BackgroundMineral based preparations are widely used for centuries as antimicrobial agents. However, the efficacy and the mode of action of mineral based preparations are uncertain due to the insufficient antimicrobial studies. Arogyawardhana Vati (AV) and Manikya Rasa (MR) are such two Rasashastra herbo-minerallic drugs commonly in India and other countries in South Asia. Despite of their well known traditional use of skin diseases, reported antimicrobial and mineralogical studies are limited. Therefore, in this study antimicrobial activities of the drugs and their organic, inorganic fractions were evaluated against Pseudomonas aeruginosa, Escherischia coli, Staphylococcus aureus, Methecilline Resistance Staphylococcus aureus - MRSA and Candida albicans.MethodsAntimicrobial activity of the drugs, their inorganic residues and organic extracts were determined using four assay techniques viz agar well diffusion, modified well diffusion, Miles and Misra viable cell counting and broth turbidity measurements. Mineralogical constituents of the drugs were determined using X-ray diffraction, while total cation constituents and water soluble cation constituents were determined using inductively coupled plasma-mass spectrometer and the atomic absorption spectrophotometer respectively. Thermogravimetric analysis was used to determine the weight percentages of organic and inorganic fraction of the drugs. Particle sizes of the drugs were determined using the particle size analyzer.ResultsAV and MR drugs showed antibacterial activity against both gram positive and gram negative bacterial species when analyzed separately. Inorganic residues of the drugs and organic extracts showed activity at least against two or more bacterial species tested. All tested components were inactive against C. albicans. Common mineral constituents of drugs are cinnabar, biotite and Fe-rich phases. Drugs were rich in essential elements such as Na, K, Ca, Mg and Fe and toxic elements such as Zn, Cu and As. However, the water soluble concentrations of the toxic elements were below the detection limits. Both drugs have significantly higher percentages of organic constituents and volatile minerals and particle sizes of drugs are in the nanometer range.ConclusionsAV and MR Rasashastra preparations could provide alternatives to synthetic antibiotics against human bacterial infections. Improved solubility and reduced particle sizes are influential physicochemical properties used to enhance the antimicrobial efficacy of the drugs. Therefore, traditional knowledge on the use of antimicrobial mineral sources could provide a novel path for the producing of effective antimicrobial drugs. However, further chemical and toxicological studies are urgently needed for a greater understanding of their toxicity to humans.
Background Mica drugs, a group of herbo-metallic traditional preparations comprising biotite mica as the major mineral ingredient, are prescribed for skin disorders and respiratory ailments and other chronic conditions in South Asian countries, particularly India and Sri Lanka. Mica-based drugs (Abhrak drugs) are subjected to unique and varied preparation procedures and the bioactivity of the drugs can be affected by drug-processing conditions, the ingredients used and the mica composition. The current study aimed to evaluate and compare, on the basis of their physical and chemical characteristics, the antimicrobial potential of two commercial mica drugs AbBb (Abhrak bhashma) and AbCh (Abhrak Chenhuram) and two mica drugs ABL1 (Abhrak Bhasma Laboratory Prepared 1) and ABL2 (Abhrak Bhasma Laboratory Prepared 2) prepared in the laboratory under different conditions. Methods Antimicrobial activity of all four drugs was assessed at 10 mg/ml concentration against Pseudomonas aeruginosa, Escherischia coli, Staphylococcus aureus, methicillin-resistant S. aureus (MRSA) and Candida albicans using well diffusion assay, agar dilution assay and Miles and Misra method. Major and trace metal constituents of the drug samples were measured using atomic absorption spectrometry. Mineralogical properties, bacteria-mineral interactions, morphological changes in microbes and the surface characteristics of the drugs were determined using X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM). Results The drugs ABL1, ABL2 and AbBh exhibited antimicrobial activity against only Gram-positive organisms (S. aureus and MRSA) when tested with Miles and Misra method (broth method). Mineralogical studies (XRD) revealed that biotite mica was altered into secondary clay minerals and iron oxides in the commercial drug AbCh while the other three drugs had altered mica and iron oxide phases. The essential elements (Na, K, Ca and Mg) required for microbial functions were present in varying extents in all four drugs while they were present in exceedingly high amounts in AbCh having comparatively high cation-exchange capacity, consistent with the observation that AbCh was inactive against all the microbes tested. The three drugs (ABL1, ABL2 and AbBh) showing antimicrobial activity contained comparatively high amounts of Fe, Zn and Cu that are known to display antimicrobial properties at high concentrations. SEM studies revealed that the drug particles adhered and entrapped the bacterial species, presumably modifying the physiochemical characteristics of the bacteria and eventually causing lethality. Conclusion Three of the four mica drugs inhibited the tested Gram-negative bacteria and the antibacterial activity of the mica drugs depends on their constituents and the methods of preparation.
Temperature-induced mineral alterations are extensively used in traditional pharmaceutical industry. Studies on the traditional heating methods for enhancing pharmaceutical properties and on the toxicity of mineral-based medicines are limited. This study focuses on the effect of thermal alterations on mineralogical and chemical changes of biotite with respect to two traditional drugs (Abhrak Bhasma and Abhrak Chendhuram). Samples of the drugs and heat-treated and untreated biotite minerals were characterized using X-ray diffraction analysis, Fourier-transform infra-red spectroscopy, thermogravimetric analysis and differential scanning calorimetry. Total and water-soluble cation concentrations of drugs were measured using atomic absorption spectrometry. The study reveals that the degree of collapsing the biotite structure increased with the thermal oxidation process that produced nanoparticles of crystalline and amorphous iron oxides and secondary silicates. The thermal products of biotite had nano-crystallinity and high water solubility. The study suggests that modern pharmaceuticals can be developed from mineral-based traditional drugs.
With a few paleoclimatic assessments in Sri Lanka using calcareous nannofossils as paleoclimatic proxies, the current study focuses on reconstructing the temporal evolution of sea surface paleoclimatic conditions (thermocline and nutricline levels) by studying samples from Dorado-North hydrocarbon exploration well, Mannar Basin. The recovery of well-preserved calcareous nannofossils from Late Paleocene to Late Eocene sediment samples was made possible using the standard smear slide preparation method. Semiquantitative analysis was conducted examining the relative abundance of Discoaster, coccolith size distribution and stratigraphic distribution of Reticulofenestra and Coccolithus under the polarizing light and scanning electron microscopes. Observing two different co-occurrences of the above-mentioned parameters indicates growing eutrophic conditions from the Late Paleocene to the Late Eocene which were identified from the selected sediment sequence from the Mannar Basin. The sudden influx of terrigenous sediments and the intensified greenhouse climate that occurred during the Late Eocene could be considered for the observed rapid expansion of eutrophication conditions around 55 Ma.
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