Increasing Extract Concentration Research Articles

Thermodynamic and Kinetic Parameters of Methanolic Extract of Leaves of Cochlospermum Tinctorium as Eco-friendly Inhibitor for Corrosion of Mild Steel in HCL Medium

Thermodynamic, kinetic and adsorptive parameters of methanolic extract of leaves of Cochlospermum tinctorium as eco-friendly inhibitor for the corrosion of mild steel in HCl medium were evaluated through the weight loss method at 303 K and 311 K. The inhibition efficiency, %IE, increased with increase in extract concentration, but found to be better at 303 K than 311 K. The decrease in %IE with increase in temperature with the average value of 81.88 kJ/mol for activation energy, E a , and the values of free energy, ÄG, for the adsorption process are all supportive of physical adsorption mechanism. The values of heat of adsorption, Q ads,, are all negative, an indication that the adsorption process was exothermal. The half-life, t 1/2 , value increased with increase in inhibitor concentration and low at high higher, implying the inhibitor performance increased with increase in the extract concentration and decreased with rise in temperature. The data best fitted the Langmuir adsorption isotherm.

Blood coagulating effect of marigold (Tagetes erecta L.) leaf and its bioactive compounds

Marigold (Tagets erecta L.), being an ornamental plant, posses medicinal properties like antimicrobial, insecticidal, wound healing and blood coagulation properties. Our recent works mainly focus on blood clotting activity of marigold leaf extracts. Blood clotting activity of leaf extract was examined using prothrombin time (PT) test by Owren method. The optimization of marigold leaf coagulating activity at different concentration of leaf extract and blood was done with Response surface method (RSM). Experiments showed that there was decrease in coagulation time with increase in extract concentration. Marigold leaves extract has shown very good blood coagulation property in lesser quantity i.e., in the range of μl. Also, phenolic compounds (like gallic acid, scopoletin, ferulic acid, quercecetin) were identified and quantified, which shows that because of presence of them, marigold leaf extract shows coagulation property. Antifungal, antibacterial and antioxidant activity are also analyzed. From the above findings, it can be concluded that along with antibacterial, antifungal and antioxidant properties, marigold leave extracts are also having very good coagulation property; so, in further research it can be developed as an antiseptic with coagulation property and can be developed as a potent product in the field of medicine and ointment.

Study of allelopathic effects of Eucalyptus erythrocorys L. crude extracts against germination and seedling growth of weeds and wheat

Allelopathic materials inside a tree can produce positive or negative change in the survival, growth, reproduction and behaviour of other organisms if they escape into the environment. To assess these effects, this work was carried out to evaluate the allelopathic impact of Eucalyptus erythrocorys L. on seed germination and seedling growth of two weeds: Sinapis arvensis L. and Phalaris canariensis L.; on one cultivated crop: Triticum durum L. Aqueous; and on ethanolic leaf extracts of E. erythrocorys L. The study was effected using four concentrations (10, 20, 25 and 30 μL/mL) while distilled water was used as a control. The results showed that the E. erythrocorys L. crude extracts had an inhibitory effect on seed germination and seedling growth of both studied weeds and wheat. The inhibition rate was increased by the increase in extract concentration. Only ethanolic extracts of E. erythrocorys L. induced a significant inhibition of seed germination of durum wheat. The effect of E. erythrocorys L. crude extracts was more severe on weeds than on durum wheat. These results indicate that the seedling growth, especially radicle elongation, was the more sensitive indicator to evaluate the effects of extracts than was the seed germination.

Antibacterial Activity and Mode of Action of <i>Mentha arvensis</i> Ethanol Extract against Multidrug-Resistant <i>Acinetobacter baumannii</i>

