 13,27-cycloursane (1), phyllanthone (2), globraunone (3), three phenolics: methyl 3,5-dihydroxy-4-methoxybenzoate (4), methyl 3-methyl-4-hydroxybenzoate (5) and guaiacol (6), as well as two phenol derivatives: 4-formaldehyde phenone (7) and 6-methoxy-2H-inden-5-ol (8). The study identified 4 and 6 as natural antioxidant compounds with potential as antimicrobial agents.

Acetylcholinesterase inhibitor from Anthocleista vogelii leaf extracts

BACKGROUND

Anthocleista vogelii (Planch) is used in folk medicine in conditions related to inflammation and oxidative stress. This suggests that some of its constituents could possess ability to reduce oxidative damage to cells and ameliorate inflammatory conditions which are two prominent features in the brain of a person suffering from Alzheimer's disease.

AIM OF STUDY

The leaf extracts were investigated for their bioactive constituents in our quest for novel compounds for the management of Alzheimer's disease.

MATERIALS AND METHODS

Anthocleista vogelii crude leaf extract obtained from 80% methanol was successively partitioned with n-hexane, dichloromethane (DCM), ethyl acetate (EtOAc) and n-butanol. This gave four solvent fractions of the crude extract. These fractions and isolated compound were subjected to acetylcholinesterase (AChE) inhibitory activity test using the microplate assay method. The structure of the isolated compound was determined using spectroscopic methods (1D and 2D NMR, and MS).

RESULTS

The results of the acetylcholinesterase inhibitory assay revealed that n-BuOH and ethyl acetate fractions had the best activity with IC₅₀ of 564.58 and 727.63 µg/mL respectively. Activity directed fractionation of each of these fractions led to the isolation of the same compound identified as a C-glucosylflavone; isovitexin-7-O-methyl ether (swertisin). This rare C-glucosylflavone co-exist as two rotamers and exhibited duplication of NMR signals. It is reported from this plant for the first time. Swertisin displayed better acetylcholinesterase inhibitory activity with IC₅₀ of 32.09 µg/mL than physostigmine (eserine) with IC₅₀ of 56.09 µg/mL used as a standard.

CONCLUSIONS

This study reports isolation and characterization of a rare C-glycosylflavone; isovitexin-7-O-methyl ether (swertisin). Isolated compound exhibited duplication of NMR signals and better acetylcholinesterase inhibitory activity than eserine used as a standard. The activity exhibited by this compound suggests that it could be useful in the management of Alzheimer's disease.

ISOLATION AND CHARACTERIZATION OF CHEMICAL CONSTITUENTS FROM CHRYSOPHYLLUM ALBIDUM G. DON-HOLL. STEM-BARK EXTRACTS AND THEIR ANTIOXIDANT AND ANTIBACTERIAL PROPERTIES

Background:

The plant, Chrysophyllum albidum is indigenous to Nigeria and its stem-bark has wide application in traditional medicine for the treatment of infections and oxidative stress related diseases. The aim of the study was to isolate the chemical constituents responsible for the antioxidant and antibacterial activity from the stem-bark of the plant in order to justify some of its ethnomedicinal uses.

Materials and Methods:

Crude extract of stem-bark of Chrysophyllum albidum obtained from 80% ethanol was successively partitioned with ethyl acetate (EtOAc) and n-butanol. The solvent fractions and isolated compounds were tested for antioxidant property using 2-2-diphenyl-1-picrylhydrazyl. Antibacterial activities were also assessed by means of agar-diffusion and broth micro dilution methods. EtOAc fraction was repeatedly fractionated on column chromatography to afford four compounds and their chemical structures were established using NMR (1D and 2D) and MS.

Results:

Chromatographic fractionation of EtOAc fraction with the highest antioxidant and antimicrobial activities afforded stigmasterol (1),: epicatechin (2),: epigallocatechin (3): and procyanidin B5 (4).: Procyanidin B5 isolated for the first time from genus Chrysophyllum demonstrated the highest antioxidant activity with IC50 values of 8.8 μM and 11.20 μM in DPPH and nitric oxide assays respectively and equally demonstrated the highest inhibitory activity against Escherichia coli (MIC 156.25 μg/mL), Staphylococcus aureus (MIC 156.25 μg/mL), Pseudomonas aeruginosa (MIC 625 μg/mL) and Bacillus subtilis (MIC 156.25 μg/mL).

Conclusion:

The antibacterial and antioxidant activities of epicatechin, epigallocatechin and procyanidin B5 isolated from Chrysophyllum albidum stem-bark validate the folkloric uses.

