HumulusLupulus01

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Humulus lupulus, more commonly known as hops, is a member of the mulberry family (Moraceae)

Perennial herbaceous vine, living 10–20 years, with horizontal and vertical roots, the horizontal roots spreading out at depth of 20–30 cm and giving rise to fibrous roots in upper layers of soil, the vertical roots developing downward to depth of 152 cm with spread of 183–244 cm with no fibrous roots; stems annual, slender, climbing, up to 9 m in length, often with stout hooked hairs; leaves opposite, cordate, 3- to 5-lobed, margins serrate, petioles slightly fleshy with stout hooked hairs; plants dioecious with unisexual flowers on separate plants, but occasionally monoecious plants occur, in which case male or female flowers are often infertile; wind-pollinated; female inflorescence cone-like, 2.5–5 cm long; male flowers in long racemes.

Native to North America, Europe and western Asia; now cultivated in North and South America, Africa, Asia and Australia also. Naturalized in many areas as in roadsides, waste places. Hops grow throughout the North and South islands of New Zealand; they are also cultivated in both New Zealand and Tasmania for beer-brewing.

In 1976, ca 100,000,000 kg of hops were grown, solely for the brewing industry (Bradford, 1979). Bitter substance obtained from glandular hairs of strobilus used by brewers for giving aroma and flavor to beer. Originally used for their preservative value, the hops were only later noted to impart a flavor to beer. There is one German patent for adding hops to sausages as a "natural" preservative. Substance prevents gram-negative bacteria from growing in the beer or Wort. Amount of essential oil varies from 0.2–0.5%. Oil of Hops also used in perfumes, cereal beverages, mineral waters, and tobacco. Stems are source of fiber like soybean stalks, cotton stalks, flax shives and similar agricultural residues and have, been suggested for pulp or biomass production. Fiber has relatively high lignin and low pentosan content, with a cellulose content lower than any of them. Sometimes used for filler material in corrugated paper or board products, but unsuited for corrugated paper because of low pulp yield and high chemical requirement or for production of high-grade pulp for specialty paper. Young bleached tops used as a vegetable, especially in Belgium. Romans ate the young shoots like asparagus. Chopped very fine and dressed with butter or cream "the young shoots are excellent" (Fernald et al., 1958). Alcoholic extracts of hops in various dosage forms have been used clinically in treating numerous forms of leprosy, pulmonary tuberculosis, and acute bacterial dysentery, with varying degrees of success in China. Hops extracts are said to have various biological activities (antimicrobial activities due to the bitter acids, especially lupulone and humulone), strong spasmolytic effects on isolated smooth muscle preparations; hypnotic and sedative effects (disputed by one report); estrogenic properties were not observed in a more recent study; and allergenic activity on humans, causing contact dermatitis due to the pollen. Extracts are used in skin creams and lotions, in Europe, for alleged skin-softening properties. Extracts and oil are used as flavoring in nonalcoholic beverages, frozen dairy desserts, candy, baked goods, gelatins, and puddings, with the highest average maximum use level of 0.072% reported for an extract used in baked goods (Leung, 1980). According to Grieve, hops steeped in sherry make an excellent stomachic cordial. Leaves and flower heads have been used to produce a fine brown dye (Grieve, 1931). Recently, counterculture entrepreneurs have apparently succeeded in grafting hops tops on marihuana bottoms and getting a "heady hop". Conversely, they might have succeeded in getting a perennial marihuana by grafting the annual herb onto the perennial hop.

Folk Medicine
Dried strobili used medicinally as a bitter tonic, sedative, hypnotic. The decoction from the flower is said to remedy swellings and hardness of the uterus. A cataplasm of the leaf is said to remedy cold tumors. The dried fruit, used for poultices and formentations, is said to remedy painful tumors. The pomade, made from the lupulin, is said to remedy cancerous ulcerations (Hartwell, 1967–1971). Reported to be anaphrodisiac, anodyne, antiseptic, diuretic, hypnotic, nervine, sedative, soporific, stomachic, sudorific, tonic, and vermifuge, hops is a folk remedy for boils, bruises, calculus, cancer, cramps, cough, cystitis, debility, delirium, diarrhea, dyspepsia, fever, fits, hysteria, inflammation, insomnia, jaundice, nerves, neuralgia, rheumatism, and worms (Duke and Wain, 1981). Moerman (1982) gives interesting insight on Amerindian uses of a plant alien to them originally. Delaware Indians heated a small bag of leaves to apply to earache or toothache. More interesting was the Delaware use of hops as a sedative, drinking hop tea several times a day to alleviate nervousness. Cherokee, Mohegan, and Fox also used the plant as a sedative. George III is said to have slept on a pillow stuffed with hops to alleviate some symptoms of his porphyria. I would personally not hesitate to drink a chamomile-hop-valerian tea as a sedative or herbal sleeping potion, but I would never recommend it to anyone else. The antibiotic principle lupulone is tuberculostatic (Duke, 1972).

