- Azolla is a genus of seven species of aquatic ferns in the family Salviniaceae. They are reduced in form and specialized, looking unlike typical ferns but ore like duckweed or some mosses. It is considered an invasive plant in wetlands, freshwater lakes, and ditches, and can substantially alter aquatic ecosystems and biodiversity. (32)
- The weed can cover bodies of water, and the myth that no mosquito can penetrate the coating of fern to lay its eggs in water has earned the common name 'mosquito fern'.
Azolla pinnata is an aquatic, free-floating, and clump-forming macrophyte, with short branches and slender roots. Leaves are 2-lobed and in two rows; one of the lobes afloat, about 1.5 millimeters, the other submerged and larger. Leaves are 1 to 2 millimeters long, green, blue-green to dark-red in color, coated by tiny hairs that imparts a velvety appearance and provides water-repellency which help keep the plant afloat.
- Found throughout the Philippines.
- In stagnant waters like pools and ponds.
- Native to much of Africa and Asia from China to Japan, India, Brunei.
- Widely distributed in southeast Asia, throughout the Pacific including Australia and New Zealand.
- Study of sun-dried Azolla pinnata for nutritive value as feed yielded dry matter (DM) of 89.73%, organic matter 75.73%, crude protein 23.49%, crude fiber 14.7%, ether extract 3.7%, total ash 24.26%, acid insoluble ash 7.94%, calcium 2.58%, and phosphorus 0.26%. (see study below) (5)
- Study of total phenolic content was 95.25 µg GAE/mg extract while total flavonoid content was 41.13 µg CE/mg extract. (see study below) (6)
- Phytochemical evaluation of various extracts yielded phenols, flavonoids, saponins, tannins, carboxylic acids,
carbohydrates. Aqueous extracts demonstrated higher phytoconstituents, followed by acetone, benzene, chloroform and ethanol. (11)
- GC-MS analysis of methanol solvent extracts revealed 27 peaks indicating 27 phytochemical compounds of which 17 were characterized. The major 5 highest peaks were diethyl phthalate (20.449%), Bis(2-ethyhexyl) methylphosphonate (17.960%), sulfurous acid, cyclohexylmethyl pentadecyl ester (17.038%), methacrylic acid dodecyl ester (8.305%), and 2,4,4,6,6,8,8-heptamethyl-1 nonene (8.529%). (see study below) (20)
- Phytochemical screening using various solvent extracts yielded phenols, flavonoids, tannins, saponins, steroids, proteins, and carbohydrates.
The methanol extract showed maximum occurrence of phytochemicals. Anthraquinones and alkaloids were absent in all the extracts. (see study below) (23)
- Phytochemical analysis showed presence of peonidin 3-O-glucoside cation, vitexin, rutin, thiamine, choline, tamarixetin, hyperoside, astragalin, and quercetin. (see study below)
At maximum growth rate, it can double its biomass in 1.9 days.
Studies have shown biosorbent, phytoremediative, antioxidant, antibacterial activities.
- In the Philippines, reported use by farmers as ingredient to salads, pinangat, mungo and omelet dishes. (15)
- No reported folkloric medicinal use in the Philippines.