A new bioactive thiophenolic glycoside from the leaf of Massularia acuminata (g. Don Bullock) ex Hoyle (Rubiaceae)

BACKGROUND

Massularia acuminata is a small tree or shrub of tropical rainforest. The leaves are used in Nigerian ethno-medicine for the treatment of microbial infections and pharmacological report suggested the leaf extract as possessing antioxidant activity. This study was therefore carried out to determine the most antioxidant and antimicrobial active fraction(s) of Massularia acuminata leaf and the constituent(s) responsible for the activities.

MATHERIALS AND METHODS

The leaf of Massularia acuminata was investigated for in vitro antioxidant and antimicrobial activities, using a 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay and agar dilution method respectively.

RESULTS

The ethyl acetate fraction demonstrated the best activities among the partitioned fractions tested. Bioassay guided purification of the most active ethyl acetate fraction led to isolation of a new thiophenolic glycoside, characterized as 4-(3',3'-dihydroxy-1-mercaptopropyl)phenyl glycosylpyranoside.

CONCLUSION

The isolated compound from the leaf of Massularia acuminata demonstrated antioxidant and antimicrobial activities and may be responsible for the activities of leaf extract and its ethyl acetate fraction, hence this may justify its ethnomedicinal use.

Effect of NPK fertilizer on chemical composition of pumpkin (Cucurbita pepo Linn.) seeds

An investigation of the proximate composition and antioxidant profile of pumpkin seeds obtained from different levels of NPK 15 : 15 : 15 compound fertilizer application at the Obafemi Awolowo University, Ile-Ife, Nigeria was carried out. Pumpkin seeds were grown in 2010 for two cropping seasons (May to August and August to November), and the following fertilizer rates were applied: 0, 50, 100, 150, 200, and 250 kg/ha. Standard analytical methods were used to determine protein, crude fibre, ash, fat, carbohydrate, antioxidant activities, phenol, flavonoid, proanthocyanidin, and anthocyanin. The highest concentrations of the proximate and antioxidants analysed were found from the seeds of control and those treated with lower NPK rates. The mean protein, ash, crude fibre, and carbohydrate values of pumpkin seeds at zero to 100 kg NPK/ha were 27%, 1.56%, 0.56%, and 11.7% respectively. At these same levels of fertilizer, pumpkin seed oil yield was 59%. Antioxidant activities ranged from 89.9 to 90.4% while total phenol was 47 mg/100 g. Except for carbohydrate, the % concentration of nutrients and antioxidants in pumpkin seeds was significantly (P = 0.05) depressed with fertilizer rates above 100 g/ha.

Nutritional and antioxidant profiles of pumpkin (Cucurbita pepo Linn.) immature and mature fruits as influenced by NPK fertilizer

This study evaluated the influence of NPK fertilizer on protein, fibre, ash, fat, carbohydrate, antioxidant activities and antioxidant phenolic compounds in immature and mature fruits of pumpkin. The treatment consisted of six NPK levels (0, 50, 100, 150, 200 and 250 kg/ha), and was replicated six times in a randomized complete block design (RCBD). Proximate analysis and antioxidant assays were done using standard analytical methods. At control and lower NPK rates, the proximate compositions and antioxidant profile of pumpkin fruits decreased with increasing NPK fertilizer. Between the control and the highest fertilizer rate, proximate compositions decreased by 7-62% while the antioxidant profile decreased by 13-79% for both immature and mature fruits. Across all the measured parameters, mature fruit had higher proximate contents and higher antioxidant concentrations. For the high health value of pumpkin fruits to be maintained, little or no NPK fertilizer should be applied.

Doubly linked, A-type proanthocyanidin trimer and other constituents of Ixora coccinea leaves and their antioxidant and antibacterial properties

Phytochemical investigation of the ethyl acetate fraction of the methanol extract of the leaves of Ixora coccinea led to the isolation and identification of an A-type trimeric proanthocyanidin epicatechin-(2β→O→7, 4β→8)-epicatechin-(5→O→2β, 6→4β)-epicatechin named ixoratannin A-2 along with seven known compounds, epicatechin, procyanidin A2, cinnamtannin B-1, and four flavon-3-ol rhamnosides viz: kaempferol-7-O-α-L-rhamnnoside, kaempferol-3-O-α-L-rhamnoside, quercetin-3-O-α-L-rhamnopyranoside, and kaempferol-3,7-O-α-L-dirhamnoside. The structures were elucidated by the application of IR, UV, MS, 1D-, and 2D-NMR spectroscopic analyses and by comparison with literature data. Antioxidant evaluation of isolated compounds revealed that ixoratannin A-2 and cinnamtannin B-1 were the most active compounds in DPPH, inhibition of lipid peroxidation and nitric oxide radical scavenging assays. Antibacterial activities were assessed by means of agar-diffusion assays using Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Bacillus subtilis. All tested compounds inhibited the growth of B. subtilis, while only epicatechin and quercetin-3-O-α-L-rhamnopyranoside inhibited the growth of E. coli.

