Research Article

Probing the Physicochemical Behavior of Acidum Aceticum Homoeopathic Dilutions at Ambient Temperatures by using Volumetric, Acoustic and Viscometric Methods

Anil Kumar Nain¹* Neha Chaudhary², Preeti Droliya³, Raj Kumar Manchanda⁴, Anil Khurana⁴ and Debadatta Nayak⁴

¹Department of Chemistry, Dyal Singh College, University of Delhi, India

²Department of Chemistry, Ramjas College, University of Delhi, India

³Department of Chemistry, Miranda, University of Delhi, India

⁴Central Council for Research in Homeopathy, Ministry of Ayush, India

Submission: July 31, 2024; Published: April 14, 2024

*Corresponding author: Department of Chemistry, Dyal Singh College, University of Delhi, India

How to cite this article: Anil Kumar Nain* Neha Chaudhary, Preeti Droliya, Raj Kumar Manchanda, Anil Khurana, et al. Probing the Physicochemical Behavior of Acidum Aceticum Homoeopathic Dilutions at Ambient Temperatures by using Volumetric, Acoustic and Viscometric Methods. Organic & Medicinal Chem IJ. 2024; 13(4): 555872. DOI: 10.19080/OMCIJ.2024.13.555872

Abstract

The physicochemical studies of homoeopathic medicines provide better understanding regarding the presence and mechanism of their action in ultra-dilutions. The physicochemical behavior of acidum aceticum homoeopathic dilutions have been investigated from the measurements of densities, ρ, ultrasonic speeds, u and viscosities, η of pure ethanol control (91% ethanol in water) and 33 dilutions of acidum aceticum of potencies ranging from 1C to 200C at ambient temperatures and atmospheric pressure. From the experimental data, a number of physicochemical parameters, viz., the isentropic compressibilities, k_s, intermolecular free length, L_f , acoustic impedance, Z , relative association, R_A, relaxation time, τ , ultrasonic absorption, α/f² , pseudo-Gruneisen parameter, Γ , deviations in isentropic compressibility, Δκ_s, deviations in intermolecular free length, ΔL_f , deviations in acoustic impedance, ΔZ, deviations in viscosity, Δη and deviations in pseudo-Gruneisen parameter, ΔΓ have been evaluated. These parameters showed diverse behavior at certain potencies of these homoeopathic dilutions. The results have been qualitatively discussed in terms of prevailing interactions of these acidum aceticum dilutions. The results indicated that that even in extreme dilutions (50C, 110C, 150C and 160C) the molecules of acidum aceticum may be present in these homoeopathic formulations.

Keywords: Density; Ultrasonic speed; Viscosity; Homoeopathic medicines; Acidum aceticum; Hydrogen bonding

Introduction

Homoeopathic medicine has been one of the most extensively practiced alternative therapies with holistic healing approach. However, that the potency of a homoeopathic medicine increases with dilution followed by succussion (process termed as potentization) has posed two main challenges to the scientific community. Firstly, the preparation of homeopathic medicines involves ultra-high dilutions, raising questions regarding the presence of active medicine molecules at such ultra dilution levels, however, these “extremely diluted solutions” show anomalous behavior in medicinal efficacy. Secondly, the efficacy of homoeopathic medicines is well reinforced by research indications; however, there are disputes regarding questionability in biological activity of these medicines wherein the source drug is diluted beyond Avagadro’s limit, i.e., the ultra-diluted medicine formulation might be similar to the solvent. There have been few investigations to explore the existence of drug in ultra-diluted medicines [1-7] and their mechanism of action, but the question still stands unreciprocated.

