molecules
Edi o ial
A Call o a Change in Policy Rega ding he Necessi y o SDE
Tes s o Valida e he Ve aci y o he Ou come o
Enan ioselec i e Syn heses, he Inhe en Chi al S a e o Na u al
P oduc s, and O he Cases In ol ing Enan ioen iched Samples
Jianlin Han 1, Roman Dembinski 2,3, Vadim A. Soloshonok 4,5,* and Ka el D. Klika 6,*
Ci a ion: Han, J.; Dembinski, R.;
Soloshonok, V.A.; Klika, K.D. A Call
o a Change in Policy Rega ding he
Necessi y o SDE Tes s o Valida e
he Ve aci y o he Ou come o
Enan ioselec i e Syn heses, he
Inhe en Chi al S a e o Na u al
P oduc s, and O he Cases In ol ing
Enan ioen iched Samples. Molecules
2021,26, 3994. h ps://doi.o g/
10.3390/molecules26133994
Recei ed: 21 June 2021
Accep ed: 28 June 2021
Published: 30 June 2021
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1Jiangsu Co-Inno a ion Cen e o E icien P ocessing and U iliza ion o Fo es Resou ces,
In e na ional Inno a ion Cen e o Fo es Chemicals and Ma e ials, College o Chemical Enginee ing,
Nanjing Fo es y Uni e si y, Nanjing 210037, China; [email p o ec ed]
2Depa men o Chemis y, Oakland Uni e si y, 146 Lib a y D i e, Roches e , MI 48309, USA;
[email p o ec ed]
3Depa men o Bioo ganic Chemis y, Cen e o Molecula and Mac omolecula S udies,
Polish Academy o Sciences, Sienkiewicza 112, 90-363 Łód´z, Poland
4Depa men o O ganic Chemis y I, Facul y o Chemis y, Uni e si y o he Basque Coun y UPV/EHU,
Paseo Manuel La dizábal 3, 20018 San Sebas ián, Spain
5IKERBASQUE, Basque Founda ion o Science, Alameda U quijo 36-5, Plaza Bizkaia, 48011 Bilbao, Spain
6Molecula S uc u e Analysis, Ge man Cance Resea ch Cen e (DKFZ), Im Neuenheime Feld 280,
D-69120 Heidelbe g, Ge many
*Co espondence: [email p o ec ed] (V.A.S.); [email p o ec ed] (K.D.K.)
We wish o d aw a en ion o an impo an issue conce ning scien i ic p ac ice wi h
ega d o enhancing he quali y o publica ions in Molecules (as well as o o he jou -
nals). The conce n ega ds he phenomenon o he sel -disp opo iona ion o enan iome s
(SDE) [
1
], a pe asi e and omnip esen p ocess [
2
,
3
] ha occu s whene e a scalemic
sample is ac iona ed du ing any applica ion o an achi al physicochemical p ocess such as
ec ys alliza ion, sublima ion [
4
], ch oma og aphy [
5
], o a y e apo a ion [
6
], o e en dis il-
la ion [
7
]. As a consequence o he SDE, he enan iome s a e dis ibu ed disp opo iona ely
ac oss ac ions, i.e., he enan iome ic excesses (ee’s) o he ac ions a y hough he ee
in o al emains unchanged om he o iginal sample. Thus, no ma e how accu a ely
ee’s a e measu ed, hey will no e lec he ou come o an enan ioselec i e syn hesis o he
inhe en chi al s a e o a na u al p oduc i app op ia e ca e is no aken wi h ega d o
physicochemical p ocesses applied p io o ee measu emen due o he SDE phenomenon.