Purpose: To evaluate the antibacterial effect of ethanol extract of Mentha arvensis against multi-drug resistant Acinetobacter baumannii using liquid chromatography–mass spectrometry (LC-ESI-MS). Methods: Disc diffusion and microdilution assays were used to evaluate the antibacterial effect of the extract by measuring the zone of inhibition, minimum inhibitory concentration (MIC) and and minimum bacteriocidal concentration (MBC) of the extract against the test bacteria. Scanning electron microscopy (SEM) was employed to evaluate the morphological changes induced by the extract in cellular membrane of the bacteria. Reactive oxygen species (ROS) generation and protein leakage from the bacterial cells induced by the extract were also evaluated. Results: The extract showed dose-dependent growth inhibitory effects against A. baumannii with MIC and MBC of 23.5 and 72.1 μg/mL, respectively. The extract also induced potent ROS generation and protein leakage in A. baumannii bacterial cells. SEM findings revealed that the extract induced potential cellular damage which increased with increasing extract concentration. Conclusion: The ethanol extract of Mentha arvensis is a potent antibacterial agent against A. baumannii and acts by inducing lethal cellular damage to the bacterium. Keywords: Mentha arvensis , Acinetobacter baumannii , Reactive oxygen species, Antibacterial activity, Cellular membrane damage

박주가리(Metaplexis japonica Makino) 잎과 줄기 추출물의 항산화 효과에 관한 연구

The purpose of this study was to evaluate the antioxidant activity of Metaplexis japonica by using hot-water and ethanol extracts of its leaf and stem. Yields of hot-water and ethanol extracts of M. japonica leaf were high at 6.89 and 6.23%, respectively. The polyphenol and flavonoid contents in ethanol extracts of M. japonica leaf (ALEE) were high (86.96 and 60.73 mg/g, respectively). The electron-donating ability of all M. japonica extracts increased with an increase in extract concentration, with the highest electron-donating ability of 36.20~68.19% shown by hot-water extracts of M. japonica leaf (ALWE). The superoxide dismutase (SOD)-like activities of ALWE and ALEE increased with an increase in extract concentration. The nitrite-scavenging ability of the extracts was the highest at pH 1.2 and that of ALWE was higher than that of ALEE. The reducing power of 62.5 μg/mL ALEE was 0.09 and that of 1,000 μg/mL ALWE was 0.44. The inhibitory effect of an ethanol extract of M. japonica stem (ASEE) on tyrosinase was 13.81% at a concentration of 62.5 μg/mL and that of 1,000 μg/mL ALEE was 57.04%.

Bioactive Potential of Peppermint Extract Against Some Human Bacterial and Fungal Pathogens

Background: Bacterial and fungal infections are an emerging public health concern, especially in the context of nosocomial infections. This study discusses the use of peppermint (Mentha piperita L.) methanolic extract against bacterial strains such as Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, and Staphylococcus aureus and fungal species such as Trichophyton mentagrophytes, Trichophyton verrucosum, and Candida albicans. Objectives: This research aimed to investigate the inhibitory potential of M. piperita methanolic extract against some bacteria and fungi isolated from humans. Materials and Methods: The methanolic extract was prepared by standard procedure, and total phenol, total flavonoid, and total anthocyanin content were determined using a spectrophotometer. Antimicrobial activity against the aforementioned bacteria and fungi strains was evaluated using the disc diffusion method. Results: The contents of total phenol, flavonoid, and anthocyanin as well as antimicrobial activities and antifungal properties were enhanced by the increase of extract concentration. The results showed that the antimicrobial activity of leaf extract was more powerful against Bacillus subtilis (1.39 mm) than Staphylococcus aureus (1.29 mm), Escherichia coli (1.20 mm), and Pseudomonas aeruginosa (1.10 mm) based on the growth inhabitation zone. The most powerful antifungal activity of peppermint extract was observed against Trichophyton verrucosum and Trichophyton mentagrophytes (1.49 and 1.48 mm, respectively). Conclusions: Due to phenolic content, methanolic extract of M. piperita has moderate antibacterial and antifungal properties against the aforementioned gram positive and gram negative bacteria and fungi strains.

Corrosion inhibition and adsorption mechanism studies of Hunteria umbellata seed husk extracts on mild steel immersed in acidic solutions

The corrosion inhibition characteristics of Hunteria umbellata seed husk extracts on mild steel immersed in 1M HCl and H2SO4 solutions were investigated. Mass loss, atomic absorption spectroscopy (AAS), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) were used as basis for studying the corrosion inhibition behavior of the extracts. The results show that the extracts contain OH, CN and unsaturated CC functional groups which were identified as contributing to the inhibition exhibited by the extracts. The inhibition efficiency was found to increase with increase in extract concentration in the acidic solutions but decreases with increase in temperature. Specifically, the inhibition efficiency of the extracts was observed to be generally very high but more effective in 1M HCl compared to 1M H2SO4 solution. Langmuir isotherm best fits the data obtained suggesting physical adsorption as the adsorption mechanism between the extract and the mild steel substrate.

