The Antibacterial Properties of Some Plants Found in Hawaii 'a. A. BUSHNELL, MITSUNO FUKUDA, AND TAKASHI MAKINODAN1 MANY OFTHEPLANTS,both indigenous and plants were not themselves mentioned in the introduced, which now grow in Hawaii have accounts we consulted in preparing our own been used for medicinal purposes by the na list of plants to be investigated. tive Hawaiians and by the people of other Our list was compiled from several publi countries who have come to live in Hawaii. cations discussing Hawaiian pharmaceutics When, in 1934, Handy, Pukui, and Liver (Kaaiakamanu and Akina, 1922; Degener, more made their survey of the 'Hawaiian 1930; Handy, Pukui, arid Livermore, 1934; pharmacopeia, they were able to distinguish Neal, 1948); from suggestions given us by 317 differentbotanicalcomponentsin the cat a Hawaiian herbalist on' plants in current alogue of ingredients used until that time. It usage; and from hearsay and bur own per is probable that many other species of plants sonal experience with plants used by Japa which are sources of favorite 'remedies in nese, Chinese, and other ethnic groups in othercountries have been imported to Hawaii Hawaii. In preparing this list, those plants and could be added to the list prepared by' which appear to have been used against bac Handy and his coworkers (1934), who were ' terial infections were selected wherever iden concerned primarily with remedies used by tification of the plant had been established the native Hawaiians. and whenever it was likely that we would The Hawaiian remedies, especially those beable to fi~dit in orderto test it. The more derived from the lore of the kahuna lapaau common or the more famous.of the medici laau, the herb doctor of'the ancient Hawai nal plants were also included in the list, even ians, have been much praised but they have if they had been employed to treat conditions never been critically appraised; and we obviously having no bacterial etiology. Our thought that perhaps we could gain some list,then, isa heterogeneousone, byno means idea of their relative value if we studied the confined to the native Hawaiian plants,'and medicinal plants from which these remedies contains more than 275 entries. were prepared for evidences of the antibac When we began these studies we expected terial properties they might possess. to be able, in time, to study all the plants in Most of the plants wesetoutto study were our Jist, and therefore were not particularly chosen from the native Hawaiian materia concerned about the order in which we col medica, but we did not exclude plants used lected them, taking them in the haphazard for medicinal purposes by people of other sequence in which "';'e found them; but now ethnic groups. In some instances, moreover, the pressure of other duties makes it evident we studied imported plants which were re that we shall not be able to finish the studies lated to the species considered to be of value as we had planned. Rather than lose the in by the Hawaiians, even though the imported formation we have obtained, therefore, we are recording in this paper the datafrom our observations on the 101 ~edicinal plants we Department of Bacteriology, University of 1 were able to investigate before our studies Hawaii,Honolulu. ManuscriptreceivedAugust29, 1949. were forced to an end. [ 1671. 