Of Licania heteromorpha

Licania heteromorpha var. heteromorpha Bentham is a tree up to 30 m high native to the Amazonian forest. Phytochemical study of its aerial parts yielded both triterpenes and flavonoids triterpenes were obtained from the chloroform extract by silica gel column followed by RP-HPLC and were characterised as betulinic acid (11), alphitolic acid (48), 3(3-0-trans-p-coumaroyl alphitolic acid (49), 3(3-0-cw-p-coumaroyl alphitolic acid (50), 3 -0-trans-p-coumaroyl maslinic acid (51), 3fi-O-cis-p-coumaroyl maslinic acid (52), 3(3-0-tnms,-/ -coumaroyl-2a-hydroxy-urs-12-en-28-oic acid (53), 3 3-0-m-p-coumaroyl-2a-hydroxy-urs-12-en-28-oic acid (54) [see Fig. (2) and (6)] [15], Compounds 11 and 48-54 were identified comparing their H and 13C NMR data with those previously described. Triterpenoids 48-54 were found for the first time in Licania, while betulinic acid had been isolated previously from L. carii [9]. On the other hand, flavonoids were isolated from the chloroform-methanol and methanol residues by Sephadex LH-20 and HPLC they were identified as myricetin 3-0- 3-D-galactopyranoside (17), myricetin 3-0-a-L-rhamnopyranoside (32), myricetin 4 -methylether-3-0- 3-D-glucopyranoside (55), myricetin 4 -methylether-3-0-a-L-rhamnopyranoside (45), myricetin 3,4 -di-0-a-L-rhamnopyranoside (56), myricetin 7-methylether 3,4 -di-0-a-L-rhamnopyranoside (57), and myricetin 4 -methylether-3-0- 3-D-galactopyranoside (58) [see Fig. (2), (4), and (6)]. The last three myricetin derivatives were new natural compounds [16]. Known compounds were identified by comparison of their H and l3C NMR spectra with those reported in the literature [15]. 

The first screening on cytotoxic activity regarding plants of Licania genus was accomplished by Suffness et al. in 1988 on the ethanolic extract of L. heteromorpha [19]. The plant showed cytotoxic activity in vitro in colon carcinoma 38 and B16 melanoma models. 

Similarly to L. densiflora, L. heteromorpha is unusual for its biosynthesis of methoxylated flavonoids glycosides (with the methoxyl groups at C-4 of ring B and C-7 of ring A). The production of such flavonoids could be a response to local environmental factors. In comparison to the other Licania species, L. heteromorpha predominantly yields flavonol glycosides instead of flavones or flavanones. 

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