the following detailed description of the invention is provided to aid those skilled in the art in practicing the present invention . even so , the following detailed description should not be construed to unduly limit the present invention , as modifications and variations in the embodiments herein discussed may be made by those of ordinary skill in the art without departing from the spirit or scope of the present inventive discovery . the contents of each of the references cited in the present application are herein incorporated by reference in their entirety . artemisinin is available in large quantities from natural sources such as artemisia annua l . the expertise required to convert it into an active compound is well known in the art . earlier studies with b . sulfurescens disclosed that very poor hydroxylation substrates could be converted into acceptable ones by introducing an amide group that appears to enhance bonding between substrate and the hydroxylating enzyme complex . the substrate chosen for the work described herein is a derivative of dihydroartemisinin , ( iii ), prepared by the procedure of brossi et al . ( 8 ), which yielded a hydroxylated derivative , ( iv ), while retaining the peroxide grouping required for biological activity . its structure was established by mass spectroscopic , 1 h , and 13 c nmr studies . earlier studies by hufford et al . ( 10 ) on the action of a number of fungi on ( i ) and ( v ) identified several transformation products in which the peroxide bridge had been destroyed . the present selection of beauveria sulfurescens was based on reports that this fungus accepts a variety of substrates ( 11 ), and studies conducted by the present inventors with p - alkyl - n - acetylaniline . also useful in the present invention are mutants of b . sulfurescens capable of hydroxylating derivatives of artemisinin . beauveria sulfurescens was grown in three liter flasks each containing 250 ml of media prepared from 20 gm . dextrose and 10 gm . neopeptone per liter , for two days . the mycelia were then separated and resuspended in 200 ml of phosphate buffer ( 0 . 1m ), ph 7 . 5 , and ( iii ) was added ( 300 mg in 2 . 4 ml dimethylformamide ). after shaking for 3 days , the mycelia and buffer were extracted with ethyl acetate , and a uv - absorbing transformation product was isolated by flash chromatography on silica gel employing ethyl acetate - hexane ( 40 : 60 ) as eluent . further purification by hplc using the same solvent system yielded ( iv ) ∂ α [ d 25 ° c . - 22 . 8 ° ( c 0 . 1 , meoh ) in 3 . 4 % yield . its mass spectrum ( 252 cf plasma desorption ) exhibited a peak at m / z 442 ( mol . ion + na +), corresponding to addition of 16 mass units , consistent with the insertion of an oxygen atom . the 1 h spectrum showed the presence of only two methyl groups with a new multiplet ( 2h ) at δ 3 . 48 . one of the methyl groups , the singlet at δ 1 . 4 , corresponds to the c - 13 methyl . the doublet at δ0 . 94 was assigned to the c - 15 methyl by a multiple quantum filtered cosy spectrum , which showed that the multiplet at δ 2 . 6 ( h - 9 ) is coupled both to the doublet at δ 0 . 94 and to that at δ 5 . 78 ( h - 10 ). the methyl at c - 6 had therefore been converted into a hydroxymethyl group . a dept experiment and heteronuclear correlation spectrum confirmed that the methylene carbon at δ 64 . 6 bears the protons at δ 3 . 48 . the presence of the peroxide group , implied by the molecular weight , was deduced from a comparison of the 13 c chemical shifts for the quaternary carbons ( δ 104 . 5 and 80 . 2 ) at the terminus of the peroxide bridge , in ( iii ) and ( iv ). the relevant chemical shifts ( table 1 ) were essentially identical , consistent with the continued presence of the group . table 1______________________________________summary of . sup . 13 c chemical shift assignments i iii iv via vibcarbon δ δ δ δ δ______________________________________3 105 . 22 104 . 55 104 . 53 168 . 46 169 . 34 35 . 77 36 . 33 36 . 22 68 . 76 68 . 65 24 . 79 24 . 66 24 . 19 27 . 6 27 . 8 5a 49 . 90 52 . 63 . sup . 45 . 96 . sup . α 54 . 99 55 . 76 37 . 42 37 . 35 . sup . 44 . 29 . sup . α 33 . 95 30 . 67 33 . 45 34 . 19 28 . 36 35 . 