Chemistry
According to the Wealth of India (C.S.I.R., 1948–1976), hops contain 6–12% moisture, 11–21% resins (no tetrahydrocannabinols), 0.2–0.5% volatile oils, 2–4% tannins, 13–24% protein, 3–4% fructose and glucose, 12–14% pectins, and 7–10% ash. According to Leung (1980) hops contain 0.3 to 1% volatile oil; 3 to 12% resinous bitter principles composed of a-bitter acids (humulone, cohumulone, adhumulone, prehumulone, posthumulone, etc., and b-bitter acids (lupulone, colupulone, adlupulone, etc., in decreasing concentration); other resins, some of which are oxidation products of the a- and b-acids; xanthohumol (a chalcone); flavonoid glycosides (astragalin, quercitrin, isoquercitrin, rutin, kaempferol-3-rutinoside, etc.); phenolic acids; tannins; lipids; amino acids; estrogenic substances; and many others. The volatile oil is made up mostly of humulene (a-caryophyllene), myrcene, b-caryophyllene, and farnesene, which together may account for over 90% of the oil. Other compounds number over 100, including germacratriene, a- and b-selinenes, selina-3,7(11)-diene, selina-4(14),7(11)-diene, a-copaene, a- and b-pinenes, limonene, p-cymene, linalool, nerol, geraniol, nerolidol, citral, methylnonyl ketone, other oxygenated compounds, 2,3,4-trithiapentane (present only in oil of unsulfured hops in ca 0.01%), S-methylthio-2-methylbutanoate, S-methylthio-4-methylpentanoate, and 4,5-epithiocaryophyllene (Leung, 1980). Buttery and Ling (1967) compare 5 cvs for 76 of their volatile oil components. Countering claims that the "wonder cure" GLA (gamma-linolenic acid) is found only in mother's milk and evening prim-rose, I consulted the USDA lab at Peoria, and learned that GLA was also in hops and borage, to mention just a few of the other vegetable sources.

Toxicity
Hops dermatitis has long been recognized. Not only hands and face, but legs have suffered purpuric eruptions due to hop picking. Although only 1 in 3,000 workers is estimated to be treated, one in 30 are believed to suffer dermatitis (Mitchell and Rook, 1979).

Ecology
Ranging from Boreal Wet through Subtropical Dry Forest Life Zones, hops is reported to tolerate annual precipitation of 3.1 to 13.7 dm (mean of 34 cases = 7.4), annual temperature of 5.6 to 21.3°C (mean of 34 cases = 10.0), and pH of 4.5 to 8.2 (mean of 26 cases = 6.5) (Duke, 1978,1979). Suitable for temperate climates between latitudes 35–51°N and 34–43°S, with mean summer temperatures of 16–18°C. Hops are quite hardy if other growing conditions are good. When dormant, they withstand freezing; however, a severe frost will kill young, tender vines in spring. Annual rainfall requirement is about 30 cm, distributed between March and August. Dry weather in September is best for the harvest. Hops do well over a wide range of soils provided they are fertile and moisture-holding. Light to heavy loams are best. Soil depth of 45 dm is required for the Goldings varieties.
Cultivation
Plants propagated from seed which require dormancy period for germination. More frequently propagation from layering or cuttings from established stocks each place. Plant to about 2 m x 2 m, for ca 2600 plants/ha. When growing commences early in spring, reduce shoots to 4–12. Various types of pole training are used. Fertilization requirement depends on soil type and variety of hop planted. Green manure often sown in August and plowed under to provide organic matter. Vegetative and reproductive growth of hops three years or older seem to be improved by pruning. Irrigation may be practiced. Hop cultivations in Japan and elsewhere are usually conducted by contract system between beer company and grower. In Japan, new shoots arise in April; flowers open late in June; cones begin to develop early in July; harvest begins at beginning of August.

