Psychoactive Plant Database - Neuroactive Phytochemical Collection

1. Langmuir. 2024 Sep 3;40(35):18631-18641. doi: 10.1021/acs.langmuir.4c02149.
Epub  2024 Aug 20.

Hydroxide-Source-Dependent Polymorphism and Phase Stability of Cobalt(II) 
Hydroxides in Diffusion-Driven Systems.

Dimble AK(1), Bagul ND(1), Walimbe PC(1), Kulkarni PS(2), Kulkarni SD(1).

Author information:
(1)Post Graduate and Research Center, Department of Chemistry, S. P. Mandali's, 
Sir Parashurambhau College, Tilak Road, Pune, Maharashtra 411 030, India.
(2)Post Graduate and Research Center, Department of Chemistry, MES Abasaheb 
Garware College, Karve Road, Pune 411 004, India.

Hydroxides of cobalt(II) exist predominantly in two polymorphic forms, namely, 
the blue-green α-form [α-Co(OH)2] and reddish β-form [β-Co(OH)2]. These 
hydroxides have a layered structure with interlayer galleries of around 7 and 4 
Å, respectively, for α- and β-Co(OH)2. In most of the previous studies, both the 
polymorphs were synthesized separately, and a few of them showed that the α-form 
gets converted to a thermodynamically more stable β-form via physical processes. 
In the present work, we have optimized the conditions for the simultaneous 
synthesis of both polymorphs under identical conditions in the same reactor 
using the 1D reaction-diffusion framework by employing different outer 
electrolytes. We found that the polymorph chemistry of Co(OH)2 depends on the 
source and concentration of OH- rather than other reaction conditions or later 
physical transformation. The products are characterized to confirm their 
morphology, structure, and chemical environment. We observed that the use of 
NaOH and NH4OH as the OH- precursor leads to α-Co(OH)2 only; however, with NaOH, 
a continuous precipitate is formed, and with NH4OH, periodic precipitation is 
formed. On the other hand, with hydrazine (HYZ) as the OH- source, Liesegang 
bands of α-Co(OH)2 and β-Co(OH)2 as granules are formed throughout the diffusion 
reactor. Another intriguing observation on the HYZ system is that at its high 
concentration, the bands of α-Co(OH)2 get converted to β-Co(OH)2. We articulate 
the reasons and mechanism of those observations.

DOI: 10.1021/acs.langmuir.4c02149
PMID: 39162248


2. Hypertension. 2024 Jun;81(6):1190-1193. doi:
10.1161/HYPERTENSIONAHA.124.21368.  Epub 2024 May 15.

Short-Lived Active Prorenin: Precursor of So-Called Native Prorenin.

Schalekamp MADH(1), Deinum J(2), Danser AHJ(1).

Author information:
(1)Department of Internal Medicine, Erasmus MC, Rotterdam, The Netherlands 
(M.A.D.H.S., A.H.J.D.).
(2)Department of Internal Medicine, Radboud University MC, Nijmegen, The 
Netherlands (J.D.).

The enzymatic activity of the aspartic protease, renin, is critical for its 
function in blood pressure regulation and sodium homeostasis. Incubation of 
so-called native prorenin at low pH leads to its activation. After binding to 
transition-state mimicking renin inhibitors at neutral pH, prorenin attains the 
active conformation, as indicated by immunosorbent assay using monoclonal 
antibodies specific for epitopes of the prosegment or the renin body. A 
comparison of immunosorbent assay with enzyme-kinetic assay revealed the 
intermediary steps of prorenin auto-activation/inactivation. The kinetically 
identified intermediary steps of activation/inactivation correspond with the 
published crystal structures of free renin, free prorenin, and renin in complex 
with inhibitors. Both renin and activated prorenin exist in 2 forms, α and β. 
The α form is active, and the α/β quantity ratio is 2.5. The kidney produces 
renin and prorenin, while the ovarium, placenta, and eye produce inactive 
prorenin. The production of renin by these organs has never been demonstrated. 
We propose that the so-called native prorenin in extracellular fluid, including 
the circulation, is derived, at least partly, from short-lived active prorenin. 
Its potential paracrine function is discussed.

DOI: 10.1161/HYPERTENSIONAHA.124.21368
PMCID: PMC11095897
PMID: 38748765 [Indexed for MEDLINE]

Conflict of interest statement: Disclosures None.