46 35 . 98 23 . 32 22 . 02 21 . 73 22 . 59 24 . 7 8a 44 . 80 45 . 41 45 . 22 47 . 40 47 . 19 32 . 78 31 . 85 31 . 89 30 . 42 33 . 310 171 . 92 93 . 08 93 . 10 94 . 51 101 . 712 93 . 62 91 . 55 91 . 40 90 . 98 88 . 412a 79 . 38 80 . 20 80 . 27 80 . 07 80 . 613 25 . 10 25 . 83 25 . 90 21 . 39 21 . 614 19 . 74 20 . 24 64 . 64 20 . 45 20 . 515 12 . 47 12 . 15 12 . 20 12 . 01 12 . 51 &# 39 ; 137 . 70 137 . 51 137 . 442 &# 39 ;, 6 &# 39 ; 118 . 88 118 . 84 118 . 943 &# 39 ;, 5 &# 39 ; 128 . 91 129 . 03 129 . 024 &# 39 ; 123 . 47 123 . 71 123 . 75c - o 152 . 05 151 . 89 151 . 60______________________________________ . sup . α may be interchanged . the data presented above confirm that b . sulfurescens can convert the n - phenylurethane of dihydroartemisinin into a derivative containing a hydroxyl group on the c - 6 methyl group , as depicted below : ## str1 ## since a significant amount of starting material was recovered using the above reaction conditions , a number of small - scale experiments were conducted in an effort to increase the yield in the biotransformation . it was found that if the mycelia obtained from 250 ml of media were resuspended in 100 ml of buffer and reacted with 20 mg of the substrate , the yield of the biotransformation increased to 15 %. in exploring the role the media played in stimulating the mycelia to produce high levels of the hydroxylating enzyme complex , b sulfurescens was also grown on corn steep liquors as described by johnson ( 11 ). the mycelia were isolated , resuspended in phosphate buffer at ph 7 . 5 , and ( iii ) was added . after three days , the reaction mixture was worked up as described above to yield a different metabolite , ( via ), with a molecular weight isomeric with the starting material . its structure was assigned by 1 h and 13 c nmr spectroscopy . hufford et al . ( 10b ) reported the formation of a similar metabolite , ( vib ), from ( v ). the 13 c chemical shifts of ( i ), ( iii ), ( iv ), ( via ), and ( vib ) and their assignments are given in table 1 , supra . beauveria sulfurescens ( atcc 7159 ) grown on sabouraud liquid broth modified antibiotic medium 13 ( bbl , cockeysville , md .) solidified with 2 % agar was inoculated into 250 ml of the same liquid medium in a 1 liter erlenmeyer flask . the flask was shaken at 200 rpm at27 ° for 72 hours . aliquots of this culture were employed to inoculate twelve 1 liter erlenmeyer flasks containing 250 ml of medium and approximately 100 μg of arteether . the flasks were shaken at 200 rpm at 27 ° c . for 72 hours . the mycelia were then collected by filtration , and resuspended in 200 ml of 0 . 2 m kh 2 po 4 buffer , ph 7 . 5 . arteether ( 40 mg in 0 . 4 ml of ethanol ) was then added to each flask . the flasks were then shaken for three days ; the mycelia were removed by filtration and the combined filtrates were extracted with ethyl acetate . the extracts were dried and concentrated . the residue was purified by flash chromatography on silica gel . the first metabolite eluted was 3α - hydroxyldesoxyarteether ( 27 mg ), the second 7β - hydroxyarteether ( 72 mg ), and the third 14 - hydroxyarteether ( 110 mg ). the ability of the fungus b . sulfurescens to hydroxylate the c - 14 methyl of artemisinin derivatives has enabled the present inventors to employ the reaction product obtained from arteether , the ethyl ether of dihydroartemisinin , in conjunction with conventional chemistry , to incorporate one or two deuterium ( tritium ) atoms on the c - 14 methyl group of arteether . since very little of a label at this position is removed during the drug &# 39 ; s metabolism , labelled arteether may be useful in a variety of biological studies . preliminary results on the antimalarial activity of ( iv ), below , support the conclusion of earlier structure - activity studies that the intact peroxide bridge is important for antimalarial activity . the successful preparation of an intermediate , ( iv ), that can be employed to prepare radiochemically labelled samples of ( i ) or ( ii ) in which the label is metabolically stable for studying the mode of action of these compounds represents a major advance . in addition , the intermediate can be employed to prepare new