An ob ious upsho o he SDE is ha esea che s, as e idenced in many cases, unwi -
ingly and e oneously epo he ee o hei p oduc om an enan ioselec i e syn hesis,
o an isola ed na u al p oduc , e c., i hey a e no a pains o add ess he p oblem o he
SDE. Indeed, any s udy in ol ing physicochemical p ocesses applied o chi al compounds
can all ic im o his p oblem unless known o p o en o only in ol e ei he acema es
o enan iopu e samples [
2
]. Possible means o ci cum en dele e ious impac s o he SDE
include in ol ing only condi ions ha supp ess he magni ude o he SDE o below a le el
ha is conside ed negligible and he ob ious cou ses o comple ely a oiding ac iona ion
o he sample du ing pu i ica ion o isola ion s eps o a oiding he issue al oge he by mea-
su ing he sample ee p io o he applica ion o any physicochemical p ocess concomi an
wi h ac iona ion. Howe e , as is o en he case, ac iona ion is equen ly necessi a ed
and una oidable, e.g., in ch oma og aphy [
2
,
3
], and measu ing he sample ee p io o
sample clean-up may no be conduci e o he well-being o he analy ical sys em, e.g.,
chi al LC and GC columns, o hose o he wise comp omised by he p esence o o he
chemical componen s. Thus, as has been ecommended in a ecen publica ion [
8
], one can
only be con iden ha he SDE is no unduly pe u bing he sample ee by pe o ming SDE
es s o gauge he suscep ibili y o a compound(s) o he SDE unde he applied condi ions
Molecules 2021,26, 3994. h ps://doi.o g/10.3390/molecules26133994 h ps://www.mdpi.com/jou nal/molecules
Molecules 2021,26, 3994 2 o 4
and a i ming ha pe u ba ion o he sample ee is indeed negligible o he pu pose a
hand. The au ho s o he ecommenda ion o conduc ing SDE es s, duly accompanied by
a s a emen add essing he issue o possible pe u ba ion o he ee due o he SDE, conside
i necessa y and c i ical o SDE es s o be made manda o y and become pa o edi o ial
policy o wo k in ol ing, o po en ially in ol ing, he ac iona ion o scalemic samples.
Though conduc ing SDE es s sligh ly inc eases he demands placed upon he au ho s
o a wo k, he in ended gains o doing so a e unques ionable:
-
Imp o emen in he quali y o esea ch and enabling mo e ep oducible and eli-
able esul s;
- Mi iga ion o poo , e oneous, o audulen science;
-
G ea e app ecia ion o he wo k by eade s leading o imp o ed ideas and me hods
by o he s; and
-
Reduc ion in con usion ega ding he esul s and/o unnecessa y co espondence o
clea up i ial aspec s ha a e simply handled by inspec ion o he da a.
The essence o conduc ing SDE es s is o enhance he us and e aci y o he esul s
o wo k in ol ing scalemic samples and o ele a e he quali y and eliabili y o publica-
ions. Though signi ican changes in edi o ial policy a e ela i ely uncommon, he scien i ic
necessi y o doing so in his case is clea . Indeed, he e is plen y o p eceden o wha we
a e sugges ing wi h only a small amoun o e lec ion. One could go back in ime and see
he implemen a ion o elemen al analysis (simply combus ion analysis o iginally) equi ed
as p oo o p oduc pu i y, and indeed s uc u e. Howe e , as new echnologies de elop,
a ious demands o p oo o pu i y and s uc u e and simply compound cha ac e iza ion,
hough no necessa ily made edundan , can diminish, o app op ia ely be elaxed. P ime
examples in his espec a e HR-MS and HPLC supplemen ing elemen al analysis wi h
simila declines in demand o IR spec a, mp’s, and bp’s, howe e lamen able hey may
be [
9
]. Ne e heless, new echniques as well as supplan ing adi ional me hods can also
in oduce new addi ional es s. One can also conside he seismic implemen a ion o sup-
po ing ma e ials associa ed wi h p esen -day publica ions con aining ele an da a such
as copies o spec a, ch oma og ams, e c. The e ec s o suppo ing ma e ials ha e been
p o ound, leading o g ea e cla i y, anspa ency, eliabili y, and ep oducibili y o esea ch
esul s, making hem undoub edly wo hwhile despi e he addi ional, and some imes
conside able, e o in ol ed. Thus, as new echnologies de elop o new knowledge is
acqui ed, i becomes app op ia e o adjus acco dingly he necessa y demands o p oo
o success. The SDE is e y much a case o new knowledge in luencing he change in
demands, concomi an wi h echnological ad ances, iz. g ea e sensi i i y and means o
measu e ee.