3. ACS Polym Au. 2024 Jan 12;4(2):128-139. doi: 10.1021/acspolymersau.3c00044. 
eCollection 2024 Apr 10.

Poly(vinylidene fluoride) Aerogels with α, β, and γ Crystalline Forms: 
Correlating Physicochemical Properties with Polymorphic Structures.

Suresh S(1)(2), Nabiyeva T(3), Biniek L(3), Gowd EB(1)(2).

Author information:
(1)Materials Science and Technology Division CSIR-National Institute for 
Interdisciplinary Science and Technology, Trivandrum 695 019 Kerala, India.
(2)Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201 002, 
India.
(3)Université de Strasbourg, CNRS, Institute Charles Sadron UPR22, F-67000 
Strasbourg, France.

Strategic customization of crystalline forms of poly(vinylidene fluoride) (PVDF) 
aerogels is of great importance for a variety of applications, from energy 
harvesters to thermal and acoustic insulation. Here, we report sustainable 
strategies to prepare crystalline pure α, β, and γ forms of PVDF aerogels from 
their respective gels using a solvent exchange strategy with green solvents, 
followed by a freeze-drying technique. The crucial aspect of this process was 
the meticulous choice of appropriate solvents to enable the formation of 
thermoreversible gels of PVDF by crystallization-induced gelation. Depending on 
the polymer-solvent interactions, the chain conformation of PVDF can be 
modulated to obtain gels and aerogels with specific crystalline structures. The 
crystalline pure α-form and piezoelectric β-form aerogels were readily obtained 
by using cyclohexanone and γ-butyrolactone as gelation solvents. On the other 
hand, the γ-form aerogel was obtained using a binary solvent system consisting 
of dimethylacetamide and water. These aerogels with distinct crystalline 
structures exhibit different morphologies, mechanical properties, 
hydrophobicities, acoustic properties, and electrical properties. Measurement of 
thermal conductivity for these aerogels showed exceptionally low thermal 
conductivity values of ∼0.040 ± 0.003 W m-1 K-1 irrespective of their crystal 
structures. Our results showcase the fabrication approaches that enable PVDF 
aerogels with varied physicochemical properties for multifunctional 
applications.

© 2024 The Authors. Published by American Chemical Society.

DOI: 10.1021/acspolymersau.3c00044
PMCID: PMC11010255
PMID: 38618004

Conflict of interest statement: The authors declare no competing financial 
interest.


4. Heliyon. 2024 Feb 27;10(5):e27131. doi: 10.1016/j.heliyon.2024.e27131. 
eCollection 2024 Mar 15.

Impact of crystal polymorphism of rifaximin on dissolution behavior.

Toukabri I(1), Bahri S(1), Sfar S(1), Lassoued MA(1).

Author information:
(1)Laboratory of Chemical, Galenic and Pharmacological Development of Medicines 
(LR12ES09), Faculty of Pharmacy of Monastir, University of Monastir, Monastir, 
Tunisia.