Synergistic extraction and separation studies of Ce(III) from acidic nitrate medium using binary mixture of Cyanex 921 and Cyanex 923 in kerosene

ABSTRACTThe effect of parameters like shaking time, nitric acid, nitrate ion, extractant concentration, temperature, diluents, and phase volume ratio on the extraction of Ce(III) from acidic nitrate medium using binary mixture of Cyanex 921 and Cyanex 923 in kerosene has been investigated. Synergism was observed in the range 0.001-1.0 mol/L HNO3. With increase in extractant concentration and O/A phase volume ratio, extraction increases while with increase in nitric acid concentration and temperature, extraction decreases. Sulphuric acid and hydrochloric acid are found to be effective in stripping. Separation factors for Nd/Ce are higher as compared to those for Ce/La and Pr/Ce.

Removal of pyridine from dilute aqueous streams using hollow fiber supported liquid membranes

The removal of pyridine from aqueous phase using hollow fiber supported liquid membranes has been investigated. Effect of several parameters such as feed concentration, extractant concentration, type of extractants, etc. has been studied. Organic solvents such as, 2-nonyl phenol (2-NP), 4-nonyl phenol (4-NP), stearic acid (SA), and di-(2-ethylhexyl) phosphoric acid (D2EHPA) were used as extractants. It was observed that the initial flux of pyridine increased with an increase in extractant concentration. The investigations showed that phenolic-based extractants (4-NP or 2-NP) were better for pyridine removal as compared to other extractants. The equilibrium experiments have been carried out by varying stirring speed and time in order to find the reaction kinetics and equilibrium time. Mass transfer-based model was used to explain the removal of pyridine for three different modules. Scale-up experiment shows nearly similar flux values of pyridine at both the scales. The model results were found to be in good agreement with the experimental observations. The results have been explained on the basis of steric effects, acidity of the extractant molecules along with the overall mass transfer resistance for the transport of pyridine.

English

Voacanga africana (Stapf) and Rauwolfia vomitoria (Afzel) (Apocynaceae) are traditional plants widely used in folkloric medicine. Methanol extracts of V. africana bark (VAB) and leaves (VAL), and R. vomitoria bark (RVB) and leaves (RVL) were evaluated for antioxidant and anthelmintic potentials. The antioxidant properties of the extracts were determined by the DPPH free radical scavenging method using ascorbic acid as reference antioxidant. The IC50 values were then determined. Four concentrations (20, 30, 40 and 50 mg/mL) of extracts were evaluated for in-vitro anthelmintic activity by determining the effects of the extracts on the paralytic and death time of Pheretima posthuma using albendazole (ABZ) (10 mg/mL) as reference standard. Results reveal that, all the extracts exhibited some level of antioxidant activity with IC50 values of 187, 43, 610 and 967 µg/mL for VAL, RVB, VAB and RVL, respectively. VAB and RVB demonstrated significant anthelmintic activity. RVB at a concentration of 50 mg/mL had a paralytic time of 11.17 ± 0.088 min (p < 0.001) with reference to ABZ. It also demonstrated a concentration dependent reduction in death time of the worms at all concentrations tested. VAB demonstrated a concentration dependent effect on the worms with decreasing paralytic and death times upon an increase in extract concentration. It also showed significant paralytic and death times (p < 0.001) at concentrations of 30, 40 and 50 mg/mL with reference to albendazole. Key words: Paralytic time, free radical, death time, anthelmintic activity, Pheretima posthuma, Voacanga africana, Rauwolfia vomitoria.

Genotoxicity assessment of two common curing weeds: Hyptis suaveolens (L.) Poir. and Leucas indica (L.) R. Br.

