Department of Biotechnology, Graphic Era University, 566/6 Bell Road, Clement Town, Dehradun 248002
Email: himaniab@gmail.com
Received: 12 Sep 2014 Revised and Accepted: 15 Oct 2014
ABSTRACT
Hippophae salicifolia (commonly known as Seabuckthorn) can be regarded as a rich natural source of multivitamins. High amounts of vitamins A, B1, B12, E, K and polyphenols account for its vast nutraceutical properties. Some studies have established the superiority of H. salicifolia over other close relatives in terms of bioactive components. Despite all its valuable properties, the plant has an ignored status- both commercially and ecologically. The pharmaceutical, nutraceutical and cosmetic industries continue resorting to other Hippophae species which have comparatively lower nutrient content. To add to it, lack of information about the importance of H. sailcifolia among the growers is leading to degradation of natural populations in some regions. The article aims to provide an insight into different aspects of H. salicifolia and highlight the need for research and development pertaining to the species.
Keywords: Hippophae salicifolia, Vitamin, Medicinal properties, Nutraceutical value, Nitrogen fixation, Commercial value.
INTRODUCTION
The genus Hippophae (family Elaeagnaceae) comprises of five species viz. H. rhamnoides L., H. salicifolia D. Don, H. neurocarpa Liu & He, H. tibetana Schlecht and H. goniocarpa. However, as per the classification reported by [1, 2, 3, 4] the genus is divided into seven species and nine subspecies based on morphological variations. Among them, H. salicifolia can be considered as one of the most valuable in terms of high vitamin C content high quality fruit, high yield and less thorns [5, 6]. Fruits and vegetables viz. Citrus fruits, kiwi fruit, tomatoes etc. are regarded as excellent sources of vitamin C. However, none of these available plant species are at par with significantly high vitamin content of Hippophae salicifolia fruit. As shown in table 1 H. salicifolia possesses a considerably high amount of vitamin C as compared to Citrus aurantifolia (lime) which is most commonly used vitamin C source. Like other Seabuckthorn species H. salicifolia is also a rich source of carotenoid, minerals, vitamin B, vitamin E and vitamin K [7]. This adds to advantage of H. salicifolia in terms of its nutritional value [7, 23].
Habit, Habitat and Morphology
H. salicifolia grows widely in regions of China and Russia with large but uneven distribution in Eurasia between 27 and 69°N latitude and 7°W and 122°E longitudes. In India, H. salicifolia is most common and widely distributed Hippophae species which is restricted to the Himalayan region, between 1500-3600 m a. m. s. l. including the north-west Himalayan region of Himachal Pradesh, Uttarakhand and eastern India [7-12]. H. salicifolia prefers to grow in low humidity, alluvial gravel, wet landslips and riverside. However, it can also grow in arid to very wet conditions [7, 13]. It is hydrophilous in nature; growing preferably in areas receiving an annual precipitation of 400-600 mm. It has also been reported to grow in regions with annual moisture-range of 600-700 mm. Though, the ideal temperature conditions are –100C (in winter) to 300C (in summer), the plant has also been growing in areas of Finland at a temperature range of +400C to –400C, though better germination rates are observed only at a temperature of 240C -260C [7]. Thus, the species can be regarded as stress-tolerant which can survive a range of temperatures, high soil pH (about 8.0) and increased soil-salinity.
H. salicifolia commonly known as wonder plant, green hope or ‘cold desert gold willow leaf, arboreal or Chuk, Tarwa [14], is a dioecious shrub or a small tree, about 2m to 6m high and 50 cm in diameter with a thick grey crown. The bark is brown or black in colour with a rough appearance (fig. 1a). The leaves are alternate, narrow, lanceolate with a greyish appearance [15]. Flowering occurs only in about 3 –4 years old plant. Male inflorescence has 4 to 6 apetalous flowers which release pollens at a temperature of about 60C to 100C. In case of female inflorescence, there is only a single apetalous flower with one ovary and one ovule. Pollination via insects is impeded by the fact that both the male and female flowers lack nectarines which are instrumental for attracting insects. The pollination is, thus, extensively wind – dependent. The fruits (5.51 to 7.24 mm size) are generally round but may also be ovate in some cases. They are initially pale green in colour and turn golden-brown on ripening around the month of September [16] (fig. 1b). The berries have a tough skin covering the juicy pulp and a small, hard, oval seed (fig. 1c). The review aims to provide an insight into the pharmacological, commercial and ecological potentials of H. salicifolia – the undermined multipurpose plant.
