Nanostructured gold in ancient Ayurvedic calcined drug 'swarnabhasma'

Abstract

Background: Swarnabhasma (calcined gold) is a famous ancient Ayurvedic medicine. However, its detail characteristic investigations are very limited.

Objective: Herein, investigation of swarnabhasma is demonstrated using ancient and ultramodern techniques to understand the physicochemical nature of this drug, and to understand whether the mercury [Parada] used during preparation method marks its presence in swarnabhasma.

Materials and methods: The investigated swarnabhasma was prepared by repeated incinerations of Au-Hg-Lemon juice amalgamation and sulphur. The bhasma was tested by all traditional tests of rasashastra. It was characterized by X-ray diffraction (XRD), Field Emission Scanning Electron Microscope (FE-SEM), Field Emission Transmission Electron Microscopy (FE-TEM), Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES), Energy Dispersive X-ray Fluorescence (EDXRF), Fourier Transform Infrared Spectroscopy (FTIR), and gravimetric analysis.

Results: Traditional tests of rasashastra were complied by the sample. XRD confirms that swarnabhasma consists of principally pure gold at nanoscale. FE-SEM showed agglomerated particles. FE-TEM showed that swarnabhasma contains highly crystalline nanostructured gold comprised with spherical gold nanoparticles of size, 5-20 nm. ICP-AES exhibited absolute absence of Hg and presence of Au, Si, Ag, Al, Ca, Cu, Fe, K, Mg, Mn, Na, P, Sr, Ti, and Zn. EDXRF confirmed the absence of mercury and confirmed the presence of Au, Si, Zr, Nb, S, Cl, K, Ca, Fe, and Ni. FTIR confirmed presence of water molecules adsorbed over surface of bhasma. Gravimetric analysis confirmed presence of 95% gold.

Conclusion: Nano-structuring of gold enhances the surface area as well as activity. The present investigation shows that the entire process from rasashastra confers the unique nanostructure to gold and same is responsible for its medicinal potential. This nanomedicine is highly stable, which is specified as niruttha and apunarbhava in rasashastra.

Keywords: Ayurveda; Bhasma; Cancer; Catalytic; Characterization; Gold; Mercury; Nanoparticles; Parad; Rasashastra; Swarnabhasma.

Fig. 1

Figure showing making of swarnabhasma by traditional process of rasashastra. a) Pure gold, b) Heating of gold, c) Quenching them in kanchanar decoction d) Drying of gold, e) Amalgam of Au and Hg, f) Au–Hg amalgam and sulfur is placed in earthen saucer, g) Sharav samputa, h) Bhasma formation after repeated incineration, i) Sample of swarnabhasma.

Fig. 2

Shows images of A) Swarnabhasma (gold bhasma), B) Fine particles of the bhasma getting lodged in fine finger lines (rekhapurnatva), C) Rice grain floating over the bhasma layer over water (unama). D) No fume production on heating by strong butane flame (nirdhuma), E) Dremel versaflame butane torch used for heating during nirdhuma, niruttha and apunarbhava tests and F) Bhasma particles floating over water surface (varitaratva).

Fig. 3

Niruttha test: A) Pure silver sheet, B) Swarnabhasma kept over silver sheet, C) Heating by flame in a crucible, D) Finally no weight change in silver, no adhesions over it after heating. E) This is enlarged view during niruttha test showing silver sheet and swarnabhasma being heated by Dremel versaflame torch, after which there was no change in appearance of bhasma.

Fig. 4

Apunarbhavatva test: A) Seeds of Abrus precatorus (gunja), B) Powder of the seeds, C) Mixing of Abrus precatorus seed powder, ghrita, honey (madhu), borax (tankana) and jaggery (guda), D) Formation of bolus of swarnabhasma and all these ingredients, E) Heating of bolus in a crucible, F) Charred mixture showing no shiny particles, and no relapse of shiny gold metal., G) This is enlarged view of the bolus being charred, H) This is an enlarged view of 4F showing black colored charred mixture, no any shiny gold particles can be observed.

Fig. 5

X-ray Diffraction pattern (XRD) of swarnabhasma.

Fig. 6

This shows the FE-SEM micrographs of swarnabhasma. Fig. 6A and B depicts the morphology of swarnabhasma. Fig. 6C and D represent the magnified images of the sample which depict the cluster of nanoparticles.

Fig. 7

FE-TEM images of swarnabhasma. Fig. 7A and B are low magnification FE-TEM images of swarnabhasma which clearly show flower-like morphology of size 500–600 nm. Fig. 7C shows high magnification TEM images of swarnabhasma which clearly shows spherical particle of gold with size 5–20 nm. Fig. 7D is cropped image of single gold nanoparticle in investigated swarnabhasma. From Fig. 7D, it is clear that the growth of nanoparticles is along the (111) plane. Electron diffraction pattern is shown in inset of Fig. 7D which confirms the crystalline structure of the bhasma. Fig. 7G shows the gold nanoparticles of polycrystalline nature.

Fig. 8

Fig. 8A is the EDXRF results and 8B exhibits FTIR pattern of investigated swarnabhasma.

Fig. 9

9A- TGA of Au–Hg–S-Citrus juice amalgam in 1:2:16 proportions, 9B- TGA of Au–Hg-Citrus juice in 1:2 proportions, 9C- Closed assembly (sharav samputa) in which actual heating takes place in limited air while bhasma is prepared, 9D- After 14 heating cycles in puta, gold converted to bhasma.