- Fodder / Feedstuff: Studies have shown enormous potential as livestock feed. In Asia and parts of Africa, used to feed pigs, ducks, chickens, cattle, fish, sheep, goats and rabbits. (8) Study showed Azolla meal has potential as feedstuff for chicks, with chick diets formulated with inclusion of AZM up to 10%. (14) Deficiencies in methionine, histidine and fiber make A. pinnata unfit as sole feed for animals; however, amino acid composition compares well with reference protein sources, with lysine content more that twice that of maize. (15) (also read below: 16)
• Supplemental Feed for Silver Barb: Thai silver barb could be substituted with fresh A. pinnata, contributing to a higher profit margin without lowering growth and product quality. (see study below) (22)
• Adsorbent / Methyl Violet: Study evaluated the potential of Azolla pinnata as adsorbent for methyl violet. Results suggest that asola has great potential as a low-cost adsorbent for the removal of methyl violet in real life application. (3)
• Removal of Lead and Zinc from Polluted Water: Study evaluated the uptake of lead and zinc by Azolla pinnata (water velvet) in solutions enriched with 1.0, 2.0, 4.0, and 8.0 mg/l of the two metal ions. Uptake of both metal ions was highest at initial concentration of 1.0 mg/l. The effect of metal ions on biomass growth was also studies. (4)
• Rhizofiltration of Pb: Study showed the potential of Azolla pinnata to remove Pb(II) from aqueous environment through rhizofiltration, one of the phytoremediation strategies. Results showed A. pinnata is a suitable candidate for removal of Pb from polluted waterways. (7)
• Potent Feed Source for Livestock: Chemical analysis showed sun dried azolla is rich in crude protein content and has a potential as natural protein source for livestock feed. (see constituents above) (5) Enormous potential as livestock feed due to its high nutritive value (high proteins, essential amino acids, vitamins, minerals, growth promoter intermediaries), its ability to proliferate without inorganic nitrogen fertilization, and its high rate of growth in water without displacing existing crops or natural ecological systems. (8)
• Comparative Antioxidant Activity: Study evaluated the antioxidant potential of two Azolla species: A. pinnata and A. rubra by DPPH free radical scavenging assay and Ferric reducing assay. Azolla pinnata extract exhibited marked radical scavenging and reducing potential compared to A. rubra. Higher antioxidant efficacy was attributed to the higher content of total phenolics and flavonoids. Ascorbic acid was used as standard. (see constituents above) (6)
• Anticaries Activity: Study investigated the anticaries activity of two Azolla species viz., A. pinnata and A. rubra. Inhibitory activity of methanolic extract was tested against six oral isolates of Streptococcus mutans. While the isolates were susceptible to both extracts, A. pinnata displayed higher inhibitory effect as evidenced by wider inhibition zones and low MIC values. Results suggest potential use in the treatment of dental caries. (9)
• Alternate Protein Supplement to Ruminants: Study showed Azolla to be a good source of protein supplement with 21.37% crude protein with highest B protein fractions, moderate source of energy (1759 kcal ME/kg), high dry matter and organic matter digestibilities, and rich in trace minerals. (10)
• Fertilizer Alternative and Additive: Nitrogen fertilizer recovery by lowland rice can be as low as 10% and rarely exceeds 60%. Azolla contributes to the nitrogen (N) nutrition of rice plant through biological N fixation. Study assessed the influence of A. pinnata on floodwater chemistry, rice yield, total dry matter and N uptake of rice. Results conclude Azolla brought an additive effect and has potential as efficient fertilizer alternative or supplement in rice cropping system in Dano. (13)
• Potential of Azolla pinnata as Livestock Feed Supplement: This aquatic fern is a good source of high quality protein, contains 21-23% crude protein, and contains almost all essential amino acids, vitamins, ß-carotene, minerals and appreciable amounts of bio-polymers. Study explored the nutritive potential of AP as balanced feed for livestock. Trial of protein supplementation for two months was conducted on cattle, goat, and chicks. Results showed increased milk production (10-15%), meat by weight (8-10%), and egg laying capacity (10-15%) in milch animals, goats, and chicks, respectively. It is a potential protein supplement for livestock during lean periods and has a promising climate change adaptive capacity. (16)
• Larvicidal / Aedes aegypti: Study evaluated the larvicidal efficacy of A. pinnata using fresh and powdered form against third-stage larvae of Ae. aegypti. Results demonstrated the biocontrol efficacies of fresh and powdered A. pinnata against Ae. aegypti late third-stage larvae. The powdered application was best in lab scale experiment. Results provide evidential framework for A. pinnata's potential as a larvicidal agent. (17) (20)