longer acting and more potent antimalarials . the antimalarial activity of various hydroxylated artemisinin derivatives obtained via the present method was determined by drs . s . anderson and w . k . milhous at the division of experimental therapeutics , walter reed army institute of research , washington , d . c . the malarial strains employed in this survey include d6 , w2 , and ga3 . in table 2 , below , the - pharmacological data are reported as ic - 50 , indicating the concentration , in ng per ml , of compound required to inhibit growth of the parasite at the 50 % level . the smaller the indicated value , the more active the compound against the malarial parasite . for comparative purposes , control experiments were conducted employing arteether and artemisinin , the most effective artemisinin derivatives known to date , as well as chloroquine . table 2______________________________________antimalarial activity of dihydroartemisininderivatives against plasmodium falciparum in vitrocompound malarial strain ic - 50 , ng / ml______________________________________14 - hydroxy - n - phenylcarbamoyl d6 2 . 0dihydroartemisinin ( iv ) 7β - hydroxyarteether d6 12 . 6 w2 2 . 78 ga3 8 . 8314 - hydroxyarteether d6 12 . 6 w2 2 . 77 ga3 8 . 18artemisinin d6 0 . 97 w2 0 . 79 ga3 1 . 58arteether d6 0 . 73 w2 0 . 28 ga3 0 . 498chloroquine d6 6 . 63 w2 41 . 38______________________________________ as shown by the data in table 2 , 14 - hydroxy - n - phenylcarbamoyl dihydroartemisinin ( iv ), 7β - hydroxyarteether , and 14 - hydroxyarteether , products obtained via the microbial hydroxylation process described herein , exhibit antimalarial activity against the strains tested . this demonstrates the utility of compounds obtained via the present inventive method . the invention being thus described , it will be obvious that the same may be varied in many ways . such variations are not to be regarded as a departure from the spirit and scope of the invention , and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims . 2 . ( a ) z . ye , k . van dyke , and v . castranova , biochem . biophys . res . commun . 165 , 758 ( 1989 ) ( b ) z . ye and k . van dyke , ibid . 159 , 242 ( 1989 ) ( c ) z . ye and k . van dyke , ibid . 155 , 476 ( 1988 ) 3 . &# 34 ; tropical diseases , progress in international research ,&# 34 ; 1987 - 1988 , 43 - 54 , who special programmed for research and training in tropical diseases , 1989 . 5 . qinghaosu antimalarial coordinating research group , chinese medical journal , 92 , 811 ( 1979 ). 6 . d . l . klayman , a . j . lin , n . acton , j . p . scovill , j . m . hoch , w . k . milhous , a . d . theocharides and a . s . dobek , j . of natural . products , 47 , 715 ( 1984 ). 7 . ( a ) china cooperative research group on qinghaosu , j . of traditional chinese medicine , 2 ( 1 ) 9 - 16 ( 1982 ) ( b ) a . brossi , b . venugopalan , l . d . gerpe , j . j . c . yeh , j . l . flippen - anderson , p . buchs , x . d . luo , w . milhous , and w . peters , j . med . chem ., 1988 , 645 ( c ) a . j . lin , m . lee , and d . l . klayman , j . med . chem . 1989 , 32 , 1249 . 8 . x . luo , h . j . c . yeh , a . brossi , j . l . flippenanderson , and r . gilardi , helv . chim . acta , 67 , 1515 ( 1984 ). 9 . x . d . luo and c . c . shen , medical research rev . 7 , 29 ( 1987 ). 10 . ( a ) i . s . lee , h . n . elsohly , e . m . croom , and c . d . hufford , j . nat . prod . 52 , 337 , 1989 ( b ) i . s . lee , h . n . elsohly and c . d . hufford , pharm . res ., 7 , 199 ( 1990 ). 11 . ( a ) r . a . johnson , oxidations in organic chemistry , academic press , inc ., pp . 131 - 210 , 1978 ( b ) j . d . fourneron , a . archelas , b . vigne and r . furstoss , tetrahedron , 43 , 2273 ( 1987 ) and earlier references . 12 . china cooperative research group on qinghaosu and its derivatives as antimalarials , j . of traditional chinese medicine , 2 , 45 ( 1982 ). 13 . m . m . gottesman and i . pastan , trends in pharmacological science , 9 , 54 , ( 1988 ). 14 . y . zhao , a . li , p . xie , h . hou , w . gu , m . jia , x . liu , and t . lei , j . med . chem . 7 , 287 ( 1987 ). 15 . w . xuan , y . zhao , a . li , p . xie , and y . cai , j . med . chem . 8 , 282 ( 1988 ).