In vitro antiplasmodial and cytotoxic activities of sesquiterpene lactones from Vernonia fimbrillifera Less. (Asteraceae)

In v itro ant ip lasmod ia l and cytotox ic act iv it ies o f

sesqu iterpene lactones from Vernon ia f imbr i l l i fera Less . (Asteraceae )

Anné l ise  Bord ignon ^a  , M iche l  Frédér ich ^a , A l l ison  Ledoux ^a , P ierre - Er ic  Campos ^b , Patr ic ia  C lerc ^b , Thomas  Hermann ^c , Joë l le  Quet in -Lec lercq ^d and Ewa  C ieck iew icz ^a

a

Labo ra to ry o f Pha rmacognosy , CI RM , Un ive rs i ty o f Liège , Liège , Be lg ium ;

Labo ra to i re de Ch im ie des Subs tances Na tu re l les e t de Sc iences des Al imen ts ( LCSNSA) , Facu l té des Sc iences e t Techno log ies , Un ive rs i té de La Réun ion , Sa in t -Den is , La Réun ion ;

Sec teu r No rd , Pa rc Na t iona l de La Réun ion , Sa in t -Den is , La Réun ion ;

d

Pha rmacognosy Resea rch G roup , Louva in Drug Resea rch Ins t i tu te , Un ive rs i té ca tho l ique de Louva in , Be lg ium

ABSTRACT

Due to the in v i t ro an t ip lasmod ia l ac t iv i ty o f lea f ex t rac ts f rom Ve rnon ia f imb r i l l i fe ra Less . (Asteraceae ) , a b ioact iv ity -gu ided fract ionat ion was carr ied out . Three sesqu iterpene lactones were iso lated , name ly 8 - (4 ’ -hydroxymethacry late ) - dehydrome l itens in (1) , onopordop icr in ( 2) and 8 α- [4 ’ - hydroxymethacry loy loxy ] -4 -ep i -sonchucarpo l ide ( 3) . The ir structures were e luc idated by spectroscop ic methods (1D and 2D NMR and MS ana lyses ) and by compar ison w ith pub l ished data . The iso lated compounds exh ib ited ant ip lasmod ia l act iv ity w ith IC50 values ≤ 5 μg/mL.

Cytotox ic ity o f the compounds aga inst a human cancer ce l l l ine (HeLa ) and a mouse lung ep ithe l ia l ce l l l ine (MLE12 ) was assessed to determ ine se lect iv ity . Compound 3 d isp layed prom is ing se lect ive ant ip lasmod ia l act iv ity (S I  >  10 ) .

CONTACT Anné l ise Bo rd ignon abo rd ignon@u lg .ac .be

1 .Introduct ion

Accord ing to the Wor ld Hea lth Organ izat ion (WHO 2016) , ma lar ia caused at least 429 000 deaths g loba l ly in 2015 . Among these , 70% were ch i ldren under the age o f fve and 99%

were due to the paras ite spec ies P lasmod ium fa lc ipa rum. The fght aga inst th is ma jor pub l ic hea lth prob lem is threatened by the rap id emergence and spread o f paras ite stra ins res istant towards ava i lab le approved treatments . Urgent eforts are there fore needed to ident i fy new ant ima lar ia l drugs . As such , our research g roups dec ided to study Reun ion Is land as a poten- t ia l source for the d iscovery o f new ant ip lasmod ia l metabo l ites . Th is natura l patr imony has been ident ifed as a b iod ivers ity hotspot due to its numerous endem ic spec ies and its pre- served ecosystems (Myers et a l . 2000) . The Nat iona l Botan ica l Conservatory o f the Mascarenes ind icates that Ve rnon ia fmb r i l l i fe ra Less . is an endem ic spec ies from Reun ion Is land , loca l ly named ‘bo is de source ’ , wh ich g rows in the hum id trop ica l forest (Lavergne and Véra 1989) . To the best o f our know ledge , ne ither phytochem ica l nor pharmaco log ica l works have been per formed up to now on V . fmb r i l l i fe ra. Th is study iso lated and determ ined the structure o f three ant ip lasmod ia l sesqu iterpene lactones . Compounds were add it iona l ly tested in v i t ro for the ir cytotox ic ity and the ir se lect iv ity ind ices were estab l ished .

2 .Resu lts and d iscuss ion 2 .1 . Chem ica l compos it ion

An ant ip lasmod ia l b ioassay -gu ided fract ionat ion o f the CH

C l

extract from V . fmb r i l l i fe ra leaves was carr ied out and three compounds ( 1–3) were obta ined as act ive ing red ients (F igure 1) . Based on the ir NMR and HR -ES I -MS data and through compar ison w ith those a lready descr ibed in l iterature , the ir structures were estab l ished as 8 - (4 ’ -hydroxymeth- acry late ) -dehydrome l itens in (1) (Rusta iyan et a l . 1979; Cardona et a l . 1989; Garc ía et a l . 1996) , onopordop icr in (2) (Lonergan et a l . 1992) and 8 α- [4 ’ -hydroxymethacry loy loxy ] -4 -ep i -son - chucarpo l ide (3) (Rusta iyan et a l . 1986; Garc ía et a l . 1996) .