The measurements of physicochemical properties and parameters derived from these properties of aqueous and mixed-aqueous solutions of electrolytes, amino acids, carbohydrates, drugs, etc. have been supportive in depicting the predominant interactions, which are found valuable in understanding of solute-solvation/hydration behavior of solute [8-14]. The homoeopathic formulations are ultra dilute solutions, so their physical properties, viz., density, ultrasonic speed and viscosity can be measured at varying potency and temperature. The physicochemical properties derived from these experimental data deliver valuable information regarding the physicochemical behavior, prevailing interactions and mechanism of action of these homoeopathic medicines. There have been few physicochemical studies on extremely diluted solutions of inorganic salts [15-19] and homoeopathic medicines [20-22] have been reported by using conductivity and pH metric measurements. These studies provided exciting and substantial information on the behavior of these ultra-diluted solutions. To the best of our information, very few physicochemical studies on homoeopathic medicines using volumetric, acoustic and viscometric have been reported in the literature [4,22-24].

In continuation to earlier research on the physicochemical behavior of ultra-diluted homoeopathic formulations [25-29], here we report the results of the study on the physicochemical behavior of homoeopathic dilutions of acidum aceticum. Acidum aceticum is a highly useful homeopathic remedy prepared from potentization of acetic acid. It is used in the treatment of several health complications. It is used to tackle the symptoms associated with anemia and also relieves conditions of inflammation in the body. It relieves signs of fatigue, exhaustion and is also used in the treatment of hemorrhage. It is also recommended for various health issues like stomach disorders, weak heart rate and ulcers in genitalia. Therefore, the physicochemical investigation of the homoeopathic dilutions of acidum aceticum shall be interesting and useful for better understanding of the behavior and its mechanism of action.

In the present study, the densities, ρ , ultrasonic speeds, u and viscosities, η of pure ethanol control (91% ethanol in water) and 33 dilutions of acidum aceticum in ethanol control with potencies ranging from 1C to 200C (with intervals of 2C till 30C, and then with intervals of 10C till 200C) at 293.15, 298.15, 303.15, 308.15, 313.15 and 318.15 K and atmospheric pressure. From these experimental data, the isentropic compressibilities, k_s, , intermolecular free length, L_f , acoustic impedance, Z , relative association, RA , relaxation time, τ , ultrasonic absorption, (α/f2 ) , pseudo-Grüneisen parameter, Γ , deviations in isentropic compressibility, s Δk , deviations in intermolecular free length, f ΔL , deviations in acoustic impedance, ΔZ , deviations in viscosity, Δη and deviations in pseudo-Grüneisen parameter, ΔΓ have been calculated. The variations of these parameters with potency and temperature are qualitatively discussed in terms of interactions/ physicochemical behavior of these ammonium carbonicum homoeopathic formulations.

Experimental

The homoeopathic formulations of various potencies of acidum aceticum used in the study were prepared in accordance with Homoeopathic Pharmacopoia of India [30]. The acetic acid (s.d. fine chemicals, India, mass fraction purity > 0.995) was used for preparation of various potencies of acidum aceticum. The ethanol control (91% ethanol in water) has been prepared by using the ethanol (E. Merck, India, mass fraction purity > 0.995) and triple distilled water. The densities and ultrasonic speeds of the samples were measured by using high precision digital vibrating tube Density and Sound Analyzer (DSA 5000M, Anton Paar, Austria). The principle used in density measurement is based upon oscillating U-tube principle while the speed of sound is measured using a propagation time technique. This instrument is equipped with both density and ultrasonic cells, with reproducibility of ±1 × 10⁻³ kg·m⁻³ and ±1 × 10⁻² m·s⁻¹ for density and ultrasonic speed, respectively. The temperature for both cells was kept constant by using built in Peltier thermostat within ±0.01 K. The equipment was calibrated with triply distilled degassed water and with dry air at atmospheric pressure [10,11]. The operating working frequency used for ultrasonic speed measurements is 3 MHz. The standard uncertainties related to the measurements of density, ultrasonic speed and temperature were found within ±0.05 kg·m⁻³, ±0.5 m·s⁻¹ and ±0.01 K, respectively.