168 PACIFIC SCIENCE, Vol. IV, July, 1950 METHODS assay or were frozen and held at _ 10° C. until they could.be studied. The method of measuring the antibacterial Extracts of the whole plants or of certain properties of plants isessentially the same as separated portions of them-as, for example, that devised by the Oxford group (Abraham the roots, the stems, the leaves, the flowers, et al., 1941) for assaying penicillin and since the fruits, or of any indicated combinations adapted to the assay of other antibiotics pro- of these-were obtained by first cutting the duced by micro-organisms. It is a method b plant material into small pieces and y then which has been used in other parts of the subjecting these fragments to high pressures, world to appraise medicinal plants (Pederson ranging from 15,000 to 20,000 pounds per and Fisher, 1944; Lucas and Lewis, 1944; square inch, achieved by means of a Carver Sanders, We?-therwax, and McClung, 1945; hydraulic press. No water or solvent of any Carlson et al., 1946', and many others). It kind was added to the plant material, and in is based upon the assumption that an agent almost all cases the specimens yielded ample which ,acts upon a test organism to achieve amounts of tissue fluids for the purposes of a particular effect will also act upon other the study. related organisms in asimilarmanner. While The e~tracts'of the different portions'of the assumption isnot always substantiated by the plants were kept in separate beakers,and experimental evidence, it is tenable often 'were placed immediately in a refrigerator enough to give the method some usefulness . until the next step in the assay could be per asa "screening test" for distinguishing agents formed. In most instances the period of sror- that are "likely" to be effective from those . age was only 1 to 2 hours; in no case was It which are "likely" to be ineffective. It is a longer than 4 hours. method which ·has its deficiencies, certainly, Most of the extracts were assayed for their but it is better than no method at all. antibacterial effect upon three test strains of The plants to be studied were collected bacteria: Micrococcus pyogenes var. aureus over a period of 2 years as they could be (until recently known' as Staphylococcus found on the island of Oahu. Most of them aureus), Escherichia coli, and Pseudomonas were obtained on or near the University of aeruginosa. A few of those extracts studied Hawaii campus and in the adjacent Manoa early in these investigations were tested . Valley. Whenever feasible, specimens of the against M. pyogenes var. aureus and E. coli complete plant-roots, stems, leaves, buds, only. Seventeen of the plants, which the lit flowers, and fruits-were obtained, either all erature described as having been employed at once or during those seasons when'they to combat.iritestinal infections, were tested could be found. In the case of a plant of against five different strains of enteric patho which only certain pottions had been used gens as well as against the three standard in the native pharmacopeia, we were careful cultures. The enteric pathogens used were: to collect and to study at least those pre- Salmonella typhosa, Sal. montevideo, Sal. scribed portions of the plant if not all of it. schottmuelleri, Shigella paradysenteriae BH, Many of the plants, or many of the.parts of and Shig. paradysenteriae III-Z. Cultures of the different species,were tested several times all of these test organisms were'obtained from during the course of our study, in several in- the stock culture collection of the Depart- stances'by each of us independently. ment of Bacteriology, University of Hawaii. The specimens were taken to the labora- Pure cultures of the test bacteria were c. torysoon after theywere collected,and either grown in nutrient broth at 3r for 24 , were subjected immediately to the process of hours before they'were used. When an assay Antibacterial Properties of Plants-BUSHNELL, et at. 169 was about to be performed, 0.5 ml. of'the tract or of varying dilutionsof it into the broth culture of the test organism was inocu inoculated medium before it had solidi~ed­ lated into 100 rnl. of melted nutrient agar but the penicup