Histomorphological and morphometric studies of the pancreatic islet cells of diabetic rats treated with extracts of Annona muricata

Microanatomical changes in the pancreatic islet cells of streptozotocin induced diabetic Wistar rats were studied after treatment with methanolic extracts of Annona muricata leaves. Thirty adult Wistar rats were randomly assigned into three groups (control, untreated diabetic group, and A. muricata-treated diabetic group) of ten rats each. Diabetes mellitus was experimentally induced in groups B and C by a single intra-peritoneal injection of 80 mg/kg streptozotocin dissolved in 0.1 M citrate buffer. The control rats were intraperitoneally injected with an equivalent volume of citrate buffer. Daily intra peritoneal injections of 100 mg/kg A. muricata were administered to group C rats for two weeks. Post sacrifice the pancreases of the rats were excised and fixed in Bouin's fluid. The tissues were processed for paraffin embedding and sections of 5 mum thickness were produced and stained with H & E, Gomori aldehyde fuchsin, and chrome alum haematoxylin-phloxine for demonstration of the beta-cells of islets of pancreatic islets. Histomorphological and morphometric examination of the stained pancreatic sections showed a significant increase in the number, diameter, and volume of the beta-cells of pancreatic islets of the A. muricata-treated group (5.67 +/- 0.184 N/1000 mum(2), 5.38 +/- 0.093 mum and 85.12 +/- 4.24 mum(3), respectively) when compared to that of the untreated diabetic group of rats (2.85 +/- 0.361 N/1000 mum(2), 2.85 +/- 0.362 mum and 69.56 +/- 5.216 mum(3), respectively). The results revealed regeneration of the beta-cells of islets of pancreatic islet of rats treated with extract of A. muricata.

Morphological and morphometric studies of the aorta, pulmonary trunk, and heart of streptozotocin-induced diabetic Wistar rats

Micro-anatomical changes in the aorta, pulmonary trunk, and left ventricle of Wistar rats were studied after the administration of streptozotocin. Twenty adult Rattus norvegicus were randomly assigned into two groups (control and diabetic) of ten rats each. Diabetes mellitus was experimentally induced in the diabetic group of rats by daily intra-peritoneal administration of multiple doses of 40 mg/kg streptozotocin dissolved in 0.1 M sodium citrate buffer for five consecutive days. The control group was given the equivalent volume of citrate buffer. The animals were monitored for four weeks after streptozotocin administration. Post sacrifice, the left ventricle, aorta, and pulmonary trunk were excised, weighed, and fixed by immersion in 10% formol saline. The tissues were processed for paraffin embedding, and sections of 6 mum thickness were produced and stained with H & E for general histological observations, and Verhoeff-van Gieson elastic fibre stain to demonstrate elastic fibres in these cardiovascular structures. The data obtained were analyzed with descriptive and inferential statistics. Histopathological and morphometric examinations of the stained sections showed a significant increase in the thickness of the tunica intima of aorta (t = -7.49; df = 9; p < 0.05) and pulmonary trunk (t = -10.81; df = 9; p < 0.05) in diabetic rats (14.59 + or - 1.189 mm and 11.307 + or - 0.863 mm, respectively) when compared to that of the control group (3.62 + or - 0.353 mm and 3.22 + or - 0.244 mm, respectively). In addition, the distribution of elastic and collagen fibres was sparse in the hearts of the diabetic group when compared to that of the control group. The findings of this study demonstrated that diabetes mellitus might cause some alterations in the microanatomy of cardiovascular structures.

Pharmacological properties of the extract and some isolated compounds of Clausena lansium stem bark: anti-trichomonal, antidiabetic, anti-inflammatory, hepatoprotective and antioxidant effects

ETHNOPHARMACOLOGICAL RELEVANCE

Clausena lansium (Fool's Curry Leaf) is used for various ethnomedical conditions in some countries, including bronchitis, malaria, viral hepatitis, acute and chronic gastro-intestinal inflammation, and as a spicy substitute of the popular Curry leaf tree (Murraya koenigii).

AIM OF THE STUDY

This study was to evaluate the ethnomedical uses of the stem bark in inflammatory conditions, hepatotoxicity and to determine the anti-diabetic and anti-trichomonal properties of the plant.

