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PubMed2004

Microwave-assisted extraction of quercetin and acid degradation of its glycosides in Psidium guajava leaves.

Microwave-assisted extraction (MAE) and microwave-assisted hydrolysis (MAAH) were developed for the sample preparation of guava leaves prior to GC determination of quercetin and its glycosides. Ethanol was selected as the solvent. The optimum MAE temperature, particle size, solvent volume and MAE time are 120 degrees C, 40 - 60 mesh, 20 mL and 5 min, respectively; the optimum MAAH temperature and time, HCl concentration, solvent are 100 degrees C, 5 min, 1.2 mol L(-1) HCl and ethanol, respectively.

Acids↗
PubMed2006

Hepatoprotective activity of Psidium guajava Linn. leaf extract.

The study was designed to evaluate the hepatoprotective activity of P. guajava in acute experimental liver injury induced by carbon tetrachloride, paracetamol or thioacetamide and chronic liver damage induced by carbon tetrachloride. The effects observed were compared with a known hepatoprotective agent, silymarin. In the acute liver damage induced by different hepatotoxins, P. guajava leaf extracts (250 and 500mg/kg, po) significantly reduced the elevated serum levels of aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase and bilirubin. The higher dose of the extract (500 mg/kg, po) prevented the increase in liver weight when compared to hepatoxin treated control, while the lower dose was ineffective except in the paracetamol induced liver damage. In the chronic liver injury induced by carbon tetrachloride, the higher dose (500 mg/kg, po) of P. guajava leaf extract was found to be more effective than the lower dose (250 mg/kg, po). Histological examination of the liver tissues supported the hepatoprotection. It is concluded that the aqueous extract of leaves of guava plant possesses good hepatoprotective activity.

Acetaminophen↗
PubMed2000

Erratum. H.M. Shaheen, B.H. Ali, A.A. Alqarawi and A.K. Bashir. 'Effect Of psidium guajava leaves on some aspects of the central nervous system in mice'. Phytotherapy research 14(2) 2000, 107-111

The original article to which this Erratum refers was published in Phytotherapy Research 14(2) 2000, 107-111. Following publication of this paper in the March 2000 issue of Phytotherapy Research (14(2), 107-111), it has come to our attention that Figure 3 was printed incorrectly. The correct Figure 3 appears below. The publishers would like to apologise for any confusion caused.

Journal Article↗
PubMed1985

[Volatile acids in tropical fruits: cherimoya (Annona cherimolia, Mill.), guava (psidium guajava, L.), mango (Mangifera indica, L., var. Alphonso), papaya (Carica papaya, L.)].

The volatile acids extracted by pentane/dichloromethane (2 + 1) from tropical fruit pulps were identified and determined by capillary gas chromatography (HRGC) and combined capillary gas chromatography-mass spectrometry using EI- and CI mode (HRGC-EI/CIMS). In cherimoya (A. cherimolia, Mill.) fruit pulp 47 acids were characterized; major compounds were hexanoic (3 mg/kg) and octanoic (1 mg/kg) acid. Fifty one acids were identified in guava (P. guajava, L.), 54 in mango (M, indica, L., var. Alphonso) and 56 in papaya (C. papaya, L.). (E)-cinnamoic acid (0.4 mg/kg) and (Z)-3-hexenoic acid (0.2 mg/kg) were determined as major constituents in guava; in mango 5-hydroxy-(Z)-7-decenoic acid (2 mg/kg) and 3-hydroxyoctanoic acid (1.1 mg/kg) and in papaya pulp butanoic acid (1.2 mg/kg) were established as major constituents.

Acids↗
PubMed2000

Purification, molecular cloning, and expression of the gene encoding fatty acid 13-hydroperoxide lyase from guava fruit (Psidium guajava).