method seemed to be the cooled to 41 C. This heavily seeded agar one which gave the most consistent and the 0 medium was then poured into sterile petri most clear-cut results, and it w::s adopted for dishes, about 10 ml, to.a dish, and the me continued use. dium was allowed to solidify at room tem Just before each extract was tested for its perature. After the medium had solidified, effect upon the bacteria, its pH was deter one or two sterile porcelain penicups were mined by means of a Macbeth line-operated placed upon the surface of the agar. pH meter..A series of tests was also per The plant extract being tested was then formed to determine the inhibitory effect of placed in the appropriate penicup, 0.2 ml. of H-ions and OH-ions in buffer solutions of extract in each cylinder. 'At first extracts assorted pHin order to ascertain whether or were tested in duplicate until, with time and not the inhibitoryeffectsof the different plant the perfection of our techniques, we found extracts might be merely a reflection of their thatduplicate platings were unnecessary. The pH values. The buffer solutions were pre plates were incubated in the upright position paredfrom tablets each of which, upon being at 37.50 C. for 24 hours, at which time they dissolved in 100 ml. of distilled water, gave were examined for the degree of inhibition a solution of specified pHvalue.f achieved bythe plant extracts as they diffused Informationconcerningthe plants reported into the medium from the bases of the peni- . in this paper is presented in Table 1, which cups. In most of the instances in which inhi shows (1) the major plant group and the bition wasachieved, it was denoted bya clear family to which each plant belongs; (2) the halo-like zone in the medium around the scientific name of the plant; .(3) the com penicup, with the heavy growth of uninhib mon names of the plant, in both English and ited bacteria making the 'medium opaque Hawaiian; and (4) epitomes of the usual around the periphery of the zone of inhibi purposes for which the plant was employed, tion. A few of the'plant extracts produced according to the references consulted in pre a considerable discoloration or opacity in the paring the list (the specific references are medium around the penicups, but in only a cited in the table). very few instances did this discoloration inter We can make no claim to being taxono fere with determinations of the extracts' ef mists and have based our presentation ofthe fects upon the test organisms. systematic relationships of these 'plants upon The degree of antibacterial effect was re the manner in which Neal hasset them forth flected directly, of course, in the size of the in her recent book In Gardens of Hawaii zone of inhibition: the greater the zone, the (1948). In her,introduction to thiscompen more potent the extract. The diameter of the dium, Miss Neal states that she has followed zone could be measured quite easily in most the system of Engler and Prantl for the flow instances and was recorded, in millimeters, ering plants, and the arrangement of A. ]. for each extract tested. Eames for the ferns and fern .allies. .Several other techniques for determining The single specimen of alga collected, the efficacy of the plant extracts were also Gracilaria furcellata, was identified by Dr. tried-s-such as using filter paper discsof vary Marion 1. Lohman, associate professor of bo ing sizes soaked in the plant extract before tany at the University of Hawaii. Most of the they were applied to the inoculated agar, or "The tablets areproduced by the Coleman Elec actuallyincorporating 1 ml. of the plant ex- tric Company, Maywood, Ill. I 170 PACIFIC SCIENCE, Vol. IV, July, 1950 TABLE 1 SCIE~TIFIC AND COMMON NAMES OF THE PLANTS TESTED, THEIR