TLC bioautography-guided isolation of essential oil components of cinnamon and clove and assessment of their antimicrobial and antioxidant potential in combination

This study aimed to evaluate possible synergistic interactions on antimicrobial and antioxidant efficacy of clove and cinnamon oil components in combination and characterization of compounds responsible for synergistic interactions using TLC bioautography followed by checkerboard titration, isobologram analysis, and spectrometric characterization. Among the combinations tested, cinnamaldehyde from cinnamon oil and eugenol from clove oil in combination showed a synergistic antimicrobial interaction against foodborne microbes Listeria monocytogenes (fractional inhibitory concentration index (FICI): 0.31), Salmonella typhimurium (FICI: 0.41), and Aspergillus niger (FICI: 0.48), and synergistic antioxidant efficacy (combination index: 0.78) in in vitro model. Cinnamaldehyde/eugenol blend did not show any cytotoxic effect (IC₅₀ > 1000 μg/ml) in human normal keratinocyte cell line. The results provide evidence that the cinnamaldehyde/eugenol blend may help in designing a more potent novel natural antimicrobial and antioxidant agent in food and pharmaceutical industries.

Synergistic antibacterial, antifungal and antioxidant efficacy of cinnamon and clove essential oils in combination

The present investigation aimed to evaluate antibacterial, antifungal and antioxidant efficacy of essential oils of three commonly used spices (black pepper, cinnamon and clove) in combination along with chemical characterization and toxicity evaluation. Among the possible combinations tested, cinnamon/clove oil combination showed synergistic antibacterial activity against foodborne bacteria Staphylococcus aureus, Listeria monocytogenes, Salmonella typhimurium and Pseudomonas aeruginosa and synergistic antifungal activity against Aspergillus niger as well as synergistic antioxidant potential in DPPH radical scavenging model system. GC-HRMS analysis revealed that out of thirteen identified components from clove oil, eugenol was found to be the main constituent of the oil; whereas out of twenty one identified constituents from cinnamon oil, the main component was cinnamaldehyde. Cinnamon/clove oil combination did not show any cytotoxic potential at recommended dosage level (IC₅₀ > 2000 µg/ml). The results provide evidence that cinnamon/clove oil combination might indeed be used as a potential source of safe and effective novel natural antibacterial, antifungal and antioxidant blend in the food and pharmaceutical industries. To the best of our knowledge, this is the first time a combination of essential oils has been tested as natural preservatives to prevent both microbial proliferation and oxidative deterioration at sufficiently low concentrations.

Evaluation of antioxidant potential of essential oils of some commonly used Indian spices in in vitro models and in food supplements enriched with omega-6 and omega-3 fatty acids

The aim of this study was to evaluate and compare the antioxidant potential of essential oils of some commonly used Indian spices (black pepper, cinnamon, clove, coriander and cumin) in various in vitro models and in food supplements enriched with omega-6 and omega-3 fatty acids. In vitro antioxidant potential was evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging and Fe²⁺ ion-chelating methods and lipid oxidation stabilisation potential was evaluated in bulk soybean oil-fish oil mixture and their oil-in-water emulsions using peroxide value (PV), p-anisidine value (p-AV) and total oxidation value as indicators of oxidation. Combination effects using DPPH radical scavenging and Briggs-Rauscher oscillating reaction methods were also evaluated. Test essential oils showed varying degrees of radical scavenging and Fe²⁺ ion-chelating efficacy. Clove and coriander oils showed significantly higher (P < 0.05) radical scavenging and Fe²⁺ ion-chelating potential over other tested essential oils as well as BHT and ∞-tocopherol. The anti-lipid peroxidative potential of test essential oils was found in the following decreasing order: clove > coriander > BHT > cinnamon > α-tocopherol > cumin > black pepper. Furthermore, clove and coriander oils showed synergistic antioxidant activity in combination both in DPPH radical scavenging and Briggs-Rauscher oscillating reaction methods whereas other possible combinations showed additive effects. Strong radical scavenging and Fe²⁺-chelating as well as anti-lipid peroxidative activities of clove and coriander oils provide evidence that clove and coriander oils may serve as a potential source of natural antioxidants for retarding lipid oxidation of food supplements enriched with omega-6 and omega-3 fatty acids.

Synergistic antibiofilm efficacy of a gallotannin 1,2,6-tri-O-galloyl-β-D-glucopyranose from Terminalia chebula fruit in combination with gentamicin and trimethoprim against multidrug resistant uropathogenic Escherichia coli biofilms

In recent years the emergence of multiple drug resistance microbes has become a global public health problem. The aim of the present investigation was to evaluate possible antibiofilm efficacy of a gallotannin 1,2,6-tri-O-galloyl-β-D-glucopyranose from Terminalia chebula fruits alone and in combination with gentamicin and trimethoprim against preformed biofilms of multidrug-resistant (MDR) uropathogenic E. coli isolates using microbroth dilution, checkerboard titration and kill kinetics methods. Test gallotannin showed > 50% antibiofilm efficacy after 24 h when administered alone whereas gentamicin and trimethoprim failed to do so. But in combination, test gallotannin/gentamicin and test gallotannin/trimethoprim showed 71.24±6.75% and 93.4±8.46% antibiofilm activity respectively. On the basis of FICI values, test gallotannin/gentamicin showed synergistic interactions against 71.42% and test gallotannin/trimethoprim against 85.71% biofilm forming test bacterial isolates. Kill-kinetics study confirmed their synergistic interactions. Thus, gentamicin and trimethoprim in combination with test gallotannin may have potential for treatment of urinary tract infections caused by biofilm forming MDR uropathogenic E. coli.

