Kuguacin

A kuguacin is one of several chemical compounds isolated from the bitter melon vine (Momordica charantia, kǔguā in Chinese) by J.-C. Chen and others.^[1]

Kuguacins are cucurbitacins, formally derived from the triterpene hydrocarbon cucurbitane. They include:

• Kuguacin A^[2]
• Kuguacin B^[2]
• Kuguacin C^[2]
• Kuguacin D^[2]
• Kuguacin E^[2]
• Kuguacin F: C
  ₃₀H
  ₄₂O
  ₅; 47 mg/kg, needles, melts at 275–276 °C ^[1]: 1
• Kuguacin G: C
  ₃₀H
  ₄₄O
  ₆; 23 mg/kg, needles, melts at 250–252 °C ^[1]: 2
• Kuguacin H: C
  ₃₀H
  ₄₄O
  ₅; 27 mg/kg, needles, melts at 226–228 °C ^[1]: 3
• Kuguacin I: C
  ₃₁H
  ₄₆O
  ₄; 20 mg/kg, needles, melts at 235–237 °C ^[1]: 4
• Kuguacin J: C
  ₃₀H
  ₄₆O
  ₃; 243 mg/kg, powder, melts at 166–169 °C ^[1]: 5
• Kuguacin K: C
  ₂₅H
  ₃₄O
  ₆; 130 mg/kg, powder, melts at 275–277 °C ^[1]: 6
• Kuguacin L: C
  ₂₅H
  ₃₆O
  ₄; 30 mg/kg, needles, melts at 320–321 °C ^[1]: 7
• Kuguacin M: C
  ₂₂H
  ₂₈O
  ₄; 7 mg/kg, needles, melts at 332–333 °C ^[1]: 8
• Kuguacin N: C
  ₃₀H
  ₄₆O
  ₄; 247 mg/kg, powder, melts at 140–143 °C ^[1]: 9
• Kuguacin O: C
  ₃₀H
  ₄₂O
  ₄; 20 mg/kg, needles, melts at 267–269 °C ^[1]: 10
• Kuguacin P: C
  ₂₇H
  ₄₀O
  ₄; 293 mg/kg, prisms, melts at 229–231 °C ^[1]: 11
• Kuguacin Q: C
  ₂₉H
  ₄₄O
  ₅; 11 mg/kg, needles, melts at 219–221 °C ^[1]: 12
• Kuguacin R: C
  ₃₀H
  ₄₈O
  ₄; 1357 mg/kg ^[1]: 13
• Kuguacin S: C
  ₃₀H
  ₄₄O
  ₄; 17 mg/kg, powder, melts at 174–177 °C ^[1]: 14

Kuguacins F-S can be extracted with ethanol from the stems and leaves of M. charantia. Kuguacins I, J, and Q are artifacts of the extraction process. Kuguacin R is obtained as mixture of two epimers. In this process one also obtains momordicine I,^[3] kuguacin E, 5β,19-epoxycucurbita-6,23-diene-3β,19,25-triol,^[4] karavilagenin D,^[5] 3β,7β,25-trihydroxycucurbita-5,(23E)-dien-19-al,^[6] and 3β,7β-dihydroxy-25-methoxycucurbita-5,(23E)-dien-19-al^[6] In vitro tests showed weak anti-HIV activity for kuguacins F-S, especially kuguacin Q and kuguacin S.^[1]