SYSTEMATIC RELATIONSHIPS, AND THE MEDICINAL USES TO WHICH THEY WERE PUT = = = (K & A Kaaiakamanu and Akina, 1922; Deg. Degener, 1930; Handy Handy, Pukui, and Livermore, 1934; Neal = Neal, 1948) SCIENTIFICNAME COMMON NAMES TRADITIONALUSES AS FAMILY OFSPECIES INHAWAII MATERIAMEDICA Gracilariaceae Gracilariafurcellata seaweed;limumanauea sores, skin blotches, "cure for Mont. - (?) miscarriage" (K & A: 62) Psilotaceae Psilotum nudum (1.) uprightPsilotum;moa thrush, diarrhoea in infants Griseb. (Deg.: 20; Neal: 7) Gleicheniaceae Dlcranopterislinearis falsestaghornfern; laxative (Deg.: 27) .(Burm.) Underw. uluhe Polypodiaceae Nepbrolepisbiserrata relatedtoBoston fern; not known (listed in Handy: (Sw.) Schott. okupukupu 44) CibotiumChamissoi tree fern;hapu asthma, "lung troubles" (K&A: Kaulf. 16) Pandanaceae Freycinetiaarborea climbingscrewpine;ieie general debility, thrush, high Gaud. fever (K &A: 22) PandanusRockiiMart. ascrewpine,related-to hala was used for general debil the halaofthe ity, constipation, "pain in Hawaiians chest" (K & A: 41); asthma (personal communication) Gramineae Bambusasp. "small-leavedbamboo"; ulcers arid scrofulous sores ohelaulii (K & A: 30) Coixlacryma-jobi1. Job'stears;puoheohe curative charm (Neal: 74) Saccharum ofjicinarum sugarcane;k6kea- cues and wounds, urethritis (K 1. sc. A: 6,- 53); adjuvant (Handy: 21);pulmonarydis ease (personal communica tion) Setariapalmifolia palmgrass use unknown; hearsay (Willd.)-Stapf Stenotaphrumsecunda buffalograss;akiaki, sores and ulcers on skin tum (Walt.) Ktze, manieniemahikihiki (K&A: 10) Cyperaceae ScirpusvalidusVahl. greatbulrush;aka'akai "gripping pain of the stomach naku,neki or intestines, and for intesti nal hemorrhages" (K & A: 10) Palmae Cocosnucijera1. coconut;niu general debility and cuts (K & A: 73); thrush (Handy: 22) Araceae Alocasiamacrorrbiza apekeokeo burns, stomach ache, aphrodis (1.) Sweet iac (K & A: 17) Colocasiaesculenta (1.) taro;kalo laxative (K & A: 17) Schott. Commelinaceae Commelinadiffusa dayflower;bonobono, "purifying the blood" Burm.f. makolokolo (K & A: 71) Liliaceae Allium fistulosum1. greenonion;aka'akai tuberculosis, colds, and vener eal diseases (K &A: 10) Cordylinete~minalis ti,ki,lau'i asthma, congestion of lungs, (1.) Kunth,var Ki high fever (K &A: 50) (Schort.) J.G.Baker Dioscoreaceae Dioscoreaalata1. yam;uhi high fever (K &A: 37) Musaceae Musaparadisiaca1. banana;mal'a asthma, general debility, stom ssp.sapientum (1.) ach disorders (K & A: 65 Ktze. var. 68); throat infection (per sonal communication) Antibacterial Properties of Plants-BUSHNELL, et al. 171 TABLE 1 (Continued) SCIENTIFICNAME COMMONNAMES TRADITIONALUSESAS FAMILY OFSPECIES INHAWAII MATERIi\MEDICA Zingiberaceae Alpiniapurpurata redginger use unknown; hearsay (Vieill.) K.Schum. Hedycbiumcoronariam whiteginger;awapuhi "for foetid nostrils" Koenig . keokeo (K &A: 20) ZingiberZerumbet (L.) mountainginger; cuts and sores (K & A: 19) Smith awapttbikuahiwi Casuarinaceae Casuarinaequisetijoli« ironwood astringent (Neal: 247) L. . Piperaceae Peperomia membranacea... peperomia;alaalawaimti general debility, pulmonarydis H.&A. . eases, venereal diseases, scro fulous swellings and ulcer (K & A:..13-14) Peperomialatijoli«Miq.. peperornia;alaalawainui same as above Moraceae Artocarpusincises breadfruit; ulu skin diseasesand boils (K & A: (Thunb.) L.f. 38; Handy: 31) Morus albaL.,f. mulberry; kilika use unknown; hearsay nigrobaccaMold. Urticaceae Touchardialati/olia olona,wauke-malulo "bodilyailments or'weaknesses' Gaud. (K& A: 71) Santalaceae SantalumalbumL. Indiansandalwood;re- iliahi was used for sores, vene latedtothe iliahiof real diseases (K sc A: 24; theHawaiians Neal: 278) ~ Amaranthaceae Amaranthusspinose:L. spinyamaranth; pokai use unknown; hearsay kuku