Antimicrobial potential of four mica drugs and their chemical and mineralogical properties.

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.

Characterization of biotite drugs used in traditional medicine.

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.

Using multiple methods to assess heavy metal pollution in an urban city.

Heavy metal pollution in urban cities is now an accepted fact. An understanding of the natural and anthropogenic contributions to heavy metal accumulation in these cities is necessary to develop strategies to mitigate their impacts, particularly on human health. Here, we used multiple records using geological and biological pollution indicators to assess the extent of pollution in the Colombo Metropolitan Region (CMR), Sri Lanka. Elemental concentrations of Cu, Zn, Ni and Pb were determined in four depositories: surface soil (90 samples), canal sediments and canal water (45 samples each) and vegetation (62 samples). These were mapped using GIS overlapping the road network to identify hotspots of heavy metals. While the surface soil, canal sediments and leaves of trees had higher and different amounts than background levels of heavy metals, canal water had low levels. Our results suggest that anthropogenic activities are the major source of heavy metals in an urban city, and unique natural factors, such as coastal conditions, terrain morphology and climate, combine and influence the distribution of these metals. We discuss the possible remediation of metal pollution and the necessity of a holistic multi-proxy approach to understand urban heavy metal contamination in a rapidly populating area.

The role of herbometallic preparations in traditional medicine--a review on mica drug processing and pharmaceutical applications.

ETHNOPHARMOCOLOGICAL RELEVANCE: Biotite mica enriched with Fe(2+) ions are widely used as a major mineral ingredient in traditional pharmaceutical science of alchemy (Rasashastra). Abhrak bhasma (mica ash), a pharmaceutical product containing treated mica, is utilized, for example, in Ayurvedic treatments for ailments such as gastritis, renal disease, skin disease and mainly in rejuvenation formulations. However, the untreated mica minerals may be harmful when used directly, as they carry considerably high amounts of trace-elements that can cause undesirable effects in the human body. In order to remove toxic factors and produce readily absorbable materials having high nutrient capacity, specific thermal and chemical treatments (purification, detoxification, particle size reduction and incineration) are performed during the preparation of Rasashastra. This review evaluates the chemical and pharmacological aspects of mica ash as well as the technological aspects of mica ash production. MATERIALS AND METHODS: The detailed literature review on the chemistry and scientific basis of mica ash, its preparation techniques, mica alterations and pharmaceutical applications was carried out by using published Ayurvedic text books and research articles, available from Science Direct, on mica minerals, mica ash and their physico-chemical alteration processes and pharmacological applications. RESULTS: During the purification and detoxification procedures, heating followed by quenching (in ionic medium) influences the structural distortion and the development of stress-induced cracks and spallations of the micaceous plates. Thus, the efficient diffusion of the external medium takes place at successive heating and quenching steps. Acidic organic liquids and animal byproducts can enhance the cation exchange capacity and solubility of mica. Further, these natural compounds facilitate the removal of toxic-elements in the structure. When treated-mica and paddy husks are tied up in a cloth and squeezed, particle size reduction and further detoxification takes place. Leaching out of oxidized iron coatings is accelerated when the mixtures are immersed in acidic media, by which the filtrate is enriched with oxidized iron-silicate particles. These nano-oxide particles are converted into a more favorable oxidation form for human consumption when the herbometallic mixture is incinerated in closed vessels. Recent analytical data reveals that major and minor elements in mica ash are within the limits of pharmacopoeial standards for Ayurvedic formulations. Further, recent studies show that mica ash has hypoglycemic, hepatoprotective, anthelminthic and antimicrobial properties. CONCLUSIONS: Chemical and structural modifications in mica occur during mica-based drug preparation in traditional medicine. Purification steps particularly influence the structural distortion while heating and quenching can form nano-size particles. Carboxylic acids and other organic molecules present in quenching media serve as chemical modifiers of mica. At the same time the toxic elements are leached out from mica to the quenching media through an ion exchange process. Mica ash has been successfully used for treating liver, kidney and skin related ailments in traditional medicine, and mica ash alone or its herbo-metallic formulations have different applications. Further, the recent toxicological and analytical studies validate the traditional uses of mica ash and mica ash bearing products. Further scientific studies are needed to fully establish that mica-based pharmaceuticals are safe and devoid of toxic and long term side effects.