- Brassica oleraceae has been cultivated for at least 2000 years, possibly much longer. Although considerably different in general appearance, kohlrabi, cabbage, kale, cauliiflower, broccoli and Brussels sprouts are all cultivars of Brassica oleracea. (1)
- The origin of the vegetable is uncertain. A vegetable of same description was mentioned by the Roman botanist Pliny in the 1st century A.D.
- Kohlrabi varieties are distinguished by color. Popular varieties are the Grand Duke, Kolibri F1, Purple Danube, Purple Vienna, and White Vienna. (13)
Brassica oleracea var. gongylodes is a biennial growing up to 0.5 meters, Stem base is highly shortened turnip-like swollen, globe-shaped and fleshy at the base, white, purple or green with a creamy white interior, 5 to 12 cm wide, which rests on the surface of the ground. Basal and lower cauline leaves are green, numerous, not overlapping into a head. Leaves are waxy lobed or wavy, long-petioled, emerging from the swollen stems. Left to mature, the plant bears yellow four-petaled flowers in small clusters. Fruits (siliques) are elongated.
- Study of skin and flesh of pale green and purple kohlrabis for secondary metabolites yielded 8 glucosinolates, 12 anthocyanins, 2 carotenoids, and 7 phenylpropanoids. Glucosinolates varies among different parts and types of kohlrabi. Glucoerucin contents were 4-fold higher in the flesh of purple kohlrabi than in the skin. Among anthocyanins, cyanidin 3-(feruloyl)(sinapoyl) diglucoside-5-glucoside levels were the highest. Carotenoids were much higher in the skins than the flesh. Phenylpropanoids were higher in purple than pale green kohlrabis. Cinnamic acid was 12.7 higher in in the flesh of purple kohlrabi. (3)
- Leaves yielded chlorogenic acid, catechol, epi epigallocatechin and epicatechin3-O-gallate. Peel and flesh yielded isorhamnetic-3-O-glucoside was detected in peel and flesh. Gallic acid was only found in the flesh. Hemicellulose. chlorophylls, proteins, Na, P, and microelements amounts were significantly elevated in leaves.
Sucrose was the main sugar in stem tissues. Major fatty acids were linoleic, palmitic and oleic acids. (see study below) (6)
- Study of seeds for volatile oil by GC-MS revealed main constituents of 4-methylthiobutyl isothiocyanate (55.6%), 3-butenyl isothiocyanate (27.6%). allylisothiocyanate (5.4%), 5-methylthiiopentanitrile (3.4%), 3-mediylthiopropylisothiocyanate (2.6%) and 2-phenylethyl isothiocyanate (2.4%).
- Phytochemical screening of various extracts of stem tubers yielded alkaloids, flavonoids, resins, saponins, and tannins.
(see study below) (9)
Studies have suggested antidiabetic, anti-inflammatory, antioxidant, anticancer, antibacterial properties.
- Stems consumed as vegetable; raw, cooked or fried.
- No folkloric medicinal use reported in the Philippines.
- Fodder: Used as livestock feed.
• Compositional Analysis / Kohlrabi vs Radish: The major deterrent to radish consumption is its bitter and pungent taste attributed to glycosinolates. tCompositional study evaluated kohlrabi—similar in texture and taste—as a substitute to radish. Kohlrabi contained less reducing sugars, cellulose, and pectin. Total amino acid content was 2.7-fold higher,, especially hydrophilic amino acids like aspartate, glutamate, and arginine, which might explain its comparative palatability. Glucosinolate content in radish is inner and outer section is 12 to 28 fold higher, respectively,, and a sensory test rated kohlrabi lest bitter and pungent. Kohlrabi also contained more glucoraphanin, an anticancer compound. Kohlrabi has a harder texture, and although sweeter, it contains less reducing sugars and the sweetness likely due to higher content of hydrophilic amino acids. Overall a good alternative vegetable to radish. (2)
• Anti-Diabetic / Anti-Inflammatory / Antioxidant / Green vs Red: Study evaluated the anti-diabetic, anti-inflammatory, and antioxidant potential of green (GK) and red (RC) kohlrabi cultivars. RC showed twice more TPC (total phenolic content)x and more significant antioxidant effects in DPPH, ABTS, and ONOO scavenging assays. The methanol extracts of GK and RK inhibited LPS-induced NO production in a dose dependent manner, with suppression of iNOS and COX-2 protein production. In antidiabetic and anti-inflammatory testing by protein tyrosine phosphatase (PTP1B) and rat lens aldose reductase inhibitory assays and LPS-induced NO inhibitory assays, the RK showed significantly stronger effects than GK. (4)
• Antifungal / Seeds: Study purified a 8.5-kDa antifungal peptide, BGAP. from a crude extract of seeds of Brassica oleracea var. gongylodes. BGAP showed a broad spectrum of antifungal activity with half maximal inhibitory concentration of 17.33, 12.37, 16.81, and 5.60 µg/mL towards Colletotrichum higginsianum, Exserohilum turcicum, Magnaporthe oryzae, and Mycosphaerella arachidicola, respectively. BGAP brought about increased cell membrane permeability, increased reactive oxygen species production, decreased mitochondrial membrane potential, and an accumulation of chitin in the hyphal tips of M. arachidicola. (5)
• Antibacterial / Antioxidant / Leaves, Flesh, and Peel: Study evaluated the antioxidant and antibacterial activities of leaves, flesh, and peel extracts. Leaves showed significantly high antibacterial (MIC 0.625 mg/mL), antiradical EC50= 0.26-0.32 mg/mL), antioxidant (EC50=0.46 mg/mL) activities. (see constituents above) (6)
• Effect on Proliferation of Preadipocytes: Study evaluated the effects of Kohlrabi on proliferation and differentiation of pig preadipovytes and 3T3L1 cells. Kohlrabi decreased proliferation of pig adipocytes but had not effect on differentiation of the cells. (8)
• rGO Nanoparticles / Anticancer / Biomass: Study reports on the easy green synthesis of reduced graphene oxide (rGO) and green synthesis approach to prepare gold nanoparticles (AuNPs) The using biomass of B. oleracea var. gongylodes. Au/rGO NC was also evaluated as photosynthesizer system for the photothermal therapy (PTT) of MCF-7 breast cancer cells. Results showed the nanomaterials caused efficient destruction of cancer cell and has potential as an excellent theranostic agent in Photothermal therapy. (9)
• Antibacterial / Stem: In antibacterial screening of B. oleracea stems, the the ethanol solvent showed maximum inhibition against gram positive bacteria Staphylococcus aureus while the chloroform solvent showed maximum inhibition again Gram negative Serratia marcescens. (see constituents above) (10)
• Antimicrobial Against Fish and Human Pathogens: Study evaluated methanol and ethanol extracts of B. oleracea var. gongylodes against fish and human clinical and food borne pathogens using disc diffusion and micro-dilution broth methods. Results showed varying degrees of antimicrobial activity on 5 of 6 tested fish pathogens. Against 12 human clinical and food borne pathogens the extracts showed inhibition zones in the range of 9.27-14.53. Some extracts showed more efficacy than traditional antibiotics. Results suggest a potential source of a natural preservative for feed/food and pharmaceutical industry. (11)
• Effect on Mesenchymal Stem Cells Viability and Apoptosis: Study evaluated the effect of Kohlrabi extract on viability and apoptosis of mesenchymal stem cells. Results showed a significant difference between cell viability between extract treated group and control. Study showed positive effects on cell survival while having inhibitory effects on apoptosis. (121)
- Seeds in the cybermarket.