Nyctaginaceae MirabilisJalapaL. four o'clock;Mniahiahi poultices, purgatives (Neal: 288) : Batidaceae BatismaritimaL. pickleweed;akulikuli "leaves have medicinal value" kai (Neal: 291) Portulacaceae PortulacaoleraceaL. pigweed;akulikulikula, general debility (K & A: 24) ihi-ai,lumaha'i Cruciferae Nasturtium officinaleR. watercress;leeo "for dry throat and cold in the Br. head," asthma (K & A: 64). I tuberculosis (personal com munication) Crassulaceae Bryophyllu1lJpinnatum air-plant fevers (Neal: 329) (Lam.) Kurz. Pittosporaceae PittosporumTobira relatedtothebo'au/aof bo'aurawasusedforsores(Neal: (Thunb.) Ait. theHawaiians . . 335); scrofula (K & A: 44) Rosaceae RubusrosaejoliusSm. thimbleberry use unknown; hearsay Leguminosae Acaciacon/usaMerr. Formosakoa use unknown; chosen for its re lationship to AcaciaKoa AcaciaKoaGray koa,kabilikolo general debility, diseases of the skin (K & A: 46) CassiaLeschenaultiana cassia;lauki use unknown; hearsay DC. CrotalariaincanaL. rattlebox;pikakani use unknown (listed in Handy: 74) . Crotalariamucronata ratrlebox;pikakani use unknown; hearsay Desv. DiocleauiolaceaMart. seabean;maunaloa cuts, skin diseases, "purifying . the blood" (K & A: 65) Leucaenaglauca (L.) ' falsekoa; koahaole use unknown; hearsay Benth, MedicagosativaL. alfalfa use unknown; hearsay Prosopiscbilensis algaroba; keawe dysentery, sore throat (Mol.) Stuntz (Neal: 363) 172 PACIFIC SCIENCE; Vol. IV, July, 1950 TABLE 1 (Continued) SCIENTIFICNAME COMMON NAMES TRADITIONAL USESAS FAMILY OFSPECIES INHAWAII MATERIAMEDICA Tamarindusindica1. tamarind;wi'awa'awa "used medicinally in India" (Neal: 366) Vigna marina (Burm.) nanea,okoleomakili general debility, asthma, boils Merr. and cuts (K & A: 33) Rutaceae Citrusa1trantifolia lime use unknown; hearsay (Christmann) Swingle Peleasp. alani general debility, "purifying the blood," skin diseases: "makes the skin immune to certain diseases" (K & A: 16) Euphorbiaceae Aleuriiesmoluccana candlenuttree;kukui general debility,asthma,scrofu (1.) Willd. lous sores, ulcers of skin (K & A: 56-57); diphtheria (personal communication). Ettphorbiahirta1. hairyspurge; cathartic, gargle, poultice kokokahiki,akoko (Handy: 19); thrush (Deg.: 198) Euphorbiapulcherrima poinsettia;koko use unknown (listed in Handy: Willd. 39, 44) EuphorbiaMiliiCh.des crown-of-thorns use unknown; hearsay Moulins EuphorbiaTirucalli1. pencilplant use unknown; hearsay Huracrepitans1. sand-boxtree "leprosy and other conditions" (Neal: 451) Ricinuscommunis1. castorbean;koli,pdaila fever (K & A: 55) Anacardiaceae Mangiferaindica1. • mango; manako astringent (Neal: 457) Schinusterebintbijolius Christmasberrytree; use unknown; hearsay Raddi wilelaiki Sapindaceae Cardiospermum balloonvine,hearrseed; rheumatism, digestive and pul Halicacabum1. inalua,poni« monary disorders (Neal: 467) Dodonaeaviscosa1. aalii,kumakani rash and itch (K & A: 2) "Malvaceae Hibiscustiliaceus1. haukaekae laxative (Neal: 49); congested chest, sore throat (K & A: 40) Malvastrum coroman falsemallow poultices (Neal: 485) delianum (1.) Garcke SidafallaxWalp. ilima general debility,asthma, "fallen womb," laxative (K & A: 26; Neal: 485) Sterculiaceae Waltheriaamericana1. hialoa,uhaloa, asthma, sore throat, pulmonary kanakaloa complications (K & A: 37; Neal: 503; personal commu nication) Guttiferae Calophyllum Alexandrianlaurel; useunknown (listed in Handy: Inophyllum1. truekamani 43; Neal: 513) Passifloraceae PassifloraedulisSimsf. yellowlilikoi use unknown; hearsay fiavicarpaDegener Passifiora[oetidaL.var. runningpop,redpassion use unknown; hearsay fruit Passifiorasp. greenlilikoi use unknown;'hearsay Caricaceae CaricaPapaya1. papaya;nikana,be'i skin diseases (Neal: 527); deep curs (K & A: 43) Cactaceae Oponti«megacantha pricklypear;panini