The viscosities of the samples were measured by using microviscometer (Lovis 2000M, Anton Paar, Austria) at temperatures, (293.15 - 318.15) K, and atmospheric pressure. The rolling ball principle was used in the measurement of viscosity, having a calibrated glass capillary with a steel ball as supplied by manufacturer. The calibration of capillary was accomplished by using viscosity standard fluids. The temperature was controlled to ±0.02 K by an automatic built in Peltier thermostat. The standard uncertainties for viscosity measurements and temperature were estimated to be within ±0.5% and ±0.02 K , respectively.

Results

The values of densities, ρ , ultrasonic speeds, u and viscosities, η of homoeopathic formulations of acidum aceticum as function of potency (in centesimal) at different temperatures are listed in (Tables 1-3), and are presented graphically in (Figures 1-3), respectively.

The values of the isentropic compressibility, k_s , intermolecular free length, L_f, acoustic impedance, Z , relative association, RA , relaxation time, τ , ultrasonic absorption, (α/f2 ) and pseudo- Grüneisen parameter, Γ have been calculated by using the relations [25,31-36].

where K’ is temperature dependent constant [= (93.875 + 0.375T) × 10-8]; T is the absolute temperature; o ρ and o u are the density and ultrasonic speed of the ethanol control, respectively; p α is the isobaric expansivity and T k is the isothermal compressibility. The values of p α and T k are calculated using the relations [36,37].

The values of k_s , L_f , Z , R_A , τ , (α/f² ) and Γ are given in (Tables 4-10). The deviations in k_s , L_f , Z , η and Γ of ethanol control due to addition of acidum aceticum with dilution and succussion are signified by the deviation in the values of these properties. The deviations in isentropic compressibility, s Δk , deviations in intermolecular free length, f ΔL , deviations in acoustic impedance, ΔZ , deviations in pseudo-Gruneisen parameter, ΔΓ and deviations in viscosity, Δη have been calculated by using the relations [25,28].

where the superscript ‘o’ represents the values for pure ethanol control (91% ethanol in water). The variations of s Δk , f ΔL , ΔZ , Δη , τ , (α/f² ) and ΔΓ with potency, C of acidum aceticum and temperature are presented graphically in Figures 4-10, respectively.

Discussion

A close inspection of Tables 1-3 and Figures 1-3 indicates that the values of ρ , u and η of acidum aceticum in ethanol control are greater than those of ethanol control for all the potencies (1C to 200C) at each investigated temperature and these values decrease with increase in temperature. The values of ρ , u and η are maximum at 1C and then decrease in presence of acidum aceticum with dilution till the potency 2C and after that these values increase to maximum at 4C. Thereafter, these values decrease till 6C, then increase to maximum at 8C and thereafter these values increase slightly up to 26C, and again decrease till 28C and thereafter, these values increase regularly up to 50C (Figures 1-3) with successive dilutions. After exhibiting maximum at 50C these values decrease to 60C and then remain nearly constant till 200C, except exhibiting maximums at potencies 110C, 150C to 160 C (Figures 1−3). Additionally, the values of values of η exhibit a maximum at 16C (Figure 3), which is not observed in case of ρ and u values (Figures 1 and 2). The observed anomalous trends in ρ , u and η values at certain potencies, viz., 1C, 4C, 30C to 50C, 110C, 150C and 160C showing larger values than the other potencies. This indicates that these potencies exhibit a different solution structure as compared to other potencies and ethanol control, may be due interaction between acidum aceticum and ethanol-water molecules.