Hyptis suaveolens and Leucas indica, two common weeds were selected for the present study, to reveal their probable cytotoxic potential. The meristematic root tips of Allium cepa were used for testing the cytotoxic property of the aqueous leaf extracts containing both polar and non-polar compounds, and that containing polar compounds alone, at different concentrations (0.125, 0.25, 0.5, 1 and 2%) and at different time durations, using distilled water as negative control. Mitotic squash preparations were made using a standard protocol. The mitotic index of the treated root tip cells was found to be decreasing and the abnormality percentage was found to be increasing with increase in extract concentration when compared with the control. Maximum cytotoxicity was observed in the extract containing both polar and non-polar compounds. Both the tested plants were found to be cytotoxic. The abnormalities noticed were of both clastogenic (nuclear lesions, nuclear fragmentation, etc.) and non-clastogenic (aberrant cell wall formation at cytokinesis, ball metaphase, etc.) types. Both plant extracts were found to significantly (P<0.05) inhibit root growth of Allium cepa with an EC50 value of 1.92% (R(2)=0.594) for Hyptis and 1.58% (R(2)=0.757) for Leucas. The results were also analysed statistically by using analysis of variance followed by appropriate post hoc tests. These two weeds are aromatic plants comprising of essential oils that are volatile, natural complex compounds characterized by a strong odour and formed as secondary metabolites. In nature, essential oils play an important role in the protection of the plants as insecticides by reducing their appetite for such plants. When specifically targeted the concept of effectively exploiting these weeds for the formulation of herbal insecticides/pesticides may be possible in the near future.

Rothmannia longiflora extract as corrosion inhibitor for mild steel in acidic media

The inhibitive effect of the aqueous extract of Rothmannia longiflora (RL) on the corrosion of mild steel in 1 M HCl and 0.5 M H2SO4 solutions was investigated by weight loss measurement as well as potentiodynamic polarization and electrochemical impedance spectroscopy measurements. The extract was found to efficiently inhibit the corrosion process in both environments and inhibition efficiency increased with increasing extract concentration as well as rise in temperature. Data from electrochemical measurements suggest that the extract functioned by adsorption of the organic matter on the metal/corrodent interface, inhibiting both the anodic and cathodic half reactions of the corrosion process. The result obtained from this study clearly shows that RL functioned as a good inhibitor for the corrosion of mild steel in 1 M HCl and 0.5 M H2SO4 solutions and the inhibiting efficiency value increased with the inhibitor concentration. The adsorption of the RL on the mild steel surface in acid solution obeyed Langmuir adsorption isotherm.

야생 및 재배 참취 에탄올 추출물의 항산화성

The purpose of this study was to evaluate the functionality of ethanol extract of Aster scaber by analyzing anti-oxidant components and anti-oxidant activities, which was grown in wild and culture field. The yields of Aster scaber ethanol extracts were high after blanching treatment. The polyphenol content of dried Aster scaber grown in wild was 35.59 mg/g, which was higher than that of Aster scaber grown in culture field. The electron donating ability in all Aster scaber extracts were increased with increase in extract concentration, and the electron donating ability was the highest in extracts of the dried Aster scaber after blanching. The SOD-like activity of Aster scaber was the highest in its extract grown in wild field. In addition, the SOD-like activities of extracts of the dired Aster scaber after blanching were highest among the extracts of cultivated Aster scaber. The nitrite scavenging ability of extracts was increased at pH 1.2, and those was the highest in wild fresh Aster scaber. The inhibition effects on xanthine oxidase and tyrosinase were increased with increase in extract concentration, and the inhibition effects of extracts of Aster scaber in wild field were higher than those grown in culture field. Therefore, the consumption of Aster scaber would provide beneficiary effects due to its antioxidant activities and prevention of aging. The development of various processed food using Aster scaber will promote the consumption and its values.

In vivo evaluation of graded fresh leave extracts of vernoniaamygdalina and ocimumgratissimum on some oxidative stress indicators in rats