constipation (K & A: 73) Salm-Dyck Antibacterial Properties of Plants-BUSHNELL, et al. 173 TABLE 1 (Continued) SCIENTIFICNAME COMMONNAMES TRADITIONALUSESAS FAMILY OFSPECIES INHAWAII MATERIAMEDICA Thymeliaceae Wikstroemiaoahue-nsis akia laxative, asthma (K & A: 8); (Gray) Rock fish poison (Neal: 540; Deg.: 224-225) . Punicaceae PunicaGranotum1. pomegranate; used in Orient (Neal: 551) pomaikalana Combretaceae TermlnaliaCatappaL. tropicalalmond;false '''used medicinally" (Neal: 551) kamani Myrtaceae Ettcalyptttssp. eucalyptus;nttholani fevers, sores, pains, rheumatism (K & A: 73) EugeniaCttmini (1.) Javaplum use unknown; hearsay Druce ' EugeniamalaccensisC' mountainapple;ohiaai general debility, thrush, sores.. cuts (K & A: 31-32); throat infection (personal commu nication) Metrosiderosmacropus ohia lebua,ohiahamau sore throat, bronchitis, con H.&A. sumption, wounds (Handy: 20) Psidittm Gttaidva1. guava;kttawa "medicinal tea" (Neal: 556); deep cuts, sprains, diarrhoea, intestinal hemorrhages (K & A: 55) Apocynaceae Neriao:Oleander1. oleander;oleana skin diseases (Neal: 611) Tbeoetiaperuoiana be-still,yellowoleander "used medicinally"(Neal: 610) (Pers.) K. Schum. Convolvulaceae IpomoeaBatatas (1.) sweetpotato;ttala medicinal uses (Handy: 21); Poir. asthma, constipation, "fallen womb" (K & A: 35-36) IpomoeacongestaR.Br. morningglory;koali purgative,healing broken bones awahia (Handy: 19; K & A: 52; Neal: 623); relief of mus cular pain (personal commu nication) Ipomoeapes-caprae (1.) beachmorningglory; "good for the expectant moth Sweet pohuehue er" (K & A: 73) Boraginaceae Messerschmidiaargentea treeheliotrope;tabin» use unknown; hearsay (1.f.) Johnston Verbenaceae LantanaCamara1. lantana; lakana use unknown; hearsay Stachytarphetacayen vervain;oi "used in tropical America" nensis(1.C.Rich.) (Neal: 639) Vahl. Solanaceae Capsicum [rutescens1. redpepper;nioi pains in back, rheumatism, swollen feet (K & A: 72) Lycopersicon escttlentum currant tomato;ohia use unknown; hearsay Mill. ssp.Galeni makanahele (Mill.) Luckwill Solanum nodi/lorum blacknightshade; disorders of respiratory tract, .Jacq. popolo skin eruptions, cuts, wounds (Handy: 18; Neal: 655); trachoma (personal commu nication) Solanumsodomaeum1. appleofSodom;popolo used in Africa for skin diseases kikania (Neal: 655) 174 PACIFIC SCIENCE, Vol. IV, July, 1950 TABLE 1 (Continued) SCIENTIFICNAME COMMONNAMES TRADITIONALUSESAS FAMILY OFSPECIES INHAWAII MATERIAMEDICA Plantaginaceae PlantagoIanceolataL. narrow-leaved plantain; sores or boils (Handy: 21); laukahi general debility,constipation, boils (K & A: 58); diabetes and "to clear the system" (Neal: 695) PlantagomajorL. broad-leaved plantain; same as above laukahi Rubiace~e MorindacitrifoliaL. Indianmulberry;noni broken bones, deep curs (K & A: 73); curs, bruises, sores, wounds (Handy: 18) Cucurbitaceae MomordicaCbarantiaL. bittermelon,balsam used in the preparation of a pear Japanese remedy for skin ail ments,headache,constipation (Neal: 709) Goodeniaceae Scaevola[rutescens beachnaupaka;naupaka "used medicinally in Malaya" (Mill.) Krausevar. kahakai (Neal: 720); curs and skin serice«(Forst.f.) , diseases (K & A: 72) Merr, ScaevolaGaudichau mountainnaupaka; same as above dianaCham. naupakakuahiwi Cornpositae BidenspiloseL. beggartick;relatedto "used medicinally" (Neal: 742) theko'oko'olauof theHawaiians Erigeron albidus related toCanadaflea "used medicinally in Java" (Willd.) Gray bane;iliohe (Neal: 733;listed in Handy: 42) plants were identified for us by Dr. Harold feetion once it had begun.We know, too, St. John, professor of botany and chairman that studying the effects of these plants upon of the Department of Botany at the Univer bacteria in vitro does not test them under the sityof Hawaii. \VIearegrateful for