2 .2 . B io log ica l act iv it ies : ant ip lasmod ia l and cytotox ic act iv it ies

The three sesqu iterpene lactones (1–3) iso lated from the CH

C l

extract o f V . fmb r i l l i fe ra ( leaves ) demonstrated in v i t ro ant ip lasmod ia l act iv ity w ith IC

va lues o f 2 .96 ± 0 .86 , 3 .37 ± 0 .56 and 3 .27 ± 1 .32 μg/mL (n = 3 , see Tab le S1 ) , respect ive ly , aga inst the 3D7 stra in o f P . fa lc ipa rum . Th is study is the frst report o f such act iv it ies concern ing 1 and 3. The

F igure 1 .  Chem ica l s t ruc tu res o f compounds 1–3.

ant ip lasmod ia l act iv ity o f 2 has a lready been descr ibed in A rc t ium nemo rosum Le j . (Z immermann et a l . 2012) . The cytotox ic act iv ity o f the compounds was a lso assessed in order to determ ine the ir se lect iv ity . A l l tested compounds showed cytotox ic act iv it ies (rang- ing from 10 .17 ± 0 .88 to 35 .48 ± 0 .15 μg/mL , n = 3 ) aga inst both mamma l ian ce l l l ines HeLa and MLE12 . As stated in the l iterature , these compounds have a lready been found to be cytotox ic (Lonergan et a l . 1992; Form isano et a l . 2012; Ko l l i et a l . 2012) . However , accord ing to WHO gu ide l ines (P ink et a l . 2005) , compound 3 has a prom is ing se lect iv ity index , be ing 10 t imes more potent aga inst P . fa lc ipa rum (Tab le S1 ) . Severa l structure–act iv ity re lat ionsh ip stud ies (P icman 1986; Scott i et a l . 2007) have h igh l ighted that α,β -unsaturated ketones seems to be cruc ia l for the b io log ica l propert ies o f these compounds due to the ir part icu lar react iv ity (e .g . M ichae l -type add it ion ) towards free th io l g roups . Neverthe less , the h igher se lect iv ity o f compound 3 , as shown in our work , cannot be eas i ly exp la ined . The presence o f an a ldehyd ic mo iety on th is compound cou ld perhaps contr ibute to its se lect iv ity , and w i l l be the focus o f further stud ies .

3 .Conc lus ion

To conc lude , th is study both revea led and confrmed the in v i tro ant ip lasmod ia l and cytotox ic act iv it ies o f three sesqu iterpene lactones iso lated from V . fmb r i l l i fe ra. To the best o f our know ledge , th is is the frst report o f the ant ip lasmod ia l act iv ity and the iso lat ion o f com- pounds 1 and 3 from the Ve rnon ia genus . These fnd ings just i fy that p lants o f th is genus are st i l l to be cons idered as a r ich source o f compounds (Dog ra and Kumar 2015) , part icu lar ly sesqu iterpene lactones , w ith potent ia l ant ip lasmod ia l act iv it ies .

Supp lementary Mater ia l

Exper imenta l , b io log ica l act iv ity data and fu l l NMR data are ava i lab le on l ine .

Acknow ledgments

The authors grate fu l ly acknow ledge fnanc ia l support from the European Comm iss ion and the Reg iona l Counc i l o f Reun ion Is land : B IOMOL -TCN prog ramme (Act iv ités Thérapeut iques , Cosméto log iques et Nutraceut iques de Mo lécu les Issues de la B iod ivers ité Terrestre , Mar ine et M icrob ienne de la Zone Sud - Ouest de l ’Océan Ind ien ) , ERDF (European Reg iona l Deve lopment Fund 2920 ) . The fo l low ing reagent was obta ined through BE I Resources Repos itory , N IA ID , N IH : P lasmod ium fa lc ipa rum, Stra in 3D7 , MRA - 102 , contr ibuted by Dan ie l J . Carucc i . The authors w ish a lso to thank the laboratory o f Pharmacognosy from the Un ivers ité catho l ique de Louva in (MASSMET p lat form ) and part icu lar ly Dr . Mar ie-F rance Herent for record ing MS spectra . The authors wou ld a lso l ike to thank Dr . A lexandra Manos -Turvey and Matthew Sa ive for the ir ed itor ia l ass istance .

D isc losure statement

No potent ia l conf ict o f interest was reported by the authors .

Fund ing

Th is research was supported by the Be lg ian Nat iona l Fund for Sc ient ifc Research (FNRS ) [grant number

T0190–13 ] .

ORC ID

Anné l ise Bo rd ignon     http ://orc id .org/0000 -0003 -1954 -5994

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