MATERIALS AND METHOD

Anti-trichomonal, in vivo and in vitro antidiabetic and insulin stimulating, anti-inflammatory, hepatoprotective and anti-oxidant activities using Trichomonas gallinae, glucose loaded rats and in vitro insulin secreting cell line (INS-1 cell), carrageenin-induced rat paw oedema, CCl(4)-induced hepatotoxicity and DPPH scavenging ability methods respectively for the extracts and some isolates were determined.

RESULTS

A dichloromethane extract was superior over methanolic extract with respect to an anti-trichomonal activity which was measured after 24 and 48 h. The isolated compounds imperatorin and 3-formylcarbazole had the main anti-trichomonal activity (LC(50)s of 6.0, 3.0 and 3.6, 9.7 microg/mL after 24 and 48 h, respectively). Methanolic extract (100 mg/kg) induced maximum and significant (p<0.05) anti-hyperglycaemic activity of 15.8% at 30 min and a 38.5% increase in plasma insulin at 60 min, compared to control. The increase in plasma insulin after 60 min, compared to 0 min, was 62.0% (p<0.05). The significant 174.6% increase of insulin release from INS-1 cells (in vitro) at 0.1 mg/ml indicates that it mediates its antidiabetic action mainly by stimulating insulin release. Imperatorin and chalepin were the major active constituents increasing in vitro insulin release to 170.3 and 137.9%, respectively. 100 mg/kg of the methanolic extract produced an anti-inflammatory activity after 4 h. A sedative effect was not observed. 100 and 200 mg/kg of methanolic extract administered i.p., reduced CCl4-induced hepatotoxicity firstly by 5.3 and 8.4% reduction in phenobarbitone-sleeping time respectively, secondly by reversing the reduction in serum liver proteins by 7.0-8.8%, serum AST, ALT and ALP activities by 27.7-107.9% and thirdly by diminishing increased values of plasma AST, ALT and ALP activities by 13.2-83.8%. The extract exhibited antioxidant activities.

CONCLUSION

The hepatoprotective activity of C. lansium is partly due to its anti-oxidant and anti-inflammatory properties and confirms its folkloric use in the treatment of gastro-intestinal inflammation, bronchitis and hepatitis. In addition the use of C. lansium stem bark would be useful in diabetes and trichomoniasis.

Anti hyperglycemic activities of Annona muricata (Linn)

This study was designed to determine the effects of methanolic extracts of Annona muricata (Linn) on the blood glucose level of streptozotocin-induced diabetic Wistar rats. Thirty adult Wistar rats were randomly assigned into three groups (A, B and C) of ten rats each. Group A was the control, Group B was untreated hyperglycemic group and group C was A. muricata-treated group. Hyperglycemia was induced in groups B and C by a single intraperitoneal injection of 80 mg/kg streptozotocin dissolved in 0.1 M citrate buffer. The control group was intraperitoneally injected with equivalent volume of citrate buffer and all the animals were monitored for four weeks. Daily intra peritoneal injection of 100 mg/kg A. muricata was administered to group C rats for two weeks and the animals were monitored for another two weeks. The data obtained were analyzed with descriptive and inferential statistics. The result showed a mean body weight of 206 +/- 7.74 g, 173.29+/-5.13 g and 197 +/- 5.62 g respectively for the control, untreated diabetic and A. muricata-treated diabetic group, and a mean blood glucose concentration of 3.78 +/- 0.190 mmol/L, 21.64 +/- 2.229 mmol/L and 4.22 +/- 0.151 mmol/L for the control, untreated diabetic and treated diabetic groups respectively. A significant difference exists between the blood glucose concentrations of treated and untreated hyperglycemic groups of rats. The result of this study demonstrated that A. muricata possesses anti-hyperglycemic activities.

Antibacterial activity of Piliostigma thonningii stem bark

Piliostigma thonningii stem bark 60% methanolic extract exhibited activity against six out of eight bacterial isolates at a concentration of 20 mg/ml.

Preliminary evaluation of cytotoxic properties of Raphia hookeri fruit mesocarp

The aqueous and n-butanol fractions of the methanolic extract of Raphia hookeri fruit mesocarp was evaluated for cytotoxic properties using three different bioassays. The n-butanol fraction exhibited greater cytotoxicity than the aqueous fraction when tested against brine shrimp, mosquito larvae, and 5-day old tadpoles, the cytotoxicity towards the tadpoles being the most pronounced (LC(50)=0.83 ppm).

Antibacterial activity of Nicotiana tabacum leaves

Nicotiana tabacum leaf 60% methanolic extract exhibited antibacterial activity against six out of nine bacterial isolates at a concentration of 25 mg/ml.