Harvesting
Hops are usually picked by hand. However, more recently, picking machines weighing about 160 kg are able to pick 8–10 kg/hr in 5–7 days, 500–700 kg of cones can be picked from 10–14 ha. Hops collected in September when they are ripe, carefully dried by artificial heat and packed in bags or bales. From bloom to harvest requires about 40 days. Sometimes hops are treated with sulfur dioxide to improve the color and prevent change of active principle. Hops deteriorate upon aging and exposure to atmosphere. Drying is an important process as moisture content must be reduced from 80% to 6%. Kiln-drying is practiced in some humid areas.

From about 1950 to 1970, claims had been made that hops contained high quantities of estrogens (Fenselau 1973). Fenselau, et. al. (1973), assessed the degree of estrogenic activity in hops. They tested purified essential-oil fractions, alpha and beta bitter acids, and organic solvent extracts for estrogenic activity (Fenselau 1973). They also examined several dilutions by uterine-weight assay in immature female mice (Fenselau 1973). All tests indicated that hops lacked estrogenic activity (Fenselau 1973).

Another study by Fenselau (1976), tested samples of hops to detect for the presence of tetrahydrocannabinol, THC. This psychotropic compound is the active chemical component of Cannabis sativa (marijuana). They used the selected ion mode on a combined gas chromatograph - mass spectrometer to assay for the compound in 17 samples (Fenselau 1976). No THC was found in any of the samples (Fenselau 1976).

In 1989, H. lupulus was one of twelve plants studies for the treatment of diabetes mellitus (Swanston-Flatt 1989). The studies were done in vivo in normal and streptozotocin-induced diabetic mice (Swanston-Flatt 1989). Streptozotocin is an older intravenous chemotherapeutic (Anon. 1999c). It is used in the treatment of symptomatic or progressive metastatic islet and non-islet cell carcinoma of the pancreas (USP 1995). It also has diabetogenic and hyperglycemic effects (USP 1995). It has been shown to induce diabetes and lower pancreatic insulin content in insulin promoter-mB7-l transgenic mice when given in low doses (Harlen 1995). The mice were given preparations of the herb for 28 days (Swanston-Flatt 1989). In normal diabetic mice, the hops showed no effect on their basal plasma glucose and insulin, glucose tolerance, insulin-induced hypoglycemia, and glycated hemoglobin (Swanston-Flatt 1989). In the streptozotocin diabetic mice, the hops did not significantly affect the parameters of glucose homeostasis listed above or in pancreatic insulin concentration (Swanston-Flatt 1989).

Other modern day experimentation has led to the observance of a variety of possible medicinal uses of H. lupulus, including antibacterial activity (Langezaal 1992; Simpson 1992), treatment for gastritis (Krivenko 1989; Torosyan 1974), and even cancer prevention (Anon. 1998, Buhler 1999, Yasukawa 1995).

Two studies were done on the antibacterial and antimicrobial activity of H. lupulus. Simpson (1992) performed experiments on H. lupulus to determine what factors determine its antibacterial activity. It was determined that a decrease in pH caused the greatest stimulation of antibacterial activity in the weak acids (trans-isohumulone, humulone, colupulone and trans-humulinic acid) of the hops plant (Simpson 1992). The trans-isohumulone was found to have the greatest activity (Simpson 1992). Other monovalent cations stimulated activity, but not to the extent observed by protons (Simpson 1992). Divalent cations produced mixed reactions (from little effect to reduced effect) (Simpson 1992.) The activity of the trans-isohumulone was also found to be antagonized by lipids and beta-cyclodextrin (Simpson 1992). Langezaal (1992) did a study on the antimicrobial effects of essential oils and extracts of H. lupulus. He isolated the essential oils by hydrodistillation and the extracts by soaking the strobiles in chloroform (Langezaal 1992). The compounds had anntimicrobial effects against Bacillus subtilis, Staphlococcus aureus and Trichophylon mentagrophytes var. interdigitale but none against Escherichia coli and Candida albicans (Langezaal 1992).

In 1974, Totosyan conducted a study of H. lupulus in 46 chronic hyposecretory gastritis patients. A decoction of H. lupulus was given to the patients and in 36, a positive therapeutic effect was observed (Totosyan 1974). This was due to the high secretory-motor stimulating effect of the hops (Totosyan 1974). Later, another stuliy of this type was done by Krivenko (1989). He gave an herbal complex of H. lupulus, Achillea millefolium, Urtica dioica, Cichorium, Polygonum, Matricaria chamomilla, Helichrysum arenarium, Calendula, and corn stigmas to patients suffering from chronic hyposecretory gastritis, chronic hepatocholecystitis and/or angiocholitis (Krivenko 1989). No results were reported in this document.