Guava fruit was identified as a particularly rich source of 13-hydroperoxide lyase activity. The enzyme proved stable to chromatographic procedures and was purified to homogeneity. Based on gel filtration and gel electrophoresis, the native enzyme appears to be a homotetramer with subunits of 55 kD. Starting with primers based on the peptide sequence, the enzyme was cloned by polymerase chain reaction with 3' and 5' rapid amplification of cDNA ends. The sequence shows approximately 60-70% identity to known 13-hydroperoxide lyases and is classified in cytochrome P450 74B subfamily as CYP74B5. The cDNA was expressed in Escherichia coli (BL21 cells), with optimal enzyme activity obtained in the absence of isopropyl-beta-D-thiogalactopyranoside and delta-aminolevulinic acid. The expressed enzyme metabolized 13(S)-hydroperoxylinolenic acid over 10-fold faster than 13(S)-hydroperoxylinoleic acid and the 9-hydroperoxides of linoleic and linolenic acids. 13(S)-Hydroperoxylinolenic acid was converted to 12-oxododec-9(Z)-enoic acid and 3(Z)-hexenal, as identified by gas chromatography-mass spectrometry. The turnover number with this substrate, with enzyme concentration estimated from the Soret absorbance, was approximately 2000/s, comparable to values reported for the related allene oxide synthases. Distinctive features of the guava 13-hydroperoxide lyase and related cytochrome P450 are discussed.

Aldehyde-Lyases↗
PubMed1993

Studies on antimutagenic effects of guava (Psidium guajava) in Salmonella typhimurium.

The water and chloroform extracts of guava were tested for their antimutagenicity. The water extract was effective in inactivating the mutagenicity of direct-acting mutagens, e.g., 4-nitro-o-phenylenediamine, sodium azide, and the S9-dependent mutagen, 2-aminofluorene, in the tester strains of Salmonella typhimurium. The chloroform extract was inactive. Autoclaving of the water extract for 15 min did not reduced its activity appreciably. The enhanced inhibitory activity of the extracts on pre-incubation suggests the possibility of desmutagens in the extracts. Besides ascorbic acid and citric acid, the major constituents of the extracts, the role of other antimutagenic factors in the extracts cannot be ruled out.

Antimutagenic Agents↗
PubMed2001

Characterization of volatiles in strawberry guava (Psidium cattleianum Sabine) fruit.

Volatile compounds were isolated from strawberry guava fruit by simultaneous steam distillation-solvent extraction according to Likens-Nickerson. Compounds were identified by capillary GC-MS and sensorially characterized by sniffing GC. Two hundred and four compounds were identified in the aroma concentrate, of which ethanol, alpha-pinene, (Z)-3-hexenol, (E)-beta-caryophyllene, and hexadecanoic acid were found to be the major constituents. The presence of many aliphatic esters and terpenic compounds is thought to contribute to the unique flavor of the strawberry guava fruit.

Alcohols↗
PubMed2000

[Physicochemical and microbiological evaluation of 3 commercial guava jams (Psidium guajava L.)].

Four different production batches were taken from each brand. Samples were purchased from retail markets in Maracay, Cagua and Turmero. (Venezuela). The average physical and chemical values were: vacuum = 38.81 cm Hg; pH = 3.28; titrable acidity (%citric acid) = 0.59%; degree Brix = 67.24; reducing sugars = 55.28%; total sugars = 62.28, and the color parameters a = +14.44, b = +8.77 and L = 17.09. Molds, yeast and aerobic plate counts were lower than 10 UFC/g; it reveals an excellent microbiological quality of the product. The studied jams degree Brix and acidity fulfil COVENIN (1) requirements for jam products, but not pH range. In agreement with variance analysis, there were highly significance differences between the samples and among the shares of each sample for all physical and chemical properties evaluated.

Analysis of Variance↗
PubMed1978

[Effect of storage on the levels of ascorbic acid and beta-carotene in freeze dried red guava (Psidium guayava L.)].

The retention of ascorbic acid, beta-carotene and sensory properties of freeze-dried red guava pulp stored during 18 months in hermetically sealed brown glass flasks, at room temperature (ca. 25 degrees C) was studied. The results showed that the losses during freeze-drying were of 8.13% for ascorbic acid and 0.63% for beta-carotene. During storage more pronounced losses of these elements occurred during the first six months, becoming progressively smaller and almost irrelevant at the end of the period. The sensory evaluation of the reconstituted pulp showed that the retention of flavor was good. A Gompertz curve was fitted to observe data and showed to be efficient in explaining the trend of reduction for both elements under study. The excellent retention of ascorbic acid, the relatively fair retention of beta-carotene during processing and storage of freeze-dried red guava pulp, and the good conservation of flavor of the reconstituted pulp are evidences of the importance of this process for preserving and storing fruit pulps.

Ascorbic Acid↗
PubMedDate not supplied

Soil as a possible source for the severe fruit rot of guava (Psidium Guajava l.) due to Phytophthora Nicotianae var. parasitica (Dastur) Wat. at Kurukshetra (India).