their help conditions in vivo in which they were in and their encouraging interest in these stud tended to be used: there are so many factors ies. At Dr. St. John's suggestion, herbarium involved in the living body which might con specimens of the plants studied were pre tribute important assistance to the medicinal pared by us and are.preserved in the Depart agent when it isproperly applied. bythe herb ment of Bacteriology at the University of alist. The purists among admirers of the Hawaii. . . kahuna'j lore will also point out that we did not use.the ancient .prescriptions exactly as DATA AND DISCUSSION they were applied bythe kahuna. To this our answer must be that, in this initial stage of We are well aware of the shortcomings of the investigation, we were concerned with this approach toan appraisalof the medicinal studying the effects of the component parts plants found in Hawaii, if only because so of the prescriptions, hoping that later, when many of these plants were not used primarily for their effect against bacteria: they' were we had found all of the components, we used as cathartics, vermifuges, emollients, could put them together to see if they are astringents, analgesics, counterirritants, and any more .effective when they are used cone. other saluraries, as well as for their action in currently than when they are used alone. . preventing infection and for treating an in- The number of kinds of plants available Antibacterial Properties of Plants-BUSHNELL, et al. 175 for study was limited, too. Many of those .It is difficult, then, to tabulate easily the which played an important part in the kahu results obtained in this study. Wehave finally na's pharmacy were difficult to obtain even decided to do what the Hawaiians did, and in their day,and are even harder to find now. to treat each separate part of a plant as an Someof them have become extinct or inacces entity of its own-if only because we found, sible,and most of the plants grow in habitats as they did, that the different parts of the so far removed from the laboratory that they plant vary astonishingly in their pharma are not conveniently available for study. cological properties. The numberofspeciesof bacteria we could We set some arbitrary standards of effi use to determine the "spectrum" of activity cacy, basing thesestandards upon the Oxford of a plant-that is, the range of its effective group's definition of a unit of penicillin-s nessas an antagonistic agent for the different that amount of penicillin which gives an in species of bacteria- was so limited by the hibition zone 24 mm. in diameter-and the time and facilities at our disposition that we work of Sanders et at. (1945) in appraising could not possibly expose.all of the different the antibacterial substances in plants col micro-organisms which might have assailed lected in Indiana. Four categorieswere estab a susceptible Hawaiian. lished, based upon the diameters of the zones Nonetheless,the determination of the anti of inhibition obtained with the plant extracts . bacterial effect of extracts of the different .against anyone.o] the test organisms: medicinal plants offersthe one feasible means 1. Very effective: zones more than 20 for assaying-them in the absence of human mm. in diameter cases to study or of laboratory animals to 2. Moderatelyeffective: zonesbetween experiment upon. 10 and 20 mm. in diameter 3. Slightly effective: zones less than Before very many plants were tested it be 10 mm. in diameter came evident that there were great variations 4. Ineffective: no apparent zone of in effectiveness of the plant extracts obtained from the different species of plants, and, in inhibition deed,often among extracts obtained from the The summarized data: of our studies are several