The development of Terminalia chebula Retz. (Combretaceae) in clinical research

Medicinal plants are part and parcel of human society to combat diseases from the dawn of civilization. Terminalia chebula Retz. (Fam. Combretaceae), is called the 'King of Medicine' in Tibet and is always listed at the top of the list of 'Ayurvedic Materia Medica' because of its extraordinary power of healing. The whole plant possesses high medicinal value and traditionally used for the treatment of various ailments for human beings. Some of the folklore people used this plant in the treatment of asthma, sore throat, vomiting, hiccough, diarrhea, dysentery, bleeding piles, ulcers, gout, heart and bladder diseases. The plant has been demonstrated to possess multiple pharmacological and medicinal activities, such as antioxidant, antimicrobial, antidiabetic, hepatoprotective, anti-inflammatory, antimutagenic, antiproliferative, radioprotective, cardioprotective, antiarthritic, anticaries, gastrointestinal motility and wound healing activity. But no systematic updated information on the therapeutic effectiveness of Terminalia chebula, a popular herbal remedy in India and South-East Asia has so far been reported. This review highlights an updated information particularly on the phytochemistry and various pharmacological and medicinal properties of Terminalia chebula Retz. and some of its isolated compounds, along with their safety evaluation. This may provide incentive for proper evaluation of the plant as medicinal agent against the human diseases and also to bridge the lacunae in the existing literature and future scope which may offer immense opportunity for researchers engaged in validation of the traditional claims and development of safe and effective botanical medicine.

Anti-inflammatory, anti-lipid peroxidative, antioxidant and membrane stabilizing activities of hydroalcoholic extract of Terminalia chebula fruits

CONTEXT

Arthritis is inflammation of one or more joints. Terminalia chebula Retz. (Combretaceae) fruit is mentioned in Ayurveda as useful in treating arthritic disorders.

OBJECTIVE

This work was undertaken to evaluate the anti-inflammatory, antioxidant, anti-lipid peroxidative and membrane-stabilizing effects of hydroalcoholic extract of Terminalia chebula fruits and also to establish a possible association between them.

MATERIALS AND METHODS

In vivo anti-inflammatory activity of T. chebula fruit extract at different doses ranged from 50 to 500 mg/kg, p.o. was evaluated against carrageenin-induced inflammation in rats. Human erythrocyte hemolytic assay was used for in vitro anti-inflammatory activity testing with 50 to 500 µg/ml fruit extract. Antioxidant potential of test fruit extract (10 to 100 µg/ml) was evaluated using TBARS and DPPH methods. The fruit extract was standardized for total phenolic content using Folin-Ciocalteu method.

RESULTS

The standardized extract at 250 mg/kg, p.o. dose caused 69.96% reduction in carrageenin-induced rat paw edema and demonstrated 96.72% protective effect on human RBC membrane stability. Besides, T. chebula fruit extract significantly reduced the in vivo formation of TBARS in carrageenin-induced rat liver with IC50 94.96 mg/kg, p.o. and also in vitro radical scavenging activities in DPPH assay method with IC50 42.14 µg/ml. The standardized extract contains phenolics 118.5 mg gallic acid equivalent/g of extract.

DISCUSSION AND CONCLUSION

These promising findings support the traditional use of T. chebula fruits in the treatment of arthritic disorders and suggest that radical quenching may be one of the mechanisms for its anti-inflammatory activity.

Possible mechanism of hepatoprotective activity of Azadirachta indica leaf extract: part II

Hepatoprotective activity of Azadirachta indica leaf extract against paracetamol induced hepatic damage in rats has already been reported. In the present investigation effects of Azadirachta indica leaf extract on blood and liver glutathione, Na+K(+)-ATPase activity and thiobarbutiric acid reactive substances against paracetamol induced hepatic damage in rats have been studied with a view to elucidate possible mechanism behind its hepatoprotective action. It was interesting to observe that Azadirachta indica leaf extract has reversal effects on the levels of above mentioned parameters in paracetamol hepatotoxicity. Possible mechanism behind the results are discussed.

Possible mechanism of antihyperglycemic effect of Azadirachta indica leaf extract: part V

Effect of Azadirachta indica leaf extract on serotonin inhibition in glucose mediated insulin release in rat pancreas was studied in vitro to elucidate the possible mechanism of antihyperglycemic effect of A. indica leaf extract. A. indica leaf extract blocks significantly (P < 0.05) the inhibitory effect of serotonin on insulin secretion mediated by glucose.