Background: Vernoniaamygdalina and Ocimumgratissimumare widely used plants in the tropics. The leaves of these plants are popularly acclaimed to have medicinal values, with scarce information on the effect of graded extracts in mediating oxidative stress. The interest on these leaves derives from the need to have an insight to the possible effect of thesegraded leaves extracts may have on oxidative stress. Objectives: The objective of the study was to examine the effect of graded extracts of Vernoniaamygdalina and Ocimumgratissimum leaves specifically on free radical inhibition, reducing power and lipid peroxidation in rat liver and kidneys. Methods: The leave samples were collected and air dried, homogenized and sieved to obtain particle sizes of ≤ 0.250mm. Aqueous and methanolic extracts of samples were obtained and used to assay for total alkaloid and phenolic contents, free radical scavenging activity, reducing power and the extent of lipid peroxidationin liver and kidneys were determined, using standard analytical assays. Results: Phenolic contents of both leave extracts were higher in aqueous medium vernoniaamygdalina (0.85 ± 0.07mgGAE/g) and Ocimumgratissimum (1.59 ± 0.13mgGAE/g). The alkaloid contents of the leaves were higher in methanolic extracts, with Ocimumgratissimum highest (0.96 ± 0.04μg/g) and vernoniaamygdalina (0.38 ± 0.01μg/g). The reducing power of these leaves increased with increasing extract concentrations. Ocimumgratissimum had the highest reducing power in both methanolic (3.00 O.D) and aqueous (2.82 O.D) medium in comparison with respective butylatedhydroxytoluene (BHT) (2.49 O.D) and ascorbic acid (2.16 O.D) controls. The ability to scavenge free radicals increased with increasing extract concentrations in both leaves with highest percentages in aqueous extracts. Ocimumgratissimum(95.90%) and vernoniaamygdalina(98.80%) compared to control (100%).The leave extracts of both plants significantly (p<0.05) increased lipid peroxidations in liver and kidneys of rats. Conclusion: Fresh leaves of Ocimumgratissimumand vernoniaamygdalina have shown potentials to be valuable in reducing powers and free radical quenching.

Aqueous extract of Agrostemma githago seed inhibits caspase-3 and induces cell-cycle arrest at G1 phase in AGS cell line

Ethnopharmacological relevanceA weed plant belonging to the Caryophyllaceae family, Agrostemma githago is used in folk medicine to treat cancers and warts. Aim of the studyThe aim of this study was to evaluate the cytotoxic effect of the aqueous extract of A. githago seed on gastric cancer cell line (AGS) and to investigate the mechanism of apoptosis induction in these cells. Materials and methodsSeeds of A. githago were collected from the suburban area of Ardabil Province, northwest Iran. After preparing the aqueous extract, dry matter was harvested with the lyophilizing technique. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to assess the cytotoxicity. Apoptotic cells were detected by staining with ethidium bromide/acridine orange (EB/AO). Diamidino-2-phenylindole (DAPI) staining was used for cell-cycle analysis with a flow cytometer. The annexin V binding level, caspase-3 activity, and B-cell lymphoma-2 (Bcl-2) level were also measured to confirm apoptotic cell death. ResultsAfter the aqueous extract of A. githago seed was incubated for 24, 48, and 72h, inhibited cell growth was observed with IC50 values of 13.51±0.7, 4.37±1.01, and 2.42±0.8µg/ml, respectively. The EB/AO staining method demonstrated that the extract exerts its cytotoxic effect mainly via apoptosis, in accordance with the annexin V, blc-2, and caspase-3 results. The extract showed a concentration-dependent increase in annexin V binding to externally exposed phosphatidylserine as well as caspase-3 activity. The bcl-2 protein level showed a proportionate decrease with the increase in extract concentration. The cell-cycle analysis revealed that the extract can arrest cells at the G1 checkpoint. ConclusionThe findings of this study revealed the cytotoxic effect of the aqueous extract of A. githago seed on gastric cancer cells (AGS) mainly via apoptosis and the cell-cycle arrest at the G1 checkpoint. Therefore, the extract can be potentially used in gastric cancer therapy in vitro.

Corrosion inhibition of aluminum in biodiesel by ethanol extracts of Rosemary leaves

Rosemary extract was used to control aluminum corrosion in biodiesel. Weight loss and polarization methods were used to test corrosion inhibitor efficiency. Surface morphology was tested by scanning electron microscopy (SEM). The inhibition efficiency increased with increase in extract concentration and decreased with temperature, suggesting the occurrence of physical adsorption. Adsorption of extract on aluminum surface is spontaneous and obeys Langmuir's isotherm. Polarization measurements revealed that Rosemary extract act as a mixed-type inhibitor with predominant anodic effectiveness. The activation energy as well as the heat of adsorption were calculated and discussed.

The morphological changes of Phaseolus vulgaris L. exposed to the aqueous extracts of the leaves of Juglans regia L.