Recent research has examined the role of H. lupulus on cancer prevention. Songsan (1990) used spectral methods to establish the structures of isoxanthohumol, xanthohumaol, and two new chalcone derivatives 3-(isoprenyl)-2,4-dihydroxy-4, 6- dimethyoxychalcone and 2,6 dimethyoxy-4,4-dihydroxychalcone. In 1998, xanthohumol was shown to inhibit the activity of the enzyme cytochrome P450, a component in the activation of the uncontrolled division of cancer cells (Anon. 1998). This research, conducted by Buhler (1999) looked at the effects of the flavonoids and chalcones of hops on cancer chemoprevention and cancer chemotherapy. A study by Yasukawa (1995) looked at the effects of another compound in hops: humulon, on tumor promotion. It was shown that humulon inhibited 12-O-tetradecanoylphorbol-13-acetate (TPA) induced inflammation (Yasukawa 1995). Humulon also had a pronounced inhibition of the tumor promoting factor of TPA on the growth of mouse skin tumors that had been activated by 7, 12-dimethylbenz[a]anthracene (Yasukawa 1995).

It is evident that more research needs to be conducted before proven medicinal significance of H. lupulus can be claimed. Clearly, the emphasis of the research will be on cancer prevention. And in this era, with the discovery of compounds such as Vincristine and Vinblastine in Vinca roseus, the possibility may not be so unrealistic.

LITERATURE CITED
Anon. 1998. Beer Hops May Help Prevent Cancer. http://www.junkscience.com/news/thisbud.htm.

Fenselau, C., S. Kelly, M. Salmon, & S. Billets. 1976. The absence of tetrahydrocannabinol from hops. Food Cosmet. Toxicol. 14(1):35-39.

Fenselau, C., & P. Talalay. 1973. Is estrogenic activity present in hops? Food Cosmet. Toxicol. 11(4): 597-603.

Harlan, D.M., M.A. Barnett, R. Abe, K. Pechhold, N.B. Patterson, G.S. Gray and C.K. June. 1995. Very-low-dose streptozoticin induces diabetes in insulin promotor-mB7-l transgenic mice. Diabetes 44: 816-823.

Krivenko, V.V., G.P. Potebinia. & V.V. Loiko. 1989. Experience in treating digestive organ diseases: with medicinal plants. Vrachebnoe Delo 3: 76-78.

Langezaal, C.R., A. Chandra, & J. J. Scheffer. 1992. Antimicrobial screening of essential oils and extracts of some Humulus lupulus L. cultivars. Pharmaceutisch Weekblad. Scientific Edition 14(6):353-356.

Simpson, W.J. & A.R.W. Smith. 1992. Factors affecting antibacterial activity of hop compounds and their derivatives. Journal of Applied Bacteriology 72(4):327-334.

Songson, S., S. Watanabe. & T Saito. 1990. Chalcones from methanol extracts of Humulus lupulus. Kawasaki Med Journal. 16:117-125.

Swanston-Flatt, S.K., C. Day, P.R. Flatt, B.J. Bould & C.J. Bailey. 1989. Glycaemic effects of traditional European plant treatments for diabetes: Studies in normal and streptozotocin diabetic mice. Diabetes Research 10(2):69-73.

Torosyan, A.A. & K.S. Mardzhanyan. 1974. Common hop (Humulus lupulus) and its use in chronic hyposecretory gastritis. Biol. Zh. Arm. 27(3): 87-92.

United States Pharmacopeial Convention, Inc. 1995. USP-Dispensing Information. Vol. I. Drug Information for the Health Care Professional. Rand McNally, Mass.

Yasukawa, K., M. Takeeuchi & M. Takido. 1995. Humulon, a bitter in the hop, inhibits tumor promotion by 12-O-tetracanoylphorbol-13-acetate in two-stage carcinogenesis in mouse shin. Oncology 52 (2): 156-158.

Hops are an effective aid in combating nervousness, tension, digestive disorders and insomnia. Although much less potent than pharmaceutical sleep aids, they still have a powerful effect and need to be used appropriately for optimal performance. A qualified or experienced herbalist can help.