Proe. Indian Acad. Sci. (Plant Sci.), Vol. 97, No. 4, August 1987, pp. 315-323. 9 Printedin India. Chemosystematics of some Indian members of the Acanthaceae M DANIEL and S D SABNIS Phytochemistry Laboratory, Department of Botany, Faeulty of Science, The MS University of Baroda, Baroda 390 002, India Abslraet. Fifty-eighttaxa belonging to 3 subfamiliesof Acanthaceae have been screened for leal"flavonoids, phenolie acids and aucubins. The patterns of distribution of leal"pheno- lics among the taxa invr suggest that: (i) there ate 3 well-definedtaxonomie groups; (ii) the treatment of Thunbergiaceae as distinct from Acanthaceae(Sensu stricto) is justified; (iii) Nelsonioidear appean to be an intermediatelink between Thunbergiaceae and Acan- thaceae, and its inelusion within Aeanthaee.ae is justilicd and (iv) Thunbergiacear is relatively more primitive than Aeanthaeeae. KeywortLs. Chemotaxonomy;flavonoids: acanthaeeae. 1. Introduction The circumscription of Acanthaceae--a predominantly tropical and subtropical family is a subject of controversy (Nees Von Esenbeck 1847; Lindau 1895). Mohan Raro and Wadhi (1965) elevated Thunbergioideae to a distinct family status on mor- phological grounds. This proposition was ably supported by Chaubal (1966) and Sahi and Dixit (1969). Cronquist (1981) does not support this contention, but finds Mendoncioideae more distinctive than the Nelsonioideae and Thunbergioideae and prefers to keep the two latter subfamilies within Acanthaceae while elevating the former subfamily to a distinct family Mendonciaceae. Bremekamp (1953) transferred Nelsonioideae to the Scrophulariaceae and kept it near the tribe Rhinantheae. Paly- nological evidences (Chaubal 1966; Raj 1961) supported Bremekamp's view, but embryological (Mohan Raro and Wadhi 1965; Johri and Singh 1959) and morpho- anatomical characters (Ahmed 1974a) do suggest the elose affinity of Nelsonioideae to Acanthaceae. Except Nair et al (1965), Govindachari et al (1965) and Harborne (1967) on the phenolic chemistry of the family Acanthaceae, there is no comparative account on the patterns of distfibution of phenolics in the family. The present paper reports the patterns of distribution of leal phenolics and aucubins among 58 taxa of the family Acanthaceae and their systematie significance. 2. Materials and methods The plants were collected from various localities in Gujarat, Madhya Pradesh and Kerala. The voueher specimens have been deposited in the University Herbarium. The methods followed for the extraction, isolation and characterisation of flavonoids and phenolic acids have been described elsewhere (Daniel and Sabnis 1977). Aucubins were tested using Trim-Hill colour test (Harborne 1973). 315 316 M Daniel and S D Sabnis 3. Resuits The distribution of various flavones, flavonols, glycoflavones, proanthocyanins, phenolic acids and aucubins aro presented in tables 1 and 2. Of the 58 taxa screened, 47 contained flavones, flavonols, glycoflavones and proanthocyanins. Thirty five species contained flavones as o-glycosides. Apigenin, luteolin and/or their mono-, bi- or trimetboxy derivatives were the common flavones in most of the taxa investigated. 6-Hydroxy or 6-methoxy flavones were found in 7 taxa. Glycoflavones were isolated from 15 species. Vitexin and iso-vitexin were the most common glycoflavones. 4'-OMe Vitexin was confined to Bremekampia neilgherryensis, Haplanthus verticiUaris and Ecbolium linneanum. 6-Methoxy Vitexin was restricted to Justicia procumbens var. simplex. In at least 6 species, flavone-o- glycosides and glycoflavones were found together. In Adhatoda zeylanica glycofla- vones were found in association with flavonols and they were the solo flavonoids in 8 taxa. The subfamilies Nelsonioideae and Thunbergioideae were rich in glycoflavones but poor in flavones. 6-Oxygenated flavones were entirely absent from these sub- families, but were conŸ237 to the subfamily Acanthoideae. Flavonols, kaempferol, quercetin, my¡ and their monomethoxy derivatives were found in 4 species of the tribes Odontonemeae and Justicieae. In no plant flavones and flavonols did eccur together. Proanthocyanins were raro and restricted to the 3 taxa; in Hygrophila auriculata and Acanthus ilicifolius they were found alongwith flavones and in Elytraria crenata with glycoflavones. Of the 19 phenolic acids identified from the extracts, 14 were benzoic acids and the rest were cinnamic acids. Vanillic and syringic acids were present in more than 60~ of the taxa studied, p-OH Benzoic acid was recorded in about 50~ of the taxa. This compound was not observed in any member of the Nelsonioideae and Thunber- gioideae, whereas vanillic acid and any of the cinnamic acids were also not found in the latter subfamily. Gentisic and protocatechuic acids were found in all the members of Thunbergioideae studied. Aucubins were found only in Staurogyne glutinosa and Barleria prionitis. 