To date the allelopathic interactions between plants didn’t explained, whether some substances are produced by plants to counteract competition or these substances are randomly generated and they are transferred from generation to generation. For that reason an attempt was made to investigate the influence of the aqueous extracts of dried leaves of walnut (Juglans regia L.) at concentrations of 3, 5 and 10% on the germination, growth, weight and morphology of bean (Phaseolus vulgaris L. cv. Laurina). The results indicate that increasing concentration of extract has a stimulating effect on seeds germination in comparison to the control. Extracts at a concentration of 3% and 10% inhibited the growth of the majority of organs and caused reduction of their fresh and dry weight. Whereas the extract at a concentration of 5% stimulated plant growth.

Efficacy of ginger-based treatments against infection with Gyrodactylus turnbulli in the guppy (Poecilia reticulata (Peters))

Monogenean infections of commercially farmed fishes are responsible for significant economic losses and existing chemical therapeutants, often stressful to the fish, pose associated risks. As part of a recent trend to move towards the use of alternative, plant-based remedies for commonly occurring aquaculture-related diseases, the efficiency of ginger (Zingiber officinale) was investigated against the monogenean parasite Gyrodactylus turnbulli in the guppy. In vitro trials revealed the clear anti-parasitic effects of ginger. Ethanolic and aqueous extracts, prepared from freeze dried ginger, were tested. An increase in extract concentration was associated with reduced time to parasite immobilisation, with ethanolic extract being more efficient; at 75 and 200ppt aqueous ginger extract parasites died at 65.6±2.8 and 1.8±0.2min, respectively, whereas at 5 and 40ppt ethanolic extract parasites died at 26.1±0.7 and 4.9±0.3min, respectively.Bathing G. turnbulli-infected fish in ethanolic ginger extract (i.e. 5 and 7.5ppt for 90 and 30min, respectively) significantly reduced infection prevalence and intensity when compared to the water and ethanol controls. The higher concentration (i.e. 7.5ppt) proved as equally effective as Praziquantel, the conventionally used chemical treatment for gyrodactylosis, with the fish appearing to be completely cleared of the infection in both cases. Oral treatments of G. turnbulli-infected guppies with diets supplemented with 10 and 20% ginger powder proved to be ineffective in decreasing parasite load. These findings demonstrate that immersion in ginger extract offers an effective, alternative treatment against monogenean infection in fish.

Adsorption Properties of Azadirachta indicia Extract on Corrosion of Aluminium in 1.85 M Hydrochloric Acid

The crude extract of Azadirachta indica was used in the corrosion inhibition study of aluminium metal coupons in 1.85 M hydrochloric acid environment by gasometric technique. The coupons were immersed in test solutions of uninhibited 1.85 M HCl and those containing extract concentrations of 10%, 20%, 30%, 40% and 50% (v/v) at room temperature. The rate of the reaction was captured by monitoring the volume of hydrogen gas evolved as a result of the interaction. The inhibition efficiency of the extracts and the adsorption isotherm of the process were calculated using Frumkin, Freundlich, Langmuir and Temkin adsorption theories and the surface morphology studied using Scanning Electron Microscopy (SEM). It was observed that the plant extract retarded the acid induced corrosion of aluminium and the volume of hydrogen gas evolved reduced with increasing extract concentration. The adsorption studies revealed that Langmuir isotherm is the best model for the adsorption of Azadirachta indica (R2 = 0.999) on aluminium surface. This implied that the Azadirachta indica extracts with aluminium metal undergoes chemisorption.

Adsorption Properties of Azadirachta indica Extract on Corrosion of Aluminium in 1.85 M Hydrochloric Acid

The crude extract of Azadirachta indica was used in the corrosion inhibition study of aluminium metal coupons in 1.85 M hydrochloric acid environment by gasometric technique. The coupons were immersed in test solutions of uninhibited 1.85 M HCl and those containing extract concentrations of 10%, 20%, 30%, 40% and 50% (v/v) at room temperature. The rate of the reaction was captured by monitoring the volume of hydrogen gas evolved as a result of the interaction. The inhibition efficiency of the extracts and the adsorption isotherm of the process were calculated using Frumkin, Freundlich, Langmuir and Temkin adsorption theories and the surface morphology studied using Scanning Electron Microscopy (SEM). It was observed that the plant extract retarded the acid induced corrosion of aluminium and the volume of hydrogen gas evolved reduced with increasing extract concentration. The adsorption studies revealed that Langmuir isotherm is the best model for the adsorption of Azadirachta indica (R2 = 0.999) on aluminium surface. This implied that the Azadirachta indica extracts with aluminium metal undergoes chemisorption