A close perusal of Tables 4 and 5 indicate that the values of s k and f L for acidum aceticum potencies are less than those of ethanol controls for all the potencies at each investigated temperature and these values increase with increase in temperature, which indicates significant interaction between acidum aceticum and ethanol water molecules. The values of s k and f L are minimum at 1C and then increase in presence of acidum aceticum with dilution till the potency 2C and after that these values decrease to minimum at 4C. Thereafter, these values increase till 6C, then decrease to minimum at 8C and thereafter these values decrease slightly up to 26C, and again increase till 28C and thereafter, these values decrease regularly up to 50C (Tables 4 and 5) with successive dilutions. After exhibiting minimum at 50C these values increase to 60C and then remain nearly constant till 200C, except exhibiting minimums at potencies 110C, 150C to 160C (Tables 4 and 5). These variations in Δk_s and f ΔL are expressed in terms of deviations in isentropic compressibility, s Δk and deviations in intermolecular free length, f ΔL and are shown graphically in Figures 4 and 5. Figures 4 and 5 indicate that the values of s Δk and f ΔL are negative and these values are minimum at 1C and then increase in presence of acidum aceticum with dilution till the potency 2C and after that these values decrease to minimum at 4C. Thereafter, these values increase till 6C, then decrease to minimum at 8C and thereafter these values decrease slightly up to 26C, and again increase till 28C and thereafter, these values decrease regularly up to 50C (Figure 4 and 5) with successive dilutions. After exhibiting minimum at 50C these values increase to 60C and then remain nearly constant till 200C, except exhibiting minimums at potencies 110C, 150C to 160 C (Figure 4 and 5). This indicates that at potencies 1C, 4C, 30C to 50C, 110C, 150C and 160C are less compressible and 2C, 6C and 28C are more compressible than the other potencies, indicating that the potencies 1C, 4C, 30C to 50C, 110C, 150C and 160C exhibit more compact solution structure and the potencies 2C, 6C and 28C exhibit less compact solution structure as compared to other potencies. The minimum in s Δk and f ΔL values at potencies 1C, 4C, 50C, 110C, 150C and 160C indicate that these have most compact solution structure, hence, these potencies show diverse behavior which may be due interaction between acidum aceticum and ethanol-water molecules.

A close perusal of Table 6 and Figure 6 indicate that the acoustic impedances, Z of potencies of acidum aceticum are more than those of ethanol control for all the potencies at each investigated temperature and the values decrease with increase in temperature, which indicates significant interaction between acidum aceticum and ethanol molecules. Figure 6 indicates that ΔZ values are positive, i.e., Z values for acidum aceticum are more than those of ethanol control. These ΔZ values are maximum for maximum at 1C and then decrease in presence of acidum aceticum with dilution till the potency 2C and after that these values increase to maximum at 4C. Thereafter, these values decrease till 6C, then increase to maximum at 8C and thereafter these values increase slightly up to 26C, and again decrease till 28C and thereafter, these values increase regularly up to 50C (Figure 6) with successive dilutions. After exhibiting maximum at 50C these values decrease to 60C and then remain nearly constant till 200C, except exhibiting maximums at potencies 110C, 150C to 160 C (Figure 6). This indicates that at potencies 1C, 4C, 50C, 110C, 150C and 160C offer more resistance to the propagation of sound waves through the solution due to more compact structure then the other potencies. The variations in values of Z and ΔZ of these potencies may be due interaction between acidum aceticum and ethanol-water molecules.

A close perusal of Figure 7 indicates that the viscosities, η of potencies of acidum aceticum are more than those of ethanol control for all the potencies at each investigated temperature and the values decrease with increase in temperature, which indicates substantial interaction between acidum aceticum and ethanol molecules. Figure 7 indicates that Δη values are positive, i.e., η values for acidum aceticum are more than those of ethanol control. These Δη values are maximum for potency 1C and then decrease till potency 4C and after that values increase till potency 8C and then remain nearly constant on more dilution till 14C, thereafter these values increase and exhibit a maximum at 16C and thereafter from 18C the values remain nearly constant till 30C and thereafter these values increase regularly up to 50C (Figure 7) with successive dilutions. After exhibiting maximum at 50C these values decrease to 60C and then remain nearly constant till 200C, except exhibiting maximums at potencies 110C, 150C to 160 C (Figure 7). The maximums in values of Δη at 1C, 4C, 16C, 50C, 110C, 150C and 160C potencies may be due interaction between acidum aceticum and ethanol-water molecules. It is observed that the variations observed in the values of measured properties, ρ and u η ; and calculated parameters, s k , f L , s Δk , f ΔL , ΔZ and Δη support each other.