parts'of the same plant. There was . presented in Tables 2-6 and in a simple list also considerable variation in effectiveness of ing of the ineffective extracts '(see p. 179). many of the extracts against the several dif Table 2presentstheresults of thestudieswith ferent test organisms. buffersolutions ofdifferent pHvalues. Tables TABLE 2 EFFECT OF BUFFER SOLUTIONS OF DIFFERENT pH UPON THE TEST BACTERIA ZONES OF INHIBITION (IN MM.) ACHIEVED BY 0.2 ML. OF . TEST ORGANISMS BUFFER SOLUTIONS pH 3.0 . pH 4.0 pH5.0,6.0,8.0 Micrococcus pyogenes var. aureus 10 0 0 Escherichia coli . . . 10 8 0 Pseudomonas aeruginosa 12 8 0 Salmonella typhosa . 8 0 0 Salmonella montevideo 10 0 0 Salmonellaschottmuelleri . 12 8 0 Shigella paradysenterlae BH 13 0 0 Shigella paradysenteriae IlI-Z 13 0 0 176 PACIFIC SCIENCE, Vol. IV, July, 1950 '3-6 are concerned with the antibacterial ef-' This isan observation that has direct bear fects of the plant extracts and present this ing upon the results disclosed in this study information: (1) the scientific name of the of extracts from Hawaiian medicinal plants, plant; (2) the part of the plant yielding the for,in a number of instances- aswill be seen extract being tested; (3) the pH of the ex from Tables 3 to 6-it was found that the tract; and (4) the diameters of the zones of zones of inhibition produced by the extracts inhibition, measured in millimeters, devel were far greater than were the zones of in oped against the different test organisms.' hibition produced bythe buffer solutions hav Wherever, by intention or by accident,a par ing the same pH values as didrhe extracts ticular bit of information was not obtained, being tested. In those extracts having a-pH a question mark (?) indicates this fact; the more acid than 3.0,·moreover, the .degree of words "not tested" mean that the organism inhibition achieved by the extracts was sig (usually Ps.aeruginosaj was not used in the nificantly greater than that achieved by the testing of a particular extract; the symbol buffer solutionof pH 3.0. On the other hand, "qns" means "quantity not sufficient" to ob asthe liston page 179 shows,there were also tain a pH determination; the symbol "0" many extracts of moderate acidity which ex means no apparent zone of inhibition. erted no inhibitory effect at all upon the test Thetestsshowed that veryacid buffer solu bacteria. tions (pH 3.0 and 4.0) are only moderately ,The implication here isthat,in those plant effective in their ability to inhibit growth of extracts which are potent in their degree of the test organisms, and that solutions with inhibition of the test bacteria..it is not so pH values ranging from 5.0 to 8.0 had no much the mere pH of the extract that is the effect at all. effective antibacterial agent, but rather the TABLE 3 EXTRACTS WHICH EXHIBIT VERY EFFECTIVE ANTIBACTERIAL PROPERTIES (with zone of inhibition 20-rnm. or more in diameter) DIAMETER OF ZONES OF INHIBITION pH (IN MM.) PART OF PLANT OF EX- M. Ps.aeru- NAME OF PLANT PROVIDING EXTRACT TRACT pyogenes E.coli ginosa Dicranopterislinearis. leavesandstems 4.6 21 0 13 - Alpiniapurpurata leaves . 6.6 10 22 20 AcaciaKoa stems 5.6 20 0 0 Tamarindusindica ripe fruit 2.4 30 30 not tested fruit, aqueousextract ? 25 24 nottested greenfruit 2.5, 25 26 25 0° Citrusaurantifolia fruit 2.6 27 25 25 Haracrepisans flowers 4.5 20 14 (discolored) Passifloraedulisf.flavicarpa green,fruit 3.4 27 28 30 ripefruit 3.7 22 22 20 Passiflor«foetidavar. fruit 4.2 15 32 15 Passiflor«sp. flowers 5.6 10 35 10 PunicaGranatum whole fruit" 3.5 20 20 15 fruit-rind 3.7 22 0 13 Eugeniamalaccensis seeds 4.7 25 0 0 bark" 5.9 20 0 nottested leaves" 5.4 20 0 nottested Metrosiderosmacropus stems 4,9 30 8 8 PsidiumGuajava ' leavesandflowers ? 20 10 nottested *SeeTable 6.