As a consequence, he ecommenda ion o conduc ing manda o y SDE es s has come
as a esul o he ma u a ion o he s udy o he SDE phenomenon. Sys ema ic esea ch in o
he SDE o e he las wo decades has e ealed [
2
,
3
] ha he SDE phenomenon is ubiqui ous
in e ms o he ypes o o ganic molecules in ol ed, is omnip esen , and can be expec ed
o p ac ically all physicochemical condi ions/ echniques, hus esul ing in mani es a ion
o he SDE wi h a consequen e ec on epo ed expe imen al da a. Objec i ely, he a ional
conclusion ha one can d aw om he weal h o da a on he SDE is ha mis akes in
epo ed s e eochemical ou comes a e simply una oidable, unless app op ia e ca e is
aken in ega d o he SDE. Thus, he sugges ed change in edi o ial policy eques ing
au ho s o acknowledge he p oblem o he SDE, o example, by e e ing o app op ia e
ci a ions [
8
,
10
,
11
] and o conduc app op ia e es s, is a na u al e olu ion and p og ession
bo ne ou o inc eased knowledge and echnical capabili y which con inues he g ow h
and de elopmen o he c a o s e eochemis y.
I is wo h poin ing ou ha esea che s can be judicious in selec ing which and how
many es s a e app op ia e and in conduc ing, a he e y leas , he minimal necessa y.
As has been poin ed ou [
8
], no mally no much addi ional wo k is equi ed as no e e y
compound in a se needs o be es ed, pe haps only he one mos likely o be conduci e
o exp essing he SDE unde he applied p ocess and o condi ions which a e also mos
Molecules 2021,26, 3994 3 o 4
likely o be conduci e owa ds he SDE occu ing in a high magni ude consis en wi h he
applied condi ions. Fo example, compounds possessing SDE-pho ic g oups ( unc ional
g oups which, when p esen in a compound, ende he compound pa icula ly p one o
exp essing he SDE [
12
]) o hose which a e pa icula ly pola and a e hus suscep ible o
exp essing he SDE ia no mal-phase ch oma og aphy [
2
,
5
,
8
], while ola ile compounds
a e suscep ible o exp essing he SDE [
2
,
8
] ia sublima ion [
4
], du ing o a y e apo a-
ion [
6
,
13
], o upon long- e m s o age [
14
–
17
]. Thus, he judicious selec ion o he mos
pola and/o ola ile compounds in a se oge he wi h he physicochemical p ocess and
condi ions, as app op ia e, can expedi e he e alua ion p ocess. Howe e , no only is
a oidance o e o a possible bene icial ou come and a clea incen i e o conduc SDE
es s, bu SDE obse a ions o high magni ude o unusual occu ence can con ibu e o he
wo k (as well as he s udy o he SDE in gene al) and may well cons i u e a s udy in hei
own igh ; a highligh example being he SDE examina ion o he mos in amous o d ugs,
halidomide [
18
]. As was s essed in he pape by J. Han, e al. [
8
], “i is impossible o ind
any scien i ically based a gumen agains he p oposal o imp o e he quali y o epo ed
da a, c edibili y o esea ch, and public pe cep ion o science as a sel -co ec ing en i y”.
Au ho Con ibu ions:
Concep ualiza ion, V.A.S.; w i ing—o iginal d a p epa a ion, K.D.K.;
w i ing— e iew and edi ing, J.H., R.D., V.A.S., K.D.K. All au ho s ha e ead and ag eed o he
published e sion o he manusc ip .
Funding: This esea ch ecei ed no ex e nal unding.
Ins i u ional Re iew Boa d S a emen : S udy did no in ol e humans o animals.
In o med Consen S a emen : S udy did no in ol e humans o animals.
Da a A ailabili y S a emen : No applicable.
Acknowledgmen s:
V.A.S. g a e ully acknowledges suppo om IKERBASQUE, he Basque Foun-
da ion o Science.
Con lic s o In e es : The au ho s decla e no con lic o in e es .
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