Severe fruit rot of guava due to Phytophthora nicotianae var. parasitica (syn. P. parasitica Dastur sensu stricto) was observed during the months of July and August in 1976 at Kurukshetra (India). The pathogen was successfully isolated from the soil below the infected fruit trees using ripe guava fruits as baits as well as by using a selective medium at regular intervals for a period of one year. Presence of the pathogen in the soil below the guava trees and its isolation from the soil for a period of one year, i. e. the next fruiting season of guava trees indicated that perhaps the soil is the main source of infection.

Fruit↗
PubMed2002

Tropical fruit trees as bioindicators of industrial air pollution in southeast Brazil.

Psidium guajava L., Psidium cattleyanum Sabine and Mangifera indica L. were tested under field conditions as possible tropical bioindicators of industrial air pollution. The study was performed around the industrial complex of Cubatão, SE Brazil, which comprises 23 industries, including fertilizer, cement, chemical, petrochemical, and steel plants, with 110 production units and 260 emission sources of pollutants. Saplings were exposed to environmental conditions during four periods of 16 weeks each (September 1994-September 1995), at four different sites in the coastal mountains near the industrial complex: the Valley of Pilões River (VP), the reference area; the Valley of Mogi River (VM), with high contamination of particulate matter, fluorides (F), sulfur (S) and nitrogen (N) compounds; Caminho do Mar (CM1, CM2), mainly affected by organic pollutants, S and N compounds, and secondary pollutants; and Paranapiacaba (PP), affected by secondary pollutants, such as ozone. M. indica did not adapt to the climatic conditions at the exposure sites. In the two Psidium species, the presence of visible symptoms, root/shoot ratio, foliar contents of F, S and N, amounts of ascorbate (AA) and water-soluble thiols (-SH), as well as peroxidase activity (POD) were determined. P. guajava showed higher foliar accumulation of F, S and N, more pronounced alterations of biochemical indicators, and less visible leaf injury than P. cattleyanum. P. guajava may be used as an accumulative indicator in tropical climates, while further studies will be needed before P. cattleyanum might be applied as a sensitive species in biomonitoring programs.

Air Pollutants↗
PubMed2005

Antibacterial and wound healing properties of methanolic extracts of some Nigerian medicinal plants.

This study was conducted to evaluate methanolic extracts of Ageratum conyzoides, Anthocleista djalonensis, Napoleona imperialis, Ocimum gratissimum, and Psidium guajava for antibacterial and wound healing properties. Antibacterial properties of the extracts were studied against eleven wound isolates (Staphylococcus aureus (four strains), E. coli (two strains), Pseudomonas aeruginosa (one strain), Proteus spp. (three strains), and Shigella spp. (one strain)) using the well diffusion method. Wound healing properties of Ageratum conyzoides, Anthocleista djalonensis, Napoleonaea imperialis, and Ocimum gratissimum were determined using the excision wound model. Extract of Napoleona imperialis inhibited growth of all the test bacterial strains while Psidium guajava and Anthocleista djalonensis extracts prevented growth of 81.8 and 72.7% of the test organisms, respectively. Ageratum conyzoides and Ocimum gratissimum extracts did not inhibit growth of any of the test organisms. More than 90% wound healing was recorded in the extract and cicatrin powder treated groups by 14 days post surgery, where as 72% healing was observed in the distilled water-treated group. The percentage healing in the distilled water-treated group was significantly different (P<0.001) from those of extract and antibiotic-treated groups.

Animals↗
PubMed2000

Antiamoebic and spasmolytic activities of extracts from some antidiarrhoeal traditional preparations used in Kinshasa, Congo.

Three major extracts from some traditional preparations, based on medicinal plants, used as antidiarrhoeal agents were investigated for their putative antiamoebic and spasmolytic activities in vitro. Results indicated that both biological activities are concentrated in the polyphenolic fraction, and not in the saponin or alkaloid containing fractions. The most active polyphenolic extracts were those from Euphorbia hirta whole plant, leaves of Alchornea cordifolia, Crossopteryx febrifuga, Nauclea latifolia, Psidium guajava, Tithonia diversifolia, stem bark of Harungana madagascariensis, Mangifera indica, Maprounea africana and Psidium guajava, inhibiting Entamoeba histolytica growth with MAC < 10 micrograms/ml. The same extracts, at a concentration of 80 micrograms/ml in an organ bath, also exhibited more than 70% inhibition of acetylcholine and/or KCl solution-induced contractions on isolated guinea-pig ileum.

Amebicides↗