INTRODUCTION: Rifaximin is an intestinal antiseptic which has five (pseudo) 
polymorphs α, β, γ, δ and ε. These last (pseudo)polymorphs have different 
physicochemical properties. The objective of the study is to assess the impact 
of rifaximin polymorphism on its dissolution rate which could affect its 
bioavailability.
MATERIAL AND METHODS: The analytical validation of dissolution assay method by 
UV-Visible spectrophotometry was carried out according to ICH Q2. The 
physicochemical characterization (solubility test, FTIR, DSC, XRD) was carried 
out on four active pharmaceutical ingredient (MP1, MP2, MP3, MP4). MP1 and MP2 
were used by the manufacturer of generic brand 1 (G1) and MP3 and MP4 were used 
by the manufacturer of generic brand 2 (G2). The comparative in-vitro 
dissolution study was carried out on the leader brand (P), G1 and G2.
RESULTS: The four MPs were analyzed by XRD. The results of analysis showed that 
MP1 and MP4 were a mixture of α form and amorphous form. MP2 had an amorphous 
form and MP3 had a crystalline form β. The spectra of FTIR showed that the four 
MP had characteristics bands of rifaximin in the domain 4000-400 cm-1. The 
differences between the spectra of the four MPs were observed among the 
amorphous form (MP2), around the region 1800 to 1820 cm-1 which is attributed to 
the vibration of the CO group. An additional difference observed among the 
amorphous form (MP2) is around the region 1400 cm-1 which is attributed to the 
banding OH. The thermograms of MP1, MP2 and MP4 showed endothermic peaks which 
are probably attributed to the departure of water which indicate that MP1, MP2 
and MP4 are pseudopolymoph (hydrate). For the four MPs, probably the melting 
points are interrupted by the phenomenon of phase transformations 
(Crystallization) which are reflected by exothermic peaks around 
200°C-250 °C.Our results showed that the crystalline polymorphism of rifaximin 
influences its solubility. According to the results of the solubility test, the 
β crystal form of rifaximin (MP3) had the lowest solubility (3.47 μg/ml). MP2 
had the highest solubility (8.35 μg/ml) and MP1 and MP4 had intermediate 
solubilities (5.47 μg/ml and 6.74 μg/ml). Comparative in vitro dissolution 
results showed that the dissolution profile of P was not similar to that of G1 
and G2 (% dissolution (P)30min = 60%; % dissolution (G1) 30 min = 100% and % 
dissolution (G2) 30 min = 115%; f1(P versus G1) = 44; f1(P versus G2) = 61) in 
M1, while G1 and G2 had comparatively similar dissolution profiles (% 
dissolution (G1) 30 min = 100%; % dissolution (G1) 30 min = 110%; f1 (G1 versus 
G2) = 14) in M1.
CONCLUSION: This study highlighted the impact of rifaximin polymorphism on its 
physico-chemical properties (crystal structure, thermal behavior, solubility) 
and on its dissolution behavior which could affect the rifaximin 
bioavailability.

© 2024 Published by Elsevier Ltd.

DOI: 10.1016/j.heliyon.2024.e27131
PMCID: PMC10915558
PMID: 38449665

Conflict of interest statement: The authors declare that they have no known 
competing financial interests or personal relationships that could have appeared 
to influence the work reported in this paper.


5. RSC Adv. 2024 Jan 30;14(6):4129-4141. doi: 10.1039/d3ra08481g. eCollection
2024  Jan 23.

Quantification of crystallinity during indomethacin crystalline transformation 
from α- to γ-polymorphic forms and of the thermodynamic contribution to 
dissolution in aqueous buffer and solutions of solubilizer.

Hasegawa K(1), Goto S(1), Kataoka H(1), Chatani H(1), Kinoshita T(1), Yokoyama 
H(1), Tsuchida T(1).

Author information:
(1)Faculty of Pharmaceutical Sciences, Tokyo University of Science 2641 
Yamazaki, Noda Chiba 278-8510 Japan s.510@rs.tus.ac.jp.

The thermodynamic properties and dissolution of indomethacin (INM) were analyzed 
as models for poorly water-soluble drugs. Physical mixtures of the most stable 
γ-form and metastable α-form of INM at various proportions were prepared, and 
their individual signal intensities proportional to their mole fractions were 
observed using X-ray powder diffraction and Fourier transform infrared 
spectrometry at standard temperature. The endothermic signals of the α-form, 
with a melting point of 426 K, and that of the γ-form, with a melting point of 
433 K, were obtained by differential scanning calorimetry (DSC). Furthermore, an 
exothermic DSC peak of the α/γ-phase transition at approximately 428 K was 
obtained. As we computed the melting entropy of the α-form and that of its 
transformation, the frequency of the transition was quantitatively determined, 
which indicated the maximum of the α/γ-phase transition at an α-form proportion 
of 68%. Subsequently, the thermodynamic contributions of the α- and γ-forms were 
analyzed using a Van't Hoff plot for solubility in aqueous solutions at pH 6.8. 
The dissolution enthalpies for α- and γ-forms were 28.2 and 31.2 kJ mol-1, 
respectively, which are in agreement with the quantitative contribution 
predicted by the product of the temperature and melting entropy. The 
contribution of melting entropy was conserved in different dissolution processes 
with aqueous solvents containing lidocaine, diltiazem, l-carnosine, and 
aspartame as solubilizers; their γ-form Setschenow coefficients were -39.6, 
+82.9, -17.3, and +23.2, whereas those of the α-form were -39.7, +80.4, -16.7, 
and +22.7, respectively. We conclude that the dissolution ability of the solid 
state and solubilizers indicate their additivity independently.

This journal is © The Royal Society of Chemistry.

DOI: 10.1039/d3ra08481g
PMCID: PMC10825737
PMID: 38292264

Conflict of interest statement: There are no conflicts to declare.