4. Discussion The patterns of distribution of flavonoids and phenolic acids do suggest the recog- nition of 3 distinct taxonomic groups. Thunbergioideae is characte¡ by the uniform presence of glycoflavones and absence of 6-oxygenated flavones, proantho- cyanins, aucubins, vanillic, p-OH benzoic and cinnamic acids. Flavones are also raro in this group. The chemical characteristics, together with other characters such as climbing habit, prominent bracteoles, absence of cystoliths, presence of axillary flowers, a smaU sized calyx, panduraeform glandular hairs (Ahmed 1974b) and cus- hion shaped funiculus forming a sort of obturator, justify the recognition of Thunbergioideae asa distinct family related to Acanthaceae--a view also expressed by Mohan Ram and Wadhi (1965) and Bremekamp (1953). The chemical data on the two representatives of the subfamily Nelsonioideae indi- cato that it is intermediate between Thunbergiaceae and Acanthaceae (Sensu stricto) and perhaps forms a connecting link between the two closely related families. This subfamily is similar to Thunbergiaceae in the absence of flavonols, 6-oxygenated 'l'able I, The distrihulion of flaw~noids aml aucubins in some members of the aeanthaceae (afler Lindau 1895). 1 2 3 4 5 6 7 8 9 10 II 12 13 14 15 16 17 18 19 20 21 22 23 Subfainily Nelsonioideae Elytraria crenuta Vahl + + t + Slaurogyne glutinosa O. Kuntze + "t- + Subfamily Thunbergioideae Thunbergia erecta T. Anders. t,,S 7: fragrans Wall. T. grandiflora Roxb. T. mysorensis T. Anders. Subfamily Acanlhoideae Tribe Hygrophilaeae Hemiadelphis polysperma Nees Hy#rophila auriculata Heine + + E" H. quadrivalvis Nees H. serpyllum T. Anders. + + Tribe Strobilantheae Gantelbaa urens Bremek. + Hemigraphis ele.oans var. crenata Clarke + r t~ H. hirta T. Anders. H. latebrosa var. heyneana Bremek. + Strobilanthus callosus Nees S. scaber Nees + S. wiyhtianus Nees Tribe Ruellieae Daedalacanthus" nervosus T. Anders. Dipteracamhus patulus var. alba Bhandari D. prostratuL~ Nees + Eranthemum roseum Br. + + + Ruellia haikiei Woodr. + R. colorata Wall. + R. taberosa Linn. ".-..3 Table 1. (Contd.) ,...,to, oo 1 2 3 4 5 6 7 8 9 10 II 12 13 14 15 16 17 18 19 20 21 22 23 Tribe Barlerieac + Barleria crlstata Linn. + + B. grandiflora Dalz. e,, B. prattensis Sant. + + B. prionitis Linn. B. strioosa Willd. g~ Lepidagathis cuspidata Nees + ~t L. bandraensis Biatter Neuracanthus sphaerostachyus Dalz. Tribe Acantheae + q~ Acanthus iliclfollus Linn. BlepharIs asperrima Nr162 ha B. linearifolia Pers. B. madaraspawnsis (L.) Heyne + B. repens Roth -4- + Crossandra undulaefolia Salisb. + Tribe Andrographideae + Bremekampia neiloherryensls Srer + Haplanthus verticillaris Nees + Indonessiella echioides Sreem. Tribe Asystasiear Asyslasia dalzelliana SanL + + A. ganfletica T. Anders. A. travancoria Bedd. Tribe Odontoneaear Dicliptera verticillata Christr Ecbolium linneanum Kurz + Peristrophe bicalyculta Nees + l~hinacanthus r Nees + + § Runoia pectinata Nees ~+ + R. repens Nees t~ Table I. (Contd.) I 2 3 4 5 6 7 8 9 10 II 12 13 14 15 16 17 18 19 20 21 22 23 ~" Tribe Justicieae Adhatoda zeylanica Medic. + + + Beloperone gultata Brandegce. B. violacea Planch. and Linden Jacobinia bolit,iensis Woodr. + t% ,1usticia betonica Linn. + J. neesii Ramam. g~ .I. procumbens var. simplex Yamazaki r J. trinervia Vahl !, Echioidin; 2, Apigenin; 3, 4'-OMe Apigenin; 4, 7-OMe ApiBenin; 5, Luteolin; 6, 7-OMe Luteolin; 7, Y-OMe Luleolin; 8, 7, 4'-DiOMe Luteolin; 9, 7, Y, 4"-TriOMe Luteolin; 10, Scutellarein; I 1, 6-OMe Scutellarein; 12, 6-OH Luteolin; 13, 6-OMe Luteolin; 14, Kaempferol; 15, 7-OMe Kaempferol; 16, Quereetin; 17, 3'-OMe Quercetin; 18, Myricetin; 19, Vitexin and lsovitexin; 20, 4-OMe Vitexin; 21, 6-OMe Vitexin; 22, Proanthocyanins; 23, Aucubins. t-~ Table 2. The distribution of phenolic acids in some members of Acanthaceae. o 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Subfamily Nelsonioideae Elytraria crenata Vahl + + + + + + -[- Staurogyne glutinosa O. Kuntze + + + q- + Subfamily Thunbergioideae Thunbergia erecta T. Anders, + + + + T. fra.qrans Watl. + + T. orandiflora Roxb. + q- -I- + T. mysorensis T. Anders. + -I- "t- + + Subfamily Acanthoideae Tribe Hygrophileae Hemiadelphis polyspermus Nees Hyorophila auriculata Heine + + + + + tt. quadrivalvis Nees q- + + + 4- + H. serpyllum T. Anders. + Tribe Strobilantheae Gantelbua urens Bremek. 4- + + Hemigraphis elegans var. crenata Ciarke + + + + H. hirta T. Anders. + q- + + H. latebrosa var. heyneana Bremek. + Strobilanthus callosus Nees -I- + "1- + q- S. scaber Nees S. wightianus Nees + + + + + Tribe R uellieae Daedalacanthus nervosus T. Anders. + + + Dipteracamhu.~ patulus var.