Table 1: It shows comparison in Vitamin C content of primary vitamin rich fruits [7, 23].
Species | Vitamin C (mg/100g fruit) | Vitamin K (mg/100g) |
Hippophae salicifolia | 2984.0 ± 18.5 | 100-200 |
Actinidia chinensis | 120-180 | - |
Citrus sinensis | 50.0 | - |
Lycopersicon sp | 11.8 | - |
Citrus aurantifolia | 29 | - |
Table 2: It shows a comparative estimation of vitamin C and polyphenol content in the berries of three Seabuckthorn species [23].
SB species | Vitamin C (mg/100g) | Polyphenols (mg/100g) |
H. rhamnoides | 230.5 ± 2.9 | 521.3 ± 3.2 |
H. salicifolia | 2984.0 ± 18.5 | 591.3 ± 4.2 |
H. tibetana | 878.9 ± 6.5 | 571.9 ± 3.5 |
Fig. 1: (a-c) Hippophae salicifolia D. Don. (a) Naturally growing H. salicifolia plant (b) Fruits of H. salicifolia (c) Seeds of H. salicifolia
Ecological Impact
H. salicifolia is useful in reclaiming and conserving soil, especially on fragile slopes, due to its extensive root system. Because it is resistant to drought and tolerates soil salinity and low temperatures, it is suitable for many situations that are simply too demanding for most plants. Riverbanks, lakeshores, steep slopes and other susceptible terrain can benefit from the establishment of seabuckthorn. Windbreaks made up of H. salicifolia are effective at preventing wind erosion in open areas [17].
The root system of H. salicifolia is an extensive, sub-terranean rhizomatous type that help in strong soil -binding, soil stabilization and water retention. The roots are in symbiotic association with Frankia in its nodules and nodulation varies with plant height [18]. This Frankial association accounts for atmospheric nitrogen fixation, hence adding to the soil-fertility [7, 19]. The expanded root-system helps to fix atmospheric nitrogen @60 - 80kg/ha/ annum. This property aided by rapid growth, strong coppicing, wide ecological adaptations of the plant makes it efficient for soil conservation, improvement and restoration of degraded land in hilly areas [20]. Enhanced nitrogen supply from the plant has also been shown to augment the growth of trees like poplar, pine etc. [21, 22].
Chemical constituents and nutritive value
Pharmacological investigations on H. salicifolia have established the species to be a rich source of vitamins, the content being 5-100 times higher than in other fruits/vegetables (Table 1). The fruits are particularly rich in vitamins A, B1, B12, C, E (including α, β, γ - VE), K and are a rich source of a large number of polyphenols (flavanoids: isorhamnetin, quercetin, myricetin, kaempferol and their glycoside compounds and non-flavanoids) [7, 23]. A comparative estimation of vitamin C and polyphenols content in the berries of three sea buckthorn species (H. rhamnoides, H. salicifolia and H. tibetana) from India showed Vitamin C content in H. salicifolia to be 10-fold greater than other species (Table 2). Higher phenolic content in H. salicifolia as compared to H. rhamnoides has also been confirmed [24-23].
Sea buckthorn species have been extensively studied to contain low amounts of oil and lipophilic components like carotenoids. Similar constituents are also present in H. salicfolia (commonly called sea buckthorn). Major carotenoid pigments include δ and β -carotene, lycopene flavoxanthin, progestin, cryptoxanthin, violaxanthin and neoxanthin [23, 25, 26]. The seed-oil is a rich source of highest vitamin E (1290 ppm-1919 ppm) while vitamin K content ranges from 1.1 - 2.3 mg/g [7]. It also possesses high amounts of triacylglycerol [26] and β-carotene content as compared to other Hippophae species [23].
High nutrient and bioactive content of the fruit has yielded H. salicifoila a reputation of ‘Super-fruit’. It has been widely used in traditional system of medicine for treatment of asthma, skin diseases, gastric ulcers, lung disorders, cough, diarrhoea and menstrual disorders [23, 27]. Towering multivitamin content, flavanoids and fatty acids in H. salicifolia account for its antioxidant, antibacterial, antifungal, anti-cancer, antiinflammatory, immunomodulatory, radio-protective, adaptogenic, anti-cancer, anti-atheroscelerosis and anti-sterility properties [28-33].