A close perusal of Table 7 indicates that the values of A R for 1C, 4C, 30C to 50C, 110C, 150C and 160C potencies of acidum aceticum are more than 1 and exhibit maximums at these potencies, other potencies show varying values. The values of A R decrease with increase in temperature. The changes in values of A R solution in presence of acidum aceticum are due to different extents of breaking/formation of hydrogen-bonded associates in ethanol controls and their interaction with acidum aceticum with successive dilutions and succussions. The values of A R decrease with increase in temperature, may due to breaking of associations/ interactions between the component molecules.

A close perusal of Table 8 and Figure 8 indicates that the relaxation time, τ for acidum aceticum potencies is more than those of ethanol controls for all the potencies at each investigated temperature and these values decrease with increase in temperature. The τ value is the time in which the structural deformation caused by propagation of ultrasonic wave is restored in the medium through translational motion, which indicates significant interaction between acidum aceticum and ethanolwater molecules. These τ values decrease from 1C to 2C and then increase till potency 4C and after that values decrease till potency 6C and then increase till 8C and remain nearly constant on more dilution from 8C to 14C, thereafter these values increase and exhibit a maximum at 16C and thereafter from 18C the values remain nearly constant till 30C and thereafter these values increase regularly up to 50C (Figure 8) with successive dilutions. After exhibiting maximum at 50C these values decrease to 60C and then remain nearly constant till 200C, except exhibiting maximums at potencies 110C, 150C to 160 C (Figure 8). This indicates that at potencies 1C, 4C, 16C, 50C, 110C, 150C and 160C possess more compact solution structure as compared to other potencies. The maximum in the values of τ for 1C, 4C, 10C, 12C, 70C and 140C potencies indicate that the structural deformation by propagation of ultrasonic wave is restored slowly, which may be due substantial interaction between acidum aceticum and water-ethanol molecules.

The loss of energy of ultrasonic waves by the concerned medium is called ultrasonic absorption or attenuation (α/f² ) . The (α/f² ) values for acidum aceticum potencies are more than those of ethanol controls for all the potencies at each investigated temperature and these values decrease with increase in temperature (Table 9 and Figure 9). As expected, the trends of ultrasonic absorption resemble with the relaxation time (Figure 9). The viscosity appears to be the main factor accountable for ultrasonic absorption in these homoeopathic dilutions. The (α/f² ) values decrease from 1C to 2C and then increase till potency 4C and after that values decrease till potency 6C and then increase till 8C and remain nearly constant on more dilution from 8C to 14C, thereafter these values increase and exhibit a maximum at 16C and thereafter from 18C the values remain nearly constant till 30C and thereafter these values increase regularly up to 50C (Figure 9) with successive dilutions. After exhibiting maximum at 50C these values decrease to 60C and then remain nearly constant till 200C, except exhibiting maximums at potencies 110C, 150C to 160 C (Figure 9). The enhancement in (α/f² ) values for 1C, 4C, 16C, 50C, 110C, 150C and 160C potencies reflect a more ordered structure and significant interactions among the constituents may be due the presence of physical interaction because of hydrogen bonding.

A close perusal of Table 10 and Figure 10 indicates that the pseudo-Grüneisen parameters, Γ for acidum aceticum potencies is more than those of ethanol controls for all the potencies at each investigated temperature and these values decrease with increase in temperature, which indicates substantial interaction between acidum aceticum and ethanol-water molecules. Figure 10 indicates that ΔΓ values are positive, i.e., ΔΓ values for acidum aceticum potencies are more than those of ethanol control. These ΔΓ values are maximum for potency 1C and then decrease till potency 4C and after that values increase till potency 8C and then remain nearly constant on more dilution till 14C, thereafter these values increase and exhibit a maximum at 16C and thereafter from 18C the values remain nearly constant till 30C and thereafter these values increase regularly up to 50C (Figure 10) with successive dilutions. After exhibiting maximum at 50C these values decrease to 60C and then remain nearly constant till 200C, except exhibiting maximums at potencies 110C, 150C to 160 C (Figure 10). The maximum in the values of ΔΓ for 1C, 4C, 26C, 50C, 110C and 150C to 160C potencies may be due substantial interaction between acidum aceticum and water-ethanol molecules.