• Silver Nanoparticles / Whole Plant: Study evaluated the potential of A. pinnata whole plant in green synthesis of nanoparticles (NPs). The plant and extraction method seemed attractive for industrial scale production of nanoparticles. (18) Study reports on an easy, eco-friendly and low cost synthesis of silver nanoparticles using A. pinnata to reduce silver nitrate (AgNO3) to silver nanoparticles. (28)
• Phytoremediation Potential for Heavy Metal Pollution: Study assessed the ability of A. pinnata for removal of Cr, Ni, Cd and Pb through rhizofiltration. The presence of Cr, Ni, Cd, and Pb caused maximum inhibition of A. pinnata growth by 47%, 54%, 52%, and 45% respectively. Metal selectivity of A. pinnata was Pb > Cd > Cr > Ni. Azola pinnata has potential as a good phytoremediation tool for the mitigation of heavy metal pollution. (19) Study evaluated its ability to accumulate different concentrations of Cd. Overall, A. pinnata is an effective, eco-friendly and low-cost treatment technology and can be used as a reliable way for biomonitoring of cadmium and in pollutant assessment. (24)
• Reduction of Paper Mill Pollutants: In the study, the aquatic plant Azolla pinnata was used to remove pollutants from effluent of paper mill. The maximum removal percentage for effluent of paper mill was 84.3%, 90.6%, and 82.6% respectively for TDS, BOD, and COD. Results concluded A. pinnata was successfully used for eradicating all pollutants from paper mill effluent and has potential for use in industrial waste water. (21)
• Supplemental Feed for Silver Barb: Aquatic fern Azolla pinnata has significant high food value with good proportion of protein, vitamins and minerals. Study suggested the 25% of commercial fish feed of Thai silver barb could be substituted with fresh A. pinnata, contributing to a higher profit margin without lowering growth and product quality. (22)
• Antimicrobial / Antioxidant: Study evaluated extracts of the fern using various solvents for antimicrobial and antioxidant potential. Results showed marked free radical scavenging activity and reducing power potential using DPPH and FRAP assays. Study showed the aquatic pteridophyte as a rich source of antimicrobial compounds with potential against pathogenic microbes and a powerful antioxidant against oxidative stress. (see constituents above) (23)
• Effect of Hydrocarbon Exposure (Diesel Contamination) on A. pinnata in Phytoremediation Process: Study evaluated the ability of small water fern A. pinnata to survive when exposed to diesel contaminants. Results showed the concentration of diesel must not exceed 0.5 mL/L (v/v) in phytotoxicity test, the nest stage of the phytoremediation process, because 50% of withered plants means the plant cannot survive high diesel concentrations. (25)
• Biodiesel Using Azolla pinnata: Biodiesel is a renewable substitute for neat diesel. Algae has been identified as a potential source of biodiesel. Study evaluated Azolla pinnata macro-algae for biodiesel production by trans-esterification process. FTIR and GCMS showed the feasibility of algae based biofuel. Using physicochemical parameters of Flash point, Fire point, Calorific value, Cloud point, Pour point and Viscosity, the results obtained with A. pinnata were very close to conventional diesel. (27)
• Inhibition of Salmonella typhi: Study evaluated dried Azolla extract for ability to inhibit growth of Salmonella typhi. using doses of 20, 40, 60, 80, and 100% b/v. Results showed treatment with A. pinnata 60, 80, and 100% of Salmonella typhi showed results were not significantly different. Study suggests that the extract can be used to inhibit growth of Salmonella typhi bacteria. (29)
• Antioxidant / Anti-Inflammatory / Anti-Apoptotic in Lead-Induced Hepatotoxicity: Study evaluated the protective potential of A. pinnata extract (APE) against lead-induced hepatotoxicity in male Wistar albino rats. Administration of APE ameliorated lead-induced alterations in liver function and structure. The extract is a protective and curative agent against leaf-induced hepatotoxicity via its antioxidant, anti-inflammatory, and anti-apoptotic impacts. (30)
• Adulticidal and Ovicidal Against Aedes Mosquitoes / Bioinsecticide Potential: Study showed effectiveness of Azolla pinnata extracts against Aedes aegypti and Ae. albopictus mosquitoes. In adulticidal test, mortality increased as concentration increased with LC50 and LC95 of 2572.45 and 6100.74 ppm, respectively, against Ae. aegypti, and 2329.34 and 5315.86 ppm, respectively, against Ae. albopictus. Ovicidal test showed 100% eggs mortality for both species for concentrations tested at 1500, 1000, 500, 250 and 125 ppm. Results indicate suggest bioactive compounds responsible for adulticidal and ovicidal activity and repellency towards the mosquitoes. LC-MS analysis yielded three important compounds: 1-(O-alpha-D-glucopyranosyl)-(1,3R,25R)-hexacosanetriol, pyridate, and nicotinamide N-oxide. All three have been used in emulsion and non-emulsion type of cosmetics against mosquito vector such as Culex pipens and Anopheles app. Results show potential for development of natural product against dengue vectors. (31)