Seed oil of H. salicifolia is employed in several pharmaceutical preparations and can be stored for a period of about 6 months at a temperature of 14.6°C - 26.1°C. It is used for bacterial disinfection, tissue regeneration, inhibition of platelet –aggregation, improved blood-circulation, treatment of gastric ulcers and diminishing inflammation [26, 32, 34, 35]. Vitamin K content of the seed oil makes it useful in promoting blood coagulation [7].
The high amount of triacylglycerol and fatty acids in seed-oil account for its use in a variety of skin-treatments and cosmetic preparations like moisturizers, lotions and creams for skin care [36]. It is also used in many nutraceutical formulations and as a natural preservative. The plant products are also processed for commercial preparations of a variety of oils, juices, alcoholic beverages, tea, food colors, candies, biscuits, ice-creams etc. [37, 38].
Currently more than 150 pharmaceuticals/nutraceuticals companies around the world (viz. Beijing Huiyuan Group Youyu Co., Ltd., Inner Mongolia Prosperous Earth Trade Co., Ltd., Era Biotechnology (Shenzhen) Co., Ltd., Earnest International, India) are engaged in the utilization of Seabuckthorn contents in manufacturing life saving drugs, health tonics, food, cosmetics etc. with China being the lead producer [7, 39-43].
Consequently, extensive and constantly increasing use of Seabuckthorn products has created a huge market for H. salicifolia species (owing to its significantly high amounts of active ingredients) and assures heavy economic returns to the providers. This widens the scope of income generation for H. salicifolia growers and subsequent poverty alleviation.
Other uses
Besides its efficient medicinal usage, H. salicifolia plant has manifold applications as an efficient source of timber, fuel and fodder. The plant as a whole is used as fences around houses and cultivated-fields for protection against wild animals. The seed cake can also be used as animal feed due to its rich protein and mineral content [44, 45]
Propagation
H. salicifolia is generally propagated by hardwood/softwood cuttings, root suckers and seeds [7, 43, 46]. Rapidly increasing human interventions, unscientific cutting and root-sucker collection practices, forest-fires and extensive grazing of animals in the forests have resulted in severe loss of forest stocks. This in turn has posed a serious problem of non-availability of sufficient quality initial planting material. Conventional approaches of propagation alone cannot guarantee mass multiplication of this species as they are beset with several constraints. Large scale propagation via cuttings and root suckers is hampered due to the problem of large-space requirement and cumbersomeness (e. .g. bulkiness and thorniness of cuttings). Moreover, propagules obtained via vegetative methods are successful only if they root. Further year round, vegetative propagation is difficult due to seasonal specificity of material. This supplemented with short growing season have also aided in hampering mass multiplication of the species.
Comparatively, propagation of the species through seeds seems a better and easy option. Seed dormancy and poor germination rates (about 20- 30%) are known to hamper large scale multiplication via seeds. Pre-sowing treatments with chemicals like thiourea, potassium nitrate, sodium chloride, warm-water, gibberellic acid, sulphuric acid etc. Have been reported to significantly improve the germination rates [14, 32].
As a result, there is a severe lack of appropriate agro-technology packages to promote propagation of this species. In Indian Himalayan Region, anthropogenic interferences have led to degradation of natural stands of the species. This may be attributed to lack of knowledge distribution and rural sensitization on an importance of H. salicfolia [47].
Application of alternative reproducible micropropagation strategies through plant biotechnological interventions has become inevitable for the germplasm preservation and mass multiplication of disease-free plants of H. salicfolia with a clear indexing of the male and female plants. Besides, mass propagation of H. salicifolia will avoid ignorant mixing with other Hippophae species having comparatively less nutrient content. In this context, some initiatives viz phytochemical profiling of H. salicifolia have been taken [48]. Nevertheless, the area calls for further concerted researches.
To our knowledge, there is no published report on in vitro propagation of H. salicifolia till date and much work remains to be done in this direction.
CONCLUSION
Multipurpose usage, ecological benefits, high economic returns yet ignored status of H. salicifolia indicate a tremendous scope for exploring different aspects of the species. There are no established agro-techniques for promoting its cultivation. Only preliminary studies have been done to provide information regarding germination and viability of H. salicifolia seeds and propagation via cuttings. Biodiversity studies at morphological, biochemical and genetic levels will enable establishment of variability within the existing germplasm of the species. The screening will also enable selection of genotypes with high levels of bioactive compounds. Besides, enhanced researcher-farmer interactions to ensure effective measures for better plantations, germ plasm maintenance, utilization of existing resources, careful collection of fruits and utilization of medicinal properties need to be implemented for this valuable species.
CONFLICT OF INTERESTS
Declared None
REFERENCES