It has been observed from the analysis of the studied physicochemical parameters, viz., k_s, , f L , Z, R_A, Γ , s Δk , f ΔL , ΔZ , Δη , τ , (α/f² ) and ΔΓ that all the potencies show more compact solution structure in comparison to pure ethanol control; and the potencies 1C, 4C, 16C, 50C, 110C, 150C and 160C exhibit more compact solution structure than the other studied potencies. The difference in the physicochemical properties of these acidum aceticum dilutions in ethanol control (91% ethanol in water) clearly specify that the presence of medicine which results in substantial structural modifications in solution for all the potencies and it is more distinct in certain potencies. The results can be qualitatively discussed in terms of interactions prevailing in these acidum aceticum dilutions in ethanol-water controls. The key factors which may be affecting the solution structure are the nature of solute, the presence of medicine molecules and the potentization process.

It has been well-known that hydrogen bonding is one of the most important weak interactions amongst the molecules in solution leading to the formation of well-defined molecular aggregates, called as dissipative structures [4,20]. It has been reported [38] that potentization process permanently alters the physicochemical properties of the solution. The succussion process excites the formation of dissipative structures and these dissipative structures are exaggerated by presence of ethanol and medicine molecules [38] (acetic acid dissociated into H+ and acetate ions). The results may be understood by considering the interactions that can take place between H+ and acetate ions and the molecular aggregates of water-ethanol molecules, i.e., dissipative structures [18]. The hydrogen bonding in ethanol-water will be significantly affected by the presence of H+ and acetate ions in solution and it can be assumed that the effect of medicine molecules is likely to alter after each successive dilution and succussion on moving from one potency to another next potency. A qualitative comparison between various potencies can be considered due to the nature of driving force that leads to formation of aggregates (due to solvation of these ions by polar ethanol/water dipoles) between H+ and acetate ions and dissipative structures of ethanol-water molecules [19,39]. This driving force is supplied by the succussion process in which a vast amount of mechanical energy (∼404.3 Newton-meter by 10 strokes) [40] is transferred. This transfer of energy due to successive dilution and succussion process is responsible for different/anomalous behavior of acidum aceticum of different potencies. It had also been reported in literature [5,7] that same medicine of different potency displays diverse behavior due to vehicle-molecule structure (ethanol-water aggregates) generated by potentization process.

Conclusion

The densities, ultrasonic speeds and viscosities of ethanol control, 33 formulations of acidum aceticum in ethanol control are measured for potencies from 1C to 200C at six different temperatures and atmospheric pressure. Using these experimental data, various acoustic parameters, viz., k_s , L_f , Z, R_A, Γ , Δk_s , f ΔL , ΔZ , Δη , τ , (α/f² ) and ΔΓ have been calculated. The results have been qualitatively discussed in terms of interactions/ physicochemical behavior of these extremely dilute homoeopathic formulations of acidum aceticum in ethanol. The potencies 1C, 4C, 10C, 12C, 70C and 140C exhibit more compact solution structure as compared to other potencies and ethanol control. It is found that the interactions can take place between H+ and acetate ions and the molecular aggregates of water-ethanol, i.e., dissipative structures. Hence, these potencies might have diverse behavior in terms of properties and efficacy when utilized in practice. It can be qualitatively concluded that even in high dilutions the molecules of acidum aceticum might be present in these homoeopathic formulations, however it needs to be confirmed from other more precise spectroscopic and other techniques.

Acknowledgement

The authors are thankful to Central Council for Research in Homeopathy (CCRH), Ministry of AYUSH, Govt. of India for providing financial assistance to carry out this collaborative study.

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