Xanthones, flavonol and proanthocyanidins in l eaves

would lead to hi gher antioxidant a ctivity. In addition,

del B ano e t a l. [28] found that some a ntioxidat i ve com-pou nd s wer e se le ct iv el y bio syn th es i zed by th e l eav es bu t

the compounds do not exist in flow ers. Our p revious

study [ 4] also showed that rutin and chlorogenic acid

were presen t in B. kock ianaan d C. surattensisleaves

but t hey w ere absent in their respective flowers. Th is

may be due to higher stress level experienc ed by the

l e av es i n t he p r o c es s o f p h o t o s yn t h es i s , w h er e e xc es s i v e

lightenergymaybeabsorbedbytheleaftissues.The

ch loro ph yl ls wo ul d al so un derg o ph ot osen sit iza tio n pro -cess (process of transfer ri ng absorbed light e nergy),

which may trigger the productio n of high ly reactive che-mical speci es at cellular le vel [29]. Therefo re, le af tissue s

wo uld need to ge ner ate hig hly effe ct ive ant iox ida nts and

free radical scave ngers to aid in quen ch ing and re mov-ing the ROS and to minimize the photosensitization-induced oxidative damage.

Compared to the r esults sho wed in most plants,

exception was seen in B. kock iana . B. kockiana showed

averyuniquetrendof TPCandfreeradicalquenching

ability distribution i n t he le aves and flowers among the

nine selected plants. The TPC and free ra dical quench-ing a bili ty were si gnificantly h igher in f lowers than

leaves. Our earlier report [4] showed the presence of

high anthocyanins content in B. kockiana flowers.

Ant hocyan ins whic h act as visu al at tracta nt fo r pot enti al

pollinators ( i.e. insects) may h av e c ontributed to the

high phe nolic content and strong free radical scaven ging

power of B. koc kianaflower extract. Anthocyanins are

the c ommon p ig ments in coloured flowers th at could

term inate radical chain rea ction, preve nt both enzy matic

and non-e nzymatic lipid peroxidatio n of cell membranes

by binding with fatty radicals [4].

An antioxidative x anthophy lls an d lutein we re found

In c. Sura ttensis flower [4]. Lutein prot ects pho to-induc ed free radical damage in plant t issues in 2 ways:

filters off the high e nergy blue l ight and s cavenges the

reac tive chemical species [30]. T he presence of rutin

(95.7 mg/100 g) and chlorogenic acid (9.13 mg/100 g) in

extract would exhibit antioxidant activities. Our previous

study [ 4] has s hown that rutin was present in C. surat-tensis fl o we r s a nd l ea v es ex t r ac t s ( 13 . 3 mg ru ti n eq ui v a-lent/100 g a nd 29 .6 mg rutin e quivalent/100 g,

respectively), assessed u sing aluminium chloride

method. Rutin (95.7 mg/100 g) and chlorogenic a cid

(9.13mg/100g)inextract wo uld exhibit antioxidant

activities [4].

Antibacterial activity and phytochemicals screening

All e xtracts were not ac tive ag ainst Gram ne g ative bac-te ria. This could b e due to the p rese nc e o f outer mem-brane a s a per meability barrier in Gram negat ive

bac t eria. The presen ce of porin a t t he outer m embran e

of Gram negative bacteria restrict ed the diffusion of

many ant ibio tics a nd the mul tidrug effl ux pumps at the

tran sme m bran e would a lso pump o ut t he an tiba cteri al

agents through the ac tive eff lux proc esses whic h would

hencecreatea higher intrinsicresistanceforGram

negative bacteria [31]. It is interesting to not e that t his