A PHARMACOGNOSTICAL STUDY OF THE CHINESE DRUG HSIA-KU-TSAO

1. Hsia-ku-tsao (夏枯草) is the dried fruiting spikes of Prunella vulgaris L. It is the common "heal-all" of Europe and America, and was formerly used in hemorrhages, diarrhea and as a gargle in sore throat. It is used in fevers and also as an anti-rheumatic, alterative or tonic remedy. Research work in recent years showed that Hsia-ku-tsao has diuretic, antibiotic and hypotensive activity. 2. The morphology, histology and diagnostic characters of the powdered Hsia-ku-tsao are examined and described in detail with 17 plates of illustration. 3. The important diagnostic features of Hsia-ku-tsao are as follows: Bract: (1) Both epidermises observed vertically are composed of wavy-walled epidermal cells with striated cuticle. Over the veins, however, the epidermal cells have rectilinear walls; (2) Outer epidermis is densely covered with non-glandular and glandular hairs and possesses numerous elliptical, caryophyllaceous type of stomata; inner epidermis is devoid of stomata and hairs; (3) Glandular hairs possess a single celled stalk and two celled head. Non-glandular hairs are of two kinds: one is unicellular, conical or somewhat curved hairs with hick warty walls, 20-60μ in length ; the other is uniseriate, 2-12-celled, varies in length, from 30 to 2700μ, usually 150-400-1000μ, the basal cell up to 80 μ in diameter at the base, one or some of the cells more or less collapsed, the outer walls with striated cuticle or many small warts; (4) Mesophyll is composed of 5-7 layers of irregularly arranged spongy arenchyma cells rich in chloroplastids. No differentiation was observed. Calyx: (1) Epidermal cells of both surfaces have striated cuticle and wavy vertical walls. But numerous caryophyllaceous type of stomata and glandular, nonglandular hairs are present on the outer epidermis only; (2) Hairs are similar to that of bract, but non-glandular hairs 2-11-celled, up to 3000 μ in length, usually 500-1500 μ, the basal cells usually 70 μ wide at the middle; (3) Mesophyll, of several layers of irregular-shaped cells. Stem: (1) Epidermis consists of a layer epidermal cells bearing cuticle; nonglandular, 2-12- celled hairs with warty walls, up to 2600μ in length, 85μ wide at the middle; (2) A zone from 1 to 7 layers of collenchyma beneath the epidermis, well developed in the angles of he stem; (3) A narrow zone of cortical parenchyma, about 9-11 rows of thin-walled cells; (4)A narrow phloem, and a broad xylem of numerous wood wedges separated by medullary rays 1-cell in width; (5) Pith, a broad central zone of large parenchyma cells; up to 100μ in diameter. (6) Stone cells, crystals of calcium oxalate and starch grains are absent. Leaf: (1) Upper epidermis cells with thick cuticle and wavy anticlinal walls and numerous elliptical caryophyllaceous type (rarely ranunculaceous type) of stomata and hairs. (2) Hairs of several types: unicellular, non-glandular hairs with warty walls, up to 30 μ in length; uniseriate non-glandular hairs, up to 9-celled, but mostly 2-7-celled, with warty walls, and up to 840μ in length; deep-seated glandular hairs with a 1-celled stalk and a 2-celled head; (3) Mesophyll, dorsiventral, a palisade layer consisting 3 rows of columnar cells; a spongy parenchyma region made up of about 5-8 rows of chlorenchyma cells and numerous fibrovascular bundles. (4) Lower epidermis is similar in aspect to upper epidermis except that stomata are more numerous. (5) Palisade ratio 6-7-8. Nutlet: (1) Epicarp, consisting of a single layer of polygonal cells with a mucilaginous outer wall covered by a very thin sheath of cutin, the wall showing swell upon coming in contact with water; (2) Mesocarp, consisting of 1-4 layers of stone cells, and there is a layer of thin-walled cells containing microcrystals directly beneath it. (3) Endocarp, consisting of a single layer of strongly lignified stone cells. 4.Six samples of Hsia-ku-tsao have been analysed by the method described in Chinese Pharmacopoeia 1953. The results obtained are as follows: moisture 13.68 per cent; ash, 7.18 per cent; acid-insoluble ash, 1.35 per cent; water extract, 6.36 per cent; foreign organic matter, 0.45 per cent. 5. The results of "fluorescence test" obtained are as follows: Spike: dark brown to violet. Water extract: greenish blue, with brownish violet edge. Ether extract: bright blue. Chloroform extract: light violet to violet.