A comparative evaluation of some blood sugar lowering agents of plant origin

A comparison of blood sugar lowering activity of four important medicinal plants (Azadirachta indica, Gymnema sylvestre, Catharanthus roseus and Ocimum sanctum) were carried out against normal and streptozotocin-induced diabetic rat models. The plant extracts decreased the blood sugar level in varying degrees. Blood sugar lowering unit (BLU) of activity of each leaf extract and tolbutamide was calculated by ED50 values. Statistical analysis revealed significant (P < 0.05) variation among the treatments as well as doses with regard to their blood sugar lowering capacity. A. indica leaf extract was found to have the most potent blood sugar-lowering activity followed by C. roseus, G. sylvestre and O. sanctum.

Possible mechanism of antihyperglycemic effect of Gymnema sylvestre leaf extract, part I

1. Effect of water soluble fraction of alcoholic extract of G. sylvestre leaves on glycogen content by isolated rat hemidiaphragm was studied in normal and glucose fed hyperglycemic rats. 2. The leaf extract by itself failed to alter the hepatic glycogen content in normal rats. 3. In glucose fed rats, the leaf extract lowered the glycogen content of the tissue significantly (P<0.05) and this was further lowered when both exogenous insulin and leaf extract was administered. 4. The results are discussed.

Possible biochemical mode of anti-inflammatory action of Azadirachta indica A. Juss. in rats

The water soluble part of alcoholic extract of A. indica leaves at a dose of 200 mg/kg, p.o., exerted significant antiinflammatory activity in cotton pellet granuloma assay in rats. The extract also inhibited significantly the biochemical parameters (viz. DNA, RNA, lipid peroxide, acid phosphatase and alkaline phosphatase) studied in cotton pellet exudate.

Effect of Azadirachta indica hydroalcoholic leaf extract on the cardiovascular system

1. The effect of Azadirachta indica hydroalcoholic leaf extract on the cardiovascular system was studied. 2. The leaf extract was found to reduce a dose-dependent hypotensive effect without altering the amplitude or rate of respiration. 3. In isolated frog heart, there was no noticeable change in amplitude of contraction or rate of the heart at lower doses of leaf extract. However, at higher doses, there was temporary cardiac arrest in diastole. 4. The results are discussed.

Possible mechanism of antihyperglycemic effect of Azadirachta indica leaf extract. Part IV

1. Effect of epinephrine on the increment index calculated from intravenous glucose tolerance tests and on hepatic glycogen before and after A. indica leaf extract treatment was studied in normal and streptozotocin-induced diabetic rabbits. 2. A. indica leaf extract, in itself, was found to have no action on peripheral utilization of glucose or on hepatic glycogen. 3. The reduction in peripheral utilization of glucose and glycogenolytic effect due to epinephrine action was blocked by A. indica leaf extract, however, almost completely in diabetic rabbits and to a certain extent in normal ones. 4. The results are discussed.

Effects of chemically-induced stress on blood viscosity of rabbits

Disease-induced stress in a living system needs its characterization before quantification. We address this problem by studying the flow behaviour of blood of rabbits. The flow behaviour of rabbit blood, both normal and streptozotocin-induced diabetic was observed by plotting viscosity levels against known shear stress. The curves obtained from normal animals showed a curvilinear relationship between eta and tau, whereas the curves obtained from the blood of the induced diabetic animals showed a 'thixotropic' nature i.e. viscosity varies inversely with shear stress. The results obtained were (a) increased viscosity associated with increasing doses, (b) the lower the shear stress, higher was the viscosity and (c) significant variation of viscosity levels between normal and induced-diabetic rabbits observed by increased stress. The possible interpretation of the results in the light of rheological properties of blood is discussed.

Hypoglycemic effect of Ocimum sanctum leaf extract in normal and streptozotocin diabetic rats

Oral administration of alcoholic extract of leaves of O. sanctum led to marked lowering of blood sugar level in normal, glucose fed hyperglycemic and streptozotocin induced diabetic rats. Further the extract potentiated the action of exogenous insulin in normal rats. The activity of the extract was 91.55 and 70.43% of that of tolbutamide in normal and diabetic rats respectively.

Hepatoprotective activity of Azadirachta indica leaves on paracetamol induced hepatic damage in rats

Effect of A. indica leaf extract on serum enzyme levels (glutamate oxaloacetate transaminase, glutamate pyruvate transaminase, acid phosphatase and alkaline phosphatase) elevated by paracetamol in rats was studied with a view to observe any possible hepatoprotective effect of this plant. It was interesting to observe that serum enzyme levels were much elevated in paracetamol induced animals than in those receiving a combination of paracetamol and lead extract. It is stipulated that the extract treated group was protected from hepatic cell damage caused by paracetamol induction. The findings were further confirmed by histopathological study of liver.